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APRS Shopping List & a Few (More) Q's

rvmills

Well Known Member
Pete, Sam, Allen and the VAF APRS Brain Trust:

Christmas letter to Santa has APRS gear on top (well, right behind a healthy family and the safety of our troops), and Tech License Exam Q&As are printed for study. Took 2 cold (pre-study) exams and scored 77 and 80 (like the site said, "Good, but not Great, you need to study more"). Some study planned, then off to take the exam. So I'm contemplating the install options, which have morphed slightly after doing some SARL racing, and I hoped to bounce a few questions off the gang. Apologies in advance for the length.

One racing mod I'm going to work on this winter is to make flat wingtips to play with during the races. The flat wingtip will not accomodate the APRS gear (and I want to track while racing), and if I need to disable smart beaconing for the races, accesibility is now a bigger issue than I origianlly thought. So rather than copy Pete's original wingtip install, I'm going to move the unit into the cockpit. This opens up some alternative GPS and antenna options, which generates some of my planning Q's.

My plan has been to go with the Byonics MT8000FA and a Byonics GPS2. First couple questions relate to that set up:

1. Does the MT8000FA now come with a case, or will I need to fab that (as Pete did in his original post)?
2. Does the MT8000FA have a DB-9 receptacle for the GPS2 cable (can't tell from the web pic). If not, does it come with instructions on how to install one?
3. Is that DB-9 connector also where I will connect the computer for configuration?
4. Do you think the same USB to Serial cable that I use to update my Dynons will work to connect my computer to the MT8000FA?
5. Do I need the MV-12 regulator to attach the MT8000FA to ship's power?
6. Is the 5V GPS2 plug and play with the MT8000FA on ship's 12V power (saw the warning about not plugging it directly into the Tiny Track3, and just want to make sure its OK with the MT8000FA).

On GPS selection...the GPS2 is inexpensive and easy to connect, but I want to make sure I'm not overcrowding my dash and might cause GPS interference. I have a 396 with antenna on the dash, along with the XM hockey puck and my SPOT (which after APRS will be for OK/Help/911 messages, and not tracking). Will adding the GPS2 to the dash cause interference?

I've considered just splitting the blue data out wire from the 396 to my Dynon to get the GPS feed, but the Byonics site description of the MT8000FA says "simple 2 wire GPS connection". What would that second wire be if I splice into the 396 data line...ground perhaps? To be honest, just using the GPS2 would be much simpler, as I wouldn't have to rummage around behind the panel to get to that data wire...so as long as the GPS2 won't interfere with the 396, that's the way I'll go...just wanted to ask just in case.

Lastly, a couple on the antenna. With the unit in the cockpit, I can now use the antenna that currently is connected to my COMM 2, which is a sheriff SAR radio (136-174 MHz). It is a Comant bent whip (CI-122) that has not been trimmed, but works as is with that radio. I'd prefer not to add a third antenna to the belly (racing and cable routing considerations), so I'm contemplating using a switch to switch that antenna between the SAR radio and the APRS (APRS on unless I'm on a SAR mission that requires that radio). I've seen some switch possibilities, and as I looked at it, I even thought that perhaps I could make it a three way switch, and add a short cable to plug a handheld VHF radio into, in the event that my SL-40 COMM 1 goes down.

Here's a 4 way switch from MFJ Enterprises I'm considering (can't find a 3 way, but this might work):
rfswitch.jpg


It has ISO-239 connectors, and I'd either have to build RG-400 cables that have ISO-239 on the switch end and BNC's on the radio/antenna end, or use ISO-239 to BNC adapters.

Questions that arise from this idea are:
7. Do you think the switch itself or the 239-BNC adapters would leak RF and impact other avionics? (MFJ says the switch's isolation is better than 50dB at 500 MHz and 60dB at 30 MHz).
8. Do you think the one antenna would work for the SAR radio at 136-174 MHz, the APRS at 144-148 MHz and the handheld at 118-135 MHz? It seems to work without trimming for the SAR radio, so I thought the same might be true for APRS? Whaddya think?

Might be trying to do too much with one antenna, and the handheld would be the first to drop from the list, expecially if I need to trim the antenna for the APRS. If that is the case, how much would I need to trim?

I know that's a lot of Q's, and thanks for your patience in reading through it all. Any thoughts or ideas are most welcome! Thanks again!

Cheers,
Bob
 
My plan has been to go with the Byonics MT8000FA and a Byonics GPS2. First couple questions relate to that set up:

1. Does the MT8000FA now come with a case, or will I need to fab that (as Pete did in his original post)?
2. Does the MT8000FA have a DB-9 receptacle for the GPS2 cable (can't tell from the web pic). If not, does it come with instructions on how to install one?
3. Is that DB-9 connector also where I will connect the computer for configuration?
4. Do you think the same USB to Serial cable that I use to update my Dynons will work to connect my computer to the MT8000FA?
5. Do I need the MV-12 regulator to attach the MT8000FA to ship's power?
6. Is the 5V GPS2 plug and play with the MT8000FA on ship's 12V power (saw the warning about not plugging it directly into the Tiny Track3, and just want to make sure its OK with the MT8000FA).

1. You can use the plastic sleeve the tracker ships in.

2. Yes, yes.

3. Yes.

4. Don't think so, you need a null cable, very easy to make. Or, use the Dynon cable with a null modem. (I can't recall if the Dynon cable is a null cable or not....)

5. YES!

6. The tracker can provide 5vdc for the GPS2.


On GPS selection...the GPS2 is inexpensive and easy to connect, but I want to make sure I'm not overcrowding my dash and might cause GPS interference. I have a 396 with antenna on the dash, along with the XM hockey puck and my SPOT (which after APRS will be for OK/Help/911 messages, and not tracking). Will adding the GPS2 to the dash cause interference?


Probably impossible to say, you will just have to try it.

I've considered just splitting the blue data out wire from the 396 to my Dynon to get the GPS feed, but the Byonics site description of the MT8000FA says "simple 2 wire GPS connection". What would that second wire be if I splice into the 396 data line...ground perhaps? To be honest, just using the GPS2 would be much simpler, as I wouldn't have to rummage around behind the panel to get to that data wire...so as long as the GPS2 won't interfere with the 396, that's the way I'll go...just wanted to ask just in case.

Second wire is ground which you probably won't need if all your equipment is connected to aircraft ground. Splitting the existing GPS data feed should work, just use whichever setup works best for you.


Lastly, a couple on the antenna. With the unit in the cockpit, I can now use the antenna that currently is connected to my COMM 2, which is a sheriff SAR radio (136-174 MHz). It is a Comant bent whip (CI-122) that has not been trimmed, but works as is with that radio. I'd prefer not to add a third antenna to the belly (racing and cable routing considerations), so I'm contemplating using a switch to switch that antenna between the SAR radio and the APRS (APRS on unless I'm on a SAR mission that requires that radio). I've seen some switch possibilities, and as I looked at it, I even thought that perhaps I could make it a three way switch, and add a short cable to plug a handheld VHF radio into, in the event that my SL-40 COMM 1 goes down.

Your antenna should work great as is.

Here's a 4 way switch from MFJ Enterprises I'm considering (can't find a 3 way, but this might work):
rfswitch.jpg


It has ISO-239 connectors, and I'd either have to build RG-400 cables that have ISO-239 on the switch end and BNC's on the radio/antenna end, or use ISO-239 to BNC adapters.

Questions that arise from this idea are:
7. Do you think the switch itself or the 239-BNC adapters would leak RF and impact other avionics? (MFJ says the switch's isolation is better than 50dB at 500 MHz and 60dB at 30 MHz).

Just gonna have to try it . :)

8. Do you think the one antenna would work for the SAR radio at 136-174 MHz, the APRS at 144-148 MHz and the handheld at 118-135 MHz? It seems to work without trimming for the SAR radio, so I thought the same might be true for APRS? Whaddya think?

Should work fine. The tracker can handle up to a 20:1 VSWR mismatch but you shouldn't be anywhere close to that.

We'll be looking forward to seeing your rig in action!
 
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aprs

what sam said . also another option for racing may be the Byonics AIO. all you would need to do is hook up antenna . GPS and power (AAA bats.) all in a waterproof case . a bit larger in size but a neat package .

The Micro-Trak AIO has been confirmed to run nearly 8 days when used with typical AA alkaline batteries, and the default settings. The default settings include a transmission every 2 minutes. SmartBeaconing is not recommended for the MT-AIO, since that setting requires the GPS to be constantly powered, and battery usage will be limited to only a day or two. That said, it is still an option.

MT-AIOs ordered after April 10, 2009 (PCB Ver 1.4) can handle an input voltage of 12V - 24V and can be connected directly to a 12V vehicle electrical system. For older versions, in order to connect to a standard automobile power system (between 12.8V and 14.4V DC), use the Micro-Volt 12

Gary
 
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Listen to Sam!

Hey Bob,

Just listen to Sam! Hard to get an answer in when Sam answers in 14 minutes.

I agree on the antenna - just try it - it won't be perfect, but it does not need to be.

Let us know how it comes out.
 
Sam,

Thanks for the detailed reply!

Will get the MV-12 and will check on the USB to Serial cable. Its actually a Radio Shack, so don't know if its null or I need the null modem. I'll check it at the airport, get the numbers and look it up...maybe post the part number here to see what you think.

I'll try the GPS2 first and see if it all works. If there is an issue between the 396 and Byonics antennas, then I'll go for the 396 splice and sell the GPS2. But it'll be a good (and cheap) experiment that others may find useful too.

Just talked to MFJ and they agreed the 1704 (pictured in the OP) would work. Just ordered it, and will give it a whirl. MFJ also has the PL-259 to BNC adapters as well, so I ordered some of them as well (turns out PL-259 is the female adapter that screws onto the SO-239 male threads).

Gary, looked at the AIO, but it's a bit large, and I do want to smartbeacon when not racing, so I think I'll stay the course with the MT8000FA. Thanks though!!

Pete, thanks as well...and yes that was really fast (I was out shovelin' snow and came back to find it!!). I plan to keep the jpole, and perhaps use it as a mobile igate antenna for racing, as Sam suggested in another thread. And if my plan falls apart, who knows, I may be back in the wingtip! ;)

Now to fab up a bracket to place the 8000FA and the ant switch under the panel to keep the wiring runs minimal. Figure I'll use the COMM 2 cb for power to an on-off switch in the panel, then place the ant switch and the tracker just below the panel to make switching and configuration somewhat accessible. Off to the airport to shovel a little more snow and do some APRS ergo-planning!

Thanks again very much for all the feedback!!

Cheers,
Bob
 
what sam said . also another option for racing may be the Byonics AIO.
The Micro-Trak AIO has been confirmed to run nearly 8 days when used with typical AA alkaline batteries, and the default settings. The default settings include a transmission every 2 minutes. SmartBeaconing is not recommended for the MT-AIO, since that setting requires the GPS to be constantly powered, and battery usage will be limited to only a day or two. That said, it is still an option.



Gary

Like grholderbein, I'm seriously considering the MT-AIO, for several reasons. I just passed my Tech exam last night, and even though I'm not a pilot yet, I can think of numerous applications for a totally portable APRS system. I'm an avid cyclist and will bring it along on those long rides, especially in the evenings. I'm not overly paranoid, but I typically ride solo and we have had too many instances lately where bikers are run off the road and end up injured in a ditch, hoping a passing motorist will spot them. I also do alot of hunting in areas with dense vegetation. It will be nice knowing someone can see where I am. Also for those long roadtrips to see the relatives. Instead of grandpa calling every 30 minutes to ask where we are, he can watch our progress himself on the internet. I don't know how ideal the AIO is for aviation, but would think it should work well there too.
 
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Now to fab up a bracket to place the 8000FA and the ant switch under the panel to keep the wiring runs minimal. Figure I'll use the COMM 2 cb for power to an on-off switch in the panel, then place the ant switch and the tracker just below the panel to make switching and configuration somewhat accessible. Off to the airport to shovel a little more snow and do some APRS ergo-planning!

Thanks again very much for all the feedback!!

Cheers,
Bob

Velcro, my man.......the tracker weighs next to nothing. :)
 
I'll try the GPS2 first and see if it all works. If there is an issue between the 396 and Byonics antennas, then I'll go for the 396 splice and sell the GPS2. But it'll be a good (and cheap) experiment that others may find useful too.

Just talked to MFJ and they agreed the 1704 (pictured in the OP) would work. Just ordered it, and will give it a whirl. MFJ also has the PL-259 to BNC adapters as well, so I ordered some of them as well (turns out PL-259 is the female adapter that screws onto the SO-239 male threads).

I recently purchased a GPS2 and it has a 6-ft cable that should allow you to mount the little receiver any number of places away from the glare shield if necessary.

I would forgo the antenna switch and just disconnect/reconnect antenna leads as necessary, no need to complicate the installation. That antenna switch looks BIG. ;)

You will need a SMA connector for the tracker.
 
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Improvements to MT-8000 FA

Just FYI, we have made a few changes to the MT-8000FA. First, we attach the DB-9 connector to the board before shipping, since a number of people had difficulty soldering the connector to the board edge connector. The downside is that the MT does not fit in the shipping tube, and you would have to nibble or grind the ears of the connector to make it fit. Let me know if you need a spare end cap to adapt to your installation approach and I will get one out to you.

We added a user adjustable deviation control to the board. This was primarily for foreign government applications on non-ham frequencies, but is kind of nice to dial the modulation down in areas where the digis have really tight front ends. ( generally a result of using converted commercial gear)

The static bleeder resistor that I have been adding to any repairs you send me is now standard equipment. No amplifiers have blown from static since I added the part. ( a .02 cent part saves a 20 dollar amplifier module.....pretty good insurance!)

One really cool new feature is the addition of the miniature 6 pin connector that will allow you to plug a GPS 3 ( The same as a GPS 2 without the case, magnet, etc,) to build a more compact installation. The 6 pin, 4 inch jumper cord is included with the GPS 3 receiver, which mounts wonderfully with double sided tape)

One requests for you installers: Please do not stick the MV-12 power supply on top of the plastic enclosure for the MT-8KFA! The RF fields are too high and will result in general havoc. Another occasional issue is people attaching a rubber duck to the SMA without supporting the connector. This has resulted in snapping the SMA connector of the MT board.

Best regards,

Allen
VHS
 
Just FYI, we have made a few changes to the MT-8000FA. First, we attach the DB-9 connector to the board before shipping, since a number of people had difficulty soldering the connector to the board edge connector. The downside is that the MT does not fit in the shipping tube, and you would have to nibble or grind the ears of the connector to make it fit. Let me know if you need a spare end cap to adapt to your installation approach and I will get one out to you.
<snip>
One really cool new feature is the addition of the miniature 6 pin connector that will allow you to plug a GPS 3 ( The same as a GPS 2 without the case, magnet, etc,) to build a more compact installation. The 6 pin, 4 inch jumper cord is included with the GPS 3 receiver, which mounts wonderfully with double sided tape)

Here is a photo showing how the tracker fits in the shipping tube after the connector ears are trimmed:

tracker-1.jpg


Photo is of my old MT-300 but the MT-8000FA fits the same way.

The addition of the 6 pin connector for the GPS3 is a cool feature. This opens up the possibility of rolling our own version of an all-in-one tracker.
 
Sam and Allen,

I'm rethinking the antenna switch, as our local avionics guy said the MFJ mechanical switch could cause an issue, whereby if I switch the antenna to the SAR radio and forget to turn off the APRS, if the APRS transmits with no antenna load, it will fry (and same thing in the reverse direction). In thinking about it, just moving the antenna coax from APRS to SAR or vice-versa could do the same thing. However, if I'm smart with my on-off switches, I should be able to avoid that. However, guccidude1 Dan has a small smart switching box that may work. Gotta look at it, then will go with what seems best (and is most "Bob-proof" :)).

And if I go with the coax switching routine, it should be OK to use a female BNC to SMA adapter, right?

Roger the velcro...just thinking about fabbing a little metal case with an on-off switch, and perhaps a cb on it as well. Also thinking about using the COMM2 5A cb, since I won't use both units at the same time.

Yunno, just thought...what cb size would be appropriate for the APRS, given its draw and short runs of 22 ga wire (figuring 22 would work for power/ground)?

On the MV-12. I'm figuring the instructions will show it, but the terminal blocks on it are where power and ground are run to the cb and the ground buss right? Then the MV-12 is somehow wired to the MT8000FA, right?

Allen, thanks for the update on the 8000FA...and the warning on the MV-12 means don't mount it to the outside of the plastic shipping case if I use that for the final casing...is that correct? Can it be mounted in a metal or plastic electric project case, adjacent to the tracker itself?

Really appreciate the discussion...thanks much!!

Cheers,
Bob
 
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Sam and Allen,

I'm rethinking the antenna switch, as our local avionics guy said the MFJ mechanical switch could cause an issue, whereby if I switch the antenna to the SAR radio and forget to turn off the APRS, if the APRS transmits with no antenna load, it will fry (and same thing in the reverse direction). In thinking about it, just moving the antenna coax from APRS to SAR or vice-versa could do the same thing. However, if I'm smart with my on-off switches, I should be able to avoid that. However, guccidude1 Dan has a small smart switching box that may work. Gotta look at it, then will go with what seems best (and is most "Bob-proof" :)).

And if I go with the coax switching routine, it should be OK to use a female BNC to SMA adapter, right?

Good points. The ultimate solution is an aprs-dedicated antenna. :)

Be very careful with the SMA connector on the tracker, it could easily be damaged if subjected to much strain. I suggest an adapter cable with SMA on one end and BNC on the other so the connector swapping won't occur at the tracker.


Roger the velcro...just thinking about fabbing a little metal case with an on-off switch, and perhaps a cb on it as well. Also thinking about using the COMM2 5A cb, since I won't use both units at the same time.

Yunno, just thought...what cb size would be appropriate for the APRS, given its draw and short runs of 22 ga wire (figuring 22 would work for power/ground)?

Size the CB for your wire run, the tracker pulls very little current. A 1-amp inline fuse might be the easiest solution.

On the MV-12. I'm figuring the instructions will show it, but the terminal blocks on it are where power and ground are run to the cb and the ground buss right? Then the MV-12 is somehow wired to the MT8000FA, right?

MV-12 manual is here:

http://www.byonics.com/microtrak/MicroVolt12_v2.0.pdf

Allen, thanks for the update on the 8000FA...and the warning on the MV-12 means don't mount it to the outside of the plastic shipping case if I use that for the final casing...is that correct? Can it be mounted in a metal or plastic electric project case, adjacent to the tracker itself?

Really appreciate the discussion...thanks much!!

Cheers,
Bob

One option is to locate the MV-12 at the source of aircraft bus voltage (mine is mounted in a 1.5" long piece of the plastic shipping sleeve, no mounting support needed). Only one wire will need to go to the tracker provided your antenna is grounded to the airframe.
 
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Good points. The ultimate solution is an aprs-dedicated antenna. :)

Be very careful with the SMA connector on the tracker, it could easily be damaged if subjected to much strain. I suggest an adapter cable with SMA on one end and BNC on the other so the connector swapping won't occur at the tracker.

Size the CB for your wire run, the tracker pulls very little current. A 1-amp inline fuse might be the easiest solution.

MV-12 manual is here:

http://www.byonics.com/microtrak/MicroVolt12_v2.0.pdf

One option is to locate the MV-12 at the source of aircraft bus voltage (mine is mounted in a 1.5" long piece of the plastic shipping sleeve, no mounting support needed). Only one wire will need to go to the tracker provided your antenna is grounded to the airframe.

Thanks Sam!

I know this multi-tasking of the antenna is sub-optimum, but I'm avoiding putting another antenna on the belly...part for the racing, and part because I'd like to not have to remove and re-rivet the above-spar side channels, which have gotten a bit crowded with wires now anyway. I do have another (old) Comant 122 that was given to me by the avionics guy, and could put that up near the gear leg. Maybe use that for the SAR radio and just remove it for races. But then my belly will start to look like guccidude1's E-RV-9A ELINT bird! :p

Will see what the box Dan (gucci) has looks like.

Roger the SMA patch cable...I know exactly what you mean. If I go with the box, I'll run it from the box to an SMA at the tracker. If I go with switching, I'll have a length of cable from the tracker to the adapter, rather than switch at the tracker. If I dedicate a third antenna, will just use an SMA fitting.

On the MV-12 connection (and thanks for the link to the manual) it looks like unregulated bus voltage goes to one lead, ground goes to another, and regulated 12V comes out of the third. That is the wire to the tracker, correct?

The manual appears to say that the MV-12 pulls 3A nominally and up to 5A max...if I'm reading it correctly. So I'm thinking that I should pull 12V from the buss through a 5A cb (like my COMM 2 cb) to go to the MV-12. Would you (and Allen) concur?

Do you think I'd also need the 1A inline fuse between the MV-12 and the tracker. I'm probably making this more complicated than it needs to be (a mind is a terrible thing...:rolleyes:)

And on the grounds, if the MV-12 is grounded, and and the antenna is grounded, then the tracker need not be grounded...is that what you are saying there? Showing my "I know just enough about electricity to be dangerous" side...always learning!!

EDIT: just thought of another Q (I got a million of 'em)...in Allen's post, are you saying that mounting the MV-12 next to the tracker will cause RFI, or is it just mounting it to the same plastic sleeve will cause some issues. If its a proximity issue, what would you recommend the min separation be between MV-12 and MT8000FA?

Thanks again!

Cheers,
Bob
 
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On the MV-12 connection (and thanks for the link to the manual) it looks like unregulated bus voltage goes to one lead, ground goes to another, and regulated 12V comes out of the third. That is the wire to the tracker, correct?

Correct.

The manual appears to say that the MV-12 pulls 3A nominally and up to 5A max...if I'm reading it correctly. So I'm thinking that I should pull 12V from the buss through a 5A cb (like my COMM 2 cb) to go to the MV-12. Would you (and Allen) concur?

That oughta work. Or use an inline fuse if your on a switched circuit to avoid having to punch another hole in your panel for the CB. My tracker is on the strobe circuit.......flip on the strobes and I'm trackin'.... :)

Do you think I'd also need the 1A inline fuse between the MV-12 and the tracker. I'm probably making this more complicated than it needs to be (a mind is a terrible thing...:rolleyes:)

Yeah, that is probably more complicated than necessary. Your going to have more weight in circuit protection than your entire tracker rig. ;)

And on the grounds, if the MV-12 is grounded, and and the antenna is grounded, then the tracker need not be grounded...is that what you are saying there? Showing my "I know just enough about electricity to be dangerous" side...always learning!!

Yep.

just thought of another Q (I got a million of 'em)...in Allen's post, are you saying that mounting the MV-12 next to the tracker will cause RFI, or is it just mounting it to the same plastic sleeve will cause some issues. If its a proximity issue, what would you recommend the min separation be between MV-12 and MT8000FA?

I'm not Allen but my MV-12 is only a couple of inches from the MT-8000. I suspect Allen is telling you avoid sticking the regulator on top of the tracker's RV module.
 
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Copy all Sam, thanks much!

87 on the practice exam last night after running through the question bank the first time (really pretty straight forward...now if I can remember Ohm's law :))...couple more dry runs and time to take the test, and start assembling (if I'm on the "nice" list and not the "notty" list!) ;)

Thanks again!

Cheers,
Bob
 
Another antenna Q

Pete and Sam,

Still wrastlin' with the antenna solution. That antenna switch did end up pretty big...and heavy! Still trying to avoid the additional external antenna, though I did acquire a bent whip from a local avionics guy's back room shelf (price was right...nada!). Will go with it if I have to, but...

Was considering mounting Pete's J-pole in one of my gear legs. I have the longer Rocket titanium struts, but the antenna is still quite a bit longer than a bent whip, as well as the strut. Is it a 1/2 wave antenna, and is the bent whip a 1/4 wave? Just trying to see if I'm starting to get this. ;)

I played around with it this week, and I can slide the antenna down the gear leg fairing, but I'd need to run the rest up into the cowl inside the upper gear leg fairing, and run it up along the engine mount. Then I could penetrate the FW with the coax portion to run to the panel and the tracker.

Doing this, I'll have a mostly vertical orientation, but I wanted to ask if the titanium strut, or the motor mount, or the FW will make this installation unusable. If you say no way, jose, I'll scrap it...but if it's possible, I may experiment a bit. Whaddya think?

OBTW, Santa put an MT8000FA in my stockin', and I'll take the exam while visiting the In-Laws for NYE in LA (next test in N. NV is over a month away, and I'm all studied up!) Thanks again for all the advice, and Merry Christmas!

Cheers,
Bob
 
HI Bob

Hey Bob,

The gear leg (or any big metal mass) will really mess with the RF from the antenna. How's that for being precise? That said, the horizontal j-pole next to a wing tip rib really should not work well either, but we tried it, and it works pretty well.

If it does not involve hours of work, I would try it. Post your results here for the next guy. The MT8000 can handle a high SWR mismatch on the antenna, so it should be safe. I guess that is why it is experimental radio:D

Santa is good at getting us exactly what we need if we tell her...er.. him! Study some online tests and you will nail the Ham Exam. It really is not bad at all.
 
Pete and Sam,

Still wrastlin' with the antenna solution. That antenna switch did end up pretty big...and heavy! Still trying to avoid the additional external antenna, though I did acquire a bent whip from a local avionics guy's back room shelf (price was right...nada!). Will go with it if I have to, but...

Was considering mounting Pete's J-pole in one of my gear legs. I have the longer Rocket titanium struts, but the antenna is still quite a bit longer than a bent whip, as well as the strut. Is it a 1/2 wave antenna, and is the bent whip a 1/4 wave? Just trying to see if I'm starting to get this. ;)

I played around with it this week, and I can slide the antenna down the gear leg fairing, but I'd need to run the rest up into the cowl inside the upper gear leg fairing, and run it up along the engine mount. Then I could penetrate the FW with the coax portion to run to the panel and the tracker.

Doing this, I'll have a mostly vertical orientation, but I wanted to ask if the titanium strut, or the motor mount, or the FW will make this installation unusable. If you say no way, jose, I'll scrap it...but if it's possible, I may experiment a bit. Whaddya think?

OBTW, Santa put an MT8000FA in my stockin', and I'll take the exam while visiting the In-Laws for NYE in LA (next test in N. NV is over a month away, and I'm all studied up!) Thanks again for all the advice, and Merry Christmas!

Cheers,
Bob

At first blush I would consider the gear leg installation a bad idea. But.....I've never tried it. :)

I did glue one of Pete's antennas to the bottom half of the engine cowl (U-shaped orientation left-to-right across the forward half of the cowl). It worked, but not as well as other installations. I suspect being close to the big hunk of iron really messed up the antenna (there is that technical term again....).

I tried a com antenna in the gear leg fairing and it resulted in poor performance. So I anticipate less than satisfactory results with the J-pole in the gear leg fairing. By the way, the J-pole is a 5/8 wave design.

Good luck with the exam, you will be fine. Sounds like you were a nice boy in 2009!
 
Hey Bob,

The gear leg (or any big metal mass) will really mess with the RF from the antenna. How's that for being precise? That said, the horizontal j-pole next to a wing tip rib really should not work well either, but we tried it, and it works pretty well.

If it does not involve hours of work, I would try it. Post your results here for the next guy. The MT8000 can handle a high SWR mismatch on the antenna, so it should be safe. I guess that is why it is experimental radio:D

Santa is good at getting us exactly what we need if we tell her...er.. him! Study some online tests and you will nail the Ham Exam. It really is not bad at all.

At first blush I would consider the gear leg installation a bad idea. But.....I've never tried it. :)

I did glue one of Pete's antennas to the bottom half of the engine cowl (U-shaped orientation left-to-right across the forward half of the cowl). It worked, but not as well as other installations. I suspect being close to the big hunk of iron really messed up the antenna (there is that technical term again....).

I tried a com antenna in the gear leg fairing and it resulted in poor performance. So I anticipate less than satisfactory results with the J-pole in the gear leg fairing. By the way, the J-pole is a 5/8 wave design.

Good luck with the exam, you will be fine. Sounds like you were a nice boy in 2009!

Pete and Sam: Thanks much! Hmmmm...wouldn't be too much work to rig it in the gear leg. Just one FW penetration. Kinda concerned about all the metal, as well as the electronic ignition noise (don't hear that in my radio though...then again, my comm ant is not in the cowl!).

Maybe the increased vertical polarization up the gear leg and motor mount would improve things over the cowl set up you tried...but that may be wishful thinking.

Just talked to guccidude1 Dan, and he thinks looping it up and down my gear leg, then only having the coax go into the engine compartment might work. Not sure I have room in the gear leg though...full of foam.

OK, so to see if I have the length right...300/144MHz=2.083 meters X .625 = 1.30 meters. So if I measure the antenna, it'd be 1.3m, eh. (Can I get credit for that on the test now! ;)) And why 5/8 wave...or is that a question on the "Extra" exam? ;)

How much of the ant should be vertical...or is it the more vertical, the merrier? And Pete, what is the little notch in the antenna with the yellow tape on it (inquiring minds want to know...just for the heck of it).

If I do go with the gear leg idea, any recommendations on how to ground the antenna?

If you are any good with antennae you could make a matching stub and use the gear leg itself as an antenna.

Norman...one could surmize from my questions that I'm no good at all with antenna's! :) So please school me if you would...what is this matching stub of which you speak? And how does one make such a beast?

Thanks guys...kinda fun sleuthing this out. You'll probably laugh when, in a month or so, I post that I sucked it up and just put another antenna on the belly! ;)

Cheers,
Bob
 
OK, so to see if I have the length right...300/144MHz=2.083 meters X .625 = 1.30 meters. So if I measure the antenna, it'd be 1.3m, eh. (Can I get credit for that on the test now! ;)) And why 5/8 wave...or is that a question on the "Extra" exam? ;)

How much of the ant should be vertical...or is it the more vertical, the merrier? And Pete, what is the little notch in the antenna with the yellow tape on it (inquiring minds want to know...just for the heck of it).

If I do go with the gear leg idea, any recommendations on how to ground the antenna?

Bob,

Here are some links that will bring you up to speed on the J-pole:

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9293

http://www.vcars.org/tech/J_Pole2M.html

The only ground for the TV-lead J-pole is via the coax feed line.
 
Antennea

Bob:

I have one of Ryan Howell's J-Pole antennas in the wing tip of my -8. I placed it about 3/4 of the way out to the tip and glued it in in an up and down zig-zag pattern so as to get as much of a vertical component as possible.

I also placed the AIO in the wing tip with the MV-12 mounted in the box with the AIO. I made a fiberglass shelf on the inside of the tip at about the same forward location as the spar. It can see at least 90% of the sky at this location.

I have been getting excellent results with this setup.

The only problem you will have with this setup is enabling-disabling smart beaconing.

However the antenna location gives a no drag unobtrusive installation with somewhat less than perfect performance.

For optimum performance, place that stainless whip properly shortened underneath at or near mid wing.
 
There Sam goes again. I go to the hangar to chip ice and shovel snow and he goes and answers all the questions!!

How cool is it to have the great technical resources that we have here on airframes, engines, avionics, heck, just about everything!

I don't know enough to tell you how the gear leg will work. Theory says more vertical is better - I think the gear leg will interfere with the signal, but if it is easy, it is worth a try.
 
It would require a lot of experimenting and having the right test equipment to match tune the gear leg to make it an antenna but it could be done. Do a search on "antenna matching stubs" you should be able to get your answers there. If some of the brilliant Hams on this list got into it and post the materials used and the dimensions used we could all have some pretty good hidden antennae.
 
It would require a lot of experimenting and having the right test equipment to match tune the gear leg to make it an antenna but it could be done.

That eliminates me. ;)

Do a search on "antenna matching stubs" you should be able to get your answers there. If some of the brilliant Hams on this list got into it and post the materials used and the dimensions used we could all have some pretty good hidden antennae.

Uh, oh, this is definitely out of my league! :confused:
 
Over the next few days I will try and come up with some numbers to figure how well this should work. Too cold to work in the hanger for me right now.
 
That eliminates me. ;)

Uh, oh, this is definitely out of my league! :confused:

Ditto, and ditto! :) If it eliminates Sam...well what can I say...except Yilkes! ;)

Thanks for all the replies guys! Will play around a bit and let you know what I come up with...even if its only more questiions! :eek:

Cheers,
Bob
 
Bob:

I have one of Ryan Howell's J-Pole antennas in the wing tip of my -8. I placed it about 3/4 of the way out to the tip and glued it in in an up and down zig-zag pattern so as to get as much of a vertical component as possible.

I also placed the AIO in the wing tip with the MV-12 mounted in the box with the AIO. I made a fiberglass shelf on the inside of the tip at about the same forward location as the spar. It can see at least 90% of the sky at this location.

I have been getting excellent results with this setup.

The only problem you will have with this setup is enabling-disabling smart beaconing.

However the antenna location gives a no drag unobtrusive installation with somewhat less than perfect performance.

For optimum performance, place that stainless whip properly shortened underneath at or near mid wing.

FYI, The current generation of MT-AIO has a built in regulator allowing you to run from ships' voltage without having to use the MV-12 accessory power supply. There are separate inputs for unregulated and regulated ( internal battery) voltages, as well as an optional 6 pin mini DIN plug connector on the side with an external serial and power port. This port can be used for an external GPS, and Byonics has a cigarette lighter/serial cable available. You have to drill or cut a 1/2 inch hole in the otherwise water-tight case to gain access to this port, which I refuse to do on religious grounds.

The RF amplifier section will tolerate a really awful mismatch, and with a power budget of 8-10 Watts output to start, a perfect antenna match, while appealing to our inner-engineer, is not really necessary. The now-famous Howell J-pole works wonders, and appears to be a fairly good match, which compensates quite well for its horizontal polarization. ( Well, its horizontal when the plane is level at any rate)

On another note, we found that aircraft using external antennae would occasionally blow out the MOSFET amplifiers in Micro-Trak's. The culprit turned out to be static, and all current Micro-Traks have a static protection "bleeder" resistor in them, which seems to have solved that problem. This has not proven to be an issue with internal antenna.

Happy new year,

Allen
VHS
 
Allen - bleeder resistor

Is this bleeder resistor something I can add myself? If so what is the value of the resistor?
I have been running a Micro-Trak 300 with an external antenna for some time with good results. I'm using a unmodified comm antenna which also serves as a back up for my aviation handheld if needed.

http://www.mail2600.com/cgi-bin/track.cgi?call=N623RS&last=1

I like the low power and simplicity of the MT-300. I was sorry to see it discontinued.
 
Is this bleeder resistor something I can add myself? If so what is the value of the resistor?
I have been running a Micro-Trak 300 with an external antenna for some time with good results. I'm using a unmodified comm antenna which also serves as a back up for my aviation handheld if needed.

http://www.mail2600.com/cgi-bin/track.cgi?call=N623RS&last=1

I like the low power and simplicity of the MT-300. I was sorry to see it discontinued.

The MT-300 does not have a MOSFET amplifier final driver, and static has never been a problem with these. The high power units use a 10K 1/8th Watt resistor across the RF output. About a year ago, a number of people had asked about doing a run of MT-300's for balloon and aircraft use. That short run of about 100 units took just about a year to sell, so its not worth my having to do custom production runs of the RF modules,which really only become economical in runs in the thousands of units.

I still plan to do a high power, single channel, packaged unit for boats, planes, cars, etc that will run from vehicle power, and cost less than an AIO. We are exploring other microprocessors on which the new device will be based. I am considering having a few telemetry inputs on this new design, in addition to its normal functions.

73,

Allen
VHS
 
Bob,

Here are some links that will bring you up to speed on the J-pole:

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9293

http://www.vcars.org/tech/J_Pole2M.html

The only ground for the TV-lead J-pole is via the coax feed line.

For grounding...as I experimant with the jpole in the gear leg, would connecting the coax on the jpole to another coax coming from the tracker at the firewall or at a little grounding strap do the trick on grounding the antenna? In other words, connect a little SMA coupler so the outer case of the coupler screws together through the firewall or a little grounding strap.

And if I ground the MV-12, do I need to ground the antenna? If so, how did you do that in the wing or cowl installations?

Thanks!

Over the next few days I will try and come up with some numbers to figure how well this should work. Too cold to work in the hanger for me right now.

Norman...I'd also be really interested in what you come up with...just in case the jpole/gear leg idea is a flop. Thanks for braving the cold!

Cheers,
Bob
 
Progress

Well, took (and passed) the Tech exam on the 30th, then spent some time with my Father-in-Law (a HAM) assembling my tracker.

I grabbed a little project box at Sandy's Electronics and some nylon hardware from Fry's, and put things together. Probably a bit overkill, but I do want to be able to do quick config changes (to stop/start smart beaconing for races), and I want a separate on/off switch, just in case I do end up switching antennas back and forth (so I make sure not to transmit with no antenna load).

I'm still a bit of a bonehead on the grounds, and was hoping the brain-trust could take a look and check my work before I power it up. We've talked about grounding the tracker if the antenna is not grounded (as would be the case with Ryan's j-pole), and I believe Sam said only one wire (power) needs to go from the MV-12 to the tracker if the antenna is grounded. My buddy gucci Dan said I do need to ground the tracker and the MV-12, which makes sense to my pea-brain. Dan will take a look at what I've got when I get home, but while on the road, thought I'd show you some pics (wanted to show ya'll the box anyway).

aprsboxopen.jpg


In that first pic, the tracker and MV-12 are screwed down to nylon locknuts that are hot-glued to the bottom of the box. Power and ground come in from the back, via a molex for quick disconnect. The bitter ends will go to a 5V CB that protects a rarely used power outlet, as well as aircraft ground.

Red power goes under (bypasses) the MV-12 PCB and to the switch. Power then goes from the switch to the IN terminal on the MV-12. Power then goes from the OUT terminal on the MV-12 to the + terminal (right side) on the tracker.

Ground comes from the back of the box, goes under the MV-12 PCB, and loops up to the GND (center) terminal on the MV-12. I ran a small ground wire from that MV-12 GND terminal to the GND (center) terminal on the tracker. Therefore, the tracker and the MV-12 basically share the ground. That all sound kosher?

Also, the left terminal on the tracker us is unused...just checking that is correct.

Here's a pic of the tracker with the j-pole ant attached. I'm going to have a short (2-3") coax patch cord made so it'll be attached to the tracker, and I'll have a quick disconnect for the antenna just outside the box, as well as a better place to switch between the j-pole and the belly whip during testing and final decision on the antenna.
aprsboxopenwithant.jpg


Here's what it'll look like when closed up. No too big, and easy to tuck away, or velcro below the panel next to my SAR radio.
aprsboxclosed.jpg


Thanks much for putting up with all the questions. Will report back with antenna test results.

Happy New Year!

Cheers,
Bob
 
Replies in red below......

Well, took (and passed) the Tech exam on the 30th, then spent some time with my Father-in-Law (a HAM) assembling my tracker.

I grabbed a little project box at Sandy's Electronics and some nylon hardware from Fry's, and put things together. Probably a bit overkill, but I do want to be able to do quick config changes (to stop/start smart beaconing for races), and I want a separate on/off switch, just in case I do end up switching antennas back and forth (so I make sure not to transmit with no antenna load).

I'm still a bit of a bonehead on the grounds, and was hoping the brain-trust could take a look and check my work before I power it up. We've talked about grounding the tracker if the antenna is not grounded (as would be the case with Ryan's j-pole), and I believe Sam said only one wire (power) needs to go from the MV-12 to the tracker if the antenna is grounded. My buddy gucci Dan said I do need to ground the tracker and the MV-12, which makes sense to my pea-brain. Dan will take a look at what I've got when I get home, but while on the road, thought I'd show you some pics (wanted to show ya'll the box anyway).

aprsboxopen.jpg


Yes - that is correct, it looks good - the tracker needs power and ground from the MV-12 - the grounds are all common.

In that first pic, the tracker and MV-12 are screwed down to nylon locknuts that are hot-glued to the bottom of the box. Power and ground come in from the back, via a molex for quick disconnect. The bitter ends will go to a 5V CB that protects a rarely used power outlet, as well as aircraft ground.

Red power goes under (bypasses) the MV-12 PCB and to the switch. Power then goes from the switch to the IN terminal on the MV-12. Power then goes from the OUT terminal on the MV-12 to the + terminal (right side) on the tracker.

Ground comes from the back of the box, goes under the MV-12 PCB, and loops up to the GND (center) terminal on the MV-12. I ran a small ground wire from that MV-12 GND terminal to the GND (center) terminal on the tracker. Therefore, the tracker and the MV-12 basically share the ground. That all sound kosher?

Giddy-up - looking good

Also, the left terminal on the tracker us is unused...just checking that is correct.

Yep - that is the switch port to throw you over to the second profile on the tracker.

Here's a pic of the tracker with the j-pole ant attached. I'm going to have a short (2-3") coax patch cord made so it'll be attached to the tracker, and I'll have a quick disconnect for the antenna just outside the box, as well as a better place to switch between the j-pole and the belly whip during testing and final decision on the antenna.
aprsboxopenwithant.jpg


That is one sexy J-pole

Here's what it'll look like when closed up. No too big, and easy to tuck away, or velcro below the panel next to my SAR radio.
aprsboxclosed.jpg


Thanks much for putting up with all the questions. Will report back with antenna test results.

Bob- nice build. I hope the antenna works well for you! You might want to put some holes in the box that will let you see the LEDs - they will let you know when the unit it transmitting and when the GPS has a lock.

Happy New Year!

Cheers,
Bob
 
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Thanks much Pete (see, you do get to respond if we talk while Sam is gettin' his beauty sleep!) :D

My responses re-embedded...yours still in red:

Yes - that is correct, it looks good - the tracker needs power and ground from the MV-12 - the grounds are all common.

Giddy-up - looking good


good stuff...good to be "well-grounded"!

Yep - that is the switch port to throw you over to the second profile on the tracker.

Saw the small "sw" by that terminal...will figure that second profile thang out when I sign up for the upper division APRS course. ;)

That is one sexy J-pole

You and Ryan make a very nice product there Pedro. You'll get a kick out of the fact that my HAM Father-in-Law is pullin' his hair out trying to figue out the J-pole. He printed up an article on a Slim Jim J-pole, but the numbers didn't quite fit. The overall 58" is on, but the 19" short end of the J is off, and the connection point of the feed line looks different. I told him it might not be a Slim Jim, and it's probably tuned a bit for the APRS freq. I really don't understand it fully...still need to look at the links that Sam sent me on it (been on the run). Might be able to win a bet with F-i-L!

Bob- nice build. I hope the antenna works well for you! You might want to put some holes in the box that will let you see the LEDs - they will let you know when the unit it transmitting and when the GPS has a lock.

Thanks...fun stuff. I like the idea of the LED window. Good spot-check method, esecially as I do the initial testing.

Now to find my name on the ULS and get to testin'! Tracks will tell (though an avionics friend has an SWR meter and will help check it as well).

Happy New Year!

Cheers,
Bob
 
Thanks much Pete (see, you do get to respond if we talk while Sam is gettin' his beauty sleep!) :D

My responses re-embedded...yours still in red:

Yes - that is correct, it looks good - the tracker needs power and ground from the MV-12 - the grounds are all common.

Giddy-up - looking good


good stuff...good to be "well-grounded"!

Yep - that is the switch port to throw you over to the second profile on the tracker.

Saw the small "sw" by that terminal...will figure that second profile thang out when I sign up for the upper division APRS course. ;)

That is one sexy J-pole

You and Ryan make a very nice product there Pedro. You'll get a kick out of the fact that my HAM Father-in-Law is pullin' his hair out trying to figue out the J-pole. He printed up an article on a Slim Jim J-pole, but the numbers didn't quite fit. The overall 58" is on, but the 19" short end of the J is off, and the connection point of the feed line looks different. I told him it might not be a Slim Jim, and it's probably tuned a bit for the APRS freq. I really don't understand it fully...still need to look at the links that Sam sent me on it (been on the run). Might be able to win a bet with F-i-L!

Bob- nice build. I hope the antenna works well for you! You might want to put some holes in the box that will let you see the LEDs - they will let you know when the unit it transmitting and when the GPS has a lock.

Thanks...fun stuff. I like the idea of the LED window. Good spot-check method, esecially as I do the initial testing.

Now to find my name on the ULS and get to testin'! Tracks will tell (though an avionics friend has an SWR meter and will help check it as well).

Happy New Year!

Cheers,
Bob

EEEHHH-YAAAAAAA.............yawn..................

Didn't go flyin' this morning, too cold (22F, 15 kts......tee-shirt weather for Pete the Geek), so have now stumbled out of bed......... ;)

Clean installation, Bob. The only thing that might trip you up is having the MV-12 so close to the RF module of the tracker. In an earlier post Allen stated that the MV-12 shouldn't be pasted on top of the tracker, time will tell if your configuration causes any hiccups for the tracker.

By the way, installation of a stereo mini-jack will allow you to reprogram the tracker without cracking open the case. Details for the jack are in a thread on this forum.

Update: here is the post; http://www.vansairforce.com/community/showpost.php?p=246431&postcount=48

Fire it up and see how it works! Congrats on the new Tech license. :)
 
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It looks like a pretty good packaging job! One possible area of concern is bringing the power out adjacent and parallel to the RF output. I would try to route these wires as far from the RF out and antenna as possible, since high RF levels can cause the Micro-Trak to become "swamped" with RF. The main indicator for this is continuously flashing red/green LED's, which you can't visualize. Make sure you have a receiver to monitor the transmissions when you power up your final install to make sure you are not having a reset problem.

73,

Allen
VHS
 
Bob - here is a J-pole design link

We make a few mods then tune them up as best we can and test them. The father in law might be able to better tune it installed, we just do them on the bench here.

Good Luck - let us know how it comes out.


That is one sexy J-pole

You and Ryan make a very nice product there Pedro. You'll get a kick out of the fact that my HAM Father-in-Law is pullin' his hair out trying to figue out the J-pole. He printed up an article on a Slim Jim J-pole, but the numbers didn't quite fit. The overall 58" is on, but the 19" short end of the J is off, and the connection point of the feed line looks different. I told him it might not be a Slim Jim, and it's probably tuned a bit for the APRS freq. I really don't understand it fully...still need to look at the links that Sam sent me on it (been on the run). Might be able to win a bet with F-i-L!
 
EEEHHH-YAAAAAAA.............yawn..................

Didn't go flyin' this morning, too cold (22F, 15 kts......tee-shirt weather for Pete the Geek), so have now stumbled out of bed......... ;)

Clean installation, Bob. The only thing that might trip you up is having the MV-12 so close to the RF module of the tracker. In an earlier post Allen stated that the MV-12 shouldn't be pasted on top of the tracker, time will tell if your configuration causes any hiccups for the tracker.

By the way, installation of a stereo mini-jack will allow you to reprogram the tracker without cracking open the case. Details for the jack are in a thread on this forum.

Update: here is the post; http://www.vansairforce.com/community/showpost.php?p=246431&postcount=48

Fire it up and see how it works! Congrats on the new Tech license. :)

Thanks Sam...and G'Mornin! :)

I meant to ask about the proximity and location of the MV-12...good catch! That middle (widest) portion of the box provided the best spacing, but then I realized it put the MV-12 next to the RF module of the tracker. I was also hoping (as you mentioned) that since it is not stacked, it'll be OK. Allen didn't mention the position of the MV-12 as an issue in his recent post, so hopefully that's a good sign (for that aspect). (Allen, would you concur...OK as is?)

The mini-jack might be a good idea too...would prevent the need for removing the GPS antenna. Did a quick look at that thread, and will look a bit more closely after I fly home today.

Sorry it's cold there...that's good skiing weather though, where I come from (well, not the wind part!)

Thanks again!


It looks like a pretty good packaging job! One possible area of concern is bringing the power out adjacent and parallel to the RF output. I would try to route these wires as far from the RF out and antenna as possible, since high RF levels can cause the Micro-Trak to become "swamped" with RF. The main indicator for this is continuously flashing red/green LED's, which you can't visualize. Make sure you have a receiver to monitor the transmissions when you power up your final install to make sure you are not having a reset problem.

73,

Allen
VHS

Thanks Allen, will drill a hole in the top over the LED so I can check for the continuously flashing R/G LED indication during testing. Is that what you are calling "a reset problem"?

And when you say "have a receiver to monitor", do you mean have a computer to see if position reports are being sent to aprs.fi during ground testing, or should I have a reciever capable of 144-148 MHz set up to listen for something? Hitting my knowledge threshold on this piece! :eek:

Thanks for the heads-up on the power wire routing. I can drill small holes on the side, and take the power/ground wires out that-away (from the right side in the picture, in front of the MV-12, rather than from the back and then fwd, going under the MV-12). That's an easy fix, should I get the swamping effect.

Thanks much!


Bob - here is a J-pole design link

We make a few mods then tune them up as best we can and test them. The father in law might be able to better tune it installed, we just do them on the bench here.

Good Luck - let us know how it comes out.

Thanks Pete, that link describes it well. Looks like you used the recommended RG-174 coax. When I have the small patch cord made up (to connect to the tracker and come out of the box), do you think it would be OK to use RG-58 or RG-400? I know the avionics guy on the field has those...not sure about RG-174. Will ask...and probably can find it at Sandy's.

That avionics guy has an SWR meter, and wants to help me play around with the antenna install/tuning as well (good guy, likes messing around with stuff like this). When it comes to SWR, I believe the tracker, being digital, will lower it's power output if the SWR goes above 2:1. I looked in other posts for an earlier comment that said the tracker operates well, even with higher SWR (I thought it said as high as 20:1), but my F-i-L wrinkled his nose on that one...so I thought I'd re-check. As I play with the j-pole in the gear leg, and then as I try the SAR radio antenna (belly whip), what is the max SWR I should accept...and is there a level where I will damage the tracker?

Thanks again very much for all the help!

Cheers,
Bob
 
I think you will be fine with your MV-12 placement, but the actual install will be the final test. You should have at least a receiver to hear the audio when you power and test your unit. If its resetting, the red and green will flash and it will send a brief "clipped" transmission, and do so more or less continuously until you run out of batteries or the unit overheats and smokes. This will be just long enough to jam anyone competing for digi time and sending hoards of angry hams searching for you with pitchforks! In ordinary operation, the green section of the LED should be lit solidly when the GPS is locked on ( Did I mention not to route your GPS cable near the RF cable? Important safety tip!) The red LED will flash on transmission. If you are using Smart Beaconing ( and I suggest you do) the unit probably won't flash much when the airplane is stationary. If you program the alternate configuration with a fixed beacon rate, it can be a little less painstaking to trouble shoot your system. Lots of people use the alternate configuration with the emergency beacon character, if you are doing that, don't even send a single test beacon, since every ham in the free world will call the police, fire, FAA, CAP, and generally lose their collective minds. As a CAP Ground Team Leader, I like the idea of using the emergency beacon for the alternate channel. It really attracts attention.

73,

Allen
VHS
 
Allen,

Thanks very much. Couple Q's from your paragraph:

On the receiver...one of the avionics techs at the local shop is a HAM...will see if he has a 2 meter set-up to listen in with. What freq should we dial in? I looked in Sam's config thread, and looked at the manuals, but am not seeing a way to set the trasmit freq. I know the 8000FA is agile between 144 and 148, and I think I once read a couple of the freqs somewhere, but can't find it now. Is there a more in-depth manual I can refer to...I know I'm killin' you guys with questions, and don't mind reading if its out there. Hopefully all my Qs will help those that follow!

As Pete suggested, I drilled a couple holes in my case today, one in the front and one right over the LED...will be able to watch the LED during testing...don't want to get to the "smoke" portion of the test! ;) Would like to avoid pitchfork-wielding HAM posse's too!

With regards to GPS and RF cable routing...can you define "near"? I mounted the GPS antenna on the glareshield tonight, and the cable run goes behind the panel and down to the tracker. I was going to bring it under the case, and it would get to within an inch or two of the antenna cable for a short length, and would also be parallel for a few inches. Sounds like it would be better to come at the tracker from the side and stay further away. Is it also better to not have them parallel at all, as you mentioned about the power wire? (By the way, I fixed that...power and ground come out the side now. Will take a pic tomorrow).

I do plan to use smart beaconing, so will take that into consideration when testing. I think there was a discussion of a different prelim set-up to use during testing to send more frequent packets to allow easier testing...will look for that post again. To use the alternate configuration, I need a switch wired to that "sw" terminal on the tracker, correct? Could not find further info on that, and would like to learn more. It was mentioned briefly in Sam's config post, but I don't see it covered anywhere in detail (but could just be missing it...getting late!) But roger the no-emergency-beacon-test-transmission...want to avoid an EM response to my tracker, almost as much as pitchfork-armed hoards (quite embarrasing for a Sheriff SAR pilot to launch a bogus SAR on himself!)

Thanks again...we sure are fortunate to have you posting here! Between you, Pete and Sam, we have quite the team of APRS Three Musketeers, along with some other great minds to help keep us knuckleheads straight!

Cheers,
Bob


I think you will be fine with your MV-12 placement, but the actual install will be the final test. You should have at least a receiver to hear the audio when you power and test your unit. If its resetting, the red and green will flash and it will send a brief "clipped" transmission, and do so more or less continuously until you run out of batteries or the unit overheats and smokes. This will be just long enough to jam anyone competing for digi time and sending hoards of angry hams searching for you with pitchforks! In ordinary operation, the green section of the LED should be lit solidly when the GPS is locked on ( Did I mention not to route your GPS cable near the RF cable? Important safety tip!) The red LED will flash on transmission. If you are using Smart Beaconing ( and I suggest you do) the unit probably won't flash much when the airplane is stationary. If you program the alternate configuration with a fixed beacon rate, it can be a little less painstaking to trouble shoot your system. Lots of people use the alternate configuration with the emergency beacon character, if you are doing that, don't even send a single test beacon, since every ham in the free world will call the police, fire, FAA, CAP, and generally lose their collective minds. As a CAP Ground Team Leader, I like the idea of using the emergency beacon for the alternate channel. It really attracts attention.

73,

Allen
VHS
 
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On the receiver...one of the avionics techs at the local shop is a HAM...will see if he has a 2 meter set-up to listen in with. What freq should we dial in? I looked in Sam's config thread, and looked at the manuals, but am not seeing a way to set the trasmit freq. I know the 8000FA is agile between 144 and 148, and I think I once read a couple of the freqs somewhere, but can't find it now.

Standard aprs freq in the US is 144.390. Most likely your tracker is already set to that frequency. Tune any "ham" receiver (scanner, handheld, etc) to that freq and listen for a modem-like sound burst when your tracker transmits.

Your config software has a field for you to insert the tracker frequency. Look at the upper left hand corner of the config page. Manual is here on the Byonics site:

http://www.byonics.com/microtrak/mt8000fa_v2.0.zip
 
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Emergency Mode

Lots of people use the alternate configuration with the emergency beacon character, if you are doing that, don't even send a single test beacon, since every ham in the free world will call the police, fire, FAA, CAP, and generally lose their collective minds. As a CAP Ground Team Leader, I like the idea of using the emergency beacon for the alternate channel. It really attracts attention.

73,

Allen
VHS

Bob - Allen has a great point - one time the ham guys thought I tossed an emergency packet and boy did they mobilize. Here is the story:
 
Standard aprs freq in the US is 144.390. Most likely your tracker is already set to that frequency. Tune any "ham" receiver (scanner, handheld, etc) to that freq and listen for a modem-like sound burst when your tracker transmits.

Your config software has a field for you to insert the tracker frequency. Look at the upper left hand corner of the config page. Manual is here on the Byonics site:

http://www.byonics.com/microtrak/mt8000fa_v2.0.zip

Thanks Sam. That's the manual I've been reading, but I missed the freq block in my first scan of the config screen shot. I looked more closely at the one in your How to Configure thread, and didn't see the freq block. Will use 144.39 to be standard. BTW, will I need to fill that in if the tracker is pre-tuned to that freq, or will the block auto fill when it is connected to the tracker (does it sense the current freq)? Caution: high potential as a "silly question".

When it comes to using the secondary profile, I take it that I can configure the tracker's primary profile with a faster transmit rate for testing, then go back to the settings in your Config thread (I want to use what has been proven successful!) Alternatively, I can configure a secondary profile for the faster rate, but I have to provide a switch. The manual says this:

"...the bottom screw, marked ?SW? is the Configuration switch input. Note that this pin is switched to ground to change configurations and frequencies. Take care not to connect the SW input to the positive supply line, as this could damage or destroy your TT3 controller chip. Please note that the SW (switch) input is used only to select one of two configurations with which you have previously programmed the unit. It is not used in any way during computer programming of the Micro-Trak."

I get the the tracker is programmed for both profiles without ref to that switch terminal, so no need to switch it to get the second profile into the tracker. Does the sentence in red mean that I would need to install a SPST ON-OFF switch where profile 1 is the switch's OFF posit (nothing connected to the SW terminal), and profile 2 is the switch's ON posit (that sw terminal connected to the common ground wire that I have coming from the MV-12).

If that is how it works, I could sure see how, if you use that second profile as an emergency beacon, you might want to use a guarded, or lift-to-throw switch.

Pete, I remember that story...been looking for a flux-capacitor for an IO-540 ever since! To mis-quote the movie...

Bob McFly: Wait a minute, Doc. Ah... Are you telling me that you built a time machine... out of an RV?
Dr. Pete Howell: The way I see it, if you're gonna build a time machine into a plane, why not do it with some style?

Bob McFly: Are you telling me that this sucker is nuclear?
Dr. Pete Howell: No, no, no, no, no. This sucker's electrical. But I need a nuclear reaction to generate the 1.21 gigawatts of electricity I need.

Dr. Pete Howell: [running out of the room] 1.21 gigawatts? 1.21 gigawatts? Great Scott!
Bob McFly: [following] What-what the heck is a gigawatt?

At least that's the way I feel when asking all these questions...or as Mav said to Ice:

"That's right Ice...man...I am dangerous!" :D

Cheers,
Bob
 
A little more progress

First, thanks to Allen for the e-mail on the secondary profile wiring!

I took Pete's advice and drilled a couple holes to allow seeing the LED during testing (and perhaps future troubleshooting). Also took Allen's advice and re-routed the power wires out the side. I also wired in a second sub-mini toggle to select between primary and secondary profiles (and I may use that secondary as an emergency profile, as Allen discussed). Here's a couple pics:

Tracker closed up, with ON/OFF toggle on the front, and Profile 1/2 toggle on the top. You can see the LED through the top hole. The 4" RG-400 patch cord is at the back, with a female-female SMA coupler in it for the J-pole, and an SMA (F) to BNC (F) adapter next to it (for use with the COMM 2 whip antenna, for comparison purposes:
aprsclosedboxfinal1.jpg


Here's one to show the actual size, for perspective. Fits in the palm (with fingers extended:
aprsinpalm.jpg


Here's the box open. The tracker's "-" and "sw" terminals, and the MV-12's GND terminal share a common ground (tied together in a single crimped splice inside the heat-shrink"), then out to aircraft ground. Power remains unchanged from the original set-up:
aprsopenboxfinal3.jpg


I also installed Ryan Howell's j-pole in the gear leg fairing, behind the leg itself. Then ran it up the engine mount (with stand-offs) and through an existing FW penetration.
aprsjpoleatupperglf.jpg


aprsjpoleatengmountglf.jpg


This gear leg installation may be a complete exercise in futility, but as Pete mentioned, it's a cheap test, and if it works, yee haw!

In the cockpit, I made a little bracket that picked up the mounting screws for the SAR radio for support. I can slide the tracker box forward for testing, then slide it back a bit when done to recess it a bit, yet still have the ON/OFF switch and profile switch accessible, if needed.
aprsmountingbracket.jpg


If this location doesn't work out, I can always use the bracket as a sectional chart holder! :rolleyes:

Edit: Here's what it looked like with the tracker installed, configured and ready to go:
aprsboxinstalled2.jpg


I know I'm beating this install up a bit, but just havin' some fun, and enjoying the discussion, and the learning. Thanks!

Will post test flight results of the gear leg jpole in a separate thread.

Cheers,
Bob
 
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