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Archer Nav in RV-14A

mulde35d

Well Known Member
Friend
So I am about to install the Archer Nav Antenna in the left wingtip of my RV-14A and want to get others opinion before final drilling and fiberglass. I have the piano hinge attachment for he wing tips and plan to rivet the antenna ground plane to the piano hinge for grounding. I will run the AeroLED Pulsar light wires along the front as depicted in the instructions. I also plan to place a dab of proseal on the outboard tip to prevent the metal from wearing through the fiberglass

My questions are:
Is the antenna in the best place for and aft? The instructions say as far forward as possible while remaining flat. I feel like any further forward will result in a more significant upward bend at the tip. Would that effect reception or should I move it even further aft?

Any concerns with using a couple fiberglass strips in the same location as the current pieces of blue painters tape? I figure it will be more secure this way.
Archer-3.jpg
 
Here is the placement in my right wing tip, seems close to where yours will be. I did bend slightly to fit contours of tip then fiberglassed into place and the lighting wires run along the front leg as directed. It works great there, very happy with the performance with VOR and localizer/glide slope reception.
ofN.jpg
 
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I make my own wingtip VOR/LOC/ILS antennas. As shown in the photo the antenna is mounted on a short piece of thin 3/4?x3/4? angle that is attached to the end rib with a couple of screws. The advantages:
- Wingtip just fits over the antenna so the antenna stays on the plane when the tip is off. The outboard edge of the antenna fits into the wingtip outboard seam and does not move.
- You will note the Archer antenna does not extend as far out into the wingtip as there is room. Making my own antenna I can change the dimensions to use all the space outboard of the last wing rib - so the critical part of the antenna (the part that extends out) is optimized.
- Note that I mount the antenna a little aft. This gains distance from the NAV/Strobe to minimize RFI. I would never run nav/strobe/landing light wires along the antenna itself.
- The antenna is made of aluminum out of the scrap box - so trivial cost.

Disadvantage: You need to have an antenna analyzer to tune it (but then I would also consider this a prudent step for the Archer antenna, as well as the comm antennas).

Photo is an RV-14A install. Note the antenna is several inches too long. Photo was taken before tuning. The black tape is just to keep it in about the right configuration, again for tuning.

Carl
311-F95-CF-3-F7-A-4-D5-C-BBD3-4-F91-E8-C6-B5-C9.jpg
 
- Note that I mount the antenna a little aft. This gains distance from the NAV/Strobe to minimize RFI. I would never run nav/strobe/landing light wires along the antenna itself.
-

+1. Some LED lights (I don't know about yours in particular) are real noise emitters. I'd consider shielded wire for the LEDs, and run it thru the forward most part of the wing tip, back into the wing. As far from the antenna as you can get. Bob Archers' instructions apply if you have to run wires across or very close to the antenna. But if you can avoid it entirely, do so.
 
So I am about to install the Archer Nav Antenna in the left wingtip of my RV-14A and want to get others opinion before final drilling and fiberglass. I have the piano hinge attachment for he wing tips and plan to rivet the antenna ground plane to the piano hinge for grounding. I will run the AeroLED Pulsar light wires along the front as depicted in the instructions. I also plan to place a dab of proseal on the outboard tip to prevent the metal from wearing through the fiberglass

My questions are:
Is the antenna in the best place for and aft? The instructions say as far forward as possible while remaining flat. I feel like any further forward will result in a more significant upward bend at the tip. Would that effect reception or should I move it even further aft?

Any concerns with using a couple fiberglass strips in the same location as the current pieces of blue painters tape? I figure it will be more secure this way.
Archer-3.jpg

After speaking with Bob Archer a few years ago, I installed mine exactly as you are considering. Mr. Archer liked it very much because the system requires a good ground. He had only one input, ?be sure to clean the anodizing off the hinge before riveting?. The anodizing is an insulator.

Marvin

SIDE NOTE: he spent almost 2 hours with me explaining the design and his history with space program antenna design. I am still in awe that he would just give away a lifetime of knowledge to an unknown person over the phone. We lost a good one when he passed.
 
Anodizing

After speaking with Bob Archer a few years ago, I installed mine exactly as you are considering. Mr. Archer liked it very much because the system requires a good ground. He had only one input, “be sure to clean the anodizing off the hinge before riveting”. The anodizing is an insulator.


So I failed to sand off the anodizing before riveting, but the rivets and steel piano wire itself seem to still provide a good ground for the system. Now I know for next time though
 
Just another point of view

This is my input in regards to my installation of a Bob Archer VOR wingtip antenna. After all said and done, I added a separate wire from the short side of the antenna and connected it directly to the last outboard rib just to be sure I had a good ground.

Now, before anyone says anything negative about what I did, I am getting a great signal from multiple VOR stations each over 120 miles away at the time. I never headed away from any of them farther than that to see just how far I could receive a good signal.

For the ones who use this antenna, you have to admit that is a pretty good range for one of these antennas.

Brian
 
I read you blog about using the solder sleeve for the RG400 shielding which makes sense. Did you use the connectors that came with the kit and simply crimp the center wire in the RG400?

Not 100% sure at this point (memory fails) but I think I crimped a connector onto the center wire from RG400 as you describe, and onto the black (ground) wire that I prepped and used with solder sleeve to make a good connection to the shield wire on the cable. I had a full kit of my own connectors, so used those or the ones in the kit - same ring connectors so I don't think it makes much difference. I also decided to put a connector in-line in the RG-400: one cable goes directly from the back of GTN650 to the end of the wing (past last rib), the other short piece connects to the antenna. This makes it possible to remove the wingtip more easily.
 
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You will note the Archer antenna does not extend as far out into the wingtip as there is room. Making my own antenna I can change the dimensions to use all the space outboard of the last wing rib - so the critical part of the antenna (the part that extends out) is optimized.
Carl,

Thanks very much for this, you've talked me into building my own antenna. Just to be clear, you lengthened the extending part outboard of the gamma match? I assume the match lengths and angle must be maintained to keep the antenna tuning in-band.

Many thanks -

Dave
 
Carl,

Thanks very much for this, you've talked me into building my own antenna. Just to be clear, you lengthened the extending part outboard of the gamma match? I assume the match lengths and angle must be maintained to keep the antenna tuning in-band.

Many thanks -

Dave

Dave,

Look at page 13-16 of the AeroElectric Connection. Keep the ?triangle? dimensions the same - the gamma match section. Extend the arm out from the wing rib as far as you can. You will need to shorten the trailing arm (the one that runs aft) a little to compensate.

Tip - the gamma match capacitor (the piece of mica in between the two pieces of aluminum) can be made of mica or fiberglass. Use what you have. Make the aluminum plate that forms the capacitor a little long as you will trim this to achieve the best tuning match. Tuning the trailing arm length is required to resonate the antenna in the middle of the VOR band. Tuning the gamma match is required to achieve a 50 ohm impedance to match your feed line.

Tuning for resonant frequency and for impedance is an iterative process. Do one then the other in small trims. Total time is less than 20 minutes if you have an antenna analyzer (I use an MFJ 259). If you don?t have access to an antenna analyzer do not build your own. This is a perfect group or EAA chapter tool as no matter what you are doing this is the first thing to grab anytime you touch an antenna, store bought or not.

Side note - I have had success making a similar wingtip comm antenna by mounting it at the bottom of the wing rip and angling it up into the rib as much as possible. As the first third of the antenna does 90% of the radiation (it is the high current part) the angle up helps mitigate the vertical radiation issue. It will never work as well as a nicely mounted belly antenna, but it worked well enough for the Comm #2 antenna.

Carl
 
Dave,

Side note - I have had success making a similar wingtip comm antenna by mounting it at the bottom of the wing rip and angling it up into the rib as much as possible. As the first third of the antenna does 90% of the radiation (it is the high current part) the angle up helps mitigate the vertical radiation issue. It will never work as well as a nicely mounted belly antenna, but it worked well enough for the Comm #2 antenna.

Carl

+1. I have the same design (ground leg as high as possible (mine’s attached to the top skin), leading arm slanted down as much as possible. Works as described.
Carl: you have a typo, ‘wing rip’, which some may read as ‘rib’ but of course it’s ‘tip’.
 
Installed

Finished installing the Archer Nav antenna. Took the wiring advice provided in this forum and simply ran the Nav/Strobe wires parallel with the ground plane. The final open orange zip tie will secure the loop on the RG-400 cable when I attached the wing tip. I know a few of you discussed putting a BNC connector on the wing tip for easy removal, but I just can't see many reasons after the build to remove the wingtip and would rather not have the associated losses. I am just going to attach the RG-400 directly to the screws which will make wingtip removal a little more time consuming, but I can't imagine it will be that bad. Besides, I already have a bulkhead BNC junction at the wing root. Can always change it later.

Of note, after the pro-seal dried I decided I didn't need any fiberglass strips. The antenna is pretty secure

Archer-4.jpg
 
Finished installing the Archer Nav antenna. Took the wiring advice provided in this forum and simply ran the Nav/Strobe wires parallel with the ground plane. The final open orange zip tie will secure the loop on the RG-400 cable when I attached the wing tip. I know a few of you discussed putting a BNC connector on the wing tip for easy removal, but I just can't see many reasons after the build to remove the wingtip and would rather not have the associated losses. I am just going to attach the RG-400 directly to the screws which will make wingtip removal a little more time consuming, but I can't imagine it will be that bad. Besides, I already have a bulkhead BNC junction at the wing root. Can always change it later.

Of note, after the pro-seal dried I decided I didn't need any fiberglass strips. The antenna is pretty secure

Archer-4.jpg

I like the use of a more secure connector for your wingtip lights. Next time I pull off my wingtips I may change to something like that.
 
Simple 4 pin CPC. I replaced all the molex connectors across the aircraft with CPC?s. Worked great at the wingtip root as well.
 
Look at page 13-16 of the AeroElectric Connection. Keep the “triangle” dimensions the same - the gamma match section. Extend the arm out from the wing rib as far as you can. You will need to shorten the trailing arm (the one that runs aft) a little to compensate... <snip> Tuning the trailing arm length is required to resonate the antenna in the middle of the VOR band. Tuning the gamma match is required to achieve a 50 ohm impedance to match your feed line.

Many thanks Carl, that's an excellent description of building and tuning this antenna. Despite being an EE and a Ham, I'm not as sharp on antennas as I probably should be.

I have a Comet CA500 antenna analyzer that I use for Ham stuff and it will come in handy here. I'm looking forward to building and tuning this antenna!

Dave
 
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