VOR Backwards

I purchased an RV-9A with a Garmin nav/com and a Garmin Vor/ILS head. Since I fly primarily with GPS I have not paid much attention to the VOR. Today I thought I would give it a go since the VOR was located at the destination airport. Much to my surprise, the To/From flags are indicating backward and I think the deviation bar is also (although I am not sure of the later). I also check it with other VORs and both flying into and away from the station and the T0/From flags are consistently backwards.

Any hints on what I should do to correct this problem myself or is it a "Take it to the Avionics shop and bend over"?

Thanks, Ken

First, just so it has been said, double, triple, and quadruple check for pilot error in rusty vor navigation skills. It sure sounds like a perfect incorrect setting of the OBS. Then we can get on with a technical discussion. Which Garmin nav/com?

More info would be helpful: What type "Garmin nav/com"? What model "garmin vor/ILS" head? A picture of the situation would be great. Actually a panel shot encompassing the whole system would be best.

George

Upside-down

Can you describe your VOR antenna setup? I have heard that only some antennas can be mounted upside-down because they have an electronic reverse switch that compensates.

I am guessing that the antenna was installed on the bottom of the fuselage.

Ken, sounds like you have to reverse a couple of wires going from your VOR head to your CDI. If you can get a hold of a schematic and identify the two wires you can probably get someone to help you pull the pins and reverse them. Just takes a tool specific for the type pins you have. On the Mid Continent MD200-306 that I have, it's pins 9 and 10, for example. It would be the same for the right/left deviation, in this case pins 11 and 12.

[Edit: Just to be sure, be aware that if you center a "radial" on your CDI, it will indicate "From" all day long regardless of your heading, conversely if you center a "course" it will indicate "To", but I am sure you are aware of that. The point is, be sure you are in fact seeing a reversed situation before you go messing up a perfectly good system!]

Good luck!

Thanks guys, all good questions. Plane has an Apollo GX-60 IFR GPS and Comm. It also has a Holleywell KMD-150 multifunctional display with its own VFR GPS. It also has an Apollo SL30 nav/com. I have no idea where the nav antenna is or what type it is. I will check tomorrow.

The VOR CDI is a Mid-Continent MD200-3XX series.

Here is why I think the TO/FROM is backwards:

The ACU (annuncator control unit) made by Apollo and is set with NAV selected. Not GPS.

I have set the KMD GPS to fly direct to the Winslow VOR. Course and heading to the VOR is 020 (no wind). I am flying directly to the VOR on a 020heading. I have the VOR set to the Winslow VOR freq (tuned and identified). When I center the CDI with the OBS it centers on 020 but the TO/FLAG shows FROM. When I center the CDI on 200 it shows a TO. This seems backward to me. I did not purposely fly off course or rotate the OBS to see what the result was but that can be easily done.

The panel was professionally set-up and the guy I bought it from is a CFI but it still seems like I am getting an incorrect indication and I am not confident he ever flew an ILS or used the VOR for navigation.

Thanks again for any help or suggestions you can give. Plane is currently based at Glendale, AZ (Phoenix).

OK Ken, good information. You have the exact setup that I have on my RV-6. From what you describe, I believe you are correct in your assumption that the TO/FROM is set up backwards. It would appear that you have a couple of pins on your MD200-306 set up incorrectly. What I show is that the output for the TO/FROM from the SL30 is on pins 12/11 (pin 12 is TO, pin 11 is FROM). The corresponding pins on the MD200-306 are pin 9 and 10 (pin 12 on the SL30 should go to pin 9 in the MD and pin 11 on the SL30 should go to pin 10 on the MD. You could pull off both connectors and do a continuity check with an ohmmeter to verify if this is correct. My guess is that you will probably need to reverse pins 9/10 on the MD.

While you're at it, you might want to check and make sure that the L/R is wired correctly so that your CDI is directional, especially while shooting an ILS. The pin outs for this on the SL30 L/R are pins 14/13 and the L/R pins on the MD are pins 11/12. So, 14 to 11, and 13 to 12. A simple continuity check should verify this for you!

Hope this helps!

Try a VOR test site at your airport if you have one. That will tell if it is reverse sensing or not. It matters not if the antenna is on the bottom of the aircraft or not. That only applies to ADF loop antennae.

Oops

You're right Norman, I was thinking of the ADF sense loop being sensitive to installation.