[Don Patterson]

I am planning on mounting a whip antenna on the bottom of my 7a and find many to select from. Any help on zeroing in on a good antenna and the best location to mount it. Should I keep it away from any other antennas elt, transponder, etc.... Oh I have a archer nav and com in the wing tips but I here the com has some limitations. The whip will be my primary com antenna.

 

[Greg Dillon]

I installed my Comant bent whip antenna on the left side behind the spar. I placed it in a location that I could get to from inside by removing the panel covering the floor ribs in front of the seat. I also made a doubler and rivetted it to the bottom skin on the inside. Used nut plates to attach the antenna base. I ran the antenna cable thru an existing hole in the spar.

 

[erich weaver]

I think you will have a tough time finding a better deal than the RAMI antenna through Vans.

I got the bent whip and mounted it near, but not on the centerline. Since I just have the single external com antenna, Im wondering how important it is to be on the centerline - is it possible that a single off-center antenna would have any signifcant yawing affect?

erich

 

[db1yg]

I mounted my Comant bent whip on the centerline just forward of the where the angled flap motor support meets the floor (between the seats) on my RV9a. I used a 90 degree angle BNC fitting at the coax to antenna and have plently of clearance under the elevator control tube. I also included an easy to access fitting to be able to use the external antenna for my handheld in case my panel mount goes T.U.


Cheers,

db

 

[kentb]

Should I keep it away from any other antennas elt, transponder, etc.... Oh I have a archer nav and com in the wing tips but I here the com has some limitations. The whip will be my primary com antenna.

Keep antennas about 2 feet from each other. I have the same setup and am thinking about putting a splitter in for the bent whip and sharing. I would abandon the wing tip com. The Nav in the wing tip works great.

Kent

 

[Ironflight]

I'll add another vote for the RAMI or Commant on the belly. Easy to mount under the seat, good performance. I initially tried to skimp with a simple bent-rod whip antenna (where I eventually mounted the RAMI). It didn't have a BNC connector, just a threaded end. I got so much RF leakage into the cockpit that every LED on the panel lit up when I keyed the transmitter. That test convinced me to buy something better, and the bent rod went in the junk bin.

Paul

 

[MTBehnke]

Dual Comm

Do I understand correctly that you cannot/should not use a single Comm antenna with dual Comm radios?

 

[Sparky]

Cannot Share Comm Antenna

You cannot share one comm antenna between two comms like you can with nav receivers. The reason is that comms both receive and transmit. Navs only receive. If you try to use one comm antenna with two comms connected via splitter you'll either overload the non-transmitting comm's receiver or smoke the transmitting comm's transmitter.

Each comm must have it's own antenna.

I plan to use two RAMI or Commant bent whip antennas on the belly (just behind the main spar under the removeable seat panels, as Greg stated) spaced as far apart as possible. This will also place them at least three feet from my transponder antenna, which is mounted on the belly just aft of the baggage compartment.

Also it is important that none of the antennas be installed in the flow of the exhaust.

Use doubler plates and ensure you get a good ground for all skin mounted antennas by removing paint, primer, etc at the attach point.

 

[kentb]

Sparkie, good to know.

You cannot share one comm antenna between two comms like you can with nav receivers. The reason is that comms both receive and transmit. Navs only receive. If you try to use one comm antenna with two comms connected via splitter you'll either overload the non-transmitting comm's receiver or smoke the transmitting comm's transmitter.

Each comm must have it's own antenna.

I guess I will either track down my tx leak or add an additional antenna.

Kent

 

[dan]

You cannot share one comm antenna between two comms like you can with nav receivers. The reason is that comms both receive and transmit. Navs only receive. If you try to use one comm antenna with two comms connected via splitter you'll either overload the non-transmitting comm's receiver or smoke the transmitting comm's transmitter.

Each comm must have it's own antenna.

Bob Archer sells an SA-010 (I think that's the P/N) automatic antenna switch that lets you use TWO comm radios with a single antenna. It has circuitry to isolate the antenna to only the one transmitting radio when one is transmitting. As long as one isn't transmitting, both can receive.

I have not used this switch but I intend to try it on the plane I'm building.

 

[kentb]

Interesting....

Bob Archer sells an SA-010 (I think that's the P/N) automatic antenna switch that lets you use TWO comm radios with a single antenna. It has circuitry to isolate the antenna to only the one transmitting radio when one is transmitting. As long as one isn't transmitting, both can receive.

I have not used this switch but I intend to try it on the plane I'm building.

If anyone has experience with this switch, could you post your opinion on it.

Kent

 

[tc1234c]

My COM I is a Rami belly bent antenna under the pilot seat (between stick and central compartments). There is enough clearance, and I did not need a 90 degree fitting. COM II is a windscreen antenna sold by Van's for $7 (I have a slider, it does not look that bad. However, it would look very bad on a tip up). NAV is a Van's single copper strip wing tip antenna ($27) in the left wing tip. Marker beacon antenna is another copper strip in the right wing tip. Transponder rod antenna is mounted under the right gear mount. ELT antenna is mouted horizontally in the tail intersection fairing. So far everything works well. All these cheap copper strip antennas are easy to installed yet work perfectly. I have not tried to compare COM I and COM II antennas yet. Of the few times I tuned both radios to the same frequency, both received clearly.

 

[cleve_thompson]

I have mounted 1 Commant bent whip com antenna in the left gear mount of my RV9A. Someone said that this was a good place so that you could unplug it and plug in a portable com radio in case the panel mount went belly up. I mounted the second bent whip behind the spar box on the right and my transponder antenna in the front right corner near the fuel vent. The Garmin GPS antenna is mounted on the front deck just in front of the wind screen and I have Archer nav and marker beacons in the wing tips. My ELT antenna is mounting on the center post behind the seats. In this way, I think that I have 3 feet plus of distance between any 2 of my antennas. All antennas work on the ground. I hope that they will work in the air if I ever get there.