Radio transmit range

[b1x4nqb]

After flying around yesterday I discovered a weird quirk.  Radio check sounded loud and clear from the FBO and I can hear all traffic in the pattern.  I even picked up Center, and stations 20-30 miles away but when I tried to reach approach from about 20+ miles they didn't seem to hear me very clearly.   Any suggestions?  I used the best coax I could get and I used the whole turtle deck for a ground plane, made sure I have full contact with the antenna on the deck in between, etc.  For a non radio guy, I'm looking for suggestions.  Can a radio shop or your average guy use some type of gizmo to read my transmit power comming off the plane? Radio is brand new Icom a210.

Thanks,
Paul, PA

Update:  All was fine, the ends of the one connectors were labelled wrong.  I had the wire from the radio going to the Transponder Antenna and vice versa.  No need to change out anything more than just switch the ends.  Working great now!

[rubobrun]

Hey Paul
 
try a hand held to see if are getting TX audio If OK, take a floresent tube (2ft,4FT,ect.) and touch the end of the antenna while tx,ing it should  fire the tube!!
This is a very crude test but it will tell if you have RF output.
if this does not work see if you can find a SWR bridge that will handle 120mhz, put in line and see if you have a good antenna match,you will have to come up with some adapters for the BNC connectors??.
If you have a bad match the tx may shut down to protect the final amps.
  PS how is chris doing ?

    Bob Waldhaus

[Wes]

Paul,
Sounds like a "rabbit", all ears and no mouth!
Bob has some good suggestions there for ruff checks of output pwr.
You need to verify that the xmit power is reaching the antenna and the reflected power from the antenna is minimal. The best way to do this is with a Bird wattmeter, which will give you a forward and reflected power reading. Any cheapy ham swr meter that will work at VHF freqs will give you a good indication of fwd vs reflected power, but don't believe the 'power out' meter for accurate  tx level.
Best to check this AT the antenna, not at the radio.
The Icom A210 is an 8 watt radio and should be heard as well as any other aircraft radio, given any altitude.
The other thing that will make you difficult to hear, is your modulation level. Normally this is not a problem, especially with the Icom radios that have a auto' level mike audio circuit that compensates for too much or too little mike volume coming into the radio. However if you have a shorted mike circuit somewhere, the radio will still transmit your voice, but at a much reduced modulation level and listeners will have to crank up their reciever volume control to hear you. The FAA ATC will not do that! A crude way to check modulation level is with a handheld radio with the volume knob set for normal listening on a station with normal modulation level. Then, with out changing the handheld volume control, listen to your transmitter and compare sound level to the other station. If there is a significant difference in volume, (yours is weaker), then you have a mic audio problem.
If we were nearby, I could do those checks for you, but in the interim, drive up to your nearest friendly avionics shop and see if they can slap a wattmeter on it.
Any problems with antenna mounting and bonding will show up in a swr check.

Let me know how you proceed.

Wes