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Radio transmit problems..Only 5 mile range on both coms.. WHY???

A

av8toreace22

I'm New Here
Trying to figure out why both of my coms are only transmitting tops 5 miles and very scratchy...I can understand one com doing that due to a bad antenna ground.. But I have two antennas one for each com and both are exactly the same poor range and sound quality..
Shane
RV-8
N20EA
 
av8toreace22 said:
Trying to figure out why both of my coms are only transmitting tops 5 miles and very scratchy...I can understand one com doing that due to a bad antenna ground.. But I have two antennas one for each com and both are exactly the same poor range and sound quality.
Click to expand...

First off, is that while the airplane is in the air or on the ground? With the airplane on the ground, five miles is about what I'd expect; maybe less if the antennas are on the bottom.

Beyond that, I'd be inclined to start at one end of the system and progress to the other.

* Try a different microphone or headset
* Double-check that the radio tray is properly grounded
* If possible, use a standing wave ratio (SWR) meter to see how effective the antenna installations are. You'll be looking for an SWR preferably less than 1.5, though an SWR of 2 should still be pretty functional.

If none of those things pan out, have the radios bench checked at an avionics shop. They'll be able to measure the output with a dummy load.

Thanks, Bob K.
 
Hey Bob,
It's only 5 miles while flying. What has me confused is why both radios? I've seen one out of two radios or antennas do this but not both radios with the same issue.. I have Bose A20 headsets..I really hope there not bad but I will try a different pair. You never know, anything can break..
Shane
 
look at common points between the systems...

look carefully at the common points...

is the intercom okay?
headset and headphone jacks (not an issue if the intercom is okay)
audio panel (try the bypass turning the audio panel off)
connect directly to a single radio (if you can)
common ground points
disconnect one antenna and try, repeat with the other antenna

what radios?
what intercom?
 
Com 1 Icom IC-A200
Com 2 Narco 810
Intercom PSEngineering PMA4000

I'm not sure how to turn the intercom off and by pass to one radio..
Shane
 
Most, if not all, PS Engineering intercoms have an automatic by-pass directly to the radio if the intercom is turned off.
 
Nobody can help you diagnose this problem without detailed information about your antenna and radio installation.
 
Have someone with a wattmeter check the output power, this is a good "general" test of the radio and antenna system.
 
suspect the BNC connectors at either radio or antenna end. Both nay be shorted due to improper installation or the wrong BNC type i.e. not crimped type connector.
 
Find a buddy with an identical radio and do a temporary swap.

Either -

1. You have two radios with poor output (possible)

2. You have an external to the radio problem.

At least it will eliminate the radios as the problem, even if you only swap one.
 
Some thoughts

I cut and pasted all your inputs:

Trying to figure out why both of my coms are only transmitting tops 5 miles and very scratchy...I can understand one com doing that due to a bad antenna ground.. But I have two antennas one for each com and both are exactly the same poor range and sound quality..

It's only 5 miles while flying. What has me confused is why both radios? I've seen one out of two radios or antennas do this but not both radios with the same issue.. I have Bose A20 headsets..I really hope there not bad but I will try a different pair. You never know, anything can break..

Com 1 Icom IC-A200
Com 2 Narco 810
Intercom PSEngineering PMA4000

I'm not sure how to turn the intercom off and by pass to one radio..

Shane
RV-8
N20EA
__________________
Shane Wollert

RV-8 Best RV I've Flown..Love it
RV-7A
RV-3
RV-6
​

1 - You signature information suggests a lot of operational RV and communication system experience.
2 - The ability to communicate 5 miles verifies that both systems function properly and that it is a performance problem.
2 - How did you conduct the test? Who was the receiver, was the source reliable and were the results similar in communication with another site.
3 - Exact same performance problem strongly indicates a single point failure.
4 - Did the problem just arise on an airplane/system the previously was working as you expected or is this a new system in debug?
5 - The problem could be audio frequency prior to modulation since the RF section of the two different manufacturer's radios are completely isolated from the source within each radio to their separate antennas.
6 - How is the reception on the two radios? This is significant since all of the connections between the antennas and the radios are used for reception as well as transmission.
7 - My guess would be in the audio part of the system related to transmission - mic switch, mic jack, audio panel or grounding.

Bob Axsom
 
Last edited:
av8toreace22 said:
Hey Bob,
It's only 5 miles while flying. What has me confused is why both radios? I've seen one out of two radios or antennas do this but not both radios with the same issue.. I have Bose A20 headsets..I really hope there not bad but I will try a different pair. You never know, anything can break..
Shane
Click to expand...

Have you checked your headsets to see if they are set to mono or stereo? I've seen some bizarre symptoms pop up when that switch is in the wrong position.
 
Antenna grounding can also cause this,,,or lack thereof,,,Make sure the bases are properly grounded to aircraft on bare metal
 
Do NOT transmit on these radios until you can put a wattmeter on as Walt points out. An open connection somewhere can cause the modulation transistor to overheat and fail.
 
Common + or -?

Since both radios are doing this leads me to beleive it may be a common problem. Are both radios powered by a common positive connection, such as from an avionics master switch? If so, it may be a corroded or otherwise poor connection, when you key the mic it could cause a voltage drop at a poor connection point due to the increased current load. This may also occure at a common ground point. Tap into the power lead at the tray connector, with everything running xmit on that radio and check voltage drop. A drop of more than .5 volt is bad, and may be the cause of the poor transmit. Also if receivers are working good now, this would be another indicator of what I have said here is the problem. Good Luck.
 
170 driver said:
Antenna grounding can also cause this,,,or lack thereof,,,Make sure the bases are properly grounded to aircraft on bare metal
Click to expand...

I had the same problem with my iCom A210. The solution was to remove one antenna screw at a time, give each screw hole two turns with the hole deburring tool to remove the light corrosion in the hole. That solved my problem.
 
What type of antenna are being used? If you have two old style Bob Archer wingtip COM antenna's then 5 miles may be as good as it gets.
 
az_gila said:
Find a buddy with an identical radio and do a temporary swap.

Either -

1. You have two radios with poor output (possible)

2. You have an external to the radio problem.

At least it will eliminate the radios as the problem, even if you only swap one.
Click to expand...

And, while you are swapping things, put your radio into a know good airframe, and test the range.

If it works well, you can eliminate the radio as the issue.
 
[email protected] said:
look carefully at the common points...

is the intercom okay?
headset and headphone jacks (not an issue if the intercom is okay)
audio panel (try the bypass turning the audio panel off)
connect directly to a single radio (if you can)
common ground points
disconnect one antenna and try, repeat with the other antenna

what radios?
what intercom?
Click to expand...


Don't be so quick to eliminate headset and jack issues just because the intercom is ok. I recently had a DC mic fail on me. It was great on the intercom, but xmit was scratchy and barely readable. New mic and all was well.
 
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