Narco (radio, not cartel) interference with GNS530

[FloridaMan]

I'm not sure which radio is at fault of it it's the audio panel. Here are my symptoms.

 

I can listen on both radios. No problem. With the GNS530 as my transmit radio, no problem. If I switch to the Narco to transmit on and key the mic, all I hear is EERRHHHHCHHHHEHHRHRHEHHERE, but whoever's on the other end hears me fine. If I turn down the volume on the GNS530 when I transmit on the Narco radio, it works fine. 

[aviatoreb]

Huh - I have the same problem.  But gns430w.

[carusoam]

Narco 12+ radios didn't age well. They bled signals even when not transmitting. They blocked my portable GPS signals.

Narco 11 com radios weren't any better.

The company didn't age well either. They charged me $50 to look at and diagnose broken plastic parts on the "knobs" to tell me the cheap plastic parts were broken. I knew that already...

I like to support old companies, but when they don't help themselves, they will fail by their own lack of effort.

They kept my old radio. Too expensive to send back...

This was My M20C experience from the early 2000s. The company filed for bankruptcy after that, no hope of reorganizing.

Best regards,

-a-

[Marauder]

Narco did indeed have an interesting history. I still have 2 radios in my panel from them. The reason the radios are there was because the Garmin of that time frame was Bendix King and for me to move into a 155 and KT-76 was going to cost me thousands more than the Narcos. I think where Narco went in the wrong direction was with their support strategy. Most likely from not making enough on their hardware sales they probably believed they could make it up through pulling back all of the support services to their facility. This alienated the very avionics shops that were pushing their products and making revenues from supporting them. I remember a very distinct conversation with my radio shop back then. He told me in no uncertain terms that he was done selling Narcos because of the support strategy. It is unfortunate because the more we lose these companies, the less the competition for our business which ultimately resulting in higher prices.

[Gone]

It is probably the Narco radios. Electromagnetically, they are known as dirty radios. I had to change a new Garmin 340 audio panel for a PS 8000 one because it is better shielded against the junk coming out of both my 810 and my Mk 12D.

Good luck.

[carusoam]

Interesting point Edgar, the 12D is digital and designed at a different time. Partially, at least.

Best regards,

-a-

[Jerry 5TJ]

I suggest a test:  If you disconnect the COMM antenna from your GNS530 (BNC connector on the rear panel) and the problem is still there I'd look at the audio panel & intercom, the audio wiring shields (and lack thereof) and grounding.   If the (and I quote) EERRHHHHCHHHHEHHRHRHEHHERE sound is still there I'd suspect a radiated signal from the Narco radio.  

 

A similar test would be to disconnect the Narco COMM and terminate it in a 10 watt RF load and try transmitting, but the Narco may not have a connector in the coax whereas the GNS530 does have that easy-to-use BNC. 

 

If the sound goes away with antenna removal measure the Narco's antenna VSWR.   If poor that can contribute to RF spurious outputs and the "EERRHHHHCHHHHEHHRHRHEHHERE" result.

[Piloto]

Your problem is not on the Narco or G530 but on the audio panel. It appears that the receive audio for the 530 is on all the time. Check on the audio panel the switch setting for the 530. If the Phone switch for COM1 or COM2 is depressed or active you will hear that radio when transmitting. If using a KMA-24 audio panel verify all the switches are out except for the AUTO switches. It is also possible you may have a defective audio panel switch.

 

José 

[RussG]

Did anyone ever find a resolution to this issue?

 

I have a Garmin 530W and a Bendix/King KX165 for second Nav/Com.  

 

Whenever you have Com1 and Com2 active and then try and transmit, it make a horrible screeching sound in headsets.  Everyone on the other end says the radios sound fine.  

 

The audio panel is a GMA 340.  

[carusoam]

I believe they call it radio interference...

It is not normal to broadcast on two radios on the same frequency at the same time...

If people say you sound fine, which radio did they hear, com1 or com2?

There is a lot of radio technology behind the situation. Somebody will be around soon to explain...

Best regards,

-a-

[FloridaMan]

I've found if I turn off the monitoring of one radio in the audio panel that I just don't hear the interference. I typically had COM1 "armed" all the time with "Auto" set as well. When switching to COM2, since COM1 was still armed, I'd hear it. The solution was to disarm COM1. 

[RussG]

When I'm normally on with approach I try an listen to CTAF for home as I'm getting closer since approach dumps me pretty close to the airport.  I normally start updating with CTAF while I'm still on with approach, but I'm not transmitting on the same frequency.

 

If I have both Com1 and Com2 active and then try and transmit on either one when they're both active the headset screeching starts.

 

If I turn one off it doesn't do it, but that means missed calls from approach.  

 

Any help is really appreciated.

 

Russ