Mic connection

Pete1952 · August 26

I have been trying to connectme Heil PR 781 to my Flex 6400. Can anyone tell me where I can find detailed instructions.
I would if possible a step by step guide as I am new to flex radio's, one thing I have learnt so far is how frustrating it is to find any instruction.
Thanks in advance
Pete
M0VPH

Mike-VA3MW · August 26

To connect a Heil microphone with a 1/8" TS (mono) plug to a FlexRadio that requires a 1/8" TRS (stereo) input, you need to prevent the shorting that occurs when the mono plug bridges the tip and ring. The fix is to use a 1/8" TRS plug or adapter where the tip carries the audio signal, the sleeve is ground, and the ring is left unconnected. This way, the FlexRadio’s mic input receives the audio correctly on the tip without the ring being shorted to ground, which is what happens if you plug the TS connector directly. You can either rewire the mic cable to a TRS plug with the ring floating, or use a TS-to-TRS adapter designed specifically with the ring disconnected. This ensures clean audio input from the Heil PR781 (or similar mic) without distortion or muting.

There are adapters on Amazon or you can reach out to Heil to see if they have developed an adapter yet. We have provided them the information some time ago.

Mike-VA3MW · August 26

I have seen some people use one of these and then the plug the Heil mic into one sockets. I think it is the red one.

It is easy and safe to test. It will either work or not work.

let us know how you make out.

Personally, I cut my connector off and added a new TRS connector with no connection on the Ring.

Pete1952 · August 28

Thanks for getting back Mick. I tried your suggestion but unfortunatly to no availe.
I'm now wondering if I need to setup a profile for the 781.
I'll let you know how I get on.
Pete
M0VPH

Mike-VA3MW · August 28

I never use profiles for a new Mic since I can never remember what requires BIAS. I do know for sure that the HEIL Mono mic connector is an issue. Plugging a HEIL Mono Mic into a 6000 or 8000 shorts out the MIC input on the RING side. It doesn't damage anything, but it doesn't work.

Here is what I do:

plug the mic into the radio
Pick the correct MIC input in SmartSDR — In this case MIC
Go into the Radio Settings and turn on the feature that shows Mic Level During Receive
Make sure you are watching the MIC LEVEL meter
Turn MIC gain to about 75% to get started
Talk into the MIC - if it is working you will see MIC level deflection even without being in TX (why does no other radio do this?)
If you don't see any deflection - turn BIAS on - Some MICS need BIAS - I never remember which ones do - it is one of those things
Test again
If no luck, are you sure the MIC is good ? Is it the correct cable?
If it now works, set your MIC level by talking normally with the MIC LEVEL going no higher than -5dBm
Now, save you MIC profile as yours in the PROFILE manager

Mike-VA3MW · August 28

If you are going to use the TRS splitter cable, you need to make sure it is a TRS to Left and Right. Not a headset splitter.

Mic connection

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