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Low mic gain on IC-706MKIIG when RigPi connected


Mike WA0YCN
 

I’ve noticed that when I have my RigPi connected to my Icom IC-706MKIIG and try to make a QSO from the rig itself, my mic gain/power output on SSB is way lower than when I operate remote using the RigPi. If I disconnect the MFJ-5713DI (accessory) cable, the radio works fine.

Is anyone else experiencing a similar problem?

Thanks,

Mike


Colin
 

Hi Mike,

I have the same set up as you, an IC-706MKIIG and have noticed the same condition.
I have found it necessary to disconnect the MFJ-5713DI cable at the Rigpi when using the radio's microphone.
It looks like the combination of the Rigpi and microphone excessively loads the audio input circuitry.
Also using the microphone with the MFJ-5713DI cable attached can cause an audio feedback loop on transmit.
Other than the above everything else works well except for the PTT problems with this model mentioned in the group before.

Colin

VE7CQH


On Aug 17, 2020, at 8:17 PM, Mike WA0YCN <mgassman@...> wrote:

I’ve noticed that when I have my RigPi connected to my Icom IC-706MKIIG and try to make a QSO from the rig itself, my mic gain/power output on SSB is way lower than when I operate remote using the RigPi. If I disconnect the MFJ-5713DI (accessory) cable, the radio works fine.

Is anyone else experiencing a similar problem?

Thanks,

Mike


Don Melcher
 

I’m using a home brew cable into the ACC jack. I’ve done that a lot with other things and not noticed a problem you describe but I’ll check it out later this morning. My guess would be RF on the cable. Do you have ferrite beads on it. As a matter of practice I ALWAYS put them on BOTH ends of EVERY cable. I was in the HF email business and that was just standard practice on the systems I sold. 


BUT, keep in mind that you need to REMOVE the mic when using the RigPi. The mic is still hot and will pick up any ambient sound where it’s located. I had this discussion with many customers who were surprised this was the case until I pointed out that there was no way VOX could work if it wasn’t. --
73
Don
W6CZ
DM07bk


Mike WA0YCN
 

Colin,

Looking at the Audio board schematic, it appears that the IN-AUD line goes to a transformer.  I could see that loading the mic circuit in the radio.  I wonder if putting a capacitor instead of a straight wire on the jumper block might solve the problem?  What do you think?

Mike


Don Melcher
 

Can’t harm anything. That could be related to an issue I’m seeing. I connected my “homebrew” cable to the audio jacks with the radio on (dumb) and the radio turned off. Now the audio on mumble sounds like #*+£. May have been due to a ground loop? But I’m also “off grid” camping and using my own WiFi hot spot for the first time. I’ll be back to civilization Friday for a couple of days to sort out things in a known working environment and then back here Sunday. 



--
73
Don
W6CZ
DM07bk