[Elecraft] KX3 SSB ALC Mic Gain - a new problem

[John H Farmer]

Dear Don & Group,

Thanks for your suggestions.  After some more exploration, I think the problem is the MH3 and here's why:

Backing down the mic gain didn't help and neither did a firmware reload.  I was suspicious of the MH3 being at fault, as the ALC / Mic gain adjustment remained perfectly consistent and reliable in data modes.
I then remembered I had a Yamaha CM500 headset lying in a drawer. I made an adapter (thanks Walter, K6WRU for your very helpful and clear webpage describing the adapter cable) I plugged it into the KX3 mic socket and lo and behold, the KX3 plays perfectly with it - the ALC shows 5-7 bars with a mic gain of 35-37 and I get the expected RF output, which is exactly how it used to be with the MH3.

I took the MH3 apart and mechanically it all looks sound, no loose wires or dry joints, and I checked that there is indeed a bias voltage on the mic + ( tip) wire at the microphone.  There's not much to go wrong in there, so I wonder if the electret element has died.

I'll order a replacement MH3, because even though the CM500 headset works well, I like using the handmic and I've always had good audio reports using it.  

Thanks everyone for your interest.

73,

John
VK7JB

-----Original Message-----
From: Don Wilhelm [mailto:donwilh at embarqmail.com] 
Sent: Sunday, 8 October 2017 11:09
To: Dr John H Farmer <opensilence at bigpond.com>; elecraft at mailman.qth.net
Subject: Re: [Elecraft] KX3 SSB ALC Mic Gain - a new problem

John,

Try backing down the MIC Gain setting to something low or mid-range.
If you get the mic voltage too high, the mic amplifier detects that and inserts attenuation that will shut the audio from the mic down.

So bottom line, start with a low MIC Gain setting and increase it until you see 5 to 7 bars on the ALC meter.

73,
Don W3FPR

On 10/7/2017 7:53 PM, Dr John H Farmer wrote:

> Yesterday, I noted that I had no RF output on SSB and find that now I 
> get no ALC indication until the Mic gain is advanced to the maximum setting of 80.
> Nothing else has changed in my
> 
> setup.  I've checked that MIC Bias is set to ON and the TX EQ settings 
> have not changed.  I've also checked and there is indeed a bias 
> voltage on the Mic socket.