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

[Don Wilhelm]

John,

If you can find an electret microphone element, you should be able to 
replace the mic element in your MH3 microphone.

73,
Don W3FPR

On 10/8/2017 4:00 AM, John H Farmer wrote:
> 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.
>