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:donw...@embarqmail.com]
Sent: Sunday, 8 October 2017 11:09
To: Dr John H Farmer <opensile...@bigpond.com>; elecraft@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.
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