[Elecraft] Settings for CM500 on K3?

[Jim Brown]

On Tue, 14 Sep 2010 09:07:06 -0700 (PDT), Wes Stewart wrote:

>You need an oscilloscope.

Yes. Let me offer an explanation of what I think might be going on 
with your PEP meter. First, ANY meter circuit, digital or analog, will 
have some time constant, so there will be SOME averaging. I have a 
couple of wattmeters that claim to read PEP, but neither of them is 
ideal at doing so, because they are not fast enough. 

Second, when you use the TXEQ settings I recommend, you are getting 
rid of the wasted talk power in the lower octaves, and the CM500 
itself produces less wasted talk power in those lower octaves than 
many other mics. All of your TX power goes into the midrange, which 
the brain uses for speech intelligibility. The power in those lower 
octaves, because it is lower frequencies, will make a strong 
contribution to the averaging that the PEP meter is doing, so when you 
reduce that low octave power, the meter will read lower. 

So, like Wes says, you need a scope. 

Let me repeat my advice on setup. BEFORE setting front panel mic gain, 
go to TXEQ and turn down the two lowest octaves as far as they go (-16 
dB). Leave all the other octave bands set flat (OdB), or set them to 
0dB if you have changed them for some other mic. Set the Mic Gain in 
the menu to Low. NOW, follow the instructions in the K3 manual for 
setting mic gain (the proper ALC reading when you talk with 
Compression turned off), then turn up Compression to get the desired 
amount as indicated on the front panel meter (but don't go more than 
10dB of compression on peaks). THEN, get some on the air reports from 
a "good listener" who has his/her radio set for wide SSB RX bandwidth 
(a wide IF setting), and tweak the TXEQ settings if needed for YOUR 
voice. If you have a deep or muddy voice, you might want to roll off a 
bit of the third lowest octave and/or increase the two highest octaves 
by a few dB. 

BTW -- the only difference between setting up this mic and any other 
mic is the TXEQ settings that correspond to the response of THAT mic 
and YOUR voice, and the Mic Gain setting for that mic. 

73, Jim Brown K9YC