[Elecraft] KSB2 and microphone gain

[Piet Meindertsma]

I just completed a number of mods for the SSB module, described by KI6W 
('Improving the Performance of the KSB2'), by DF7KHK (increase of audio 
compression) and by DJ3FR (change R8 and R10 to 560 Ohm). After these 
modification I played a bit with the radio. During a contest last 
weekend I noticed that the SSB signal is fine. When listening to my own 
microphone signal (SSBA set to BAL), I noticed that the audio level 
varies by the band chosen (listening to the audio with a headphone). As 
with the SSBA set to BAL the output of the KSB2 is directly fed into the 
IF of the K2 receiver, I would expect a more constant level. My test 
results (using the S-meter as an indication for the signal strength) below:

band      signal strength
160m      S9+40
 40m      S9
 30m      S9
 20m      S7
 17m      S8
 15m      S9
 12m      S9
 10m      S9

As you can see:
the signal is very strong when the K2 is set to 160 meters and 
relatively weak at 20 meter. I am not (yet) complaining, just very 
curious how this difference can be explained.
(When I have some time again I want to perform the same tests, but than 
transmitting into a dummy oad and using an Icom 706 as a monitor receiver).

Piet, PA1PM