[Elecraft] re: K2

[Geoffrey Mackenzie-Kennedy]

I agree that the listening tests are essential. My approach without using 
Spectrogram was to measure the frequency response of the KSB2 and 
transmitter audio circuits combined, without compression, to get a rough 
idea as to what the BFO frequency should be. I then 'tweaked' the BFO 
frequency for 'good sound' using a direct conversion receiver with wide AF 
filter together with an audio recorder, while speaking into a HC-5 mic 
element part of a Heil ProSet Plus at different compression settings. The 
final 'tweak' of BFO frequency was done with the compression at the setting 
I use. Reports have been good using the stock 2.1 kHz filter.

BTW Ron, my K2/100 appears to be a 'Monday morning' version as a HC-5 in 
boom mike will drive it easily to full rated pep without an external audio 
preamp, but I do not use VOX with the K2.

73,
Geoff
GM4ESD


Original Message from: Ron D'Eau Claire <ron at cobi.biz>

I have found it impossible to reliably set my BFO frequency in the proper
place for SSB operation using only Spectrogram. Spectrogram is invaluable
for the first adjustment. I can get close with it, but to have audio that I
like, it's necessary to do the last step recommended in the KSB2 manual:
make the fine adjustments listening to my own signal. Not the "monitor", but
my actual signal on an auxiliary receiver.

Either that or work a buddy I trust and do the final adjustment "on the
air".

I found that the adjustment is much more critical using the stock 2.1 kHz
SSB filter bandwidth. While that bandwidth is ideal for maximum "talk power"
when signals are not strong, if the passband is just a little too low, the
audio sounds muffled. If it is too high the audio sounds "pinched", missing
important low frequencies.

I later opened up the bandwidth to 2.6 kHz bandwidth with the SSBCAPKIT.
That made the BFO alignment a lot less critical, but I still found that
actual listening tests for the final adjustments were essential.

Ron AC7AC