[Elecraft] K2: SSB FL1 OP1 weaker audio output

[Ron D'Eau Claire]

It's easier to mis-read the spectrogram display than you might think.
Or, I should say, then I might have thought from my personal experience.

So, for a first troubleshooting step, I recommend setting the BFO
frequencies to the values shown in the SSB module manual and see if
things are better. Those frequencies might not be exactly optimum, but
they are so close that most ops can set them there and never no any
difference. 

In my manual (Rev B), the recommended frequencies for OPT1 FL1 are
4913.5 for the LSB and 4916.3 for the USB. 

Possibly your symptoms might be caused by a defective crystal (or bad
solder joint to a crystal or too much solder flowed into the pad and it
is shorting to the crystal case on the top of the board), but that ought
to stand out like a "sore thumb" on Spectrogram as well. 

There will be a BIG difference in the "sound" of the USB vs. LSB until
you install the "2nd Xfil Flattening Mod" described in the Elecraft
Builder's resources. John, KI6WX,developed a variation on the mod that
produces an even slightly flatter response. See Sverre's (LA3ZA)
outstanding page of Elecraft rig mods at
http://www.qsl.net/la3za/K2/mod.html, and scroll down to "Improved
version of 2nd stage crystal filter mod".  A point of possible future
interest: This mod has NO effect on your transmit audio, only the
received audio. The 2nd Xfil is a simple crystal filter at the OUTPUT of
the i-f amplifier that is active only in receive. But it has enough tilt
to cause a very obvious difference in the sound of the upper vs lower
sideband when listening. 

Ron AC7AC
K2 # 1289


1. The audio output of the SSB FL1 OP1 filters are much weaker than FL2,
FL3, 
and FL4.  
2. Also when listening to WWV or CHU, USB is louder (6 db) than LSB.  

Transmit seems OK and looks clean on oscilloscope, Talked with a
lighthouse 
station yesterday and got 549 in LSB, but used FL2 for receive. 

Here's action taken so far:
1. Recalibrated to WWV. I'm at least within 20 Hz.
2. Read up and used Spectrogram software and adjusted BFO. It looks
pretty 
good. No obvious problem.
3. Have *not* rechecked SSB hardware yet.

Any ideas? Any one had a similar problem? 
73 & Tnx in advance,
Jim WA2UMP K2:2679