[Elecraft] Calibration of BFO

[Rich Lentz]

-----Original Message-----
From: elecraft-admin@mailman.qth.net
[mailto:elecraft-admin@mailman.qth.net]On Behalf Of Don Wilhelm
Sent: Sunday, February 03, 2002 6:25 PM
To: Rich Lentz; Elecraft Reflector; Gary L Surrency
Subject: Re: [Elecraft] Calibration of BFO


 | Rich,
 | It sounds to me like you are using a single signal rather than a wideband
 | noise source ('dead band' noise will do) when using Spectgram.


 | Try using a noise generator or band noise (with no signals present) along
 | with Spectogram and I believe you will have better luck.

I set everything up as described in the KSB2 Manual.  I then optimized the
bandpass with spectrogram.  The Settings did not change much with the
Spectrogram optimization but are now about 0.30 to 0.50 different than those
provided in the manual.  This was needed to get the bandpass so that it
started at about 500 HZ and had the desired BW (2.20, 2.0, 1.9, and 1.0 KHz
on LSB/USB and 1.5, 0.70, 0.40, and 0.10 on CW and CWR) for the upper end
point.  LSB, USB, CW, CWR use OP1 for FL1 and USB/LSB use OP1 for FL2, just
like the manual recommends.

The frequency displayed in CALL Fill on LSB and CW are all the same. And
this provides me with absolutely no shift of the received signal when
changing filters (XFIL1 - 4). On the lower bands.

However, on USB and CWR the received frequency shifts between 10 to 50 Hz.
(After reading Tom N0SS post I played with it for about an hour and got it
down to about 10 Hz for most filters.)  This is probably not a big deal on
CW as long as I select the filter before I call CQ or before I answer one.
and probably not that big a deal even if I didn't.  The problem is mostly
with PSK when I am using a Soundcard TU.  My transmitted signal will be
offset by whatever the difference is because of this offset (the transmitted
signal only uses FL1) and this causes the qso to walk up the band when I try
and use a filter.

Should I give up on this and just use LSB for PSK? Don't have the problem
with RTTY as I use the normal convention for RTTY and don't use the
"reverse" function of the software to correct for using USB.


 | Yes, set the SSB BFO first - that is the BFO that is used for transmit.

I always start with XFL1 and they are within the set ability tolerance of
the K2 for the manual settings.