K2: Transmitting a little low

[Jay-86]

It's been so long since I studied the manual, maybe someone can refresh
the step I need to do (so I don't have to relearn the complete alignment
process).  On lower SSB I'm being told I'm 100 hertz low transmitting,
but the receiver is just fine.  I don't want to mess up my cw settings
since everything is perfect (for me).  Any help moving my transmit sig
up 100 hertz (w/o using XIT!) would be appreciated.
Jay, W6JDB
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[Don Wilhelm-4]

Jay,

I suggest that you review the K2 Dial Calibration article on my website
http://w3fpr.qrpradio.com and then do a full calibration run including
the SSB filters using Spectrogram.

If that does not correct it, then re-do the calibration.  The VFO and
the BFO are about the only thing that could effects you describe.  Be
quite careful to place the low frequency corner of the SSB filter
passband at 300 Hz and you should be 'on frequency'.

You may want to listen to yourself in another receiver when you are done
rather than depending on reports from others on the air.

73,
Don W3FPR

Jay wrote:
> It's been so long since I studied the manual, maybe someone can
> refresh the step I need to do (so I don't have to relearn the complete
> alignment process).  On lower SSB I'm being told I'm 100 hertz low
> transmitting, but the receiver is just fine.  I don't want to mess up
> my cw settings since everything is perfect (for me).  Any help moving
> my transmit sig up 100 hertz (w/o using XIT!) would be appreciated.
>
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[Kevin Cozens-2]

Jay wrote:
> On lower SSB I'm being told I'm 100 hertz low transmitting,

I wouldn't go solely on the word of an off-air report about being off
frequency. The only way to be sure is to measure your transmit frequency. If
the radio of the other operator was 50Hz high and you are 50Hz low, they may
report you are off by 100Hz.

It doesn't hurt to double check the calibration of your radio if you have any
doubts. In the case of the K2, you may only get accuracy to +/- 20 Hz or so
anyway.

People are getting too spoiled by digital readouts and expecting absolute dead
on accuracy of transmitted frequency.

--
Cheers!

Kevin.

http://www.ve3syb.ca/           |"What are we going to do today, Borg?"
Owner of Elecraft K2 #2172      |"Same thing we always do, Pinkutus:
                                 |  Try to assimilate the world!"
#include <disclaimer/favourite> |              -Pinkutus & the Borg
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[David Woolley (E.L)]

Jay wrote:
> ...someone can refresh the step I need to do (so I don't have to relearn
> the complete alignment process). On lower SSB I'm being told I'm 100
> hertz low transmitting, but the receiver is just fine. I don't want
> to mess up my cw settings since

Provided that you use filter 1, configured as the SSB board filter, for
receive, the frequency determining parts of the system are the same on
transmit and receive, so if the frequency display is the same, which it
will be unless you use RIT/XIT or split, there is no official adjustment
that would work here.

If you use another filter, for receive, and it was not calibrated at the
  same time as filter 1, the rig's idea of the the IF frequency for that
filter could be wrong.  In that case, it should be fixable by
re-calibrating the filter without making any real change (although, if
the calibration is that far off, the filter may no longer be at the
correct position in the passband).  To just re-measure the required BFO
voltage and corresponding frequency, you need to tweak the filter up one
and then down one, so that the rig registers a change.

You will also need to do a PLL calibration, unless you are certain that
the 4MHz oscillator has not changed since you last did that (including
temperature changes).

Using a different filter will also produce a small error, because of the
resolution limits of the VFO and BFO, but that should be of the order of
10Hz, or less, not 100Hz.

I guess other possibilities are:

1) one of you is misjudging the zero beat frequency;

2) poor power supply regulation is causing a frequency shift;

3) RF on the chassis is getting ito the the frequency tweaking varicaps
and causing a shift.


> everything is perfect (for me).  Any help moving my transmit sig up 100
> hertz (w/o using XIT!) would be appreciated.

--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to
Elecraft products and more general topics related ham radio"
List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm>
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