[Elecraft] K1 Internally Generated Signal (Long Response)

[Mike Morrow]

Don wrote:

> While what you say about the K1 display indicating the transmit carrier 
> frequency is technically correct, I believe you are over-complicating 
> things.  The K1 (and all Elecraft products) properly calibrated will 
> indicate the transmit carrier frequency - so when receiving 10 MHz WWV, 
> the display should indicate 10000.0 kHz, and the transmit frequency will 
> be at that same frequency...

Hi Don,

I agree completely with the contents of your post.  But...the last sentence
quoted above is true **for the CW-only K1** only for the reception of a
**CW signal** that is producing a tone in the user's headphones that is
equal to the CW offset between the receiver zero-beat frequency and the
transmitter frequency.

I'll use an example.  Assume that a signal being received and the K1's
transmitted signal are both exactly on 10000.0 kHz.  The properly-adjusted
K1 display shows transmit frequency at all times (10000.0 kHz).  Next,
assume this K1's CW offset is 600 Hz.  In order to hear a beat frequency
(AF tone) equal to 600 Hz, the K1 LSB receiver's *zero-beat* frequency
must be 600 Hz *above* the received 10000.0 kHz signal...10000.6 kHz.
The K1's LCD indicates 10000.0 kHz, but a signal received on 10000.0 kHz
produces a 600 Hz beat note.  The only signal that would produce zero-beat
in this K1 is 10000.6 kHz...the receiver zero-beat frequency.

But as you have said, we do *not* define the K1 CW receive frequency as
the frequency of a signal (10000.6 kHz) that would produce zero-beat.  We
define it as the frequency of a signal (10000.0 kHz) that would produce
an AF tone equal to the CW offset (600 Hz).  We reach the same conclusion
that the 10000.0 kHz displayed is correct for both transmit and receive,
regardless of how we approach it.  :-)

OTOH, when we use this K1 to copy the LSB of WWV's 10000.0 kHz *voice* signal,
we have no mode switch on the CW-only K1 as we have with multi-mode receivers
that eliminates offsets in receiver frequency and displayed frequency.  We 
*must* tune the K1 receiver to zero-beat WWV's carrier (10000.0 kHz) in order
to copy its LSB voice signal.  Since the K1 LCD shows transmitter frequency
...0.6 kHz below the receiver zero-beat frequency...this K1 will display 9999.4
kHz as we copy those solar terrestrial indices at 18 minutes past the hour. :-)
If we transmit while zero-beat with WWV, anyone nearby who is listening to
WWV's LSB voice will hear a 600 Hz tone resulting from our 9999.4 kHz signal.

> If one follows the instructions in the manual, everything will 
> "fall into place" ... Done, no "fussing" - the key is that you tune
> a received signal to the same pitch as the sidetone - the rest is
> automatic.

We again have no differences.  Once in a while someone will come along
who thinks that setting the K1 sidetone in the menu will also set the
CW offset as well.  No such luck...that would be nice, but think of
the added complexity to make that happen in a K1!

I do not use Spectrogram...it's too sophisticated for me!  

It really wasn't my intention to raise a discussion of K1 transmit and
receive definitions and offset adjustments.  I just thought it necessary
to explain why the spurs I listed in the original posting,

> The spur just below  7000 kHz occurs at  7 x 999.875 =  6999.125 kHz.
> The spur just below 10000 kHz occurs at 10 x 999.875 =  9998.750 kHz.  
> The spur just below 14000 kHz occurs at 14 x 999.875 = 13998.250 kHz.
> The spur just below 21000 kHz occurs at 21 x 999.875 = 20997.375 kHz.

show up at zero beat on the LCD of a properly-adjusted K1 with 600 Hz
offset as follows:

> the  6999.125 kHz spur...zero beat should be  6998.525 kHz, 
> the  9998.750 kHz spur...zero beat should be  9998.150 kHz,
> the 13998.250 kHz spur...zero beat should be 13997.650 kHz,
> the 20997.375 kHz spur...zero beat should be 20996.775 kHz.

I could have said that instead of a zero-beat when tuned any of the four
frequencies shown above, my example K1 will produce a 600 Hz tone when
tuned to 6999.125, 9998.750, 13998.250, or 20997.375 kHz.  That avoids
the detail of CW offsets and sidebands.  But I can never tune for any
AF frequency just using my ears more accurately than tuning for zero-beat.
Dave Benson 15 years ago designed the firmware in his wonderful DSW-series
of mono-band CW rigs to require that the CW offset be set while comparing
two AF signals, one at 800 Hz, back and forth until they were both at
800 Hz.  Nasty work!  That and mode B-only iambic keying were about the
only things I did not like about the several DSWs that I built.

Thanks for your comments and for reading my approach.

73,
Mike / KK5F