[Kenwood] TR-7730 TX off freq.

[fredv]

Hi all.

Well I'm stumped. I adjusted the trimmer on the 46.1666 crystal and here
are my results:

If you have the dial readout set to any odd frequency, say 146.555,
you can adjust the TX perfectly. Actually I had not noticed it but it
was always
perfectly on frequency on the odd frequencies. Its just that I usually
use 146.550.
When you then adjust the dial to a even freuency, say 146.550, the TX is
off just about
5kc low.  The trimmer for TX has no effect on the even frequencies at
all. I even messed
up the TX trimmer for an odd freq by 9 kc. and the even freq was still
off only
5 kc. So it seems the even frequencies must have some other reference?
That was why when I transmitted on 146.555, thinking my tx was then
going to be
146.55, it was really 146.555, so then I was 5kc too high.

Fred
N1DEC


> Tweak the 46.1666 crystal. Its third harmonic probably heterodynes the
> transmit frequency down to something slow programmable counters can
> follow. The 42.6 crystal does the same for the receiver but puts the
> receiver 10.7 MHz. below the transmitter. The 10.24 crystal is divided
> by 1024 in the synthesizer to make a 10 KHz reference. The 10.245
mixes
> 10.7 MHz first IF to 455 kHz second IF.