In my K3S, since I have no need for a second RX, I've installed a TMP cable from
the ref board to a BNC in a spare hole in the rear panel. This gives me a point
to measure the ref osc frequency with an external counter, with the unit all
buttoned up. For that I use a FA-2 counter by BD7BTL that is referenced to a
BD7TBL GPSDO. Using a 1 Hz gate time I can get samples every 1.12 seconds, with
mHz resolution, over a serial bus.
I did a 10-minute run from power on at room temperature. Only the RX was
powered (no transmitting) Putting the data into Excel and graphing it I see an
initial increase in frequency of a couple of Hz and then it turns around and
drifts down, relatively rapidly at first then the rate slows to near zero.
Total drift was about 23 Hz, but this is at (near) constant temperature and says
nothing about temperature compensation.
Wes N7WS
On 3/31/2022 4:35 PM, Andy Durbin wrote:
"What are the uses for the TCXO option in a K3? Why would I want one?"
TCXO means "Temperature Compensated Crystal Oscillator". You need one if the
frequency drift caused by rig temperature change causes a problem at the frequencies, and
with the modes, you operate. Leave the rig powered all the time in a temperature
controlled environment and you may not need one. If you turn on a stone cold rig and
expect to operate before the temperature stabilizes then you probably do, especially
with narrow band digital modes.
Temperature Compensated tells you nothing about the accuracy of the oscillator frequency.
It just says how much the frequency will change with temperature. I don't know what
TCXO are compatible with the K3 but there are some quite nasty "TCXO" being
purchased by Kenwood TS-590 owners. Frequency stability with temperature is only one
measure of a TCXO. Spectral purity is at least as important.
Andy, k3wyc
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