[Elecraft] TCXO

[Wes]

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
>