Re: VCTCXO model and the issue with crystal aging - 2LO off the DAC range


igor-m <mikki@...>
 

I applied my TCXO mod above and it seems it works!
I removed the R11 short and soldered in a 10k smd resistor at the pads of the not populated trimp pot.
The 10k resistor is easily accessible now as it sits on "top side" of the DDS pcb when mounted in.
I also covered the TCXO and the pcb from the opposite side with 3mm piece of foam (against the "banana effect").

The measurement is as follows now:

Service menu:
HEX        FREQ 2LO
00            124.031.190
7F            124.031.640
FF            124.032.120

I get the exact 2LO frequency of 124.032.000 Hz with E6 hex.

While measuring at the dummy load (with TX RTTY method) I get my 21.200.000 with 89% set in OTH menu #51.

73 Igor

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