[OZAPRS] Frequency drift of VK6UZ-4

[Fritz Berrer]

Hi All,

Today I have checked and retuned some of the oscillators of my FT-ONE, 
APRS gate RX. As to be expected with a unlocked crystal controlled TRX 
they were off frequency to varying degrees.

The 20.000MHz PLL Reference oscillator is now set to 20.000 000 3 MHz.

The 48.615MHz PLL Reference Oscillator can't be set any higher than 
48.614825,  probably aging of the crystal - the TRX is old enough for it.

The 54.280MHz PLL Local Oscillator is now set to 54.280 001. The three 
parameters are now set within original Yaesu specifications.

Any further VCO checks and alignments I can't do as I don't have the 
Service PCB extender kit.

A carrier at 10,1476 MHZ of  -73 dBm was then injected to verify 
reception and signal level of the RX set to 10,1476 MHz USB. The APRS 
gate is set for RX only!

The test equipment used is a HP8920A RF Communications Test Set and a 
HP5335A 12 digit counter, both with their external 10MHz Reference inputs

fed from a HP Z3801A Time and Frequency Receiver.

I will monitor the setup the next couple of days, especially the 
frequency offsets generated by the DSP TNC.

My personal view of a  great gate setup would be a DSP TNC, especially 
for RX,  and a RX or TRX capable of being driven by a GPS derived 10MHz 
reference clock.

Humble apologies to those who are aggrieved by my gates previously 
reported frequency offsets. Hopefully, today's activities corrected that 
situation

and the problem is fixed now,  if not the gate will be off air permanently.

73s and good DX

Fritz Berrer,

VK6UZ