[Lowfer] R75 Frequency Accuracy

[pbunn at patbunn.com]

I have an older R75 that I bought 15 years ago and rarely used until 
recently.

I use it for LF work with a home brew RX up-converter and it has worked well 
but frequency accuracy has been quite a bit off. I attributed this to my up 
converter being a bit off and combined with the R75 error combining to cause 
the problem.

Recently I have added a Trimble Thunderbolt and have begun to find out where 
the error is. My up-converter is now phase locked to the GPS 10 Mhz output 
and yet my receiver is still 8 Hz off .

Is this more than might be expected from a typical R75 or normal. It seems 
somewhat excessive to me. I plan to add W1VDs circuit to add GPS control to 
the R75 but want to make sure that the R75 is not excessively out of spec.

The sound card was calibrated with a GPS disiplined 1KHz signal and found to 
be within .1Hz using ARGO before calibration so the error is not there.

Any comments would be appreciated.

Pat
N4LTA