gps discipline sa44/tg44a pair

Is there a way to use 10 MHz GPS to discipline a sa44/tg44a pair? Apparently the sa44 alone can be done.

Unfortunately the TG44A only has a 10 MHz output. You can use this for 0 ppm relative accuracy between the TG and SA, but for absolute accuracy, you would need a TG124A or VSG60A instead of the TG44, both of which can accept a 10 MHz input. The phase noise on the VSG60A will be much, much better than the TG124A.

Can I get a copy of schematics for the tg44a? I can put on an external reference or even manage to pull the existing oxco or whatever oscillator with an external GPS derived reference? I don’t mind taking the chance of hacking the tg44a.

I can’t provide schematics, and opening the case will void the warranty. But there is a 10 MHz TCXO on the board. We have a software correction for its measured frequency though, which might make it challenging to do what you want.

The correction can be adjusted in Spike, apparently. So if I got brazen and put in a 10 MHz external source the correction can be made. I think my warranty is long expired, I’ve had the pair since their first introduction. The sa44 does not have the front end amp in it, and dc blocks are external to both units. I have to say that spike is probably one of the best apps I have ever used.

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