[time-nuts] Need help with FTS1050A

[AC0XU (Jim)]

Time-Nuts:

I partially fixed an FTS1050A by replacing a bad +-15V regulator module. Before the replacement, the unit could not be adjusted on frequency. After replacement the oscillator is on frequeny mid-range of the digital adjustment pot. I thought it was fixed but....

However, the ADEV is horrible, around 1E-7 over wide ranges of time scale. I note that the 22V going to the RF buffers is unsteady, going up and down around 0.25V every few seconds. Maybe there is a correlation?

I haven't found schematics for the FTS1050A in any of its many variations. I have noticed on this and other FTS1050A units that the 22V goes up to around 30V for a minute or so when the unit is first powered up. Is this an attempt to improve oscillator warm-up?  In any case that seems to work o.k.

Once warmed up, the 22V line remains erratic indefinitely on this particular unit. I am guessing a bad electrolytic somewhere. a marginal 22V regulator transistor on the back panel, or maybe something wrong with the oscillator heater. Any thoughts?

Thanks-
Jim