[Premium-Rx] New meas. on Racal 9400 OCXO

[Stein-Olav Lund]

Hello again,

Thanks George, I agree the oven current follows a typical pattern for a
proportional loop,

and the freq is stable after some 10-15 min.

I have done some more measurements on the reference oscillator.

I was suspecting the instrument might have been tampered with after
decommission, as the o/p level was badly off

(unskilled soldering of o/p cable) This was easy to correct, and the
level was then right on.

Also only four of the total 20 screws on the oscillator screen box were
in place, another tell-tale)

I decided I would dare to adjust the trimmer on the 9400 OCXO and
started turning clockwise.

The freq started slowly to go down, after 5 turns I had 5.000 MHz on the
counter.

As I can deduce, a person has adjusted the oscillator before it had
reached stable temperature,

it showed only about 1.5ppm misreading at 3-5 min after switch on!

Later I will borrow a new  R&S SMB 100A signal generator and compare the
readings.

 

73's

Stein, LA9QV