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R2400 unstable

This forum exists for the purposes for discussing service monitors (This includes but is not limited to Motorola, HP, Aeroflex, GD, etc). Additional topics allowed include test procedures, interpretation of test results, where to find information about specific tests, antenna VSWR, return loss testing, duplexer and filter alignment, etc.

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leaper54
New User
Posts: 14
Joined: Thu Jul 31, 2014 5:35 am

R2400 unstable

Postby leaper54 » Mon Jul 03, 2017 8:59 am

I have managed to adjust the TCXO to correct frequency error. Thank you for the prior comments back in April.
In general, the unit works fine for ham radio work. The frequency error still seems to jump around quite a bit.
Both the Freq. Error and Deviation bar graphs swing + / - around zero. I'm thinking a power supply issue?
Anyone seen this before? On my Freq. counter, the source is very stable.

jry
Posts: 320
Joined: Fri Feb 06, 2004 3:14 pm

Re: R2400 unstable

Postby jry » Wed Jul 12, 2017 7:57 am

I would think about updating the fan if it's the original brush type. ( it was a really good fan in its day ...about 25 years ago )

The size is standard and the newer versions are brushless.

Would also add some additional filtering like an LC or RC filter in the fan power leads. The value of R would be low ...you may want to do some testing so you do not drop too much of the 12vdc to the fan. The R value depends on the fan you select and it's current draw. Higher CFM fans will pull more current.

Bigger the cap the better ...1000uf 16VDC but anything will help isolate the noise from the fan which shows up as jitter in the synthesizer output.

This helps remove any residual FM and AM on the gen and receive as well

leaper54
New User
Posts: 14
Joined: Thu Jul 31, 2014 5:35 am

Re: R2400 unstable

Postby leaper54 » Sat Aug 26, 2017 7:40 am

Thank you all! I simply added a 1000uf cap on the fan leads, and it is MUCH better. The fan had already been replaced with a brushless model. _ have ordered an inductor to add also.


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