[time-nuts] Best Rubidium Frequency Standard

EWKehren at aol.com EWKehren at aol.com
Sat Mar 12 13:39:14 EST 2016


Corby
the M100 have conformal coatings but non of the M100's that I have tested  
had potted Lamp modules.
Conformal coating is a pain but so far all we have worked on is the coil  
section and scraper and brass brush did do the job.
 will send you off list pictures of a bad disassembled lamp  module.
Bert Kehren
 
 
In a message dated 3/12/2016 1:00:53 P.M. Eastern Standard Time,  
cdelect at juno.com writes:

Mike,

If  you are planning to buy "suspect units" with the intent to repair I
would  steer clear of the PRS10.

It is true you can pay for a factory repair  but having the schematics and
theory of operation only helps for particular  repairs.

This is because a lot of the alignment parameters are stored  in memory
and there are no instructions on these alignments and how to  store them.

An example: I had a unit come in for repair. It had no  output. The
customer, a professor, said a student applied a large DC to the  output.
The output is direct from an RF transformer. It burnt open the  winding.

I thought, how hard can it be?

I popped off a good  output board from a junker and installed it. I now
had an output but the  unit would not operate properly. Part of the output
go to other circuitry  that would need to be aligned to match. No way to
do that or store the  alignment! Bummer.

Luckily the transformer was a metal can type. I  opened it up and rewound
the tiny wire output coil and that restored the  unit to operation.

After that I sold my pile of defunct PRS10 units and  don't plan to
purchase any more.

For ease of repair the HP 5065A is  first, then the FRKL and H, these have
bog standard thru hole circuitry and  the manuals are excellent. Another
of the worst is the M100 as its cards  are conformal coated and the lamp
oven assy. is potted! As you mentioned  most of the later telecomm units
are surface mount and most have some sort  of microprocessor  involved.

Cheers,

Corby

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