[time-nuts] Temex LPFRS-01 / LPRO rubidium reference repair

Bob Camp lists at rtty.us
Sun May 26 14:08:53 EDT 2013


Check the output frequency of the unit as it sweeps. I'd bet it's not quite making it to 10 MHz. Look for a trimmer cap near the master crystal. It should be possible to tweak it so the sweep makes it to either side of 10 MHz.


On May 26, 2013, at 1:43 PM, "Gerd v. Egidy" <lists at egidy.de> wrote:

> Hi,
> I bought a used Temex LPFRS-01 / LPRO from fluke.l on ebay. Unfortunately the 
> unit is broken and shows the same defect as was mentioned about a year ago on 
> this list: after warm-up it locks for a few seconds, but lock is lost again 
> after a few seconds. The lock output pulls low for a few very short intervals 
> afterwards, but that's it.
> I got a refund (but excl. the VAT I had to pay at customs), so it's just a 
> small loss. But of course I want to try to get this thing alive again.
> In the post last year it was mentioned that these used units suffered from some 
> kind of water damage inside. So I opened up the unit, but it looks clean 
> inside. Just very small signs of surface rust on the screws and connector.
> Here are some teardown photos I made:
> http://www.egidy.de/temex_lpfrs_lpro/
> I have connected the serial terminal. When using the "M" command for 
> monitoring, the unit returns detailed data. The rb signal level is too low on 
> my unit, see the screenshot at the link above.
> Was anybody here already able to fix such a unit?
> Any ideas what to look for or other insights?
> Kind regards,
> Gerd
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