[time-nuts] FRK-L Rubidium

jmfranke jmfranke at cox.net
Fri Feb 8 19:51:58 EST 2013

How long do you let it run? Does the crystal oscillator oven get warm? If 
you let it run more than 15 minutes, and the oven gets hot, the next thing 
to check is the output frequency range as the tuning voltage sweeps. Not 
having a frequency counter hurts but there are other methods. One is to use 
WWV on 10 MHz. You should hear the output slowly sweep through WWV, first on 
one side of zero beat and then through zero beat to the other side. If the 
beat stays on one side, the VCO needs tweaking to get the sweep somewhat 
symmetrical about the 10 MHz WWV signal.

John  WA4WDL

From: "Garren Davis" <garren.davis at qlogic.com>
Sent: Friday, February 08, 2013 7:12 PM
To: <time-nuts at febo.com>
Subject: [time-nuts] FRK-L Rubidium

> Been lurking on the list for a while and finally started playing with a 
> FRK-L  rubidium frequency standard. I've had
> this thing for a while and decided to power it up and see what it would 
> do. I do not get a lock. What I see is the
> lamp voltage at 8.54 volts which I think is good but the xtal control 
> voltage swings from 2 volts to 15 volts and back
> to 2 volts and keeps cycling like that. I don't have a good frequency 
> counter but I have a 3 Ghz 40 G/sample scope
> and it shows that the 10 MHz signal is there. I just don't know how 
> accurate it is. Has anyone seen a problem like
> this? Can anyone point me to a place to start debugging this? I have the 
> schematics and test tools. I am a test
> engineer so I'm not afraid to poke around in the guts of this thing. 
> Hopefully I can get this thing running. I also
> have a thunderbolt that I'll get running this weekend. I don't know how 
> deep I'll get into this time-nuts thing but
> I have this nice scope and a Wavecrest sitting in my garage and I'd like 
> to put them to use. Any help would be appreciated.
> Garren
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