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" <[email protected]>
Sent: Friday, February 08, 2013 7:12 PM
To: <[email protected]>
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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