...@febo.com] On Behalf
Of Bob Camp
Sent: Saturday, February 09, 2013 10:14 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FRK-L Rubidium
Hi
Let it run for a couple of days. If it's still up at 11V, I'd tweak it down
a bit.
Bob
On Feb 9, 2013, at 12:38 PM
measurement
Subject: Re: [time-nuts] FRK-L Rubidium
Hi Garren,
Yes, you're right. Silly me, I made the mistake of believing what was written
in the manual which says 2-12 volts. When I measure it, I see
~2-16 volts. Let that be a warning to you. This isn't the first time that
manual has led
much easier. But first
check that there is power to the heater.
- Original Message -
From: Garren Davis garren.da...@qlogic.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Monday, February 11, 2013 12:01 PM
Subject: Re: [time-nuts] FRK-L Rubidium
Hi Ed,
The voltage swings from 2v to 17v. Doesn't that mean I have about 4 to 5 volt
margin if it's locked at 12 volts?
I had to adjust the capacitor out almost all the way to get it to lock. If I
need to adjust it more can I use the C-field adjustment or should I stay away
from that?
Bob,
That was my thoughts also. The GPS receiver and serial connection to the
computer are working so I know the power connections are ok. I think I bought
this through a group buy from someone on this list and they said all were
tested before they were shipped. Maybe it was just time for the
Hi
The OCVCXO tuning voltage adjust on the 10 MHz simply centers up the sweep
process. It has no impact on the output frequency once the unit is locked up.
The C field adjustment sets the Rb on frequency once it is locked. It is only
used to set the unit on frequency.
Since the range on
Hi Garren,
Yes, you're right. Silly me, I made the mistake of believing what was
written in the manual which says 2-12 volts. When I measure it, I see
~2-16 volts. Let that be a warning to you. This isn't the first time
that manual has led me astray! I should have known better.
Did you
Hi
DAC clamped at -5 volts suggests that the TBolt has issues. First thing to
check is the -12 volt supply. If it's missing, the DAC will indicate -5 on the
screen and be sitting at 0 in real life. There are a couple other things in the
DAC circuit that can make it malfunction.
Bob
On Feb 9,
Hi
How old is the FRK? Does it look like it's been run without a heat sink for
very long? They tend to get flaky if run for a while (many months) without heat
sinking. There's nothing mysterious about it. The MTBF of the parts gets
noticeably worse as the unit heats up.
Bob
On Feb 9, 2013,
Thanks for the reply.
I found that the 12v current is only 60ma. I suppose that means the Osc. heater
is not working. I'm not having much luck with this time nuts stuff. First the
FRK and now the thunderbolt. Guess I'll start looking for another one.
Garren
On Feb 9, 2013, at 6:01 AM, Bob
Hi
The +12 V supply at 60 ma likely means that the heater in the OCXO is not
working. If you have 60 ma on the -12 V supply, it's pulling about 10X more
than it should.
Bob
On Feb 9, 2013, at 10:01 AM, Garren Davis garren.da...@qlogic.com wrote:
Thanks for the reply.
I found that the 12v
Found my problem with the FRK. R31 on the Osc board was burned and open. This
was caused by a shorted C16. Replaced and it is now locked. The lock voltage is
12.7v. Is this good or should it be lower?
Garren
On Feb 9, 2013, at 6:10 AM, Bob Camp li...@rtty.us wrote:
Hi
How old is the
Hi
Let it run for a couple of days. If it's still up at 11V, I'd tweak it down
a bit.
Bob
On Feb 9, 2013, at 12:38 PM, Garren Davis garren.da...@qlogic.com wrote:
Found my problem with the FRK. R31 on the Osc board was burned and open. This
was caused by a shorted C16. Replaced and it is
Since we're offering up faults for the FRK, I'll add one that I've
found: there's a CMOS 4060 oscillator that should go off at 8.128 kHz,
set by an adjust on test R. If this drifts off enough the lock will
never happen. It provides the FM frequency for the synth.
Dan
usually
too hot to touch). I found that the Darlington transistor that is used as a
oven heater was bad. Replacing the transistor fixed the problem.
Tom
--- On Sat, 2/9/13, Dan Rae dan...@verizon.net wrote:
From: Dan Rae dan...@verizon.net
Subject: Re: [time-nuts] FRK-L Rubidium
Hi Garren,
Congrats on your repair. Since the crystal control voltage is spec'd as
~1 to 12 Vdc, you're apparently holding onto lock by the narrowest of
margins. You definitely want to adjust the oscillator to bring that
voltage closer to the middle of it's range.
Ed
On 2/9/2013 11:38
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
Hi
First thing to check is indeed the frequency of the 10 MHz oscillator. There's
a good chance it's simply aged far enough that it will no longer lock up. If
the drift isn't super far, the oscillator can be adjusted. The TBolt and a good
counter will tell you everything you need to know about
I've let it run for hours and it gets warm. It has a heat sink and it all gets
warm. There are two adjustment screws. One under the heat sink and one on the
side of the unit. Is one for the vco and the other for the C-field?
On Feb 8, 2013, at 4:53 PM, jmfranke jmfra...@cox.net wrote:
How
Hi Garren,
I suggest that you get the Thunderbolt working first. Without a known
10 MHz source to compare to, you're flying blind. Once the Tbolt is
running, you should be able to check the frequency of the FRK by feeding
both into your scope. Trigger on the Tbolt and watch what the FRK
Well for some reason the 10 Mhz stopped working on the FRK. Don't know why.
Started up the thunderbolt. It acquired satellites but then the DAC voltage
went to -5 volts. It's been there for an hour. Will this change after the unit
stabilizes? Going to bed. Will check it tomorrow.
Garren
Do you have the service manual? If not, get it here...
http://www.ko4bb.com/manuals/index.php?dir=05%29_GPS_Timing/Efratom
As I recall there's pretty good trouble shooting in the manual. Several
years ago I fixed an FRK-H that wouldn't lock. The crystal osc had
drifted enough that the trimmer
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