Just to give the group and update... The Caritronic switching supply
in the DATUM 9390 completely failed this afternoon, so obviously it
was on its last leg. I did find Caritronics and they are very nice
people, but expensive. My friend Stu, K6YAZ told me he had a Cisco
power supply model ADP-30RB, which puts out +12 VDC at 2.0 AMPS, -12
Volts at 0.200 AMP, and 5 Volts at 3.0 AMPS. Sounds like just what I
need and it's about the same size as the DATUM outboard 12 Volt
supply that comes with the 9390. He brought it over this evening and
I was going to test it and then connect it up and see if that would
solve my problem. I quickly discovered however, my wife had other
plans for me for this evening. I may be able to do a little in the
morning, but most likely not till Monday afternoon. The ADP-30RB is
readily available on eBay (I bought two more that are guaranteed for
a total of $12.00). I'll let you know how this progresses.
Burt, K6OQK
Ed,
Thanks for you suggestions. I took a look at the control line and
saw about 100 mV of "grunge" and then took a look at the +12 volts
going to the oscillator and saw about 2 volts of the same stuff. I
then went and took a look at the DC to DC Converter's output and say
the same about 2 volts of grunge and about 1 volt of grunge on the
-12 Volt line. The 5 Volt line looks fine. I need to cobble up a
+/- 12 Volt supply (ref to ground) to substitute the on board DC to
DC Converter and see if that solves the problem.
The converter is made by a company called Caritronics. Never heard
of them. I'll see what google tells me. I don't really need the DC
to DC converter as I never run the thing off of 12 Volts, but I've
thought about it.
Thanks,
Burt, K6OQK
Date: Thu, 10 Jan 2013 10:48:38 -0800
From: Ed Breya <e...@telight.com>
Subject: Re: [time-nuts] Vectron GPSDO Oscillator stranges...
Can you completely swap the Vectron crystal oscillator modules between
the Datum units? Maybe the fault lies in the other part. If they are
GPSDOs, each must have a DAC somewhere driving the tuning control line
to the VCXO, The 10 kHz may be the DAC serial data rate, or a PWM rate
for fine tuning. A fault in that area could cause the sidebands. Maybe
you really did hear "data." If you can hang a fairly large (several uF
or more) plastic capacitor on the tuning line without causing the whole
thing to oscillate, you may be able to observe a decrease in the
sideband amplitude - a sure indicator that the tuning signal carries the
problem.
Ed
Oops - regarding that capacitance test on the tuning line, I meant to
say "up to several uF or more." You can start small to see if there's
any effect. It all depends on the impedance of the tuning line
circuitry, and the existing amount of filtering - you may need quite a
bit of C to swamp it out and show a noticeable effect. You're not
looking for necessarily "normal" or perfectly-settled operation under
the test condition, just the relative effect on the sidebands.
Ed
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
b...@att.net
www.biwa.cc
K6OQK
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