[time-nuts] Vectron GPSDO Oscillator stranges...

[Burt I. Weiner]

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 <eb at 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.
biwa at att.net
www.biwa.cc
K6OQK