[time-nuts] Odd FTS 4060 Behavior
jmiles at pop.net
Sun Jun 13 22:40:31 UTC 2010
Interesting. Solder and gold don't like each other very much, and even the
more respected manufacturers don't always seem to appreciate that, when they
rely on a soldered connection to provide some mechanical stability. This
isn't the first time I've heard of FTS oscillators behaving oddly, so it'd
be great if they could be fixed this easily. Pinning down an exact cause
might be helpful to others if the problem shows up again.
One other thing that can go wrong with OCXO testing happened to me last
night. A high-grade unit that I'd borrowed was exhibiting some severe
frequency jumps of around 6-8 Hz, visible on a couple of different counters.
I decided to watch it for awhile in case it was still settling down from
being moved, and work on some other things. Before long, I started seeing
flaky behavior from other equipment such as a signal generator and spectrum
analyzer, and the lock indicator on a 100 MHz PLL being burned in on the
rack also started flashing intermittently.
Turned out that I had accidentally left my 10 MHz distribution amp hooked up
to a 'public' Thunderbolt that's used for testing remote access via Lady
Heather and not normally connected to anything. Someone had logged in,
probably thinking they were talking to their own local unit, and set the
Thunderbolt's position manually to a rooftop near Sydney, in New South
-- john, KE5FX
> The OCXO out of the 4060 and connected to a bench power supply with no
> tuning voltages applied had to be trimmed to get on 10 MHz.
> After a while it started temporarily jumping to -1.4E-07, which could be
> reversed or provoked by knocking it on the head.
> I decided to disassemble it and found a neatly built dewar insulated
> oven inside. I just didn't like the solder joints of the gold plated
> edge connector pins on the two PCB's inside the oven that had separated
> on the component side from some of the pins. So, I resoldered them and
> stuffed everything back in the jar. After powering it up, I had to trim
> it back by about the same amount it needed in the beginning when it
> appeared to be in 'failure mode'. At the moment it appears to be no more
> vibration sensitive, but that doesn't necessarily mean I got it fixed.
> Now it's back in the 4060 (without readjusting it, the tuning voltage is
> almost exactly at center scale!), and we shall see if it behaves or not.
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