[time-nuts] Looking for Z3801 OCXO
John Ackermann N8UR
jra at febo.com
Fri Feb 5 09:22:49 EST 2016
Thanks, Warren. That's a very nice solution! I have a unit on the way from another time-nut, so I should be set.
I'm pretty sure the problem with the old unit is just aging as I watched the EFC creep for months toward the limit. I bought two units at the same time (long, long ago) and though they had similar running time, this one always had EFC values far higher than the other one, which is still running fine.
> On Feb 5, 2016, at 1:39 AM, ws at Yahoo <warrensjmail-one at yahoo.com> wrote:
> If it is off very far the first thing I'd suspect is the inner oven.
> Assuming the freq is still stable and low noise, one option is to rewire it, and make the freq adjustment accessible.
> Removing the original inner wiring wrap also provides many other advantages, and no down side that I've found.
> After modifying several, it now takes me about an hour to do.
> From the outside you can not tell that it has been modified, unless I change the crappy little blue shielded RF and EFC cables that it originally comes with, which I now always do.
> It takes about five minutes on a correctly modified unit to readjust the frequency. The adjuster nut and hole is accessible after temporarily removing the bottom outer cover, thru a 3/8 inch access hole drilled in the bottom of the outer oven that is placed *under* the bottom heater flap.
> It is easy to adjust thru the bottom of the unit and can be done without powering down or disturbing the oscillator or either oven's power.
> Picture attached of modified inside cabling, before the two shielded cables are added.
> No mess. Any goo gets cleaned up with alcohol or thrown away.
> John Posted:
> "Looking for Z3801 OCXO"
> I have a Z3801A whose oscillator has aged out of correction range, and
> thus throws an EFC alarm.
> Anyone have a still-in-range double-oven HP10811 from a unit that died
> for another reason? If so, I'd be happy to acquire it.
> (I tried disassembling one of the double-oven 10811s years ago and found
> that extracting the oscillator can from the outer oven, heater, and
> gooey insulation made such a mess that it would be impossible to
> <Modified 10811.jpg>
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