You found the secret. There is no RF wiring to the crystal. The oscillator
frequency is determined elsewhere, with a free running multivibrator that is
approximately on the right frequency. All this talk about precision is
baloney; the circuit is stable enough to fool even the experts.
And it's not even April 1 yet.
Bob
On Tuesday, December 12, 2017, 9:32:44 AM PST, Ed Palmer
<[email protected]> wrote:
It sounds like yours is different from my 8601. How old is yours? From
the label inside it looks like mine is from 1983.
Internal pictures are here:
http://s701.photobucket.com/user/edpalmer42/library/Oscilloquartz%208601%20Oscillator
If you click on 'view as story' you'll see some comments that I added to
the pictures.
Ed
On 2017-12-12 11:00 AM, <[email protected]> wrote:
> Emailed Oscilloquartz that now has another name: Advaoptical... This in my
> capacity as aresearch engineer at Onsala Space Observatory.And the oscillator
> is at my work bench. Nothingprivate/hobby about this.
> The answer was that since we do not have a service agreement,they would not
> disclose any information.
> (Compare this with Keysight who has a free downlad area for oldmanuals. IMO
> the Keysight approach benifits their businessin the long term).
> So...
> I went along and started to dissassemble the 8600-3.
> The outer case was easy. Inside is a PCB with RF buffersand temperature
> regulation circuitry.
> Then there is a thermo bottle with the ovenized oscillator.This unit is
> connected to the PCB using two flex cables.
> The oscillator unit can simply be extracted from thebottle using an Metric 3
> mm screw lightly screwed inone of the holes in the oscillator assembly.
> The assembly can be accessed by carfully unscrewingthe flex-cable end from
> the other mechanics. No needto touch the three small screws at the lid.
> Now it is starting to get intersting. I have not foundthe RF wiring into the
> crystal. The PCB in this unitseems to deal only with temperature
> regulation.Possibly, the RF is routed together with some heaterwinding.
> Or the crystal and the oscillator parts is sealedin such a way that there
> will be no wayto dissassemble it. There are several thermistorsglued inside
> to various parts of the oscillator/ovenassembly. That will make any further
> attemptsdifficult as the connecting wires are thin and delicateif they needs
> to be unsoldered.
> The construction is a nice piece of engineering.I'll give them that.
> Right now, I cannot see any typical oscillatorcircuitry (pF, nH, RF
> transistors) etc.
> I think I'll contemplate on the next movefor a day or so...
>
> Ulf Kylenfall
>
>
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