[time-nuts] Re: Sulzer 5B Quartz Frequency Standard Questions

[Bob Camp]

Hi

As you go through one of these old beasts, you never really know what is still “ok”. 

1) The set point on the inner oven may have drifted. If so the unit may be a bit off frequency. It also probably isn’t doing quite as well as it might do in terms of temperature performance. 

2) The set point on the outer oven might have drifted. If so the inner oven may be out of its “sweet spot”. Just what that target current on the inner oven is / was …. not easy to work out. 

Once the ovens are (probably) working ok.

3) The unit likely is off frequency. The crystal (and other parts) have been drifting for a *very* long time. Some will drift more than others. There’s no way to predict how far out this or that is. First step is to run the unit for at least 60 days and see where it is. They likely ran them for many months “back in the day” before they decided what was what. If it’s out at 60 days, run it another 60 days or so. 

4) Take a shot at adjusting it on frequency. Best guess the coarse trimmer bottoms out in one direction or the other. When it bottoms out you have two basic choices: You can just live with it off frequency or you can start changing things. If it’s off by several ppm changing stuff to get it back on may impact performance. Since you don’t really know if it’s the crystal or “that cap over there” you are flying a bit blind as you adjust things. We all *assume* it’s the crystal and it probably is. Other parts do indeed drift and sometimes drift a *lot* (that coil over there just might be the culprit …. ). 

Very much a task for folks with time to wait and see what happens.

Bob

> On Mar 19, 2024, at 8:56 AM, paul swed via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Agree with Martin and will add one more bit that I believe is the case. The
> cap is a glass cylinder that a piston goes into or out of. The outside of
> the glass is coated with metal. The cap is relative and in reality I may
> guess with age you are bottomed out at 2 turns.
> If thats the case look at the circuit and you need to add some capacitance
> to get the cap back in the middle range. The numbers are just relative. Not
> a big deal to get it semi-recentered.
> Paul
> WB8TSL
> 
> On Tue, Mar 19, 2024 at 12:16 AM Martin VE3OAT via time-nuts <
> time-nuts at lists.febo.com> wrote:
> 
>> Hi, Stan,
>> 
>> I read the digest so others might have already answered one of your
>> questions.
>> 
>> The copper rod and outer cylinder are not "contacts" but instead are the
>> "plates" of a small capacitor that is used the change the resonant
>> frequency of the crystal in the oven.  Turning the dial on the front
>> panel changes the amount of engagement of the copper rod inside the
>> outer cylinder, thus changing the capacity between these two "plates".
>> It's that simple.
>> 
>> Have fun!
>> 
>> 73,
>> ... Martin   VE3OAT
>> 
>> 
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