[time-nuts] HP5065a cfield issue

[Bob kb8tq]

Hi

Ok, if that still turns out to be correct … that’s just about 2 ppb. ( 1.6667…). 
To do that with the C field, you would need to make a *major* change. It’s
essentially the whole range of the pot. You already know that it’s off in the 
direction of needing more counts on the dial. I *think* the current is lowest
at that end, but I could easily be wrong. Either you need zero current or 
2X normal. Either way that should be easy to spot.

Bob



> On Dec 2, 2020, at 2:59 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Yes absolutely it can go back and it is the same offset. I can get real
> numbers from memory 3 seconds for 5ns drift and the units slow. Will
> confirm and reshare.
> Regards
> Paul.
> 
> 
> On Wed, Dec 2, 2020 at 2:52 PM Bob kb8tq <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> Just double checking….. Are we still after a change went past 1/3 of the
>> pot range?
>> 
>> Can we get the pot back to the original location and measure the frequency
>> offset
>> (even if only in a crude fashion)?
>> 
>> Best guess is still that this should be a ppb or more of shift. If it’s
>> down in the
>> 4x10^-11 range then indeed, there’s something off in the C Field setup.
>> 
>> Bob
>> 
>>> On Dec 2, 2020, at 2:03 PM, paul swed <paulswedb at gmail.com> wrote:
>>> 
>>> Corby will check. Though in looking at the cfield circuits it does appear
>>> all to be correct. Its some other odd offset that has crept in.
>>> Thanks
>>> 
>>> On Wed, Dec 2, 2020 at 1:56 PM <cdelect at juno.com> wrote:
>>> 
>>>> Paul,
>>>> 
>>>> One other thing to check.
>>>> 
>>>> Put a DC coupled scope on the C-field pot wiper and rotate the pot back
>>>> and forth.
>>>> 
>>>> Make sure there are no jumps or noise.
>>>> 
>>>> Sometimes the pot gets noisy in a section.
>>>> 
>>>> Rotating it back and forth across the bad sections will usually clean it
>>>> up.
>>>> 
>>>> Cheers,
>>>> 
>>>> Corby
>>>> 
>>>> 
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