[time-nuts] HP 10544A Repair

Bob Camp kb8tq at n1k.org
Sun Feb 28 20:10:36 EST 2016


Hi

Except …. 

The big steps give you more “thermal shock” on a BT and that slows things down. 

Bob

> On Feb 28, 2016, at 7:28 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> 
> 
> 
> On 2/28/2016 7:01 AM, Bob Camp wrote:
>> Hi
>> 
>> It’s not an electrical issue as much as a heat issue ….
>> 
>> Before you start, consider that you will be doing something like:
>> 
>> Move trimmer 1 turn CW
>> Wait 10 minutes
>> read frequency
>> Move trimmer 1 turn CW
>> wait / read
>> Move trimer 1/2 turn CCW
>> wait / read
>> Move trimmer 1/4 turn CW
>> wait / read
>> Move trimmer 1/8 turn CCW
>> wait / read
>> Move trimmer 1/16 turn CW
>> wait / read
>> Move trimmer 1/32 turn CW
>> wait / read
>> 
>> That is indeed an ideal version. You likely will do multiple steps at each of the stages rather
>> than get it right the first time. The part needs to be warmed up for a few days before you
>> can get to the 1/32 turn level. You also need a good standard to compare to.
>> 
>> Bob
>> 
> 
> Instead of that, start with the pot at max temp, and have the counter make measurements at, say, 1 second intervals as the oven warms up.
> You can tell by looking at the plot what the peak frequency is.  Now
> that you know the peak frequency you are shooting for, it will take
> a lot less trial and error to find the oven setting that produces it.
> 
> Rick
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