[ARC5] Spreadsheet record of BC-221 drift over a period of some hours.

[Leslie Smith]

Hello Ian!  I can do better than "summarize" the drift characteristics.
I can send the spread-sheet!

73 de Les Smith  vk2bcu at operamail.com



On Tue, Dec 1, 2015, at 13:12, Ian Wilson wrote:
> Hi Les,
>
> Don't have access to the yahoo group. Could you summarize the drift
> characteristics? I have informally noted that once a BC-221/LM has
> been on for about 1/2 hr, you only need to breathe on the frequency
> setting to zero beat with 10.000MHz once an hour or so.
>
> 73, ian K3IMW
>
>
> On Mon, Nov 30, 2015 at 1:36 PM, Leslie Smith
> <vk2bcu at operamail.com> wrote:
>> G'day list-readers,
>>
>> I measured the frequency of a BC-221 heterodyne frequency meter over
>> an afternoon, in 2006. I posted the result in the Yahoo Group files
>> for the Yahoo group ARC5-radio.  See BC-221, frequency stability.XLS
>>
>> For more detail about the record, move your mouse pointer over
>> cell A1.
>>
>> I reproduce the content of that cell here: 2006/09/17  <- date of
>> observation. Notes about measurement of freq drift in BC-221
>> hetrodyne freq. meter.
>>
>> (1) Measuring instrument:  Fluke 1912A Multi counter.  (see note 1
>>     for more detail)
>> (2) Condition of BC-221.  Ser. # not given here.  The instrument is
>>     believed to be in original condition; the set has not been re-
>>     capped (to my knowledge).
>> (3) Environment.  Results reported here were recorded by connection
>>     the Fluke to the output of the BC-221.  Manual record was made,
>>     the table was transcribed to this spreadsheet by hand.
>>
>> Gen Obs.  Since the measurements were made in spring, the minimum
>> freq. observed at 15:30 is consistent with the warmest part of the
>> day.  From this I infer the main cause of drift may be temperature -
>> althought one might also explore the possibility that the minimum
>> coincides with some fluctuation in mains supply.
>>
>> Note 1.  Condition of Fluke frequency meter.  I purchased this second-
>> hand.  The circumstances of the purchase lead me to believe it had
>> been used in a laboratory, then - I presume - discarded due to age,
>> as that is the fate of most laboratory gear.  A manual came with
>> the meter.  There is has no calibration history available to me.
>> The manual does state the worst case expected drift - due to
>> crystal aging.
>>
>>
>>
>>
>>
--
>> 
73 de Les Smith
>> vk2bcu at operamail.com
>> 
>> 
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