[Milsurplus] BC-221 types

[Bob Camp]

Hi

Ultimately the whole device depends on a couple of things:

1) The zero of the master crystal (adjustable so not an issue if you have calibrated it).
2) The repeatability of the tuning capacitor (I doubt it will change, but gears / bearings might wear).
3) The value of the inductor (ceramic / copper so probably pretty stable)

So, yes, they should stay pretty good for quite a while if properly cared for. The issue is weather the second and third (and fourth) order effects pile up or not…

Bob

On Jul 26, 2013, at 7:36 PM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> On 07/26/2013 06:02 PM, Bob Camp wrote:
>> Hi
>> 
>> I haven't seen a lot of difference between the models. It seems to work out as:
>> 
>> 1) Nice to have a calibration book that goes with the serial number you have.
>> 2) AC power versions seem to be more desirable than the "not AC" versions.
>> 
>> That said, it's not real clear just how accurate a > 50 year old calibration book really is. It's still a nice thing to have. I've always liked the versions with the corrector in the coil (thermal spring and rotating loop). I'm not at all sure they work any better. They are a cool piece of technology.
>> 
>> Bob
>> 
> 
> Hi Bob,
> 
> I only have LMs - the same thing only different. I have the original books for all three of them. All three of the books agree with WWV. After all these years ain't that sumthin! They're still more than good enough for amateur radio use. I suppose that even the BC-221s are good enough, too.
> 
> As for undesirable - maybe if it's been run over by a big truck....
> 
> 73,
> 
> Bill  KU8H
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