[Milsurplus] ] BC-221 question

[Bob Camp]

Hi

Back before there was dirt and most of us learned how to read there 
were BC-221's with AC supplies. Needless to say manuals were not 
something that got a lot of attention. Things like keeping the power 
supply door open when the unit was on were not anything that we paid 
much attention to. Of course this was back in the days a 221 cost maybe 
$20 or so at the local ham feast.

If you let the beast run for about eight hours or so it will stabilize 
very well even with the power supply pouring all it's heat into the 
unit. I can not say that there was any noticeable difference between a 
221 and an LM in terms of stability. With the AC supply in a second box 
the LM should have had less heat affecting it than the 221.

All of this was in a pretty typical ham shack. Reasonable temperatures, 
stable line voltage, and a zero beat with WWV as the "absolute 
reference". The reference crystal certainly was the key to the whole 
system and you wanted it at the same temperature you had last zeroed it 
at.  If you ran at a significantly different temperature then with an 
uncompensated crystal then you would have significant ( > 10 or 20 ppm) 
errors.

They are amazing gizmos ....

	Enjoy!

		Bob Camp
		KB8TQ




On Mar 6, 2005, at 8:51 AM, David Stinson wrote:

>
>
> Hue Miller wrote:
>> There may have not been mains powered "version" of the BC-221, but 
>> there is a government issue, nomenclatured A.C. power supply for the 
>> BC-221,...
>
> I've always wondered what happens to BC-221 stablity when one
> adds the heat source of an AC power supply.
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