[ARC5] BC-221s

[WA5CAB at cs.com]

Nominal B* in a BC-221 is 135VDC.  The RA-133 and PP-79/UR built post-war 
have 0D3's and a fixed dropping resistor downstream.  

Incidentally, in most RA-133's, the fixed resistor will typically have 
drifted high.  I bridged a 1 watt 14 volt Zener diode across several of them.  
This made a noticeable improvement in stability  - i.e., when switching from 
calibrate to operate.

In a message dated 10/02/2017 14:41:10 PM Central Daylight Time, 
kgordon2006 at frontier.com writes: 
> Both have homebrew AC supplies in them, both of which are well made. Both 
> include a VR 
> tube. Although I haven't checked recently, seems to me that they are 
> VR-90s.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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