[Amps] SB220

[Pete Smith]

At 09:00 AM 11/4/03 -0800, rlm < > wrote:
>****  The SB-220 has a current-limiting type filament transformer which 
>limits inrush-I to 60% of what Eimac allows.  However, a stepstart is 
>still needed because the inrush-I to the HV-transformer will eventually 
>ruin the SB-220's ON/OFF rocker switch.


What's "eventually?"  My SB-220 has been around 30 years so far, and is 
still running the original switch.  Of course, I don't cycle it every QSO 
-- seems as if I have read that the 3-500Z's filaments don't have a rigid 
filament life expectation like indirectly heated, more modern tubes, so 
there's little reason to shut them off. True?


73, Pete N4ZR
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