The 10 Ohm resistors only limit the inrush current. They have zero to do with
the delay.
The delay is set by the R/C values in the coil circuit. R includes the relay
coil itself.
The delay only needs to be long enough to limit the current pulse. Adding more
delay gains nothing.
vy 73,
Bryan WA7PRC
________________________________
From: Arnie Pfingst
To: Bryan WA7PRC
Sent: Wednesday, December 27, 2017 1:06 PM
Subject: Re: [Amps] Soft Start
When the cap let go it scared the S #% T out of me! Several people told me
about how the "un charged" cap bank draws a huge current at start up and maybe
thats why the cap let go, (they all have been changed since) the same kind of
thing happens to a tube fil, without all of the pyrotechnics. Jim why did you
select 10 ohm resistors over something higher giving a slightly longer delay?
Arnie
-------- Original message --------
From: Bryan WA7PRC
Date: 12/27/17 12:34 PM (GMT-08:00)
To: amps@contesting.com
Subject: Re: [Amps] Soft Start
FWIW, Mike WØBTU put this together, s'plaining the "Miller-Larson Effect":
http://www.w0btu.com/miller-larson_effect.html.
Though, in some cases (such as in the SB-220), there's little/no benefit,
as the filament transformer limits the current. In those cases, you're
mainly extending the life of the ON/OFF switch from yuuuge inrush current
caused by overly large HV filter capacitance.
vy 73,
Bryan WA7PRC
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