Date: Tue, 11 Jul 2017 08:16:20 -0700
From: "Jim Thomson" <jim.thom@telus.net>
To: <amps@contesting.com>
Subject: [Amps] SB220 step start blows fuses
< On a side note, if the step start is done correctly, and step start resistor
inserted into one
<leg of the 240 vac primary..... or hot leg if wired for 120 vac, you will be
able to step start the HV supply and both fils...simultaneously.
<Jim VE7RF
## I used a single 25 ohm resistor in one leg of the 240 vac line...for my
hb, external step start setup, for my drake L4B amps.
That value works out really good. Allows the B+ to ramp up to aprx 2480
vdc....and both 3-500Zs fils run at aprx 87% of full
brilliance. Once the 25 ohm step start resistor is shorted out, the 2480 vdc
jumps to 2650 vdc. Both tube fils are then at full
brilliance. Both B+ and fils are step started simultaneously. I have used
that system for several years now.
Jim VE7RF
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