[Amps] SB-220 6M conversion
jim.thom at telus.net
Sat Jun 6 13:24:03 EDT 2020
Date: Sat, 6 Jun 2020 09:28:30 -0400
From: Artek Manuals <Manuals at ArtekManuals.com>
To: n2ic at arrl.net, "Amps at Contesting.com" <amps at contesting.com>
Subject: Re: [Amps] SB-220 6M conversion
<Running in the CW position just to be on the safe side ( after all this
<amp is nearly 40 years old) Going easy on the power transformer. I can
<only get about 100 more watts in SSB position
## One other note. If you want a fast grid fuse, for a hard fault,
install a 3AGC fuse holder on the rear apron. Then wire it between
chassis and bottom end of grid shunt. Use a FAST 3agc fuse, like
a 250-300-400 ma type.
## if something goes amiss, like you lose the B+, overdrive, arc,
parasitic etc, and grid fuse opens up, you will no longer have a
path for DC grid current. Tube can no longer be driven. Power
output drops to zero, and input swr rises to infinity, and xcvr shuts
itself down.... event over.
## Install a HV fuse in series with the B+.... followed by a
50 ohm @ 50 watt wire wound.... or 2 x 25 ohm @ 25 watt
wire wounds in series.
## Then its all protected.
More information about the Amps