[Amps] SB220 step start blows fuses

Jim Thomson jim.thom at telus.net
Tue Jul 11 10:29:01 EDT 2017


Date: Mon, 10 Jul 2017 12:41:52 -0500
From: "Gary Schafer" <garyschafer at largeriver.net>
To: "'Joe'" <nss at mwt.net>, <amps at contesting.com>
Subject: Re: [Amps] SB220 step start blows fuses

Well, yes you would need a bulb in each side of the 220 circuit or two bulbs
in series (rather than parallel) on one side,
assuming that the amp is not a 4 wire amp that also uses 120 volts.

If something in the amp shorts you would have 220 volts across a single bulb
and the bulb would burn out.

73
Gary  K4FMX

##  agreed.  This is also why, if you install a separate fuse in each leg of the 240 line,
each fuse has to be rated for 240 vac.  IE:  if only one fuse blows open, you will
have 240 vac sitting across the same open fuse. 

##  Step start should consist of one resistor, or 2 in parallel,  in just one leg of the
240 line.   Ditto if the amp is wired for 120 vac, step star goes into the hot leg of the 
120 vac line. 

##  The drake amps used a separate breaker in each leg of the 240 line.  They too have to 
each be rated for 240 vac.   Same deal, if only one breaker opened  off, you have 240 vac
sitting across the open breaker. 

Jim  VE7RF 



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