[AMRadio] 220 volt AC Power Question

John Coleman ARS WA5BXO wa5bxo2006 at pctechref.com
Mon Oct 30 23:41:40 EST 2006

	That is the way I am running mine Jim.  I have two power supplies
(MOD/FINAL) 120 VOLT AC each and I run one from each leg of the 220 and a
common line for the return. (Three Wire).  The plate relay/contactor is a
three phase relay/switch but only 2 of the contactors are active of course.
The earth/safety ground is a separate wire that is connected to a ground
stake outside the shack.  I guess I could have run separate return along
with each hot leg but I don't know why I should.  I use a clothes dryer plug
and pigtail for mine.  The Filament XFMRS for the rectifiers, finals, and
modulators all run from the same phase as the modulator plate supply. And
the final plate supply is on the other phase.  There are breakers at the
pole and a 3 phase breaker in the rig. Only two lines in use; Common stays
connected at all times.  
	By the way I do not use a transformer for bias supply for either the
final or for the modulator.  Bias supply comes from diodes that are
connected through limit resistors from the 120V AC hot line.  Chassis is
connected to common AC and earth ground at all times.

John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Jim candela
Sent: Monday, October 30, 2006 7:10 PM
To: Discussion of AM Radio in the Amateur Service
Subject: [AMRadio] 220 volt AC Power Question

Hi all,

   I am building an amplifier that has a combination of 220 volt and 120
volt transformers. The HV plate supply is 220V, and the rest is 120V. I will
be keying the plate supply. My 220V outlet has phase, phase, and ground.
There is NO neutral. The outlet is not a GFCI outlet so ground current will
work, BUT.

  The BUT here is whether this is legal with the National Electric Code?
Before you say NO, consider the electric clothes dryer. These all run off
220V, and have 3 prong power cords. I have heard that in some dryers there
are 120 volt loads (lights, and timer) as well as 220V (heater and motor).
If this is true, then my approach must be OK so long as my power switch uses
a DPST switch and (double fuses)to insure everything is off when it is in
the OFF position.

Comments please...

More information about the AMRadio mailing list

This page last updated 23 Oct 2017.