[Hallicrafters] AC/DC Halli's, Grounds and HUM

[k6uuz at juno.com]

Another safety precaution is to use a 3-wire cord and plug. Connect the
safety ground (green) wire to the outside case and the neutral (white)
wire to the chassis. (double protection) and the hot (black) wire to the
switch. Sometimes this requires a small change to the wiring of the
switch. This keeps the cabinet and the chassis grounded all the time and
when turned "off" the entire radio is grounded except for one terminal on
the switch.

Ed Richards

On Wed, 13 Feb 2002 14:21:10 -0500 "JM/CO" <jmerritt2 at capecod.net>
writes:
> Anyone who insists on using these AC-DC cheapo radios without an 
> isolation
> transformer obviously has a death wish. "MCM electronics", as well 
> as "All
> Electronics" now has 1.0 amp isolation transformers in stock for 
> under $20.
> These are small enough to be easily installed PERMANENTLY inside the 
> case of
> these radios.
> Even though the present ( presumably knowledgeable ) owner may be 
> aware of
> the dangers of these sets, someone "down the line " may be killed. 
> Do
> yourself, and someone else a favor, and install one of these units.
> Oh-yeah--it will eliminate that " hum when grounded" thing too.
> Chuck N1LNH
> -----Original Message-----
> From: Phil Atchley <ko6bb at elite.net>
> To: hallicrafters at mailman.qth.net <hallicrafters at mailman.qth.net>
> Date: Tuesday, February 12, 2002 9:59 PM
> Subject: [Hallicrafters] AC/DC Halli's, Grounds and HUM
> 
> 
> >Hello All
> >I have a Halli 5R10A (5 tube AC/DC set) that I recently completely 
> recapped
> >and went through with a fine tooth comb.  While I was doing the 
> refurb I
> >installed a new line cord with a  "polarized" (one prong fatter) 
> line cord,
> >making SURE that the neutral line (fat prong) is tied to the B 
> minus side
> of
> >the power supply (as it should be).  The chassis then connects to 
> this B-
> >lead through a coupling capacitor for RF bypassing (AND AC line 
> isolation).
> >
> >The set shows ONE big quirk though (and it did when it arrived here 
> before
> >the recap).  IF I tie the ground lug (connected to chassis) on the 
> 3 screw
> >antenna strip to the station ground I get a LOT of hum.  The set 
> DOES NOT
> >like to be grounded.  This precluded using my antenna/rig select 
> switches
> to
> >apply an antenna to the set UNTIL I lifted the jumper from the 
> ground screw
> >to one of the antenna screws and operate the set in the "isolated" 
> antenna
> >mode (I.E. Doublet setup).  Doing this the hum does NOT show up and
> >everything appears to be fine.
> >
> >Question 1:  Is this typical of the Hallicrafters AC/DC rigs of 
> 5R10A, S-38
> >vintage or should I be looking for a problem somewhere? (I don't 
> remember
> >this happening on my S-120 though back in the barracks in '63 I 
> don't think
> >I used a ground)
> >
> >Question 2:  Does anybody have the schematic and service notes for 
> the
> 5R10A
> >that they could scan and send me?  The set is so simple one can 
> really do
> >all the work without them (as I did) but it'd be nice to have.  
> (No, the
> set
> >isn't on the BAMA site).
> >
> >73 de Phil  KO6BB
> >Loving home provided for wayward Boatanchor Receivers
> >ko6bb at elite.net
> >Merced, Central California
> >37.18N 120.29W CM97sh
> >
> >
> >
> >
> >
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> >dfischer at usol.com
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> >----
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