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

[Ray, W2EC]

Now we all know AC/DC sets should be used with an isolation transformer.
I'm not saying we shouldn't.


BUT.... these radios have been in use for about 50-60 years now. Has
anyone ever seen a survey as to how many people have actually been
killed or even injured by using one? 

Again, NO, I am NOT advocating using one without an appropriate
isolation transformer and proper grounding, just asking what the
statistics are for injuries/deaths that have resulted from their use
over the last 50-60 years.

Thanks, Ray

JM/CO wrote:
> 
> 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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