[ARC5] Hallicrafters S-38 is dangerous

Tue Nov 17 16:07:59 EST 2015

RE:  AC/DC appliances note that many late model TV sets both tube and solid state got rid of the expensive power transformer schemes.   I had a nice little Sony 21 inch table model color TV ( metal cabinet too) that drove me nuts when I hooked up the VCR and cable TV cable system and had major hum problems.  The problem was of course an AC ground loop caused by the AC mains being bypassed to the chassis just like the S38.  A lot of late model TVs even my Later Sony XBR so called super TV had no power transformer and in theory subjected the user to the same safety concerns attributed to the S-38.  We hams are supposed to be trained and aware of shock hazards.  BTW a great source of magnetics to construct isolation transformers is your local mom and pop recycle operation.  Take a couple of the small or large UPS power transformers, hook them up back to back and shazam!! great isolation and cheap too.

I have a pair of them boxed up in an old Heathkit Sweep Generator cabinet and use it when working on stuff like S38s and a host of other AC/DC stuff.  

73

Bob, KE6F

-----Original Message-----
From: Fuqua, Bill L <wlfuqu00 at uky.edu>
To: Peter Gottlieb <nerd at verizon.net>; J Mcvey via Arc5 <arc5 at mailman.qth.net>
Sent: Tue, Nov 17, 2015 12:54 pm
Subject: Re: [ARC5] Hallicrafters S-38 is dangerous

You can learn from your mistakes, but only if you get another chance. 
Safety
then was quite different than now. 
No GFI outlets, no air bags, no seat belts,
lead in paint, no lead free solder, Root Beer made with real root, no armor for
soldiers, jeeps instead of armored Humvees...........

If you want to relish
the past today and have today's safety you must compromise. 
  You put seat
belts in your 57 Chevy, use isolation transformers etc. 

73
Bill wa4lav

________________________________________
From: ARC5
[arc5-bounces at mailman.qth.net] on behalf of Peter Gottlieb
[nerd at verizon.net]
Sent: Tuesday, November 17, 2015 12:50 PM
To: J Mcvey via
Arc5
Subject: Re: [ARC5] Hallicrafters S-38 is dangerous

 Having been bitten
a few times as a kid I learned respect for high voltage. The extra thought
processes when working around live equipment have come in handy now that I work
with high voltage energy systems professionally.

Peter

> On Nov 17,
2015, at 12:02 PM, J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:
>
> In AC.DC
parlance, "chassis" is what they refer to the floating B- wiring buss (I use the
term "buss" loosely) . I was taken to task from folks on this terminology so I
am using it as I was told was proper.  "case" or cabinet is the metal box.Pull
up a schematic for the the s-38 and you will see a cap that goes between the
standard conical ground symbol to the fork which represents the case.I think
there is one that goes from the antenna ground terminal to the B- chassis as
well. Both have a very good potential to "light you up".
> Don't take my word
for it. see for yourself...
>
>
>
>     On Tuesday, November 17, 2015 4:34
AM, "hwhall at compuserve.com" <hwhall at compuserve.com> wrote:
>
>
> Those old
wax/paper caps are electrically leaky and couple the "hot chassis" B- buss to
>
the metal cabinet. If it shorts, the cabinet could have the full mains
>
potential. Bad things can happen...
>
> I'm getting confused maybe. Are y'all
using 'chassis' and 'cabinet' words the same? IIRC from when I safed my S-38E,
one side of the line cord via the on-off switch connected to the B- buss & the
buss was cap (& resistor in parallel) coupled to the chassis but the chassis was
insulated from the cabinet by non conductive fittings so that the metal cabinet
was floating.
>
>
>
> Wayne
> WB4OGM
>
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