[ARC5] Hallicrafters S-38 is dangerous

[Richard Knoppow]

       This was a DC version of the RCA CRM R6A designed for use aboard 
ships with DC supplies.  I thought I had a handbook for it but can't 
find it. I don't know how they arranged the power supply.

On 11/16/2015 4:41 PM, scottjohnson1 wrote:
> The RCA 8516 was a great receiver, but alas it was transformerless!
>
> Scott W7SVJ
>
>
>
> Sent from my Verizon Wireless 4G LTE smartphone
>
>
> -------- Original message --------
> From: Dennis <dennis.monticelli at gmail.com>
> Date: 11/16/2015 5:05 PM (GMT-07:00)
> To: Richard Knoppow <1oldlens1 at ix.netcom.com>
> Cc: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Hallicrafters S-38 is dangerous
>
> The SBE 33 (an early sideband xcvr) ran a doubler directly off the 
> mains and bolted the chassis directly to the metal case.  I wonder how 
> many widows it made.
>
> They isolated the case with the SBE 34.
>
> Dennis AE6C
>
> Sent from my iPhone
>
> > On Nov 16, 2015, at 3:17 PM, Richard Knoppow 
> <1oldlens1 at ix.netcom.com> wrote:
> >
> >    Badly designed only if a great many other AC/DC sets are also.  
> The S-38 and later receivers are made with the chassis insulated from 
> the metal cabinet. Unless the insulation is gone due to age nothing on 
> the outside of the receiver is connected to either side of the line.  
> There were certainly other AC/DC devices, such as cheap code practice 
> oscillators, where the chassis _was_ connected to one side of the line 
> was was hot with regard to a house ground such as a steam radiator if 
> the plug was in the wrong way. Since neither plugs or sockets were 
> polarized it was a matter of a 50/50 chance of getting bitten. Most 
> home radios and phonographs with AC/DC supplies were in wooden cases 
> which provided the insulation. However, the shafts of pots and tuning 
> capacitors could be at chassis potential. If someone pulled an 
> insulated knob off they could be in trouble.  Hallicrafters used 
> Bakelite rods for the tuning controls and plastic knobs. I don't 
> remember if the volume control o
> r bandswitch was hot. Given its simple circuit the performance is 
> quite good.  A great many five tube wonder radios were on the market, 
> mostly bc band only but some with one or more short wave bands.  The 
> AC/DC supplies were mostly to cut costs but there were parts of the 
> U.S. with DC current until fairly recently and many ships had only DC 
> current.
> >    The main danger from these sets are to the service people who 
> work with the chassis out of the cabinet. An isolation transformer 
> will prevent getting directly across the line but many are foolish 
> and  work without them.
> >
> >
> >
> >> On 11/16/2015 2:33 PM, J Mcvey via ARC5 wrote:
> >> That radio is a badly designed AC/DC set with several ways to give 
> you the "shock of your life".
> >> Check out info on how to modify it for safety. I've done a few of 
> these for people and I was amazed that this designed was allowed to be 
> sold back in the day!As they age, the danger increases too.
> >> Just another type of  Hallicrafters design debacle. No wonder they 
> are not around anymore.
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> > --
> > Richard Knoppow
> > 1oldlens1 at ix.netcom.com
> > WB6KBL
> >
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL