[ARC5] Hallicrafters S-38 is dangerous

[Richard Knoppow]

     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 or 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