[ARC5] Hallicrafters S-38 is dangerous

[Fuqua, Bill L]

  Naturally, you would probably remove the AVC on the IF when you used the feedback.

________________________________________
From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Monday, November 16, 2015 10:21 PM
To: Richard Knoppow; arc5 at mailman.qth.net
Subject: Re: [ARC5] Hallicrafters S-38 is dangerous

  Every household had at east one AC/DC radio and sometimes a AC/DC TV although in the 506 and early 60s most TV's had transformers but later went to
voltage doublers wit solid state rectifiers.
  Saying that. Imagine how a S-38 would have performed if:
1. Used replaced V5, with a 12SA7 and made it a BFO and PRODUCT detector!!!
2. You had put some adjustable feedback in the IF to make a sort of Q-multiplier for CW.
 Now that would have been cool.
I don't see why product detectors did not catch on earlier.

   73
Bill wa4lav

 ________________________________________
From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Richard Knoppow [1oldlens1 at ix.netcom.com]
Sent: Monday, November 16, 2015 6:17 PM
To: arc5 at mailman.qth.net
Subject: Re: [ARC5] Hallicrafters S-38 is dangerous

     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

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