[Hallicrafters] S38D Line safety

[Roy Morgan]

At 11:46 AM 12/5/2005, Paul Buhler wrote:
>Have started using an S38D ...the ground side of the 2 prong-plug marked 
>and make sure its plugged in on the wide slot of the wall outlet. Any 
>other ideas that reduce accidental shocking?

Paul,

Yes.

The S-38 is an AC/DC radio and has no power transformer.  So the chassis is 
more or less connected to the power line.  I say "more or less" because C27 
is a 0.02 uF cap connected from the "cold" or neutral side of the line cord 
to chassis. This thing is likely leaky and very old. Don't trust it.

Get and use an isolation transformer. Your radio doesn't draw much current 
so a small one will do. The BAMA copy of the manual says 30 watts.  If you 
don't have one and can't get one, put two filament transformers of the same 
voltage back to back, each capable of the amount of power the set takes. 
Two 12.6 volt, 3 amp transformers would be fine.

Some folks say to use a three wire grounded line cord with the safety 
ground (green) connected to the chassis and the other wires appropriately 
connected. This may be all well and good, but you run the risk of tripping 
ground fault protection devices, and if you hook it up wrong, the chassis 
is still at line voltage.  For this to be safe, you must rely on all 
outlets being correctly wired.  That is ALL outlets.  They may not be.  A 
$9 outlet tester from the hardware store will assure you of safe outlets. 
No shack should be without one.  (They don't test the current carrying 
ability of the safety ground connection, however.)

>   Edward B Richards <zuu6k at juno.com> wrote:
>
>See the first article in the March 2005 issue of Electric Radio magazine.
>It should answer your questions. Good luck

My ER subscription may have lapsed (bad!) so I don't remember seeing that 
article, but most likely it's got good information in it.  Ed's wishes of 
"Good Luck" are no doubt completely positive, but please don't rely on luck 
to make your radio safe to use.

Of course, your isolation transformer should be run with a three wire 
grounded line cord (on the input side). many were made with only two wires 
in the cord.

Don't rely on a Variac to do the job - with *very* few exceptions, variable 
voltage transformers are NOT isolating. (I have heard of some that are 
isolating, but I have never actually seen one.)  I am just now rebuilding a 
GR 10 amp Variac and will install a three wire grounded line cord and 
grounded outlet. Originally it had only two wire cord and outlet.

Be safe,

Roy




- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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