[Hallicrafters] AC Bypass Caps

[Asif Khan]

Everytime I restore  radios  I leave them out . They might been effective back in the 1930's and 40's

when the world was less 'noisy' !
Nick


-----Original Message-----
From: Glen Zook <gzook at yahoo.com>
To: Mark K3MSB <mark.k3msb at gmail.com>; List Hallicrafters <hallicrafters at mailman.qth.net>; Mike Everette <radiocompass at yahoo.com>
Sent: Sun, Dec 12, 2010 10:03 pm
Subject: Re: [Hallicrafters] AC Bypass Caps in SX-111 MK 1.


Actually, it really isn't leakage.  Capacitors are supposed to pass AC and block 
C.  Therefore, any radio with those capacitors is going to have 1/2 of the 
ains voltage on the chassis.  Of course, with 3 wire cords that voltage is 
rounded out.  It is the same with 2 wire cords when the chassis is grounded.  
hat is one of the reasons that the older equipment always had a ground terminal 
except for AC/DC which often did not).
Now when the capacitor does fail, then the full mains voltage and current then 
an definitely be on the chassis.  Otherwise, the current is limited through the 
apacitor because of the relatively high impedance inherent to the value.
These days it is questionable as to whether or not to install line bypass 
apacitors, especially in receivers.  In my opinion, leaving them out isn't 
oing to hurt anything.
Glen, K9STH
Website:  http://k9sth.com

-- On Sun, 12/12/10, Mike Everette <radiocompass at yahoo.com> wrote:
I'm sure some folks will disagree with me... but I would recommend that you not 
weat those line bypass caps.  In fact, LEAVE THEM THE HECK OUT.

f they start to leak much at all, you are going to have AC voltage on the 
hassis.  I've seen radios with between 30 and 60 volts AC on them for this 
eason.  That's enough to give you one serious jolt.  And yes, this was due to 
ine bypass capacitor leakage... not leakage in the power transformer.  In all 
y experience,  which includes ham radio, commercial two-way, avionics, and 
roadcast engineering, I have seen only two power transformers develop 
rimary-to-frame leakage; but PLENTY of leaky line bypass caps.  I damn near got 
illed once by a background-music system PA amplifier with a hot chassis from a 
eaky cap, when the back of my head touched that chassi as I was reaching my 
are and sweaty arm behind a HVAC duct to fish out a speaker lead.  
ha-ZAAAAAAM!  As a result, the very first thing I do when a "new" radio or any 
ther device comes into my life is to make REAL sure to take the things out of 
t!

 remain unconvinced regarding the benefits of having these capacitors in the 
adio at all.... except to a funeral director.

     
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