[ARC5] Command Transmitter Bathtub Capacitor Replacement

[Paul Bernhardt]

Jim,

I gave a "show and tell" lecture at the MRCG about repairing the tub 
capacitors for the ARC-5/SCR-274 receivers and transmitters.  I start with 
an exacto knife slide under the lip of the aluminum can that is bent over 
the mica insulator.  This allows a small screw driver to be used to pry up 
the lip for about 180 degrees in circumference around the edge of the 
can.  Then I use a large screwdriver to bend this lip 90 degrees to the 
mica insulator.  The exacto knife is used to pry up the mica sheet and a 
pair of long-nose pliers is used to pull the mica top up and out.  Next cut 
the three wires to the capacitors, clean out the wax and old capacitors, 
and solder three mylar 0.05 uF capacitors as replacements.  I use 
compressed air and a soldering iron to clear the solder hole in the bottom 
of the can.  Next, I have an aluminum tube whose inside diameter that just 
fits the outside of the capacitor can.  I use the tube to hold the 
capacitor while a hammer carefully bends the aluminum lip down after the 
mica is replaced.  When this is done, the capacitor looks original.

Cheers, Paul Bernhardt

At 06:35 PM 10/25/2004, Jim Hill wrote:
>Hi:
>I'm working on a 40-meter command transmitter, and plan on replacing the 
>3x.05uF bathtub capacitor.  I've heard some people open the existing 
>capacitor, remove the guts, and install small modern capacitors in the "can".
>
>How is that done?  I thought of using a Dremel tool to cut off the top of 
>the can just below the flange, install the new capacitors, and then use a 
>bead of epoxy to put things together.  Is there a better method?  Should I 
>purchase epoxy that is used with metal, or just use what I have on hand?
>
>Thanks, Jim w6ivw
>
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