[Hammarlund] Cleaning and restoring RF Cover Tag and Power Supply Choke

[Roy Morgan]

At 07:05 AM 1/1/03 -0800, Dave Faria wrote:
>GM list.  I'm trying to bring my 600 back to the best condition possible.

Dave,
A noble goal.  Carry on!

The power supply choke nearest the power transformer
>runs a little warm to the touch.

It may be leaking.  Some SP-600 chokes develop leakage between the winding 
and the case. This creates heat and overloads the B+ supply.  A fix 
published in Hollow State news some years ago to insulate the case of the 
choke from the chassis and run it that way is VERY BAD ADVICE.  You wind up 
with an innocent looking choke at B+ voltage.  The proper fix is a 
replacement choke or de-potting and re-potting the original one, or 
replacement with a conventional choke.

>   Is this normal or
>should or is it wise just to replace just to replace the filter caps?

It may not be normal..  Unhook the choke output lead and test for 
leakage.  (It is a choke input filter is it not? I can't remember.. isolate 
the choke from all capacitors though.)

By the way, the power transformer has a 120 volt primary tap. If your 
household line voltage is much above 115, use that tap.

>  I was
>also thinking about connecting my amp meter into the load side of the P.S. -
>what would be a reasonable milliamp load?

The 5R4 is rated at 250 ma max.. Expect to see 80 to 125 ma, but that is a 
guess.  (Do not use a 5U4 in that spot because it's filament draw is 
greater than the 5R4.)

Roy


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