[R-390] Floating Capacitor Cans & Other Issues

[Barry Hauser]

> 30 to 50 years from now it won't matter to me no more!  The next guy can 
> figure it out.  Don't know what they will be listening to then anyway....

Y'see!  Then don't complain when you get some radio that's been modded and 
there's no clue heh heh.

OK, instead of the standardized maintenance & mod book, leave a scribbled 
note saying "Hi there, Pilgrim.  Yup, I modded and rodded this rig 
everywhichway.  I did make detailed notations -- can be found in the inside 
jacket pocket of the suit I wore to my funeral.  A hearty har, har, har..... 
from the Next World.  Hmmmmm, wonder what kind of boatanchors they have 
there ....  Heck, if you plug a mike into the headphone jack of your 
Hallicrafters receiver while there's an aurora borealis overhead for a week, 
maybe I can tell ya'."

See below for more serious faire ...

> Well the VLF chassis top side appears to have been exposed to something 
> that has caused the tube bases...the part that actually bolts to the 
> chassis and holds the insulated piece to corrode a bit and split/crumble. 
> It may have been rodent urine exposure or who knows what.  The chassis is 
> not in bad shape it has just pretty much attacked the tube sockets.  I 
> have a box full of NOS ceramic ones that I thought I'd put in.  It's going 
> to be quite a job but I think it will be worth the effort.  Sad part is it 
> don't need a recap below the chassis as it has all ceramic caps.  But they 
> didn't put ceramics under the RF deck.....peeked in there and can see the 
> darned Black Beauties.

Yup -- they figured they'd put the latest & greatest where the sun don't 
shine.  Sprague Black Beauties (tm) were all the rage when they came out --  
hermetically sealed to last for eternitiy.  I have it on authority that they 
never leak, never split.

OK, more seriously now -- I promise -- It seems like a shame to have to 
unsolder and disturb all that just for the socket flanges.  I did play a 
trick and replaced one or two once -- by harvesting the flange off another 
socket and fitting it around.  As I recall, the plated ones on the ceramic 
sockets do not have a pre-existing split.  Not sure how they were originally 
assembled.

However, it should be easy to remove the old rusted ones by clipping the 
flanges at the thinnest part -- 90 degrees away from the screw holes. 
Remove the nuts and bolts, pull the socket away from the chassis enough to 
get at the side of the thing with a big pair of wire cutters.  Bend/twist 
enough to get the old flange off and over the leads.

Remove the flange from a new or salvaged socket the same way.  Twist it open 
and slightly outward -- i.e. enlarging the diameter a bit.  Then slip over 
the leads and around the socket.  bend back into shape and into the groove 
or slots on the socket.  Bring the ends back together - compress around the 
socket as much as possible.  Get a small clamp around the flange to hold the 
cut ends together.  Lay in a piece of solid hookup wire - 20 gauge or so --  
to add strength on the bottom of the flange -- not the side that's supposed 
to be flush with the chassis.  Use a soldering gun to solder it together.

Of course, whether this is worth doing depends on (a) the particular socket 
and assumes the new ones are the same and the flanges will fit and (b) the 
wiring to the socket -- if only a few leads and not much of a problem to 
disturb them, then, of course it's easier and better to replace the whole 
thing.  The only purpose of the flange-replacement-in place method is if 
there are some where you'd rather not unsolder the works.  Also, a major 
reason for not desoldering from tube sockets is to avoid damage to the 
lugs -- not a consideration here.  However, one annoying thing -- in most 
cases you have to preserve lead length and there's nothing to spare.  So 
that means full desoldering -- no clipping.  In the process, some of the 
lead ends will break or weaken to the point where you won't be confident 
with them.

Of course, 30-50 years from now, that pilgrim will take a close look and say 
"Whoaaahhh!  Those tube socket flanges sure look funny!"  But, at least 
there will be that note as to where he could possibly find the particulars.

Barry