[R-390] Silver solder

[Dan Martin]

----- Original Message -----
From: "Jim Temple" <jetemp@insightbb.com>
To: <r-390@mailman.qth.net>
Sent: Monday, June 24, 2002 10:05 AM
Subject: Re: [R-390] Silver solder


> Also, take the time to re solder joints that look suspicious.  Grounding
> points and deterioriated solder joints are the cause of almost all faults
in
> this radio, in my experience.
>
> Jim

You know, you can >read< something over and over and intrinsically accept it
as valid but it's not until it happens to you, in your own experience, that
you really believe it. I'd known of Jim's admonition above on deteriorated
solder joints for years and always kept a low level look-out for them. It
wasn't until I began to experience a rash of odd problems with my '67 EAC
recently that I finally experienced it first-hand. To make a long story
short, an assortment of .5-8 mHz peculiarities, including obvious AGC and
sensitivity issues got me to take out the rf deck. I had no AGC at the grid
of the first mixer and got infinite from the grid pin to ground. Ah. Open
resistor, I thought. R208, 231 or 232 have gone open. Nope. Checking each
one individually showed they were fine. Finally, after repetitive checks
over and over, I had continuity all through the AGC line ... except at one
terminal joining two resistors together - R231 and 232, as I recall. It was
fine in and fine out, but open at the solder junction. Laid a soldering iron
on it and added a touch of solder and - perfect! All was well. Funny thing
is, this was my personal 390A of several years, in immaculate condition and
gone over both by me and Chuck. The solder joint just opened one day. Like -
that!

It >does< happen! I always understood it. Now I believe it!

Dan
WB4GRA