SB401 Problem Help Please

[Gerald C. Lemay]

As Glen says, retightening of the screws will improve grounding. Heathkit
had a habit of using the edges of pc boards coming in contact with the
chassis for ground connections. Unfortunately with time the contact area
oxidizes. I would even remove all the screws and clean the contact areas
between the boards and chassis. I've used Q tips soaked with contact
cleaner. I've seen a lot of rusted hardware in my old Heathkits. I believe
the hardware they used was 3-48 screws which are not widely available
nowadays. Sometimes you can substitute 4-40 or even 2-56 hardware. Loose
hardware is not only a Heathkit problem, it applies to most old radios as
well. Just finished working on a very early Drake T-4XC with similar
problems!

> Clean the relay contacts.  You can use plain "ole"
> typing paper cut into small strips.
>
> Also loosen and then retighten ALL of the screws that
> hold the circuit boards to the chassis.  This will
> make sure that the grounding is proper between them
> and the rest of the transmitter.
>
> In fact, it doesn't hurt to slightly loosen and then
> retighten all of the hardware every couple of years
> just to remove the corrosion that sometimes builds up.
>  This also works to eliminate all sorts of problems on
> other "boat anchor" equipment that use things like
> tube sockets connected by screws to the chassis, etc.
> Loose grounds can cause all sorts of problems.
>
> Also, the solder connections can look good, but it
> would not hurt to take a soldering iron and "hit" each
> of them with a "spot" of new solder.  It is possible
> that there is an internal problem with the solder
> joint that does not "show up" by just looking.
>
> Glen, K9STH
>
>
> --- Dan Pividal N4VET <OTAKEBI at AOL.COM> wrote:
>
> The only way I can get RF output is to tap ever so
> gently on the carrier generator board or the
> mixer-bandpass board. I have checked for bad solder
> joints and have found non.
>
> =====
> Glen, K9STH
>
> Web sites
>
> http://home.attbi.com/~k9sth
> http://home.attbi.com/~zcomco
>
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