[R-390] R-390A and the Selenium Rectifier

[Barry Hauser]

Hi John

Generally a good idea to replace all seleniums with silicon as a preventive
maintenance.  I'm not exactly on schedule in that department -- lot's of
radios of various kinds with seleniums and even some copper oxide ones.

The cosmetically correct thing to "rectify" the situation is to bypass them,
leave them in place and install the silicon rectifiers or bridge next to the
original.

I haven't had a selenium fail lately -- last one I remember was when I was
about 12 years old and the Se rectifier went in the little Motorola TV (a
'47 model, I think).  Boy did that stink to high heck!  Very pungent. Lot's
of smoke.  I still can smell it more than 4 decades later.  Not sure what
the power rating was for that square-finned wonder - maybe about 5
deadhorsepower or maybe 3-skunkpower.  My uncle knew immediately what it was
that blew and replaced it with the latest technology -- one of those
shiny-tiny top hat rectifiers -- I guess it was half-wave -- not sure.  I
was amazed how small it was.

Barry




----- Original Message -----
From: "John KA1XC" <tetrode@comcast.net>
To: "R-390 reflector" <r-390@mailman.qth.net>
Sent: Thursday, November 06, 2003 10:41 PM
Subject: [R-390] R-390A and the Selenium Rectifier


> I'd like to get some wisdom regarding the selenium rectifier used to make
> the DC for the relays.
>
> I've got an Imperial (really mostly Teledyne) radio of about 1963 vintage,
> and the selenium rectifier seems to be working fine. However, I'm doing a
> top to bottom refurb (recap etc) on this radio for a friend and I'm
> wondering if this might be a likely failure down the road and would be
worth
> replacing with a silicon bridge.
>
> If this was an R-390 it would be an easy decision as the copper oxide
> rectifier stack is always toast!
>
> thanks,
> John
>
>
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