In the late 80s, I worked for 4 years at a 2-way radio
retailer (Amateur, Business & CB). We handled the
complete line of Astron supplies, and in that 4 years,
I seldom saw one of their products returned as
defective. Their linear supplies are a classic
design, based on the venerable '723. Of the few
failures we did see, there were a couple of dead 723s,
a shorted bridge rectifier, and one shorted pass
(TO-3) transistor. My personal experience is with an
RS20A I bought while employed there. It has been
continuously energized since then and has been seen
close to full load often -- zero issues. That's my
$0.02 worth.
73,
Bryan WA7PRC
--- Jim P wrote:
>
> I have to beg to differ that this series of Astrons
> (the
> linears like the RS-35M et al) are all that
> 'reliable'.
>
> I have had to replace the LM723 (I think it is)
> regulator
> on a couple of these and have since made a circuit
> change (added a resistor) to give the regulator a
> better
> chance at life.
>
> The 'symptom' of failure was the inability to
> deliver rated
> current without voltage 'sag'.
>
> It is also a good idea to add an LED (with suitable
> series
> resistor) across the unregulated DC side of the
> transformer
> and make this visible/viewable through one of the
> slots on
> the top of the supply towards the rear.
>
> This does two things: you will know when you 'lose'
> the
> regulator side of the PS but know you have unreg DC
> and
> this also provides a bleed-off path. My recollection
> is that
> there isn't a suitable bleed-off on that series
> (maybe the
> earlier ones anyway which may be what I have.)
>
> Jim P // WB5WPA //
____________________________________________________________________________________Choose
the right car based on your needs. Check out Yahoo! Autos new Car Finder tool.
http://autos.yahoo.com/carfinder/
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|