[Hallicrafters] ASTRON supplies

[Jim Wilhite]

I couldn't help but mention this since I have just pulled the lid 
off my RS 70M to see why it keeps falling out from time to time. 
Suddenly the voltage meter pins to the right then the crowbar must 
kick in and kills the supply.  I did some reading on a site about 
all the problems Astron seems to have from time to time documented 
here:

http://www.repeater-builder.com/astron/astron-index.html

Well the RS 70 has a fan controlled by a thermostat mounted on the 
right heatsink.  I looked at the wiring and couldn't believe it. 
Both leads of the fan were tied to the same incoming AC wire.  It 
could not have worked at all, so I moved it to put it across the 
line, then fired up my heat gun at the thermostat.  Now it works, 
maybe that was what caused the voltage regulation to go off on it's 
own.  I hope.

Wonder who has the best quality control in power supplies now.  I 
really don't think it is Astron.

Jim/W5JO




----- Original Message ----- 
From: "TC Dailey"


> One might also notice that the SAME regulator board is used on 
> nearly all of the ASTRON power supplies.  It's also VERY EASY to 
> convert a fixed voltage supply, such as the RS-20 or RS-35 into a 
> VS (variable voltage).  The schematic on bamb-edebris (the mirror 
> site... easier to get into) shows that one need only cut the 
> bridge on the regulator chip, install a 5K pot, and stick it back 
> together.  I converted my RS-35A into a VS-35M (with meters), 
> although I put my ammeter in series with the output, vs. the way 
> they do it.
>
> I also added a pair of standard-spacing 5-way binding posts on the 
> front of the supply, as it makes it SOOOooo much easier to use it 
> as a bench supply.
>
> Tom - WØEAJ