[TenTec] Astron SS30 power supply leave on?

Stuart Rohre rohre at arlut.utexas.edu
Wed Jun 24 19:52:14 EDT 2015

All Astron supplies I, or my club have owned have had terrible quality 
control and really off the wall circuitry.  I have had them act as 
lightning sinks on more than one occasion, either at the club station or 
at a friend ham's home.  The off the wall circuit was using a bridge 
rectifier as a full wave rectifier, ie using two of the four diodes only.

I unplug my power supplies when the station is not in use.  Comes from 
living overseas in intense thunderstorm, jungle areas.  I have seen 
appliances hit twice in two years, on the same outlet!

The Astron series pass regulator chip is the first thing to fail, as if 
it was designed as a lightning fuse.  I have diagnosed many Astron 
failures by simply asking "was this supply plugged into power and on 
during the recent storm"?  The linear regulator IC is the first thing I 
bring out of the spare parts bin, if the answer is positive.

One of our club's failed Astrons was still emitting smoke from failed 
components on Monday noon after a weekend storm.  That one was plugged 
into the AC line but turned off.  The surge arced through the switch.

The quality of wiring and soldering is often suspect.  Wires poked well 
past terminal points with excess wire out in space.  Questionable solder
joints abound.

I always check an Astron with a good DC voltmeter to make sure it is 
putting out a regulated voltage.  Another component known to fail are 
any MOVs included across the AC line connections.  Those have been known 
to fail to the point of combustion.

I would never leave a power supply on 24/7 as the risk of fire in it is 
all too real.  For a little while, an out of control DC supply can push 
some serious voltage and currents.  I have seen it happen.

Nothing about an Astron says industrial grade to me.  In fact, in TX, 
repeater owners will not put an Astron supply into a remote repeater 
site because of bad service histories with them.

As always you get what you pay for.  They are lower priced, but serve 
satisfactorily if you are able to repair them and access them easily.

We have seen the parallel transistor schemes they use on the higher 
rated supplies fail by not sharing the current equally among the 
parallel power transistors.  You have to match the transistors to each 
other to have such a scheme.  The emitter resistors usually blow, one by 
one, as the remaining transistors try to share the demand for current.

I even bought another brand of power supply that had built in voltage 
metering, to give a quick check that I did have the voltage desired for 
my main rig.

I don't mean to be too harsh, but hard earned experience makes me more 
cautions of power sources now.

Stuart Rohre

More information about the TenTec mailing list