Butch, Pat, and all:

Well, after last night's test of my RS35 transistors, where I discovered
that the two transistors on the righthand side of the supply became much
hotter than the left while running the 590 with 100 watts into a dummy load,
I then decided to take some more power readings.  I took the readings both
with the internal meter on the 590, and with my TW1.

You may recall that, the other day, the readings were 75 watts out according
to the TS590 meter, and 58 watts out according to the TW1, and the supply
meter read 13.8 volts and said I was drawing around 11 amps.  This time, the
readings were better, meaning that   My output power readings were much
closer to full power according to both the TS590 meter and my TW1.

I then asked my sighted XYL to take a look at the meters on the RS35 power
supply itself.

Even though the voltage seemed to be at a constant 13.8 volts while
transmitting into a dummy load at 100 watts, my XYL noticed that after a few
minutes, the current readings on the RS35 ammeter began to fluctuate.  They
would fluctuate anywhere from 14 amps, to 18 amps.  When I checked the
transistor heat sinks on the back of the supply for temperature, I again
found the same variation--the left-hand ones were nice and cool, while the
right-hand ones were almost too hot to touch.  Furthermore, my XYL noticed
that when I touched the heat sinks, the amperage values on the meter
fluctuated as well.

I don't mean to be obsessive about this, but this supply is making me
nervous.

I think that I'm just going to bite the bullet and replace it, and then take
my time working with someone in my local club to see if we can fix the
supply so I can at least have it as a backup.

I really would like to continue being able to run both my TS590 and TMV71A
with my rigrunner, so will be sure to purchase a supply that would be
adequate for the job.  I know some have recommended another RS35, and I
might just go with that, since I would prefer a linear supply.  However, I'm
always open to other recommendations if anyone has them.

In the meantime, I've got one or two  backup options, including the TS53, to
at least keep me on the air, both on HF and VHF/UHF.

Tom Behler: KB8TYJ


-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Butch Bussen
Sent: Friday, November 27, 2015 6:09 AM
To: [log in to unmask]
Subject: Re: RS35 Transistors

The hot ones are likely good as they are in series with the load, that is
why those supplies are called series regulaters.  I'd replace all four from
the same vendor so you have sort of a matched set.  Should be able to get
those from mouser or some one.  You will also need some silicon grease.
When you pull the transisters, watch for the thin mica insolater that is
between the chassie and transister.  Some times these stay stuck to the
chassie, or heat sink, and some times they come with the transister.  You
don't want the transister actually touching the heat sink.  A small bit of
silicon grease is used between insolator and transister and between
tinsolator and heat sink to help with heat transfer.  I'll have to see if I
can find the number, but if I were doing it, I'd go with darlingtons, I
think e c g 247 or e c g 249 which are the same, but higher current.
73
Butch
WA0VJR
Node 3148
Wallace, ks.