I appreciate this, Butch.

I really don't have the equipment and know-how to do it with confidence
myself, but I bet someone in my club will if we can work together on it.  I
have saved your description of what needs to be done, and it makes basic
sense to me.

I'm going to ask at our meeting this coming  Thursday.

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 8:38 PM
To: [log in to unmask]
Subject: Re: RS35 Transistors

I'd replace all 4 transisters, and if the 723 is in a socket, they're cheap,
so I'd replace tht as well.  Those transisters aren't to expensive as I
recall.
If you were closer, I could do it for you.
73
Butch
WA0VJR
Node 3148
Wallace, ks.


On Fri, 27 Nov 2015, Tom
Behler wrote:

> 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.
>
>