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.
>
>
|