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Re: [Amps] 3-1000 Amplifiers

To: amps@contesting.com
Subject: Re: [Amps] 3-1000 Amplifiers
From: "Roger (sub1)" <sub1@rogerhalstead.com>
Date: Thu, 12 May 2011 01:29:45 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 5/11/2011 8:57 AM, Charlie Young wrote:
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> I would expect the tube to be fine after drying it off.  However, water in 
> this RF-103 only submerged components in the bottom of the unit, including 
> the plate transformer.
>

Even transformers can be dried out.  Just a little vacuum.  Use a piece 
of steel pipe to make a chamber. 1/4" plate will serve for end plates up 
to maybe a foot in diameter. Then I'd move to half inch.  The end plates 
need little tabs fastened to keep them centered.  Then lap them in place 
just like we used to lap cylinder heads, or valves. Work down in grit 
until it's a polish.   The chamber is relatively simple to construct.  
You pump it down with a mechanical vacuum pump.  A rotary vane 
compressor will suck as well as it blows. Even an air compressor set to 
suck will do a passable job although it may need cooling.  Don't use a 
vacuum cleaner or it's likely to burn up the morto.  At any rate, put a 
gauge on the thing, pump it down as far as it'll go.  let it set until 
the vacuum has bled off to about half of what it was and fire up the 
pump again. IF you did a good job of lapping the end plates it will 
eventually reach a point where it'll hold the relatively poor vacuum.  
When that happens the transformer is pretty well dry.   You might let it 
set out in the sun for a day or two, or borrow your wife's kitchen oven 
and run it up to a bit over 212F/100C (depending on what it has for 
varnish). Let cook for a few hours. Put it back in the vacuum chamber 
and pump it down and give it a couple hours to cool.

if the transformer has not been fired up while wet, or physically 
damaged it should be in good shape.

This is a great way to recondition old transformers that may have gotten 
moisture in them, or submerged, but it's not very economical to do small 
transformers unless doing a bunch of them at one time.  Otherwise you 
don't get much back for either time or money invested.  If it wasn't so 
much work and time to remove and reinstall them, it'd probably save a 
lot of transformers in old equipment.

NOTE, check the oil in the pump after every run. If it starts to look 
milky, it definitely needs to be changed.
Not only does it affect the pumps capability, it can cause excessive 
wear in the pump.

This does not require a high vacuum.  Yes, you could use a high vacuum 
chamber, but diffusion pump oil is expensive at over $100 USD per pint 
for 704 or 705 fluid. They are a bi...bit...er bear to clean 
(particularly the chimneys) AND virtually all of the moisture would have 
to be gone before firing up the diffusion pump anyway.  OTOH after going 
down to 10-6 or 10-7 toor that sucker would be DRY! We use silicone 
fluid instead of organic fluids for two reasons.  Organics back gas like 
crazy unless you get the really expensive stuff and it's still not as 
good as the 704 or 705 fluids.

BTW the fluid in a diffusion pump when burned due to water vapor becomes 
like burned shellac, or cured epoxy and makes cleaning those chimneys a 
lot of fun. <:-))

73

Roger (K8RI)
> The survivor 3-1000z is on the say to a new home to help an idle BTI amp, 
> where hopefully it will send RF to the DX for a long time to come.
>
> 73 Charlie N8RR
>
>> Date: Wed, 11 May 2011 01:32:48 -0400
>> From: rob@cboh.org
>> To: amps@contesting.com
>> Subject: Re: [Amps] 3-1000 Amplifiers
>>
>> On Tue, May 10, 2011 at 04:01:09PM -0500, Charlie Young wrote:
>>> In 2001, Tropical Storm Allison flooded Houston and a strip of land near
>>> Lafayette LA which included my house. Our house had to be quickly stripped
>>> for a complete restoration, so any of my equipment which had been in the
>>> water was tossed in the dumpster. The flooded equipment included several
>>> amps, including the RF-103. Frustration and aggravation at the moment
>>> caused me to toss the stuff; I have long regretted not moving it to storage
>>> with the undamaged equipment. The tube has not been in the water.
>>> I pulled the tube before tossing the amp.
>> Just curious: I know you say the tube was not in the water, but would
>> an unenergized glass tube be damaged from being submerged in a flood
>> for a day or two? I would think it would not be, although I make no
>> claims of being an expert. Just rinse it off and put it back in service...
>>
>> Rob
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