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Re: [Amps] Life of tubes in ham service

To: "AMPS" <amps@contesting.com>
Subject: Re: [Amps] Life of tubes in ham service
From: "Jim W7RY" <jimw7ry@gmail.com>
Date: Fri, 29 Dec 2017 19:47:34 -0600
List-post: <mailto:amps@contesting.com>
Oh... And I have used small screws, (2-56) and nuts to hold Teflon sheet together for tube chimneys.


73
Jim W7RY
Happy New Year!

-----Original Message----- From: Jim W7RY
Sent: Friday, December 29, 2017 7:46 PM
To: AMPS
Subject: Re: [Amps] Life of tubes in ham service

Lots of Teflon and silicone on eBay.

I have also successfully used turbo charger hose. Buy it by the inch. I use
it on my 3CX800 amplifier. It's silicone sheet with a cloth cover. Used to
connect the exhaust system to a turbo charger on truck and heavy equipment
engines.


73
Jim W7RY


-----Original Message----- From: Roger (K8RI)
Sent: Friday, December 29, 2017 7:32 PM
To: amps@contesting.com
Subject: Re: [Amps] Life of tubes in ham service

Silicone rubber sheet wrapped into a cylinder works fine and requires no
machining. The ends simply overlap. The joint can be made a number of
ways including RTV. There was a RED high temp RTV available at one time
although the regular "Silicone" RTV should work  (smells like Acetic
Acid). Alpha and others have used this for years.  !/16th" Teflon sheet
should also work fine, but OTOH it is slippery and not as easy to work
with. .  The nice thing about using sheet is adding a taper is simple.
Speaking of simple, working with these sheets is simple and requires no
special tools.

At one time I had a bunch of the red, high temp rubber and the red high
temp Silastic RTV


I believe the 1/8th inch Silicon rubber might be available at many
automotive shops.

73, Roger (K8RI)

On 12/28/2017 Thursday 6:39 PM, Stan Gammons wrote:

On 12/28/2017 01:15 AM, Roger (K8RI) wrote:
"I think" the GI-7B would be an easy tube to convert to transverse cooling to replace the no longer available Eimac tubes in the MLA-2500s. The coolers are easily replaced by removing a single screw. A lathe and mill could easily build custom radiators. It'd be a simple, straight forward conversion. IM products?

73, Roger (K8RI)



I haven't decided on the cooling method. But it will probably be something along the lines of a plexigass cages with the fan mounted so the air flows up around the tubes and out the holes in the top of the cage. I've seen some use a machined piece of teflon for chimneys. A piece of teflon tubing that size is rather pricey though.

I ask on this list about IM products awhile back and the general consensus is it's not a problem.

Seems like the MLA-2500 is one of the many amps that others have converted.


73

Stan
KM4HQE



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--
Roger (K8RI)


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