[Amps] Silicone hose from Flex Technologies

[Manfred Mornhinweg]

Jim,

> ##  You would need one heck of a lot of silicone to make one sheet for a
> chimney. 

Not really! A chimney for a 4CX1500B, for example, would be about 8.2cm 
inner diameter, and at most 10cm tall. Making it a half centimeter 
thick, which is rather generous, you need 273ml of silicone caulk. A 
310ml tube of silicone caulk costs about 3 dollars locally.

If you use smaller tubes, and use two of them, you still gen get the 
chimneys for a legal limit amp from a single tube of caulk!

 > Just buy the silicone rubber sheets from mc master carr in the usa.
> You roll  it into a cylinder.. then  use silicone rubber glue to glue the edges.

I'm certain that this is a good method. But for me, that method means 
placing an import order and waiting 4 to 5 weeks for the items to 
arrive. The silicone sheets I can get locally are just those sold in 
supermarkets for kitchen use. They should do too, anyway... They are 
intended to use in an oven, and are also rated for microwave ovens.

> Silicone rubber glue looks  sorta like regular RTV glop.... but is high temp stuff,
> made for gluing silicone rubber sheets. 

I would have to use plain silicone caulk for gluing. I haven't seen 
dedicated silicone glue locally.

> The sheets are reddish colour.   They will
> take a huge amount of heat.  the sheets are also used in exhaust systems on trucks etc.

Any silicone can take a lot of heat! But some silicone is formulated to 
take a little more heat than the basic one. I wonder if that reddish 
colour is intrinsic to that high temp silicone, or if it is a dye added 
to signal that this is high temp silicone!

> You can also get  flexible silicone rubber hose... in large diam too.... used for  front brake cooling
> on high performance cars.  ( see it up to 3?  so far).

Good to know.

Anyway, I mentioned my method of making silicone parts, because it is 
useful for many things, not just tube chimneys. I have used this method 
to make grooved insulating and shock dampening washers for variable 
capacitors  - a photo is in this page, about one third down the story,

http://ludens.cl/Radiohis/ak206/ak206.html

and also I have made spacers, angled insulating flexible holders, and 
even some special size V-belts, in which I used cord to reinforce the 
silicone. Having a few tubes of silicone caulk on hand, some 
polyethylene stock to make molds, and tools, allows me to make special 
parts rather quickly, instead of cobbling them together from parts I can 
get ready made, or waiting a month or more for an import order to arrive.

 > Alpha uses rolled up sheets too.

I have seen them, and wondered at their amateurish look, which I didn't 
expect inside an amplifier of such high cost. But they work fine, so I
wouldn't complain...

Manfred

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