On 7/20/2012 2:32 PM, Roger (K8RI) wrote:
> On 7/20/2012 1:19 PM, Paul Hewitt wrote:
>> Greetings
>> A few months ago someone posted the link for this company after using some
>> of their silicone hose for a chimney(s). I bought some of the 2.5 inch hose
>> for a pair of 3cx800's I have. It is a polyester reinforced product.
>> Unfortunately the hose did not survive the microwave test I gave it. Two
>> minutes in a 1KW microwave gets it so hot you can't touch it for ten
>> minutes. It might be OK for HF but above that I would be cautious. For
>> what it's worth before you spend the money.
>
> Why not do it the way the commercial amp builders do it. Take a piece of
> about 1/8" silicone rubber sheet, roll it into a tube of the proper
> size, and use Silastic RTV (TM) or any other RTV) and make your own.
> They are cheap, easy to make, and rugged.
>
> Polyester reinforcement might not be an improvement.
>
> You can purchase the high temperature silicone (red) from Aircraft
> Spruce and other sources.
To expand on this, take a piece of conduit, wood dowel, plastic tube, or
anything else of the proper diameter (usually just a little smaller than
the OD of the tubes). Wrap the sheet around the tube and cut to leave
maybe a 1/4" overlap, Join or glue together with Silastic RTV (TM) and
use hose clamps, tape, or heavy rubber bands to hold it in place while
the RTV cures. There is a high temp version of Silastic RTV(TM). Give
it a good 12 to 24 hours to cure. Depending on length you can make a
tube long enough that you can cut 2 or 3 chimneys from it.
The nice thing is when using sheet, all you need is a different size
mandrel for each size tube. With a bit of practice you can make these
without a mandrel. It's just easier and particularly when first
starting to make them.
If worried about the "stuff" curing in the tube, after use, put the cap
back on tight, then put the whole tube in a glass canning jar that can
be sealed with a gasketed top. I have some that is now over 20 years
old and still good. Actually I've also used Tupperware to seal up tubes
that have been opened with results as good as the glass jars.
73
Roger (K8RI)
>
> Polyester reinforcement might not be an improvement.
>
> You can purchase the high temperature silicone (red) from Aircraft
> Spruce and other sources.
>
> 73
>
> Roger (K8RI)
>
>
> 73
>
> Roger (K8RI)
>
>
>
>>
>> Paul
>>
>>
>> PAUL HEWITT
>> WD7S PRODUCTIONS
>> QRO HOMEBREW COMPONENTS
>> http://home.earthlink.net/~wd7s
>>
>>
>>
>>
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>>
>
>
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