Peter & Jim,
I started using a thick fish paper and paper tubing like that used for RF
coils. You can buy it in larger diameters. I tried some with some 4CX250B's
just to see how it worked and it was ok. The tubing is made from an
electrical insulation type paper. The fish paper sheets is the blue or gray
type, and about 1/6" thick. It's the same stuff you can make transformer
bobins with. The tubes don't get hot enough to do anything to the paper,
including the larger tubes if the air is flowing. The paper tubing is made
by Precision Paper Tube. They supply the electrical/electronics industry.
Oceanstate Electronics has the fish paper. A Google search will quickly find
both.
Best,
Will
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--- In ham_amplifiers@..., "Peter Voelpel" <df3kv@...> wrote:
Hi Jim,
I use heatresistant glass cylinders I get made locally and also use
round teflon covers as you, thats works very well.
All my blowers are made by EBM.
I do not like to boost a tubes rating, I rather prefer then to use a
bigger one.
I prefer that my GG amps cannot run in too high dissipation at full
drive. They should have no problem when the antenna gets lost...
73
Peter
--- In ham_amplifiers@..., "pentalab" <jim.thomson@>
wrote:
For an experiment, I remember W7IUV had fabricated a >fiberglass
box around his YC-156.. for a chimney.
We tried the same trick... except the vertical sidewalls were
made from wood... about 9" square... top was also made from
wood.... and the original chimney was placed in a groove.. on
top of this wooden affair. Now we could increase the hole
sizes on the chassis.
The result was a huge improvement! Intead of the original 205
cfm... we are now getting an easy 320 cfm [using a Dayton
5C508 dual speed, capacitor start blower].
