Jim--here are a couple of places for chimneys -- one in the US
and one in the UK. Just do a google search for coleman + lantern
+ chimney for lots of options.
http://www.base-camp.co.uk/Wicks.htm
http://www.wholesalers-direct.com/camping-lanterns.html
And I wonder what the dimensions of these two tapered chimneys
might be. http://www.wholesalers-direct.com/5107-0481.html
http://www.wholesalers-direct.com/9950-0431.html
Dave--you are correct that one should not compromise an
expensive tube with the wrong chimney of course. But I also
hate to waste money when not needed--so I am always looking
for something from the mass-market world that can be applied
to the ham world and save some money.
The Coleman lantern chimney has been suggested for use
with 3-500s and 4-400s but in reality it does not have the
curve at the top to direct air at the anode seals so it probably
is not a good idea. I have used gallon pickle jars for 4-1000
chimneys and they work well and demonstrate that Pyrex
is not really required. And they DO curve at the top to redirect
the air towards the anode connection.
Eimac was very kind to me over the years with a number of
sample tubes--but they never shipped sockets or chimneys!
So I continue my quest for options.
The Alpha 77SX used tapered chimneys of the red silicon
rubber that are fairly easy to make. Tapered conical sections
can be laid out one paper or cardboard and traced onto the
silicon rubber. Then glued together with RTV and pressure-
clamped for 24+ hours.
Air flow THROUGH the anode cooler is the important part
and the resistance to air flow through the cooler is obviously
much higher than going around the outside of the anode
cooler. So any chimney would have to force the air through
the heat fins. So maybe the Coleman will NOT work in this
application--which is what I set out to discover. But not having
the dimensions for the chimney nor the tube made it a bit
more problematic!
Sounds like there may be some decent-priced options from
amp manufacturers. Or maybe I should start my own line
of silicon rubber chimneys after the years I spent at Alpha/Power.
(Probably not a way to get rich quick. But I am still working
on my "Will Work For Food" franchise business. For the small
sum of $199 you will receive a custom-made cardboard sign,
a uniform designed by Good Will Industries, priority locations
in major cities, and a training video on how to look pathetic.)
73--John W0UN
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