At 10:37 PM 4/18/2003 -0400, you wrote:
>Has anyone used a coleman lantirn pyrex envelope for the cooling chimney for
>a 4-1000?
>
>Did it fit? Did it work?
>
>jeff, wa1hco
Jeff,
It has been a long time since I thought about the Coleman lantern
chimneys--but my recollection is that the one for the double-mantle
lamp will fit a 4-400 or 3-500Z but no way will it fit the 4-1000.
Unless there is something new (like in the last 25 years!) available
then you are out of luck for the 4-1000.
Actually I have had very good luck with standard 1-gallon pickle jars.
I cut the bottom end off by mounting a glass cutter in a little drill-press
vise about 1 inch above the work surface and then rotate the pickle
jar around, scribing a light scratch on the jar. Then, using a piece
of nichrome wire wrapped around the scratch, I apply some current to
get the wire hot and within seconds you will hear a "plink" and the
bottom of the jar will drop off.
Some of these home-made chimneys have been used in contest
stations without any failure--but I would make sure you have plenty
of air flow just to be safe.
At one point I decided to take off the threaded top of the jars to make
them look more like a real chimney. But this had mixed results. The
glass is very thick in the area of the taper and start of the threads and
the tops did not always pop off cleanly where they were scribed. Ultimately
I decided that the threaded-neck portion of the jar actually helped keep
the moving air around the aluminum anode-cap radiator (heat sink).
I was lucky and had a friend who did the 2-way radio maintenance for
a local pickle-packing company so I got cases of new jars for virtually
nothing. If you don't have that sort of connection you will need to eat
a lot of pickles first--or make friends with the owner of a local restaurant.
And I am now seeing a lot of pickles packed in plastic jars--but you will
need to find glass ones.
It certainly isn't Pyrex (tm) but I have never had a heat failure from a
4-1000 pickle-jar chimney!
73--John W0UN
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