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Mini-Bomb
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Bill Brown 11".pSYK
28 Marine Lane
Hazelwood. Mo.
After many attempts to design a two
tuber (4-1000A or 8166) on a standard elmssis
( 13x 17 ) , I gave up in despair and went
to a larger chassis which was 15" x 26" x 6"
deep. An article was p ublished in the May
issue, 196,5 culled the "Big Bomb". I know
of more than 30 Hams that are using this
design.
The smaller rig got started one afternoon
after Bnding a very small ceramic vacuum
capacitor. After two days on the drawing
board I fina lly got all the parts laid out without
overlapping. Some features that might be
of interest arc as foIlow: Both plate a nd loading
capacitors were mounted on 3" x 5J:i" x 32"
Machine alum inum blocks, which will prevent
current losses and will add to the high
efficiency. Checks proved efficiency as high as
72%. I would like to call vour attention to
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the high voltage feed-thru. These are homemade
out of 1" round teflon extending 1" on
each side of chassis. Breakdown was better
than 30 K. Plate coil for 20 meters was
Form ed on quart bottle of TANQUERAY gin
(dia. 3%" ), length was 5\6". (T ubing %"
used) . The design of the "Mini Bomb" is
such that parasitic chokes are not necessary,
and this final was checked for this with voltage
better than 7.5 K. Chass is was chrome
plated to prevent rusting and for appearance.
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Since the tubes are in the front and centered
on the chassis; a 6" x 9" cutout was
made to view tubes. This cutout is 6~ "
from the bottom of the panel, which is steel,
and 17\6" high. Two meters (3W') were
placed above the cutout. The plate meter is
0-1.5 amp. and the output meter is 0-1 rnA
with a 0-10 rf amp. scale being used. The
large 3" Groth counter Dials rounds out the
Panel.
This final is housed in a 61 v.... cabinet
with 24" depth, in order to make room for
73 MAGAZINE