>Can anyone provide the value of the resistor used and the number of turns
>for
>the parasitic chokes used in the SB-200. The manual only lists them as a
>"prebuilt" part that came with the kit. Thanks!
>
// ... roughly 7-turns, 1/4 - 5/16 inch diameter with about 1 wire
diameter air gap between turns. The best resistors for this application
are probably Matsushita 3W MOF-type. I tested a 100-ohm 3W unit at 12W
for 1-hour. The resistor glowed dull red, the blue paint got pale, but
the resistor did not fail. The L of these resistors is low,: 11nH --
which is almost as low as an equivalent piece of copper tubing. A low-L
resistor is what's prescribed for VHF parasite suppressor service. Also,
by making the coil from resistance-wire, an approx. 60% improvement in
suppression ability results.
-- Notes: Do not wind the wire on the film resistor because the
conductive film is under the paint. / The coils should be at right angles
to each other. / The suppressor resistors should get very hot and
discolor during AØ on 10m.
cheers, Mark
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
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