Hi all,
I have a Heathkit HL2200 that was built by NC8V (SK). (Uses a
pair 3-500Z's) I bought it from him while he was still alive and he gave me
a photocopy of modifications to help the stability. One concerned the
parasitic chokes. It involved removing the current ones and just removing
the wire off the resistor. Then with the same amount of turns, it called
for a piece of nichrome wire, (available out of a hair dryer, toaster, oven
element, etc.) instead of the copper wire. So I used a silver brazing rod
($5.00 now...ouch...) to 'tin' each end so that it would be solderable.
Then it called for me to wind the same number of turns over the resistor.
Theory: The nichrome wire exhibits resistance and instead of a direct
short like the copper wire did. This resistance broadens the 'Q' of the
choke and helps quell parasitics. It certainly helped in my amplifier, as
I could tell an immediate difference, especially using a tuner with the ol'
gal.
A little off topic about the resistors but something to consider when
making parasitic chokes.
Greg Weinfurtner AEE BSS
NS8O
40192 State Route 689
Meigs County
Albany, Ohio 45710
United States of America
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