38 Special Power Mod
by Marty Himes, WB8FNH
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38 Special Power Mod
by Marty Himes, WB8FNH |
About the
AmQRP Club |
"38 Special" Power Mod
I added the power modification to my 48Special. Upon careful inspection,
of the existing modification, no changes really are necessary, I think,
other than the various ones discussed by other list members, for the
10.110 mhz version.
The inductor, L5, serves as a choke, I believe, so it may not be critical.
I had scaled up its inductance to 4.16 uH, which makes the toroid
go to 32 turns, (up from 27) but it's not a resonant component so that may
not be necessary. I'm hoping others will confirm or argue this.
The existing PI network, as modified for 40 meters in my initial
writing of this, is the same.
I read about about 3 watts into my Diawa meter, then into a homebrew
T-network tuner, which is pre-tuned with my Yeasu for the match with
the G5RV'. The low power reading is due to a 22 ohm resistor in place
of the 10 ohm part (which I did not have). It's holding back some drive
current, I think. I also have a 270 ohm resistor in place of the mod's
220 ohm part (which I did not have) which may allow a higher bias
and makes the '510 heat up a bit quicker. Not sure. This weekend I'll
add the variable power pot mod to fix that, and put the correct values in.
After setting my keyer speed, and playing for a moment with TC2 to
get a good tone in the Yeasu, I answered a CQ from a fellow in Houston.
I don't have my log sheet with me so I've forgotten his call, KC5???.
His name was Ray. Not familiar to me from this list. He reported me at
RST 589. We talked for few minutes. Said I sounded fine. No chirp,
drift, or strange stuff. I haven't checked the harmonic levels or
spurious output yet.
Good luck and publish your results!
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Page last updated: April
15, 2004