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[hfsig] 20W HF xmtr challenge

Robert Bruninga bruninga at usna.edu
Fri Aug 4 15:53:32 UTC 2006

Build a 20 Watt  HF transmitter and get $50 too!

Here is a modern scavage built amateur radio project that is reminiscent of my novice years 40 years ago, when the discarded TV set was a gold mine of parts for building a novice transmitter.  The modern day equivalent is the modern compact fluorescent bulb.  

These bulbs are a mixed blessing to the amateur radio community because they can generate RFI in the HF spectrum that is counterproductive to weak signal work.  But on the other hand, they cut one's lighting electric bill by 75%!   Each incandescent bulb replaced with a $1.99 compact fluorescent bulb can save over $52 over the life of the bulb.  So in effect, you get paid $50 to use this bulb.

"If you can't lick-em, join-em."  Instead of an RFI generator, lets make a transmitter!

Eventually this bulb will fail and this is usually due to the aging of the flourecent bulb.  So after  you have used the bulb to put $50 in your pocket, break open the base and find these components to build your 20 Watt HF  Transmitter:

2	IFR214 power mosfets
4	1N4007 rectifiers
1	22 uF 200V capacitor
1	510pF 1.2 kV capacitor
And various smaller capacitors, resistors, thermisters and zeners.

I challenge the amateur radio community to come up with a transmitter (or ther useful ham radio project (inverter power supplies, etc)  out of these components.!

A  schematic of the typical bulb is shown on Sam's Schematic Collection Website:


do an edit-search for "compact" and go right to it.  Here is a photo
of the guts inside the bulb:


P.S.  Don't pay $7 each for the bulbs!  Look for the blister packs of 6
or the "contractor boxes" of 12 at a time, and the cost gets below
$2 each.  (use one for 6 years and then when it burns out, then
start your transmitter project. hi hi)

AND not only do you save $$$ from electric use alone, but the
reduction of waste heat saves another two-times that much in
air conditioning costs in the summer!  You just made $150 bucks...

good luck!

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