View Single Post
  #8   Report Post  
Old August 25th 07, 04:42 AM posted to rec.radio.amateur.homebrew
Straydog Straydog is offline
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 76
Default My vacuum tube homebrew transmitter


See quoted material at end.

When I was a kid, I and the guys I hung out with were always playing with
high voltage. We all built Tesla coils (12-15" sparks), played with Model
T Ford spark coils (2" sparks), neon sign transformers that weighed 50
pounds and put out 15,000 volts at 30 to 50 milliamps, and
Frankenstein-type "jacobs ladders." We made sparks. We made arcs. We made
noise. We made smoke. We blew fuses. One more thing we all made was an old
fashioned "repulsion coil" (coat hangers, wire, copper or alluminum ring
that would jump up a foot when you threw the switch). We all made crystal
sets, too. Made one transistor radios, too. Built Knight kits and
heathkits.

Yes, you do NOT want to be a _klutz_ and goof off like we did. Yes, you do
not want to play "electric chair" with yourself, and yes, its a very good
idea when working with lethal voltage to keep one hand in your pocket when
anything is "live". Repeat: if you are a klutz, or accident-prone, then do
not mess around with this stuff.

Beyond that, yes, I got a few shocks. I even felt current from a 12 volt
car battery (moist hands, large metal electrods, and use one hand on each,
squeeze tight, I felt a mini-tingle). Got a nast RF burn by accidentally
touching the plate cap of a 6146 with 50 watts of 10 meters carrier. It
hurts and burnt flesh (part of my thumb) stinks like hell. I got a few
more shocks, all minor, and whenever I'm around serious voltage and
power, I definitely look twice at everything.

Most scandalous shock: Outside the house. Rainstorm coming and lightning
and thunder comes 10 seconds later, means its all about two miles away,
and I'm playing with the feedline on a 75 meter dipole with my hands, and
then the next flash of light from the lightning and--dang it--I felt that
"needle" in my hand from a pulse of electricity. Hmmmm...better get inside
the house. So, next time you are listening on HF and when the lightning
and thunder are close, and your S-meter needle is bouncing all the way to
the top, you can be thiking about 100-200 volt pulses, eh? Anyway, just
think about Ben Franklin who was flying his kites in the rain (in my case,
I was dry and the rain wasn't falling yet where I was).

W4PON
===== no change to below, included for reference and context =====

On Fri, 24 Aug 2007, Scott wrote:

Might not kill a tube, but it could kill a builder! Be careful!!

Scott
N0EDV

Straydog wrote:

FYI, FWIW...

As I recently became retired my interests have evolved towards building
homebrew tube gear. Reasons:



iii) accidental slip of the
test prod might not kill a tube but might a transistor,