[Elecraft] Vacuum-tube Projects (WAS: SMD-based kits)

[Ron D'Eau Claire]

Larry, N8LP, wrote:

Don't knock tubes. My first kit was a Harmon Kardon stereo amplifier 
with lots of tubes and no PC baord. It was great fun. I also built 
Dynakits and Heathkits with tubes. There's nothing like the smell and 
glow of vacuum tubes to warm your heart.

-------------------------

I find something special about working with vacuum tubes as well, but then I
was "raised" on vacuum tubes. Still, I've met some newer Hams who want to
mess with tubes in at least a simple unit of some sort.

A friend who really wanted to play with tubes and learn a little more about
how receivers work inspired me to create a little hybrid superhet receiver
that was described in a construction project in the November 2003 QST. It
uses three tubes that were designed to operate at no more than 12 volts
instead of the usual several hundred volts. I heard from about a dozen
people who built them. It's gratifying that the interest is still there and
that people enjoyed tackling the project. 

If tubes interest you, there are a number of e-mail lists for such
enthusiasts who build gear from scratch and who restore old gear. One place
to look is the Glowbugs, a mailing list for vacuum tube Ham enthusiasts. To
subscribe to the Glowbugs E-Mail Reflector, send mail to:
majordomo at piobaire.mines.uidaho.edu with the following command in the body
of your email message: 

subscribe glowbugs youremailaddresshere

The list runs on space on a server donated by the University of Idaho in the
USA and is managed by Conard Murray WS4S (ws4s at infoave.net).

You'll run into several names and calls familiar around here, including mine
<G>.

One thing that concerns me about encouraging ops familiar with solid state
to work with tubes is that most tubes operate with lethal voltages where
there's only +12V in our Elecraft rigs. Not that low voltages can't do real
harm, especially with a heavy-duty power supply. I've known technicians
missing ring fingers because they carelessly poked around inside a live unit
and let the ring touch a ground and a live, high-current 12 or 24 volt power
buss at the same time. Still, high voltage demands a different sort of care
and different procedures around equipment to be safe. Some of the most
famous Hams of all time and far too many ordinary operators of my generation
and before ended their lives with one careless move around the high voltages
in their Ham rigs. 

One can be safe around high voltages, but it as different as climbing a fake
rock face at the local sporting goods center and climbing El Capitan at
Yosemite park. Out in the "real world" mistakes are much more dangerous.
That was specifically why the little project I created for QST used the
special low-voltage tubes.  

Ron AC7AC