[R-390] 3DW7: A 3TF7 Tubester

[David Wise]

This started out as a private reply to Richard
McClung, and then also to Craig McCartney.
To avoid the feeling that I'm sending N
copies of a form letter, I decided to just
post my reply.  If you're not following
this thread, delete it and go on.

*      *      *

I wanted to wait until I had a prototype
instead of a breadboard, but the recrudescence
of the ballast tube thread seemed like a call.

I'm proud of my work.  AFAIK, nobody else has
tried this, and I feel I have achieved some
real innovations.  I will never recoup more
than a tiny fraction of the engineering
time; it was a labor of love.  But I still
want token compensation.  I also don't want
to undercut Chuck Rippel.  He sells a unit
for IIRC around $100.  I'd like $150.

Think it over and get back to me.  To minimize
expenses, I will not lay out a circuit board
until I have a bunch of confirmed sales.  I
arbitrarily picked ten.  For now, I have a
breadboard, and a hand-wired actual-size
prototype of an earlier, all-analog design.
Take your time, I'm still waiting for a couple
of critical components that will let me do a
full-scale test.  Right now I'm using substitutes
which can't take the full voltage range.

My VFO changes 5Hz from 17VAC to 26VAC.
I haven't measured it, but I believe this is
less than B+ or AGC-induced variations.

I've never made a product on my own before,
this is scary.  I hope I can make it look
as good as it works.

Regards,
Dave Wise