[Collins] 872a Lamp, revisited

Zap (Chris) [email protected]
Wed, 27 Aug 2003 13:01:12 -0400


A while ago I posted to the list concerning a nostalgic lamp that I wanted
to build in Collins-look, using an 872a tube.  I was curious if some of the
list members might be able to help me (cheaply.. I'm an EE student!) locate
some parts to create this beast.

I already have the tube, however about everything else is still in the
works.  Ideally I would like to put this in a small square enclosure painted
crackle finished like the A-Line.  If it had the vents on the sides, that
would be even better.  I've seen an enclosure to this once before.  Does
anyone know if there are any aftermarket boxes like this made or how I could
create one?

Secondly, I also would like to find clear red and green pilot lamps and
toggle switches like on our club's KW-1 to put on the front.  A dial for
adjusting the plate (in order to dim or brighten the tube) would be nice as
well.  I've had trouble finding the socket, and thought I was getting the
right 4 pin socket, but I believe the one I ended up with is too small (tube
is at home, socket at school).  I also need to locate the cap (medium size)

Finally I need to finalize the circuit used to actually power the tube.
Unfortunately, I haven't been taught much about transformer theory in
school.  I'd like to find a specific (and smaller) filament transformer that
can fit in the enclosure.  Is this feasable?  Secondly, I'm also not that
familiar with tube theory either.. so I'm not sure what to do with the plate
side, but I'm guessing that is where I will want to put the adjustment to
dim/brighten the lamp.  Finally, I have no idea where to find the parts that
would be optimal for this project.  Here's the data I have so far on the
tube:

Filament:
Average 5 Volts AC
Current @ 5 V avg 7.5A
Peak Tube Voltage Drop approx 10V

Peak inverse anode voltage 5000 volts max (or 10000)
Anode current peak: 5A max
Anode current avg: 1.5A max

Thanks in advance for any help you can provide.  This has been a back-burner
project of mine for too long, and I'd really like to see it become a reality
:)

73,
Chris, N9WIV