13 Jun
2024
13 Jun
'24
4:05 p.m.
On Thursday (06/13/2024 at 10:46AM -0500), Jon Elson via cctalk wrote:
On 6/12/24 22:32, Gavin Scott via cctalk wrote:
The OP mentioned that the story may have originated at Varian, where they
historically did a lot of work on high power _microwave_ stuff. I could
imagine that a roll of paper might make an OK attentuator at the end
of a piece of waveguide, into which you can dump a bunch of power.
But it probably isn't going to be a very good impedance match.
I don't see it working well at all at HF, VHF or UHF frequencies if
the RF source (transmitter) is expecting any sort of normal impedance
like a 50 ohm termination-- because how are you connecting the feedline
to this roll of paper? What is the mechanical and electrical interface
between the unbalanced (or balanced) feeder and the roll of paper?
Maybe they put an actual dummy load resistor inside the roll of paper
and were using it as a heatsink-- you know, before it lit on fire ;-)
Seems like some important details of this story are missing...
Chris N0JCF
--
Chris Elmquist
Is it possible they were thinking about really
old FAX paper which
might have been wet to support marking via an electric discharge
through it (and to (slightly) reduce the frequency with which the
receiving machine caught fire)?
Yes, there was teledeltos paper, that had a silver top layer and a carbon
layer below that.
A high voltage spark burned away the silver layer and left a black image.