[NLRS] Fwd: [Mw] Firing a gas tube noise source.

[Dr. Gerald N. Johnson]

-------- Original Message --------
Subject: [Mw] Firing a gas tube noise source.
Date: Tue, 20 Dec 2011 14:22:12 -0600
From: Dr. Gerald N. Johnson <geraldj at weather.net>
Reply-To: geraldj at weather.net
To: 'microwave at lists.valinet.com' <microwave at lists.valinet.com>
CC: Barry VE4MA <ve4ma at shaw.ca>

A few months ago, I acquired a 10 G HP X347A noise source. I planned to
use it with my portable home brew noise source power supply that I built
about 1965. That supply fires a cold 2' fluorescent tube just fine, but
after making a connector would not fire the X347A. It also runs a vacuum
diode noise source nicely.

I tried a 500 volt DC supply with a 10 hy choke (my power supply and the
HP340 both use a 2 hy choke) and test leads, and though the inductive
kick follows my retreating probe for close to a quarter inch, no flash
or light from the gas tube out of the X347A.

With gas tube in hand, I looked up a data sheet. Its an 8030/TD-41.
Seems it takes 5 KV to start. I've contemplated using a flash tube
trigger transformer to start it, I have a few, but need to find some old
catalogs for data. I've wound some 4 KV output flybacks for a battery
bug zapper project that were compact, but their high voltage winding of
#40 wire won't carry the operating current for the tube. Winding copper
hair sized wire is a pain any way, the breaking tension is less than the
friction over my index finger guiding it from a wire spool mounted on
tiny ball bearings. I found a sewing machine thread tensioner assembly
is more controllable than the friction over my index finger.

I do have an HP340A, but its been in a space age rack with the panels
recessed and the noise head would not mount because of the rack. Over
the last weekend, I moved equipment to a smaller Bud rack without side
extensions so I could eventually fit two racks next to the new work
bench. Today I tried the X347A with the HP340A where a TV sweep tube
does the triggering and it fired just fine. But its not portable. At
least now I know I have a good gas tube and the 340 controls the current
just perfectly. Now I can get on with other NF projects as soon as I
build a termination. A cable would be handy, but I can get along with
running the RF through cable or waveguide. I'll want attenuation anyway,
at least 10 dB.

Some where I have a couple AIL coaxial sources, that may have similar
tubes, but I've not found them since I moved. I know I packed them, I
just don't remember with what. And since I didn't plan much on using
them, I didn't put them in the box contents labels. I'm sure they don't
have the connections for the gas tube that are an integral part of the
HP gas tube sources.

73, Jerry, K0CQ
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