13 Jun
2006
13 Jun
'06
9:18 p.m.
On 6/13/2006 at 8:25 PM Roy J. Tellason wrote:
What did they use for a CRT? I have a 3" one in
storage that as I recall
wants something like 1000V for an accelerating potential, and a
transformer to develop that isn't exactly trivial.
My 1942 Radio Handbook shows how to build two CRT-based devices. One is a
basic scope, using a 2501A3 CRT (3"), an 80 as a B+ recitifer and another
80 as the rectifier for the anode voltage. The power transformer is a
rather odd one with 2 5v insulated windings for the 80's and a 350-0-350v
winding for the B+ and a 450v winding that's hooked to one side of the
350-0-350, so the anode rectifier receives 800 vac RMS. Horizontal and
vertical amps were both 6C6's and the horizontal sweep was generated by an
885 gas triode (sync supplied through the grid). Total valve count = 5,
exclusive of CRT.
The second is a simple modulation monitor which uses a very small 913 1"
CRT and a 5Z4 for the anode supply. Since the RF and AF signals are
applied directly to the 913's deflection electrodes, nothing more is
needed.
BTW, "UHF" back then meant that you were operating on the 56 or 112 MHz
bands--and FM was very hot on the 2 1/2 meter band.
"Microwave" was defined as 1 Meter (300 MHz) and down. Exotic strategies
to get these frequencies included magnetrons, Kozanowski and Barkhausen
oscillators and the WE 316A "doorknob" tube. A brief mention is made of
the RCA 825 "inductive output amplifier", which bears a remarkable
similarity to an klystron. Although not mentioned, the Varian brothers
were the minds behind it.
Cheers,
Chuck