[TowerTalk] Vacuum tube 100 years old today

[Chuck Lewis]

And from the October 1948 issue of QST, in a "Technical Topics" article on
page 48, headed "The 'Transistor' - an Amplifying Crystal", this excerpt -
the final paragraph:

"It doesn't appear that there will be much use made of Transistors in
amateur work, unless it is portable and/or compact audio amplifiers. The
noise figure is said to be poor, compared to that obtainable with vacuum
tubes, and this fact may limit the usefulness in some amateur applications.
These clever little devices are worth keeping an eye on". The article
describes a germanium point-contact device made by (of course) Bell Labs and
having two 'catwhisker' point contacts spaced approximately .002 inches
apart!

Staying on topic: the same issue describes a dual-band four element beam
using harmonically related bands to feed a driven element as a half-wave
dipole on the lower band and as two close spaced halfwave collinear dipoles
on the higher band. The parasitic elements were split with an L/C network in
the middle to present a series -resonant short at the low band, and parallel
resonance on the higher band (to allow them to act as half-wave collinear
phased parasitic elements) .

Multi-band full size yagis on the same boom with one feedline and no(?)
traps. Slick, huh? (grin).

Chuck, N4NM

----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>
To: <Topband at contesting.com>; "160m QTH" <160m at mailman.qth.net>;
<towertalk at contesting.com>
Sent: Tuesday, November 16, 2004 10:28 AM
Subject: [TowerTalk] Vacuum tube 100 years old today


> On Nov. 16, 1904 Fleming patented the Fleming valve. The
> vacuum tube is 100 years old today (exactly 46 years to the
> day older than I am).
>
> I was an electrical engineering student in the late 60's.
> The electronics lab stock room was full of tubes and
> sockets, and our benches had 300 volt power supplies. About
> 50% of our inventory and study was tube related. I built a
> complete 500 watt HF station, receiver and transmitter, from
> stock room parts in my spare time. Every component necessary
> was in the stock room. From a textbook I still use,
> "Electronic Amplifier Circuits" McGraw-Hill Electrical
> Engineering Series 1961, comes the following quote:
>
> "For many applications a relative newcomer, the transistor,
> is replacing vacuum tube types because of the greater
> inherent reliability, lower power consumption, and smaller
> size. However, the complete replacement of the tube by the
> transistor does not seem likely, for the latter has
> shortcomings at high temperatures and high radiation
> intensities and in the production of high power at high
> frequencies. "
>
> About ten years later I received a call asking if I wanted
> any of those old tubes, tube related books, or HV bench
> power supplies before they hit the dumpster.
>
> 73 Tom
>
>
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