Hi Leslie:
I don't understand the comment on the Wiki page about triodes with
a gain less than 1. AFAICR a triode tube can have a stable gain
into the hundreds.
If you want to build an amplifier with the maximum gain bandwidth
product the gain of each stage should be e (Wiki: math
constant) in what's called a distributed amplifier (Wiki).
I have some early RDF information at:
https://prc68.com/I/RDF.shtml
Also it turns out that Watson-Watt invented a very sophisticated
lightening strike locating system when he was working for the UK
weather bureau. In the discussion after he gave the paper it was
clear that the same system would also work in aircraft to
determine the location of beacons.
https://prc68.com/I/InstantaneousDirect-readingRadiogoniometer.shtml
It was later that he invented RADAR.
PS CRT based RDF systems like this that work for lightening
strikes that are of very short duration also work for burst
transmissions. They were at the heart of the Elephant Cage (Wiki:
Wullenweber)
systems.
PPS If there's someone who is a IEEE member could you send me a
pdf of the paper Distributed Amplification by Ginzton, Hewlett,
Jasberg, Noe et al?
https://ieeexplore.ieee.org/document/1697772
--
Have Fun,
Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.
-------- Original Message --------
Hello All:
When the Aircraft Radio Corporation built the superhets
we call SCR-274 (or ARC-5) it was all because the British
Admiralty felt the high cost of RDF (etc) was justified.
Read all about it below.
From Wikipedia:
https://en.wikipedia.org/wiki/Superheterodyne_receiver#RDF
"
RDF
There was one role where the regenerative system was not
suitable, even for Morse code sources, and that was the
task of radio direction finding, or RDF."
"The regenerative system was highly non-linear, amplifying
any signal above a certain threshold by a huge amount,
sometimes so large it caused it to turn into a transmitter
(which was the entire concept behind IFF). In RDF, the
strength of the signal is used to determine the location
of the transmitter, so one requires linear amplification
to allow the strength of the original signal, often very
weak, to be accurately measured."
"To address this need, RDF systems of the era used triodes
operating below unity. To get a usable signal from such a
system, tens or even hundreds of triodes had to be used,
connected together anode-to-grid. These amplifiers drew
enormous amounts of power and required a team of
maintenance engineers to keep them running. Nevertheless,
the strategic value of direction finding on weak signals
was so high that the British Admiralty felt the high cost
was justified."
I found the above when hunting for a little history of
the development of the superhet. My first reaction was to
send it to "our" resident historian (Hue). I admire his
extensive knowledge of radio history and enjoy reading his
postings here. Then I thought others may find the role of
the British Admiralty "interesting" and so I sent it here
instead.
I must seek information about the development of the
superhet elsewhere, it seems.
Best 2023 to all
Leslie
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