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VK3ABK > VALVES 26.12.05 11:34l 54 Lines 2297 Bytes #999 (0) @ WW
BID : 15836_VK3HEG
Read: DL1LCA GUEST OE7FMI
Subj: Re^Re: wonderful acorns.
Path: DB0FHN<DB0MRW<DB0WUE<DK0WUE<7M3TJZ<SP7MGD<VK7AX<VK3HEG
Sent: 051225/0212Z @:VK3HEG.#WEV.VIC.AUS.OC #:15836 [Ballarat] $:15836_VK3HEG
From: VK3ABK@VK3HEG.#WEV.VIC.AUS.OC
To : VALVES@WW
Hello G0TEZ and all interested.
Ian has asked about a super regen receiver and how it works. I sent a
bulletin about my use of 'acorn' vacuum tubes, those early vhf triodes
and pentodes used extensively during WW2 and by Radio Amateurs in the
years following. My use was in a super-regen/mod-osc, to give it's usual
Ham abrieviation. Super-regenerative, or super-regenerating is the proper
term as it refers to an 'advanced' regeneration that has been used in many
receiver designs, even in the solid state world.
While it is a bit difficult to draw a diagram, an explanation of the way
super-regeneration works may help Ian and others. Anyway, I'll try.
Ian is correct when he wrote...
"I ended with a p.s. saying that a super regen is NOT the same thing as
reaction."
A "super regen" is a receiver with regeneration that is stopped and started
in a process sometimes refered to as 'squegging'. By making the grid circuit
of a vacuum tube retain a bias voltage, due to a long time constant, the tube
can be made to stop it's regenerative oscillation, or "block' briefly, and
then start again. This happens cyclicly, and the circuit generates a much
enhanced regeneration by increasing, even more, the positive feedback that
causes regeneration. All this is very non-linear, rough and raucus, causing a
rushing sound in the receiver phones. This makes the circuit a very sensitive
receiver, with a broad bandwidth, but it also radiates broadband RF!
The rushing sound disappears when a good signal is received, much the same
as 'quieting' on FM. The name 'rush-box' was often applied for this reason!
And as Ian wrote...
"Almost immediately, a bull turned up where the writer mentioned being able
to "Hear the RX from miles away." "
Sixty years ago that was not a problem. No TV, and only low band AM radio,
with the nearest Ham miles away across town. One wartime portable transmitter/
receiver even had a VHF super-regen/mod-osc unit included with it's main
HF section.
By switching the 'grid-leak' resistor, and a microphone transformer into
the anode voltage supply, turned the circuit into a transmitter.
A single 'valve' (955) could become a Ham station!
I hope this is an interesting item from the past.
73. Dick. VK3ABK.
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