[Boatanchors] Receiver Technology

Wilson Lamb infomet at embarqmail.com
Fri Jan 14 15:36:38 EST 2011

I wrote the following message after giving some local talks that reminded me 
there were some years not well represented in my view of receiver evolution.

If anyone has insight to any of the questions or uncertainties mentioned, 
please drop me a note with whatever you care to offer.

Thanks, Wilson, W4BOH

>>I find I'm getting more and more interested in the RX side of old radio.
>>Sure, the TX are interesting and fun, but they really don't tell us much
>>about the operational side of old radio.  What do we really know about the
>>performance of old RX circuits?  Do you know of websites discussing
>>My guess is that the air was full of signals that few people heard because
>>they didn't know where to look or because they simply didn't have the
>>sensitivity to hear them.
>>I've been reading all the way back to Armstrong and the more I read the
>>more I wonder!  I think there are tremendous articles wauting to be
>>written on this subject, especially lab tests on original equipment.
>>Imagine even trying to determine if your tubes are any good.
>>No scopes, no grid dippers, not even a real voltmeter with any
>>sensitivity! I'm surprised they heard anythig.
>>I've read a couple of the Marconi articles, but they leave me with more
>>questions than answers.  What was his RX, exactly, and are there any of
>>them around to test?  My admittedly unscientific opinion is that he was
>>quite a huckster and probably didn't hear anything.  I remember looking at
>>early television when the only signal was from 50 mi and didn't come in to
>>my grandfather's shop much at all.  I'd watch the little national set for
>>minutes at a time trying to make a picture out of the snow and "thinking"
>>I saw something.  I was about nine.  Same for listening.  After a while
>>it's easy to hear voices, or clicks, in the static.  Actually, if he could
>>hear static he might have heard the signal, so I expect he heard mostly
>>Looking at pictures of cohehers, which I've done all my life, it's hard to
>>imagine one working on any reasonable signal level.  Have you ever seen
>>one work?
>>I'm going to start with a fairly modern regen, like with a 19 or 30, and
>>then work back and see what I can do with 01s, etc.  Armstrongs regen
>>would probably work fine with decent tubes, but it was years getting into
>>common use.  Then there were several more years of limbo before superhets
became common.
>>I built regens as a kid and still have a 1L4 that I can return to
>>operation. It was great on BC and up to 40M...I heard BC all over the
>>country at night, usually from bed...on bats, of course.

The milestones I see are: diode, regen, superhet, rationalized bandspread in 
the HRO,
and "modern" constant rate bandspread through double conversion (Collins?).

Looking back like this, I'd say we were not innovative at all and that we 
with poor receivers that were hard to tune above 40m for too many years. 
nothing in the 75A-1 that couldn't have been built in 1920!
>>I'd appreciate any references you can conveniently provide on this stuff.
Contemporary articles about getting new technologies into service would be 
of great interest.
>>Wilson Lamb

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