[Boatanchors] Receiver Technology

[Al Klase]

Hello Wilson,

I think I can fill in just a little of the information you seek:

Here's my page on short-wave communications receivers of the 1930's

http://www.skywaves.ar88.net/commrx/Receiver_Time_Line.html

I was also glad to find that my 2002 QST article on regens is once again 
available to the general public:

http://www.4shared.com/document/UOR68ogP/QST_2002_The_Age_of_the_Autody.htm?aff=7637829
(Scroll down to "DOWNLOD NOW" in the blue box.)

Enjoy,
Al

On 1/14/2011 3:36 PM, Wilson Lamb wrote:
> 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
>>> them??
>>>
>>> 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
>>> silence.
>>>
>>> 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 suffered
> with poor receivers that were hard to tune above 40m for too many 
> years. There's
> 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.
>>>
>>> 73,
>>> Wilson Lamb
>>> W4BOH
>

-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/