[Boatanchors] Cheap & Easy Selectivity

[Edward Swynar]

Hi Gang,

Well, 29 requests received here for scanned copies of the regenerative IF
"RADIO" magazine article, 29 scans e-mailed to those very same interested
parties...

Last call---have I missed anyone...?

~73!~ Eddy VE3CUI - VE3XZ


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----- Original Message -----
From: Edward Swynar
To: hbr at mailman.qth.net ; homebuilttuberadios ; Old Tube Radios ;
AmRadGear at yahoogroups.com ; boatanchors at mailman.qth.net ; Welcome to the
Novice Rigs List! ; antiquewirelessassociation at egroups.com
Sent: Thursday, August 20, 2009 3:43 PM
Subject: Re: Cheap & Easy Selectivity


Hi Again Everyone,

If anyone is interested, I just finished scanning  the regenerative IF
article from the November 1940 issue of "RADIO" magazine, and would be more
than pleased to send it along to whomever it is that might be interested...

It's two pages in length---I reduced the size & converted the files to jpeg
format, so that they might be a bit easier to download for those of us
(myself included!) who are still still on dial-up internet service.

As mentioned previously, this particular design---according to the
author---goes one step beyond the simple "...two wires side by side to
achieve regeneration in an IF stage" approach. Indeed, he says that not only
is the signal of interest boosted in strength by virtue of this circuit, but
interfering signals are actually reduced by a corresponding amount.

As anyone knows who has ever tried a regenerative IF stage, this does not
happen by design, i.e. the reduction in signal strength of adjacent
frequency QRM.

Anyway, it all sounds like a very neat design, albeit requiring the trouble
of having to wind a scramble-wound coil & installing it at the base of the
secondary winding of the IF transformer.

~73!~ Eddy VE3CUI - VE3XZ


****************************************************
----- Original Message -----
From: Edward Swynar
To: hbr at mailman.qth.net ; homebuilttuberadios ; Old Tube Radios ;
AmRadGear at yahoogroups.com ; boatanchors at mailman.qth.net ; Welcome to the
Novice Rigs List! ; antiquewirelessassociation at egroups.com
Sent: Thursday, August 20, 2009 11:13 AM
Subject: Cheap & Easy Selectivity


Good Morning All,

I just ran across a sweet little article in a 1940 issue of the old "RADIO"
magazine on a fool-proof way of adding selectivity & gain in an IF stage
that (supposedly) approaches that obtainable with a resonant crystal
filter...but without the filter insertion loss, of course.

The design is rather obscure in that I've never seen anything quite like it
in any ARRL publication. Suffice it to say that it goes a bit extra beyond
the mere "...place-the-plate-lead-into-the-IF-can" approach of achieving
feedback, yet it still looks very "do-able", and I plan to incorporate it
into my 1929-style 12-tube superhet here.

If anyone has access to any of the West Coast Handbooks of the late 30's,
you'll see the design used in the "Super/Ultra Gainer" receiver designs
described therein...

Wish me luck!

~73~ Eddy VE3CUI - VE3XZ