[ARC5] ARC-2: IF Regeneration is a "No"

[millerke6f at aol.com]

I noted the NO to regeneration, but why not.  There were a number of schemes from the good old days that added a bit of feedback around one of the IF stages and then played with the gain a bit to keep it from oscillating.  It's not an elegant solution,but it does tighten up the response a bit and the mod is independent of the L/C components and can be removed without any damage.  I played around with this technique 55 years ago with my R105/ARR15 and it worked... can't recall the specifics, but I gleaned the scheme from one of the old Surplus Conversion manuals or a CQ article. I used it until I cobbed a BC-453 into service for a better solution to that problem of barn door response curves.  That solution too was clubby, but on a kid's pocket book, it was a solution to a problem. 


Another way to look at the L/C modifications is to down load a copy of ELSIE, a filter program that's out there and model your IF section by section to see what can be done and save yourself a bunch of tweeking time.  
Food for thought


73


Bob, KE6F



-----Original Message-----
From: David Stinson <arc5 at ix.netcom.com>
To: ARC-5 <arc5 at mailman.qth.net>
Sent: Wed, Apr 2, 2014 1:57 pm
Subject: Re: [ARC5] ARC-2: IF Regeneration is a "No"



----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>

> ....Les sent me a couple of schematics of "top" vs "bottom" 
> coupling
> which jogged my memory.
>
> If you can reach the GROUND connections to the "bottoms" of the 
> two coils
> in each IF can, you can lift that ground connection and insert 
> a capacitor in
> series between that connection and ground. This results in 
> "bottom"
> coupling. You may be able to do this completely externally to 
> the IF cans.

Not a chance :-(
To reach them would require a disassembly of
the whole tuning deck and moving rack assembly
and that ain't happening.
Call me "chicken" but I think that's a sure way to turn
this excellent radio into a "parter."  Too risky.

Gonna see what I can do with the 5 pFd couplers. 

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