[ARC5] Receiver Filter Adaptor and Thoughts on Projects In General

[Bruce Long]

I have been watching active filter ics like those made by LT. I think you doubts are correct.  While I believe you could make a 455kHz bandbass filter there are usually max filter Q restrictions that would limit you to a wider bandwidth than you might like.
I briefly fooled around with using an active filter at a frequency in the 10-50 kHz region and hetrodyning the ARC-5 IF down to the new second IF frequency.  Then you can do a product/am detector at the new second IF frequency or hetrodyne back to the original 1st IF frequency and use the existing receiver detector.
Till you do all that maybe it makes sense to convert the entire receiver to solid state.  Yeah I know scarelige (spelling?) but I inherited a completely stripped- except for RF and IF resonant circuits ARC 5 receiver and I worked out a conversion to solid state which I would like to try sometime.   I actually laid out a pcb and had it made.  The problem as always is time.
I have long been selecting home ham radio projects from the perspective of offering the circuit as a kit to other interested hams.  This puts an added degree of constraint on my design projects.  The idea is to partially offset some of the money I spend on my hobby and also to be honest show off a little if I come up with something useful.
While I am well able to handle surface mount parts, increasingly I have had projects I have been working on on and off for years go down the drain because the through hole parts are no longer available.  This has been especially a problem with AGCable IF amplifiers which where designed for analog television IFs and are long gone with the wind.
So a couple months ago i started redesigning my projects converting what where originally integrated circuits into discrete transistor circuits.  It has actually been fun and I have some IF AGC-able circuits that don't seem to have ever been published anywhere else.  This is something else I'd like to breadboard and try out when I have a few hours to spare.


      From: "mstangelo at comcast.net" <mstangelo at comcast.net>
 To: David Stinson <arc5 at ix.netcom.com> 
Cc: ARC-5 <arc5 at mailman.qth.net>
 Sent: Tuesday, February 16, 2016 3:58 PM
 Subject: Re: [ARC5] Receiver Filter Adaptor and Thoughts on Projects In General
   
Dave,

You may want to see if Linear Technology has an active bandpass filter that works at 455kHz:

http://www.linear.com/product/LTC1562-2>

However, I have some concerns,

I don't know if you could make a filter with a high enough Q to replace a ceramic mechanical filter.

They are surface mount devices.

Mike N2MS


----- Original Message -----
From: David Stinson <arc5 at ix.netcom.com>
To: ARC-5 <arc5 at mailman.qth.net>
Sent: Tue, 16 Feb 2016 15:40:35 -0000 (UTC)
Subject: Re: [ARC5] Receiver Filter Adaptor and Thoughts on Projects In    General


Come on "smart people:" By now there ought to be some
single-chip active filter thingie that can do this without trying
to build a mini-computer in that space.

S
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