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

[Ian Wilson]

W8DIZ still has MC1349's, three for $5, through-hole ...

73, ian K3IMW



On Tue, Feb 16, 2016 at 1:26 PM, Bruce Long via ARC5 <arc5 at mailman.qth.net>
wrote:

> 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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