[ARC5] BC-455 IFT - selectivity solutions...

[Fuqua, Bill L]

  Digikey has a large quantity of 2949 crystals. 
I wonder if the adjustment range of the coils is sufficient to retune the Local oscillator, IFs and BFO to
accommodate a IF 119 KHz higher. It is not quite that much because these are listed as parallel resonant
with 32pF so the Series resonance is some kHz lower. Perhaps 4 or 5. 
With a few of these you could make a ladder filter for even better selectivity.
These crystals are  not even surface mount, nice HC-6/U with long leads.

73
Bill wa4lav
 
________________________________________
From: ARC5 [arc5-bounces at mailman.qth.net] on behalf of Jim Falls [radio-tuber at att.net]
Sent: Thursday, October 30, 2014 6:31 PM
To: Ken Gordon
Cc: ARC5 at mailman.qth.net
Subject: Re: [ARC5] BC-455 IFT - selectivity solutions...

There may be some floating about in various hamfest junk boxes.

I recall having several in that range for my TCS that I planned on restuffing.

I'll check tonight.

Cheers!
Jim K6FWT
CBLA #37

> On Oct 30, 2014, at 14:46, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
>
>> On 29 Oct 2014 at 18:47, J Mcvey wrote:
>>
>> So, to raise the Q, improving the L6-C12 combo with something better (
>> higher Q components?) would be the way to do it. Otherwise, it's back to
>> "regen".
>
> Actually, for a hacked-up piece-of-junque like those I am saddled with,
> Mike Murphy's WU2D, crystal-filter really appeals to me. Trouble is,
> finding 2830 KHz rocks...
>
> I checked with International Crystal Manufacturing and they need around
> $30 each for a one-off. I haven't contacted JAN yet, though.
>
> Since 2830 KHz is actually some sort of marine radio frequency, there
> really ought to be a cheaper source...
>
> In addition, there are several problems with the regenerative IF, amongst
> which is that as the signals you are working with get stronger, its
> effectiveness gets weaker, which is the opposite of what you really want.
>
>> Does that make sense?
>
> Yes. I've always liked "Q-Multipliers". I have several, but none on 2830
> Khz....yet.
>
> vy 73,
>
> Ken W7EKB
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