[Collins] KWM2A receive alignment - USB/LSB

[Steve Garwood]

I haven't checked on the center frequency of the filter yet.  I'll be
setting up the signal generator - I would like to try the 10 pf across the
crystal leads with clip leads just to see what difference it makes.  Part of
the problem now is that I can take the measurements but I'm not able to
affect any change.  Shifting the crystal frequency a bit would shed some
light on things.

Steve, N0CZV

-----Original Message-----
From: collins-bounces at mailman.qth.net
[mailto:collins-bounces at mailman.qth.net] On Behalf Of Gerald
Sent: Wednesday, February 01, 2006 11:44 AM
To: collins at mailman.qth.net
Subject: Re: [Collins] KWM2A receive alignment - USB/LSB

On Tue, 2006-01-31 at 22:15 -0500, Steve Garwood wrote:
>  
> Thank-you for all of the replies on this question!  I have now checked the
> crystals with an Optoelectronics 3000Aplus frequency counter.

> Both crystals measured a little bit off from the marked frequency.

> Y17 456.350 KHz measured 456.3823 KHz  (+.0323)

> Y16 453.650 KHz measured 453.6553 KHz  (+.0053)

> 
> I don't have any information reference +/- tolerances, but I would imagine
> it would only take a small difference in frequency to make an audible
> difference between sidebands.
> 
> Looks like crystals would be in order - Inrad looks like a good deal at
> $35.00 per pair.

> Steve Garwood, N0CZV
> 
> Attica, OH

Those are pretty small errors. You might try 10 pf across the crystal
with the 32 Hz error. 

Have you checked the response curve of the filter? Having a slope to the
passband would give the same audible result.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer

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