[R-390] Alignment of the Mechanical Filters and IF with a Spectrum Analyzer

[Mack McCormick]

Kirk,

Thank you for the feedback. Happy holidays and Merry Christmas. I'll post
my results.

Mack


On Thu, Dec 13, 2012 at 2:30 PM, <kirklandb at sympatico.ca> wrote:

>  not familiar with r-390 details but
>
>  :other than input/output matching, the mechanical filters have no
> adjustments.
>     playing with i/o matching does alter skirts etc including insertion
> loss.
>
> I regularly use a sig gen/ spec A (0 span mode) for IF alignment.
>  Have to be careful with multiple IF transformers that you don't use one
> to cancel the effects of the other.
>
> I would use the basic procedure to get "close" and then use the spec A to
> fine tune, e.g. minimum ripple in the passband.
>
>
>
> > Date: Thu, 13 Dec 2012 12:07:17 -0500
> > From: w4ax.mack at gmail.com
> > To: R-390 at mailman.qth.net
> > Subject: [R-390] Alignment of the Mechanical Filters and IF with a
> Spectrum Analyzer
>
> >
> > I have a calibrated high quality spectrum analyzer and tracking
> generator.
> > Does anyone have experience with using a spectrum analyzer to:
> >
> > 1) *Adjust the mechanical filters? *There is some literature that
> suggests
>
> > just peaking for noise can adversely affect the filter skirts.
> >
> > 2) *Stagger tune the IF?* My thought is that you could look at the
> overall
>
> > spectrum of the IF and make optimal adjustments.
> >
> > I would of course make sure that I don't load the circuit with the
> spectrum
> > analyzer to skew the results.
> >
> > Does anyone have any experience or suggestions?
> >
> > --
> > 73,
> >
> > Mack de W4AX
> > http://w4ax.com
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-- 
73,

Mack de W4AX
http://w4ax.com