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

[kirklandb at sympatico.ca]

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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