[R-390] R390A alignment question

[Ben Loper]

To help me understand, if each of the filters in a R-390A has a slightly
different bandpass + or - 455 and the IF is tuned precisely to 455 won't you
get some loss of gain anytime you select a filter slightly off of 455.  I
now understand why aligning a radio with one filter you tune for max using
the center of the single filter.  With the R-390A isn't the stagger tuning
to account for the multiple filters giving ample gain for each filter?  I
ask this question because I don't have the equipment to stagger tune the IF
and wondered exactly why it was stagger tuned in the first place.

On Tue, Jan 12, 2010 at 12:52 PM, Tisha Hayes <tisha.hayes at gmail.com> wrote:

> Until I recently changed jobs I had access to the best Rohde Schwartz gear
> for radio alignment and a nice lab to work from
>
> Now I use my HP 3324A and an assortment of other HP devices to do "paying
> myself" radio work. I was able to use the sweep generator and a Hameg
> spectrum analyzer to build a roofing filter for the R-390A. The roofing
> filter uses one of the torsion Collins filters with impedance matching
> circuits on either side to improve the 3IP on the radio. I barely notice
> the
> difference when listening with the radio and the improvements only show up
> on test equipment.
>
> The Dallas Langsford document on roofing filters was my inspiration. It is
> really useful if you plan on going down this path.
> --
> Ms. Tisha Hayes
>
> ----------------
> "I will not recant the truth. I am corn, not chaff; I will not be blown
> away
> with the wind or burst by the flail. I will survive both."
> -Walter Milne, 1558
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