[R-390] A 6kc. mechanical filter for a R-390a?

[Al S.]

I seem to recall an article somewhere?, maybe the Y2k manual or notes by
Mr. Dallas Lankford on using the modern Collins torsional filters as
roofing filters in the receiver. Using toroidal matching transformers.

Al
On Jun 14, 2017 10:04 PM, "Bob kb8tq" <kb8tq at n1k.org> wrote:

> HI
>
> You will have to use some sort of transformer match. Doing really wide
> range
> impedance matching with networks is a pain. You probably are going from
> megohms
> to hundreds of ohms …
>
> Bob
>
> > On Jun 14, 2017, at 8:57 PM, Al S. <racalra17 at gmail.com> wrote:
> >
> > I have one of the more modern blue cased Collins mechanical filters here.
> > It was apparently used in the Racal 6790 receiver BW is 6.0 kc. 526 9957
> > 040.
> >
> > This filter is designed to be used in that SS receiver and for lower
> > impedance, than the higher impedance the stock 390a filters see.
> >
> > I would like to experiment with this filter in a 390a. Any ideas on
> > toroidal matching to the IF deck in the 390a.
> >
> > Thanks
> >
> > Al VE3AJM
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