[R-390] Mechanical filter substitute

[Jon Schlegel]

Bruce,

Rochester, NY

Jon

At 01:44 PM 12/18/2007 -0500, you wrote:
>Hi Jon,   I am in Ontario, NY.   Where are you??
>
>Bruce
>
>-----Original Message-----
> >From: Jon Schlegel <ews265 at rochester.rr.com>
> >Sent: Dec 18, 2007 1:33 PM
> >To: r-390 at mailman.qth.net
> >Subject: Re: [R-390] Mechanical filter substitute
> >
> >100k - Ugh.  Now that's just convenient!
> >
> >At 12:18 PM 12/18/2007 -0500, you wrote:
> >>Hi
> >>
> >>The R-390A filters are high impedance. I don't remember the exact
> >>numbers, but > 100K ohms would not surprise me at all.
> >>
> >>Bob
> >>
> >>
> >>On Dec 18, 2007, at 12:09 PM, Jon Schlegel wrote:
> >>
> >>>Thanks for all the info guys,
> >>>
> >>>Bob C - I'll cobb in the 10k to see what happens.  BTW, Maybe Bob N.
> >>>should try using one of the Motorola Permakay filters.  Think I
> >>>still got a few around here somewhere...
> >>>
> >>>Also what are the in/out Zs of the mechanical filters.  If I want to
> >>>measure one what source/load should it be looking into?
> >>>
> >>>Jon
> >>>
> >>>
> >>>
> >>>At 09:23 AM 12/18/2007 -0600, you wrote:
> >>>>On Dec 18, 2007 9:14 AM, Bob Camp <ham at cq.nu> wrote:
> >>>>
> >>>> > Before you go to crazy - sling a 10K ohm resistor between input and
> >>>> > output directly on the filter.
> >>>>
> >>>>Good tip, Bob.   And it reminded me - at the Belevidere IL hamfest
> >>>>I saw a Collins 75A series receiver that had a homebrew "filter
> >>>>replacement" in it.  This was a small perf-board with a couple of
> >>>>chokes and capacitors which would obviously be for wideband AM but
> >>>>I thought it would be neat to give it a try.   Of course I forgot
> >>>>to go back and sketch the circuit!   Wonder if anyone knows about
> >>>>this and has the design details?
> >>>>
> >>>>73, Bob W9RAN
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> >>>
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