Peter wrote:

    "(I live in a city that thinks RFI is a
     brand of cheese - nobody cares about EMI
     filters and such). That's why I hope a
     good preselector will help me."

No amount of 'preselectoring' or filtering is going to
correct a 'bad' S/N (SIgnal to Noise) ratio due
to computer noise and other urban electrical noise
that appears "in-band and on-channel".

If, however, your receiver is experiencing "Front
End Overload" from close-by AM or SW broadcast stations
THEN a preselector can do some good!

I'm putting together a design right now that solves
a 160 M (1.8 - 2.0 MHz) problem owing to a LOT
of AM broadcasters in this area - including an
omni-directional 10 KW 1.7 MHz station.

It's been trick getting a low IL (Insertion Loss) across
the band of interest along with +40 dB of rejection
starting at 1.705 KHz and below. The second proto is
being built now with an eye on reproducability since
I was able to meet the design requirements ...

Jim


----- Original Message -----
From: "Peter L. Peres" <plp@ACTCOM.CO.IL>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, June 29, 2002 4:38 PM
Subject: Re: [EE]: stepper "digital" knob viability


> On Sat, 29 Jun 2002, Spehro Pefhany wrote:
>
> >At 12:40 PM 6/29/02 +0300, you wrote:
> >

-- snip --

> >a major nasty when it comes to designing the controller.
>
> I was thinking of a manual control, for a start. I do not know what kind
> of signals I can get (I live in a city that thinks RFI is a brand of
> cheese - nobody cares about EMI filters and such). That's why I hope a
> good preselector will help me. The signal on a whip is terrible even with
> all the computers and other noisemaking machines shut down.
>
> Peter
>

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