Path: utzoo!utgpu!watmath!maytag!watdcsu!magore
From: magore@watdcsu.waterloo.edu (Mike Gore, Institute Computer Research - ICR)
Newsgroups: sci.electronics
Subject: Re: Weather Satellite Receiver Question
Message-ID: <6398@watdcsu.waterloo.edu>
Date: 28 Sep 89 15:55:15 GMT
References: <744@anasaz.UUCP>
Reply-To: magore@watdcsu.waterloo.edu (Mike Gore, Institute Computer Research - ICR)
Organization: U. of Waterloo, Ontario
Lines: 73


Hi John,

You wrote:

>		what is a good receiver to use? I have a scanner
>that can receive 137.5MHz but it's bandwidth is either 6kHz or 200kHz.
>I understand that the appropriate bandwidth would be about 50kHz.

>What do other experimenters do in this regard?

I replaced the filters in my unit with a MuRata 10.7MA and a muRata CFM455A.
My dual band IF uses 10.7MHZ and 455KHZ. The CFM455A gives +/- 17.5 KHZ
or 35KHZ total bandwidth. This filter works for me...

	I have a list that muRata sent me with the filter docs of
authorized distributors. For your area they have: 

Phoenix:
	Future Electronics
	602-968-7140

	Sterling Electronics
	602-268-2121

Tempe:
	Acacia/Deanco
	602-894-2874
	602-882-9054

	Time Electronics
	602-967-2000

muRata Erie North America Regional Sales Office Southwest:
	714-832-9972

>P.S. - I would expect to receive the GOES satellites with a down-converter
>to the 137 MHz range, so the same receiver could be used for both.


	Yes this works and is in fact what many people do. You might look into 
a reprint for "An S-Band Receiving System for Weather Satellites; 
Emilini, G. and Righini, M.: QST, August 1980". This can be obtianed from 
Mono Smith @ NOAA/NESDIS (1-301-763-8447). I just ordered my copy.

Good Luck,

PS. For others looking for muRata parts you might try asking asking someone
at their main number for a distributor nearer your area. Otherwise you may
try Future Electronics as they seem to have stores all over North America.

	muRata Erie
	2200 Lake Park Drive
	Smyma, Georgia 30080
	404-433-7820


[ No I don't work for them :-) ]	

PPS.
	Many receivers use an mc3259 or mc3261 FM IF chip. You might
have to reduce the resistor across the quad. coil to about 22k or so.
This resistor controls the output transfer for a given frequency swing.
The higher the resistor one has will increase the output voltage from the quad.
detector for a given frequency shift. So the idea is to reduce this value
such that one gets the max. output swing for a given signal bandwidth 
*but* without clipping.


# Mike Gore, Technical Support, Institute for Computer Research
# Internet: magore@watdcsu.waterloo.edu   or   magore@watdcsu.uwaterloo.ca
# Bitnet:   magore@watdcsu.bitnet    UUCP:     uunet!watmath!watdcsu!magore
# These ideas/concepts do *not* imply views held by the University of Waterloo.