From: Jim Thompson
Subject: Re: 2 way Splitter
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Date: Tue, 17 Dec 2002 23:46:40 GMT
NNTP-Posting-Date: Tue, 17 Dec 2002 18:46:40 EST
Organization: Cox Communications
On Tue, 17 Dec 2002 22:52:38 +0000,
John Woodgate ,
In Newsgroup: sci.electronics.design,
Entitled: "Re: 2 way Splitter",
Wrote the following:
|I read in sci.electronics.design that Simon
|wrote (in <email@example.com>) about '2 way
|Splitter', on Tue, 17 Dec 2002:
|>I'm having difficulty designing a 50 ohm, 2-way, zero degree phase
|>I've seen them manufactured by people like mini-circuits, but I need a
|>greater bandwidth than they build (I require low loss at 375kHz and 50
|>MHz, but don't care about stopband performance, or performance in
|>between these frequencies)
|>I was told to do it using three resistors but don't know where to
|>start. I assume each "port" would look like 50 ohms, but am not sure
|>how to og about it.
|Three coaxial connectors mounted on a metal box, one IN and two OUT. You
|have a choice. Either connect three 50 ohm resistors (47 or 51 are quite
|good enough for jazz) in an equilateral triangle between the three
|centre contacts, or wire three 16 ohm (15 ohm are OK) resistors in a
|3-pointed star and connect each free end to a centre contact.
|To get the best results at 50 MHz, you need either carbon composition
|(UGH!) or *unspiralled* metal film resistors, which are not so easy to
|obtain. But ordinary parts may be good enough.
|Now learn the star-delta theorem and you WILL understand how to go about
John, Wouldn't the 16.67 ohm ;-) star approach have slightly better
bandwidth (presuming the R's will have about the same parallel
capacitance independent of value)?
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
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