[Amps] Length of coax from xcvr to amp affecting input swr.

[Glen Zook]

No!

The 30S-1 recommends a length of 20.5 feet but the specification for the 30L-1 was changed to basically any length of cable with 48 inches being the generally accepted length of RG58/U because that same 48 inch length is used between the S-Line receivers and S-Line transmitters for the heterodyne oscillator connections and PTO connections.  The 48 inch length between the units generally requires no realignment when the receiver and transmitter are connected as opposed to using the 100 ohm "dummy load" which is otherwise connected to the heterodyne oscillator jacks when the units are not connected together.

The 20.5 foot length of cable with the 30S-1 was selected to improve IMD, etc., and not to "match" the transmitter to the amplifier.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: R. Morris <robrk at nidhog.net>
To: amps at contesting.com 
Sent: Monday, January 2, 2012 12:43 PM
Subject: Re: [Amps] Length of coax from xcvr to amp affecting input swr.
 
On 12/31/2011 09:04 PM, Charles Harpole wrote:
> This is a common phenomena and many amp users see it with a variety of amp makes and models.  Alpha recommends 3 feet, and that works great.  There must be another magic length longer than 3 feet, but only cut and try will tell you, but I would much rather change coax length than dig into the amps.   73, HNY
>
> Charles Harpole
> k4vud at hotmail.com
>   >  From: jim.thom at telus.net
>
Collins wants 20.5 feet of RG58 to their 30L1.
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