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Re: [Amps] Alpha Input SWR

To: "MICHAEL HUGHES" <mhughes149@hotmail.com>, <w7ry@centurytel.net>, <amps@contesting.com>
Subject: Re: [Amps] Alpha Input SWR
From: "KB8NTY" <kb8nty@wowway.com>
Date: Sat, 10 Jan 2015 23:53:24 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
NY9Y -Mike,

Sounds like a neat program, thanks for link... however with all due respect...I'm thinking the "feedline" is not being referenced. It is the "transmission feedline" the coax that connects the amp to the transceiver/transmitter, not the coax that runs to the antenna.

Theory is solid, yet real time first hand experiences speak loudly. When users experience controlled SWR by means of "transmission feedline" lengths, it's is hard to convince otherwise. I would think though as has been mentioned there is a dynamic that exists, by means of use of various transceiver/amplifier's. So what one finds acceptable, may not work the same for others.

I do know that in my past history, there is textbook theory, then there is the way I am forced to implement such at times, and darn would ya know it still works, for the most part.

I expect the end results all vary based on the variable factors that contribute to the results!...Resulting in all the various different experiences posted.

Regards,
Ross  KB8NTY
http://www.rossradio.net/
https://groups.yahoo.com/neo/groups/groundradial/conversations/messages

***************************************************************************************





----- Original Message ----- From: "MICHAEL HUGHES" <mhughes149@hotmail.com> To: "Jim W7RY" <w7ry@centurytel.net>; "KB8NTY" <kb8nty@wowway.com>; <amps@contesting.com>
Sent: Saturday, January 10, 2015 9:13 PM
Subject: RE: [Amps] Alpha Input SWR


There is a web site "RFDUDE.com". There is a free, easy to use Smith Chart Program there.

Changing the length of the transmission line merely moves the complex impedance around the VSWR circle. Start with a complex impedance of say, 30 -j20. Then insert a piece of transmission line. You can change the length of the transmission line by using the up and down arrows on your keyboard. The impedance does change but it is still on the VSWR circle and is not normalized to 50 ohms.

I think someone mentioned this when this question first surfaced.

Handy little program.

Mike  NY9Y

From: w7ry@centurytel.net
To: kb8nty@wowway.com; amps@contesting.com
Date: Sat, 10 Jan 2015 17:06:26 -0800
Subject: Re: [Amps] Alpha Input SWR

I have found that I use a 6' cable between SB220s and rigs for best SWR.

I also tune the input coils using this length and advise my customers to do
the same when they use their amps.

73
Jim W7RY


-----Original Message----- From: KB8NTY
Sent: Saturday, January 10, 2015 1:01 PM
To: amps@contesting.com
Subject: Re: [Amps] Alpha Input SWR

My Amp Supply LK-500ZB GG. amp manual also states to use a 6' length coax
between your exciter's RF output and the LK-500ZB RF input connector.
Possibly the feeder length does factor in!

-73-
Ross  KB8NTY
http://www.rossradio.net/
https://groups.yahoo.com/neo/groups/groundradial/conversations/messages


***************************************************************

"Collins Radio recommends a 20.5 ft. coax between exciter and linear amp.
.Perhaps this would work with the Alpha.
73, Jim - w5ifp@gvtc.com"



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