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Re: [Amps] Alpha &&DX Conversion

To: "Paul Christensen" <w9ac@arrl.net>, <amps@contesting.com>
Subject: Re: [Amps] Alpha &&DX Conversion
From: "Jim W7RY" <jimw7ry@gmail.com>
Reply-to: Jim W7RY <jimw7ry@gmail.com>
Date: Wed, 5 Sep 2012 19:37:06 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Yup! Mee too.

I worked on a BEXT 2500 watt transmitter with an 8877. My transmitter was limited to 2200 watts output because of licensing. 24 hours a day! As I remember about 65 or 70 watts from the exciter. Plate voltage was 4100 V under load.

73
Jim W7RY


-----Original Message----- From: Paul Christensen
Sent: Wednesday, September 05, 2012 2:48 PM
To: amps@contesting.com
Subject: Re: [Amps] Alpha &&DX Conversion

"I will tell you why i run a 2 tuber, you put in 25 watts in and do 1500 easy not push a one tuber to do 1500 out. it all comes down to what you can afford. bill 73"

This may be an interesting point of reference. During my college years, I worked at a 3KW FM station in Rockford, IL as its chief engineer. The transmitter was an AEL FM-2.5K (FCC type accepted to 2.5KW output) and used a single 8877 to produce 2500-watts output at 104.9 MHz. All day long, every day, 365 days a year. A three-bay circularly polarized antenna brought ERP to 3KW.

If a 77Dx is running intermittent amateur-class service but under high duty-cycle modes like RTTY at 1500-watts output (the U.S. legal limit, for example), I think its reasonable to assume that a 8877 is already operating with sufficient headroom of roughly 1KW. For what purpose do any of us need more than 1KW of headroom from our vacuum tubes when producing 1.5KW?

Paul, W9AC
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