[Amps] The ongoing 4CX250B verbage!

Jerry Muller k0tv at adelphia.net
Tue Apr 4 05:52:29 EDT 2006

Although you couldn't tell the difference between a 4CX250 and an 8877, 
anyone operating near you in frequency could. The triodes are MUCH cleaner 
in terms of IMD than the tetrode. The 3rd order IMD performance of the 
4CX250 is not much better than -20dB where the 8877 is about -38dB.

This is coming from someone who has run and still owns a pair of 8930s for 
432, a single 8930 for 220 and a pair on 2M. I'm not planning on putting the 
2 and 432 amps on the air again if you're interested. I've already got an 
8877 for 2 and I'm building a GS35B for 432.

73, Jerry K0TV

----- Original Message ----- 
From: <exray at bellsouth.net>
To: <Amps at contesting.com>
Sent: Monday, April 03, 2006 10:00 PM
Subject: Re: [Amps] The ongoing 4CX250B verbage!

> 4CX250B tubes will reliably run 500W out for a pair( observe the AN/URC-32 
> or its commercial cousin the KWT-6). If you must have more try three, as I 
> recall, (AN/ARC-58 or TRC-75). This was 1 KW output autotune on the back 
> of a jeep.
> These military radios had to operate under rather stringent (read 
> horrible) conditions. And guess what....these " relics " did just fine!
> Yes there are better tubes available today...but the old 4CX250 family is 
> the granddaddy of all of them. If you come across a pair, and they should 
> be inexpensive,  there are many good designs which have been published 
> thru the years.
> Frankly, I doubt you could tell the difference between 3 4CX250Bs and an 
> 8877 except for the rattle of the change still in the pocket of the guy 
> with the 4CX250B rig! He can then spend money on an antenna and feed line 
> where it really counts!
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