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[AMPS] Bargain basement broadband tetrode amp

To: <amps@contesting.com>
Subject: [AMPS] Bargain basement broadband tetrode amp
From: rfamps@ic24.net (Steve Thompson)
Date: Fri, 18 Aug 2000 07:14:02 +0100

-----Original Message-----
From: Jeff Wolf <da_kang@hotmail.com>
To: W8JI@contesting.com <W8JI@contesting.com>; amps@contesting.com
<amps@contesting.com>
To: <amps@contesting.com>
Date: 17 August 2000 17:12
Subject: Re: [AMPS] Bargain basement broadband tetrode amp


Tom said:
>
>4CX250's are poor enough for IMD when operated correctly.
>
>>>I haven't had that problem.  The 4CX250/350 seems to work well in the
>>>circuits I have built them around.  Telestar also made some nice
multiband
>>>/ multitube 4CX250B amps in the 80s.  I imagine you don't like those
>>>either?


A UK firm called STC used to make 4CX250. Their data gives typical figures
of -30dBc 3rd order and -50dBc 5th order IMD at 325W pep, 2kV on the anode.
I'd say that was respectably clean. I've measured a brand new STC pair on
144MHz which came close to this - about 600W out at -30dBc.

Steve



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