[Amps] Any designs for 4CX1000A on 2m

[Fuqua, Bill L]

Got quiet all of a sudden. Anyone have some ideas?
73
bill wa4lav

________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Tuesday, June 07, 2011 10:01 PM
To: amps at contesting.com
Subject: Re: [Amps] Any designs for 4CX1000A on 2m

Another strange amplifier was a 200MHz pulsed triode amp.
It had a variation of the 8877 with no fins on it. Strange beast.
I called Ried Brandon at EIMAC to find out more about the tube.
The anode was clamped into a copper pipe which was a 1/4 wave coaxial
line.   It was driven by a solid state amplifier made by Henry Radio.

73
Bill
________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Fuqua, Bill L [wlfuqu00 at uky.edu]
Sent: Tuesday, June 07, 2011 8:05 PM
To: jtml at vla.com; amps at contesting.com
Subject: Re: [Amps] Any designs for 4CX1000A on 2m

These are really on 200 MHz and the tube is a variation of the 4CX5000A made by eimac.
They were from a reasearch MRI used with small animals I believe. They were from the
University of Kentucky Med. Center. The power supplies are rather heavy and 3 phase.
No filter capacitors in either the amplifier cabinet or the power supply cabinet.
  Can take some pictures if you are interested. However, the tubes were dropped.
They dropped the amplifier cabinets and tubes came out of the sockets.
Have sliding hairpins for plate tuning as in many FM broadcast transmitters.
73
Bill wa4lav

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From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of John Lyles [jtml at losalamos.com]
Sent: Tuesday, June 07, 2011 7:12 PM
To: amps at contesting.com
Subject: Re: [Amps] Any designs for 4CX1000A on 2m

That's impressive, I wonder how far they are derated the 4CX5000A at 220 MHz, in that amplifier. I tried using the 4CX5000A in a 5 kW FM broadcast amplifier in the early 1980s and found it difficult, switched to 4CX3000A and then Eimac introduced the 4CX3500A, which was a natural at 108 MHz.
I got the first tube for eval. from George Badger, and our product was introduced at NAB. Later, tetrode transmitter competitor still using the 5000A switched to the 3500A after we proved it could handle the power and the cathode was enough.
It had similar base but lower internal inductance than 5000A, I believe. I never touched a 4CX5000A again.

73
John
K5PRO


> That reminds me, I have a couple of 4CX5000A
> 220 MHZ amplifiers in the garage.
>   They are large and the power supplys extremely heavy.
> 73
> Bill wa4lav

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