[Amps] testing the biggest one

Jim Thomson jim.thom at telus.net
Sat Aug 3 00:24:40 EDT 2013


Date: Fri,  2 Aug 2013 13:09:56 -0600
From: "John Lyles" <jtml at losalamos.com>
To: amps at contesting.com
Subject: [Amps] testing the biggest one

I just concluded 3 days of observing the final testing of a new tetrode in the French Thales (former Thomson) factory. I can say with first hand experience that tubes will be around for a long time, at least at the power levels that make sense for them. I'm not talking about broadcast or even communication levels, but for industrial and scientific sources. This posting may not be directly applicable to amateur amplifiers, but to amplifier technology in general. On Monday the TH628 ran 600 kW key down. That's with plate power of 12.2 kV Ep at 85 amps! This was up at 200 MHz. In an amplifier smaller than the car I drive. I'd love to know of any other technology capable of this at comparable size, cost and efficiency. The perfection of the art and skill of making thermionic devices is evident here. "Awesome" is all I can think..

On Tuesday, the same amp ran up to 3 MW pulsed with 26 kV at 175 amps plate current very linearly, 66% efficient and > 14 db gain in grounded grid(s) configuration.

It gets shipped to us in USA for further testing in our PA in the southwest. There will be 2 more like this in coming months to test and install. I'm happy to be back home but have to say that time in a big tube factory dispels any notions that I continuously hear on this forum and other places (broadcasters or scientists) that tubes are gone, going, & dead end now. I challenge the same pundits to come up with a superior way to generate RF power. Maybe in the sun?

Sorry that this isn't directly applicable to our ham discussions here but as amplifier builders it is more than of "academic interest", being real hardware. 
73 K5PRO

##  Superb.  That must have been an exciting.. out of town assignment.    I challenge anybody to build a SS 10 kw 160-10m amp  for less than a 10 kw tube amp.  I say it can’t be done.   Even using a mess of those freescale devices,
the maths just don’t add up.   By the time you add on the various LP filters, and droves of combiners, switching supplies, plus a 10 kw auto tuner that will handle swrs  up to say 3:1  both the cost, and parts count is through the roof. 
The HV supply for a tube amp is dead simple. RF deck is just one tube, no socket, simple tuned input.  2 x surplus vac caps for tune + load.   Half inch cu tubing is still dirt cheap at home depot.  
Even a 10 kw  FM broadcast TX.... in tube version from energy onix is cheaper than a 10 kw SS version..which typ uses 10 x 1 kw modules and the usual mess of combiners.  

Jim  VE7RF 




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