Date: Fri, 2 Aug 2013 13:09:56 -0600
From: "John Lyles" <jtml@losalamos.com>
To: amps@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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|