John:
Thanks for stepping in for a moment. I've been "reading the mail" here for
years. Just like the sweet song of a high horsepower engine, it's something to
participate, or at least watch when such a piece of RF hardware is fired up,
even if it's only to a big dummy load.
We all know that the internet is a mixed blessing. Lots of good stuff, but also
very bad if one seeks it out. I find it quite amazing, to watch a VOA or
similar class transmitters being brought up, and put online. I've lived no more
than an hour away from Bethany, Ohio which many know was a VOA site until 1994.
Near by WLW in Mason, Ohio is on the air today covering 37 states at night, and
9 in the daytime if I recall correctly, with 50kw on 700kc.
There is quite a history there, back when WLW ran 500kw! That figure is hard to
wrap my brain around, as we are talking brute power, before any sort of antenna
gain came into play. The sheer magnitude of such an operation, and the fact
that this amount of RF could be generated in one place back when they did it,
is quite a feat in my opinion.
Water cooling, and a bunch of plate amps, at thousands of plate volts. Our
typical home 240V 200 amp electric service is good for roughly 48kw input, on a
good day.
Doubling, or tripling that 200 amp service is still peanuts compared to such an
operation.
Don N8ECH
On Saturday, September 10, 2022, 02:49:18 PM EDT, John Lyles
<jtml@losalamos.com> wrote:
I saw you mention K5PRO, Don, so I had to come out of my shell. I have
watched the 10 kW homebrew videos too. Admirable work, makes me long for
time to do modern tube-based amplifier construction at home, but I
prefer less spend the time with a camera. Even could fix some of my
trove of half-way good amplifiers. I don't use them on the air much,
just love to play with them. I still have my job, and switched to part
time this week so I could spend a little more time at home. At the
workplace, the particle factory, most of the PA's are getting >45K hours
on the filament running 24/7 for 2/3 of each year. I am happy to have
been part of their development. All the proper guidelines, cooling,
running within ratings (not at ratings), and plenty of protective
circuitry has paid off. Right now, we are looking at various
improvements and I'm working with a young team of EE's willing to ask
questions and dig in, about these ancient things, tubes. We have to
keep the technology going, and when its hundreds of kW or megawatts, the
alternative solid state must be carefully examined.
Here is an interesting recent paper from a conference last month, about
the advantages of tubes in the drivers for the Berkley 88 inch
cyclotron. Some things we never think about in ham radio are here. This
is a short term link that will be active about a week:
https://we.tl/t-4nZK77BSMm
One more paper, I wrote last month for the same conference of particle
accelerators in US:
https://we.tl/t-mogwvszTZh
My heart is still in thermionic devices although I do use LDMOS, DMOS,
GaN, and other semiconductors for smaller PA's at work (< 25 kW), but I
haven't designed a transistor amplifier in decades myself. So many
decent designs seem to be around now, and its good to see the amateur
community has engaged this techology. For those who still like using
tubes, like tuning the grid and plate, amps@contesting.com is still the
place to keep up, if you like this format as opposed to Facebook.
Speaking of tubes, I prepared a lecture at work in July, that summarizes
a lot of information about tubes, specifically focused on a historical
overview, then high power tubes used in pulsed power and RF circuits at
work. I used a lot of part numbers that are in service there, so there
are some references mentioned, just ignore those. This has been cleared
for public release.
https://we.tl/t-Blv0xVNOnQ
73
John K5PRO
> Message: 1
> Date: Sat, 10 Sep 2022 01:41:40 +0000 (UTC)
> From: Donald Fox <taurusshoguy@yahoo.com>
> To: amps@contesting.com
> Subject: Re: [Amps] 10 kw CCS on 6M. Part-3
> Message-ID: <887692576.944216.1662774100648@mail.yahoo.com>
> Content-Type: text/plain; charset=UTF-8
>
>
> As we like to say on the car forums I frequent, I'll be "that guy."
> I think the project is great, and I'm glad it's being shared here. Last time
> I looked, this IS an amplifier reflector, correct?
>
> This hoity, toity nonsense of hams sticking their nose up in the air when
> someone asks a question, or heaven forbid, shares something like this
> project, is getting really old. Reminds me of Eeyore on Winnie the Pooh. Just
> like the car forums I frequent, I listen a lot, and add to the conversation
> when I feel I can lend help.
> It's been my understanding for the 41+ years I have enjoyed this hobby, that
> part of ham radio, is the encouragement to design, and/or build some of your
> equipment. Seems to me like that is what this fellow is doing.
> Nobody knows everything, although there are some here who think they do. I
> know I don't, and have zero trouble putting it out there.
>
> As mentioned already, just because you have a fast car, does not mean you
> drive it fast on a public roadway. With 25+ years of law enforcement
> experience here, I am not aware of any state, that limits how FAST one gets
> to the speed limit, as ,long as they are not dangerous or out of control
> doing it.
>
> There is a video on Youtube, where a west coast 11 meter fellow designed and
> built his own 50kw amp. Indeed, putting it on the air is illegal as all get
> out, BUT if you a know anything about high power, he's no dummy. I would
> welcome someone with that level of high power experience (John K5PRO) comes
> to mind, in a heartbeat.
>
> It is said, that money does not guarantee brains. Neither does a ham license.
> All one has to do is dial up 7.200 or similar. Garbage like that makes ALL of
> us look bad to a potential ham.
>
> Rant mode off!
>
> Don N8ECH
>
>
>
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