If you have 1800 watts of input power and 200 watts of output power, you either
have 1600 watts total of heat or you have Instrumentation error. It can't be
neither. Alternative measurement thoughts:Have you checked for resonance of the
plate choke? Have you made alternative measurements of total input power using
primary AC measurements? Have you accurately measured tube airflow exhaust
caloric rise compared to working bands not using thermal camera? De wa3jpy P.S.
Gosh, name and callsign. I'm doomed.
-------- Original message --------From: flynth@gmail.com Date: 11/25/24 8:27
AM (GMT-05:00) To: Rob Atkinson <ranchorobbo@gmail.com> Cc:
amps@contesting.com Subject: Re: [Amps] Question about average anode current in
tetrode
amplifiers on Thanks for the understanding.Coming back to the subject. After
reading quite a bit, calculating variousthings, looking at various tables,
ripping half of my amp out andrebuilding I still don't quite understand how is
it possible to consume0.6A at 3000V, output 200W to the dummy load, and not
increase thetemperatures anywhere (I was watching with a thermal camera).I
initially thought, I had too much capacitance, too little inductancewhich
caused Q to plummet, but that was due to a misunderstanding how Q iscalculated.
I definitely had resonance, if I calculate reactance (49pf,600nH @29MHz - about
~100ohm, the copper tape I used for connectivitycontributed well under 0.2ohm)
so I had a Q of about 20. This could causehigher current, but if that was a
problem I'd see heating on thermalcamera(there was none).There is also a theory
of too much lead inductance (mentioned by Victor),I'm not dismissive of it, but
I'm not entirely convinced either.I run a sweep of my DC decoupling cap,
thinking perhaps it causes someissue as when the anode becomes the plate
capacitor, the tank energy goesback and forth through the dc blocking cap. I
put it between s21 and s22ports of my nanovna. It passed everything between 1
to 45MHz pretty muchexactly flat.Yesterday I moved the 10m coil closer to the
DC block cap and I moved theplate cap away from the enclosure wall in hope to
lower stray capacitance.All these efforts resulted in moving the resonance with
target coilinductance and no plate cap about 1MHz up to 26MHz (if I lower
thatinductance as described before I can resonate on 10m, I haven't tried it
inthe new configuration under power yet). It's unlikely I'll have time to do
any testing during the week.73,FOn Mon, 25 Nov 2024, 01:30 Rob Atkinson,
<ranchorobbo@gmail.com> wrote:> Dear F.:>> Okay, I get it; you're paranoid.
Fine -- you have every right to be> paranoid. All I can say is, it's ham
radio. We're just messing> around in a hobby. No one is trying to take over
your life. If you> are a crypto billionaire then you have reason to be
careful, and> wrapped too tight. But the people trying to steal money could
not> care less about ham radio. I appreciate that separately you verified>
that you are a ham and so on. The reason I have a problem with> mysterious
anonymous requests is that usually the intent is either> nefarious which I do
not want to aid and abet, or the questioner has a> hidden agenda. I once put
in a great deal of time and effort trying> to help someone who turned out to
have zero interest in the piece of> equipment in question. What he was really
trying to do was get> information to justify getting a higher price paid for it
on eBay.> Others may not care but I am old, and used to people being real and>
open. That's the business world I inhabit. I will respect your> privacy.
Have a nice life.>> 73> Rob> K5UJ>>> <<<Why? Privacy online is important.
Anonynymity should be the default.> This> is a public mailing list and I signed
up with my non-identifying email> address that has 3 decades of information
floating about it on the> internet. If I just post my name and call sign I may
as well have attached> it to all this communications.>> There are automated
tools bad actors can use to connect such information,> build a profile about
you or me and use it for various nefarious purposes.> Having one's name and/or
exact address (often with a phone number) is bad> enough from identity stealing
point of view. Having all the history of your> hobbies, where you lived before,
maybe where you grew up etc (stuff someone> might think to use to prove your
identity) is insane. Especially if one> lives in a country like me that
protects banks rather than people if> someone takes out a loan in your name.>>
You know, only from this year they established this facility to "block"> one's
identity from lending point of view. So what's the problem? Why not> just block
it? I did, but the law behind it is laughable. Banks are not> obligated to
honor it (not all banks anyway) and people that will take a> mortgage on your
home without you knowing know which institutions voluntary> choose not to sign
up to that database.>> There are places like qrz.com where I sign up with my
identifying> information. I keep these and my non-identifying information
separate.> Perhaps this list should be one of those places, but at the moment
I> signed. I didn't think about it and now it's done.>> I realise if someone
manually wants to connect the dots it is doable, but> I'm not expecting to be
personally targeted. Still I'm making the job for> their automated tools much
harder (until such time the writing style> analysis will be enough to ID
uniquely - maybe by then our lawmakers will> pull their collective head from
their arse and establish proper identity> protection).>>>>>> Regards,> F>>
_______________________________________________> Amps mailing list>
Amps@contesting.com>
http://lists.contesting.com/mailman/listinfo/amps>_______________________________________________Amps
mailing
listAmps@contesting.comhttp://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|