[Amps] Question about average anode current in tetrode amplifiers on

[Mark Bitterlich]

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 at gmail.com Date: 11/25/24  8:27 AM  (GMT-05:00) To: Rob Atkinson <ranchorobbo at gmail.com> Cc: amps at 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 at 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 at contesting.com> http://lists.contesting.com/mailman/listinfo/amps>_______________________________________________Amps mailing listAmps at contesting.comhttp://lists.contesting.com/mailman/listinfo/amps