3-500Z Filament To Grid Shorts, The Other Cause

Discussion in 'Amateur Radio Amplifiers' started by AF6LJ, Jan 22, 2012.

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  1. VK4TUX

    VK4TUX Ham Member QRZ Page

    What does what I posted have to do with Rich? I posted a pic I took a while back without realizing the filament had dropped, and I found out.
    So that's my deal and nothing to do with why filaments get bent, vhf parasitic s etc or Rich. Be fair!

    Adrian ... vk4tux
     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    That's cool I apologize for getting bent out of shape over it.
     
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    Everybody makes mistakes; it's how we deal with them that sets eachother apart and determines the quality of a person.

    I got angery over what I thought was a misrepresentation of a 3-500Z.
    Adrian and I cleared up the situation and each has apologized.
     
  4. AF6LJ

    AF6LJ Ham Member QRZ Page

    It just seems to be contrary to common sense to do that...
    Orr has produce3s some interesting stuff, not the least of which was his super cathode drive which works well for sweep tubes. Orr has made a number of contributions to Amateur Radio over the decades and like all of us is entitled to make a mistake now and then.
     
  5. AG6K

    AG6K Guest

     Orr's reported history regarding a UCLA fraternity would make interesting reading if there was an Amateur Radio version of "The National Enquirer".

    • Do you know how many articles by W6SAI were published in QST?

    • Rich, ag6k
     
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    I know there were at least one I can remember off the top of my head.T
    hat's where I first saw the super cathode drive article.
     
  7. AG6K

    AG6K Guest

     What was fair about refusing to publish my rebuttal to: Technical Correspondence, page 71, September 1994 QST, "Revisiting 'The Nearly Perfect Amplifier' " --- wherein you included yourself in your list of "our recognized amplifier experts". Was it just a coincidence that MFJ-Ameritron paid for 10 full pages of advertising in the following month's QST?

     then why did they ask that I write more articles, examples of which included "Parasitics Revisited" and "The Nearly Perfect Amplifier" ?

     A foot high stack of ordinary 3-mil paper would be c. 4000 pages. This seems like a bit of a stretch for an article that they told me they were pleased with before they sent the issue to the printer.

     Because even today I am still not okay with seeing my fellow Amateur Radio operators needlessly toss their $$ away.

     In the s/n Q02888 photo, both filament helices were bent and partly intact, but they had not moved. The top part of each filament helix is not seen because it had shattered into bits and dropped into the base

     who's embarrassed ?

    • Rich, ag6k
     
  8. AG6K

    AG6K Guest

     ... which is what I assumed until i started checking grid-resonance freq. with a dipmeter. After reading Fred Terman's "Radio Engineer's Handbook", Section 2, Circuit Elements, Inductance and Mutual Inductance, I realized that no matter how wide or how short a copper - or even a silver strap - is, it definitely has inductance. IOW, a literal Direct Ground is not to be found.

    • Rich, ag6k
     
  9. K9STH

    K9STH Ham Member QRZ Page

    The truth be known, although Bill Orr, W6SAI, wrote a number of articles for QST, he had considerably more articles published in CQ Magazine. This besides a number of handbooks on topics concerning amateur radio.

    I have to check to make sure, but I believe that Orr also wrote a few for 73 Magazine.

    Glen, K9STH
     
  10. G0HZU

    G0HZU QRZ Member


    That's why I'm puzzled by the people who think that grounding with copper tape is grounding the grid 'better' than the 200pF caps at med VHF frequencies. eg 70-110MHz.

    The caps will outperform the copper tape over this range as the capacitive reactance of the caps cancels some of the inductive reactance in the grid connection.

    Also, I think your dip meter method of measuring 'grid resonance' and also Tom's method of measuring 'grid resonance' are both flawed.

    But that's just my opinion based on the physics of the tube and looking at the datasheet.

    Can't somebody measure this stuff directly? I'm afraid I have no idea as to how hazardous the materials are in these tubes so maybe physical tests aren't practical or wise.
     
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