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Discussion in 'Amateur Radio Amplifiers' started by W8JI, Dec 30, 2011.

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  1. W8JI

    W8JI Ham Member QRZ Page

    That has nothing to do with learning, teaching, personal attacks, nasty posts, or censoring. No one knows why there were so many reads, or if it could have been more or less, or if it was important or not to the goals of the forum.
  2. AG6K

    AG6K QRZ Member QRZ Page

     My guess is that most people read posts here because they are interested in learning more about a complex machine. As for me, I cherish personal attacks on me because that tells me I scored a point. Example: just before the end of the Grate Parasitics Debate, when my opponent's groupies accused me of an unmentionable activity with ______, I knew that it was time to light up a Red Auerbach cigar.
    • Rich, ag6k
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    I post here for many reasons;
    Keep in mind there are a couple dozen forums here and my chief enjoyment on the radio is rag chewing.
    With that said;
    I enjoy learning and passing on my knowledge in the technical forums.
    I enjoy talking about others issues with people I have something in common with, the best part is when we disagree on any given subject, because the human race is like a artfully crafted stew, full of many interesting and interesting flavors..
    A person who limits their social interactions to just those who see the world as they do, is in a sense, a shut-in. Self sheltering in this manner, is to a great degree willful ignorance of a sort, and should be a sin.

    What the Zed is best for is what we are doing right now; discussing what is important to each of us.

    The whole discussion over dealing with parasitics motivated me to do more reading on the subject. Since I have a good understanding of the theory behind amplifier design I was able to gain insight into both approaches taken and to form some conclusions. This kind of discussion is healthy for everyone concerned enough to follow along. The other function of this whole discussion is to air misinformation and present facts. To steer those less knowledgeable in the right direction, and to demonstrate through doccumentable theory what is really going on.

  4. W8JI

    W8JI Ham Member QRZ Page

    I need to do more radio and less of this.

    I like 40M and 160M. I worked a few JA's on 160 this morning at sunrise.
  5. AG6K

    AG6K QRZ Member QRZ Page

     What's really going on is really quite simple Catwoman: All amplifier tubes have C-feedback from their output back to their input. Examples: A 811A or a 572B has 0.6pF of C-fb, A 3-400Z or 3-500Z has 0.15pF of C-fb. & an 8877 has 0.1pF of C-fb. All of them have VHF gain and a high amplification factor. At their rated f-max for "Amplifier and Oscillator Service" the 811A/572B C-fb path has 4500-Ωs of XC, the 3-500Z's has c. 10kΩ, and the 8877's has c. 6.5kΩs of feedback. If you are trying to build a VHF oscillator, it is Not likely that additional C-fb will need to be added to achieve your goal with each of these tubes/valves. However,if you are trying to build an HF amplifier, it might be good a good precaution to artificially reduce VHF amplification to avoid unwanted VHF oscillation by incorporating a L/R VHF suppressor in the anode circuit since you can decrease VHF gain as needed by decreasing the VHF-Q of your L/R suppressor. The tradeoff is c. a 0.1db loss at 28MHz.
    . As I see it, the suppressor controversy is much adoo about almost nothing.
    • Rich, ag6k

    Photo of damage by parasitic osc. in an AL-1500 amplifier (gold evaporation)
    Photo of damage by parasitic osc. in a Henry 2K-4 amplifier (bent filament)
  6. KA5ROW

    KA5ROW Ham Member QRZ Page

    I agree there is no reason to lock any thread unless it is not in good taste. At one time I would see post locked because; reason given (Brought back from the Dead).
    I saw no harm in someone going back 3 or 4 years to dig one up. If that was a problem why not just delete all threads on there one year anniversary date.

    I cut and paste many Q&A on a Word file for personal reference from QRZ and e-Ham.
  7. N4CYA

    N4CYA QRZ MODERATOR Volunteer Moderator QRZ Page

    And know when to run. Great song by the way.

    On a better note. I believe reason why some of the threads are being closed/locked is because when someone stirs the pot by trolling about something or someone let alone another forum member it causes a problem between the person or persons. Here at QRZ us Staff members have a big job here which are moderate the forums, add people to the database, deal with issues between a forum member or members then find a right solution for everyone it's hard at times trying to pick out the bad posts. When there is a problem existing between people instead of baiting it more just report it and the moderator in the section where the problem will be notified about the issue and it will be handle so it won't get worse when others join in. Threads will only be locked if there is no point of it or it's getting out of hand.
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    This is understandable.
  9. KM1H

    KM1H Ham Member QRZ Page

    It becomes increasingly hard when 2 people with a similar educational backround (or is it a lack of as Ive never determined that) provide most of the dissent and posts and have been at it almost non stop for decades across just about every available forum.

    I for one am damned tired of it.

    I vote for Sue as Mother Hen of the asylum[​IMG]

  10. AF6LJ

    AF6LJ Ham Member QRZ Page

    I would plead that both parties agree to disagree and move on..
    Both of you have contributions you can make to this forum and other forums here on the Zed.
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