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Are 3CX800A7 a good tube for longevity/SSB?

Discussion in 'Amateur Radio Amplifiers' started by KK4YDR, Feb 1, 2016.

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  1. KK4YDR

    KK4YDR Ham Member QRZ Page

    Anyways all I asked was if the 800s were a good tube and it went overboard as is usual on qrz. Thanks so far for feedback. I am sure I am smart enough to handle an 800 tube. Or a 3-500 or an 8877. Atleast the 800s are in a pair so the price to replace is only 1/2 the cost of an 8877 if only one tube roasted. Solid state is not happening with me. They pop way to easy. I could do a 3-500z amp too. I was just liking the idea of an amp with a lot of headroom (low stress on components) and a low drive so I would not beat on my ICOM rig so hard.
     
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    8877's a very good choice also. Same warmup requirement and about the same drive requirement, but just one tube and it's a brute. Available from multiple sources and the new Chinese ones are supposed to be very good.

    I've never had one fail. The 8877 in my 6m amp, built in May 1984, was "used" (broadcast pull) when I bought it for $100 in 1983 and still produces legal limit output 33 years later.
     
    KK4YDR likes this.
  3. AI3V

    AI3V Ham Member QRZ Page

    Lol. You would have to leave a amp on for pretty much your entire life to use up its filament emmision.

    Much more likely to ruin any tube by not tuning for a plate dip, but you know that, but that advice ain't quite as good for business is it?

    Toodlles.

    Rege
     
  4. AI3V

    AI3V Ham Member QRZ Page

    https://forums.qrz.com/index.php?threads/can-you-key-two-amps-with-one-signal.508318/

    OK.

    Rege
     
  5. KK4YDR

    KK4YDR Ham Member QRZ Page

    And your point?

    Its only 50 watt ss amp. Only one I own.

    Im tired of running a bandaid and I want more power. My icom blew up and I dont want to have to run 100 watts drive like a 1200 tube. But I will iff ultimately thats best choice. So what are you referring too here by snobbishly posting a thread that has nothing to do with my questions here?
     
  6. KM1H

    KM1H Ham Member QRZ Page


    What a laugh! Good damage control spin try but you have a long history on forums of bad mouthing Chinese products even when they do not deserve it and then bad mouthing anyone that says different. You are so insecure you have to resort to schoolboy taunts as a cover.

    You also should learn how to read your own post before pissin into the wind since nothing was said about cost.

    The 3CX800 and 8877 are far from unique for being fragile, the still available and used by Alpha 4CX1000A is another along with a long list of ceramic tubes going back into the 60's.


    The only thing backward around here is your understanding of the vacuum tube and the terminology used.

    That goes double or triple for you.

    If a person destroys a tube due to his own mistakes he is far from knowledgeable. Many newer hams fall into that category which is why amps have more and more fault tolerance and cockpit error survivability built in. Years ago there were several ham magazines and handbooks which tried to educate. These days QST is useless and the HB about the same in that area and only a very tiny fraction find the forums that talk about it in depth and factually.
    On QRZ there seems to be a lack of mentors to educate while keeping the wannabees, trolls, terminally misguided, etc at bay. Some mentors have left in disgust or are tired of arguing with idiots.

    It is a shame when the trolls, etc can confuse a new guy so badly that he believes him.

    First of all a ceramic tube will last as long as a glass tube if the filament types are the same such as the 3CX3000 which has a directed heated thoriated filament similar to a 3-500Z. OTOH the majority of the smaller ceramic tubes use an indirectly heated cathode which uses less filament current, has less reserve emission and a somewhat shorter emission life.
    The 8877 in average ham use should last 20-25 years; OTOH my ceramic 3CX1000A7 amp has a direct heated filament, I bought it used as a TV translator pull 30 years ago and it will still put out the same 1500W at the same drive. My 2x 3-500Z Eimacs still run full power after 30 years but dont expect that from some other date codes or Chinese versions. I finally pulled a pair of 1966 date code indirectly heated 8122's out of my 6M amp as they were down to about 600W from the original 1200-1300W; no other problems such as drifting screen current flashovers etc

    Hundreds if not thousands are still running 8873/8874/8875 indirect heated triodes from the 70-80's and 4CX250B pulls that are even older.

    Ceramic tubes have very very little problems from seal leakage and internal generated gas. Glass tubes from everywhere are prone to this and it is getting worse with age as NIB USA built tubes from WW2 to the 60's or so have often developed seal leakage, 811A, 813, 100TH, 250TH, 304TL, 4-400A, 4-1000A, etc...all popular and formerly dirt cheap. Ive had a few Cetron 572B's come thru with that nasty glow..not many...yet.

    Carl
     
    Last edited: Feb 3, 2016
  7. AI3V

    AI3V Ham Member QRZ Page

  8. KK4YDR

    KK4YDR Ham Member QRZ Page

    I just wanted to know a simple thing, being, is the 800 tube solid and future available choice. I am terribly sorry to have enrage you guys to the point of vitriol. I also didn't intend for others to cross post to threads that I created that are non-related to this one. I do own a solid state 50 watt (OH WHOOPTIE FREAKING DOO) amplifier. It is my only solid state amplifier, thus, ONLY. I will NOT buy a solid state legal or near legal limit amplifier. I do not like the small tolerances they barely allow already. I am NOT prone to mistakes however we are all human and therefore do make them. If you you do not make mistakes then remind me to go to your church and worship you as God.

    I'm done with this thread. Thanks to those whom helped.
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    It can be hard to predict the future.

    Good Luck.
     
  10. WA9SVD

    WA9SVD Ham Member QRZ Page

    That was true up through the 1950's; even QST published more than one article using4CX250's with both grids grounded, with the caveat that the tubes could be destroyed with long key-up conditions, but that was acceptable due to the low cost of Mil surplus. As you say, those times are long gone.
     

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