Taylor 3-500ZG better than NOS Eimac 3-500Z Tube

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Nov 24, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    BTW- what year are the gassy tubes from Eimac? It was when they changed plants to manufacture the tube.
  2. N8FVJ

    N8FVJ Ham Member QRZ Page

    One item to think about is Taylor 3-500ZG are noted to last about 5 years. Non gassy Eimac 3-500Z lasts much longer- perhaps 30 years. I think non gassy Eimac are better, but the gassy risk is present with Salt Lake City manufactured tubes. Perhaps earlier Eimac may be gassy too.
  3. W1QJ

    W1QJ Ham Member QRZ Page

    The worst years for Eimac 3-500 tubes were the last 4-5 years they made them. I have seen more failures of the few date coded in the 90's than any other percentage wise. There were some years where the welds to the anode were more problematic than gas. No 3-500z tube like sitting around on it's side for long periods without use. It is inadvisable to keep NOS tubes in stock not being used.
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    Well, five years vs perhaps Eimac 30 years. I bought NOS 1976 Eimac 3-500Z tubes. Seller will test tubes in a Drake L7 amps before shipping. If gassy, will refund. Anyone want a Taylor pair of 3-500ZG with less than 100 hours use for $365?
  5. N8FVJ

    N8FVJ Ham Member QRZ Page

    One 1976 tube had a short. So, he also had two matching 8212 code tubes. 12th week of 1982. Placed in a Henry amp and got 1800 watts out. So, I guess pre Salt Lake City gassy production.
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    Found info on gassy Eimac 3-500z. Tubes manufactured from 1986 to 1989 were defective. Besides gassy, the plate weld to anode post was not sufficient. Do not have exact months of manufacture. Date codes are a four digit number printed on the tube. For example: 8212 is built in 1982 on the 12th week.
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    I posted that info (and showing the Eimac 3-500Z date code) in post #27, in this thread. o_O
  8. N8FVJ

    N8FVJ Ham Member QRZ Page

    Update- 1976 tubes tested and one has a grid to filament short. Owner noticed grid was rattling around. Bad for a new tube. Fortunately he also had a NOS pair of NOS 8212 code Eimac. Tested at 1800 watts output and cherry red plates that re-gettered the tubes. Sold my Tayor 3-500ZG tubes too. I would rather have 30 year life Eimacs vs 5 year life Tayor tubes in my amp.
  9. WB3BEL

    WB3BEL Ham Member QRZ Page

    I have seen you refer to tube life on many threads here on QRZ.com.
    Maybe you have some idea of what you are trying to say, but there are lots of newer hams on this site who may be confused.

    So I would like to say when you are buying a tube that was made many years ago, you get no guarantee that it will work for any number of hours.
    You can not even estimate with any confidence how long it will last.

    You may be lucky and it works for a long time. Or you may get something that goes kaput tomorrow. This is especially true of glass envelope RF power tubes.

    Most people do not know how long the tube has been used before. They don't know how it was operated, handled, or stored. There may be clues for the knowledgeable to be able to spot an RF power tube that has been abused or mishandled. But there are lots of hidden defects as well. Some of these things were made 30 or 40 or 50 or more years ago. People's memories get hazy with the passage of time. They may think it has been in a box for all those years unused. But many have been passed from hand to hand, never tested and possibly not as unused as people thought. This is giving the most generous and optimistic interpretation on why there are so many dead, or weak RF power tubes at hamfests or on the auction sites.

    Calling these old dinosaurs NOS or Mint or unused is really a stretch. The fact of the matter is that these are uNknown Old Stuff. They are not New. They are not Stock. But they are Old.

    Sometimes you have to buy Old Stuff because it is no longer made, or it has some special meaning to you etc . So you cross your fingers and roll the dice. But buying this old stuff thinking it is a bargain (Almost as good as new) may not be as good a deal as you think.

    The name that has been painted on the tube is often just a name. It does not always mean anything about the quality of the tube. It is just some paint on the glass. Lots of tubes come from the same factory will all kinds of different names painted on them. The old trademarks and businesses that these brands once represented are not the same today. If they are actually the ones made by the original factories then the above comments on Old Glass RF power tubes applies.
    WG7X and G3YRO like this.
  10. N8FVJ

    N8FVJ Ham Member QRZ Page

    Some lie about NOS, others do sell NOS. You take your chances. My info is documented by others. Only glitch I know of is one stated the Cetron last $25K hours and another Ham recently stated Cetron 572B last 10K hours.

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