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Re: e-mail from Thomas Mayer about EC8020

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In Reply to: e-mail from Thomas Mayer about EC8020 posted by Doc B. on August 08, 2000 at 07:50:11:

Ohhh Noo are you shure!! These are the only EC8020s I've seen and they are marked EC8020. IS there a web site to see a picture? I wouldn't think the EC8010 wouldn't be able to drive the 572-10 into class A2 like these tubes do. The EC8020 has specs closer to the 5842 and the 5842 can't drive the 572-10 over class A1. The tubes I got from Richardson have plate about twice the size as 5842s. Maybe Thorsten could verify the situation. I'll give Richardson a call to see whats up.

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Re: e-mail from Thomas Mayer about EC8020 dave slagle 11:44:03 08/08/00 (5)
hey,
i think thomas is right... the EC8020 is the size of a 437A
look at
http://albums.photopoint.com/j/View?u=37049&a=237580&p=25853573&Sequence=0
for a compairison of 437A EC8020 and the 5842
dave
- Re: e-mail from Thomas Mayer about EC8020 Scholl 12:14:55 08/08/00 (4)
  From what I see of the plate suport in the picture and the tube I'm using are the same. The envelope on the National labled EC8020 is about twice the hight and maybe a little bigger in dia then the 5842. The plate size is about twice the size as well. I called Richardson and they are checking their stock. I'll report back as soon as I know. Again I don't think the EC8010 could drive the 572-10 into class A2 as it has twice the plate resistance. I've been running the National tube for several months without any plate spots. I would also think the EC8010 would start spotting run a almost twice its rating. Does anyone have a picture of the EC8010? Or better yet the EC8020 and EC8010 together?
  - Re: e-mail from Thomas Mayer about EC8020 Manfred Huber 06:09:10 08/09/00 (0)
    I have put the EC8010 next to the EC8020 on my scanner. See the picture. The diameter of the EC8010 in about 20mm while the EC8020 has a diameter of about 29mm. The EC8010 I have (Siemens) has the plate only on one side of the cathode while the EC8020 (Telefunken) has parts of the plate on both sides of the cathode. The best way to make sure it is an EC8020 would be to measure the plate resistance. The a simple way to do it would be to use a sine wave generator on the input of the amp. Use 1000Hz. Set the AC voltage on the grid of the output tube to 1.0Vrms. Now connect a 2K2 Resistor in parallel with R4. With an EC8020 the rms Voltage will drop to about 0.71V and with an EC8010 it will drop to about 0.58V (if my math is right). See http://home.t-online.de/home/mhuber/apsupg.htm for a few pictures of my EC8020 spud amp. There you will find a close-up picture of the EC8020 where you can see the two large plate finns of this tube.
    Regards
    Manfred
  - Re: e-mail from Thomas Mayer about EC8020 John D. 02:59:06 08/09/00 (2)
    I have some Siemens EC8010 marked as EC8010/8556 on the boxes and the plate structure is very similar to the Telefunken EC8020 in the picture that dave posted.
    I know that Simon Shilton of SJS has had problems in the past. He bought what he thought were EC8020 which were labelled as 8556/EC8010/EC8020 but were actually EC8010 and NOT EC8020.
    John D.
    - Re: e-mail from Thomas Mayer about EC8020 Thomas Mayer 06:33:43 08/09/00 (1)
      All,
      just a few more comments about the EC8020/EC8010 issue.
      First I'd like to make clear that I did not intend to create
      confusion about this tube. And I also don't want to imply that
      only the Telefunken EC8020s are the real thing. It might well
      be that Scott has genuine EC8020s. But what I saw on the photo
      looked suspicious to me.
      I got my Telefunkens from a german supplier. After I got the
      first batch and planned to use them, I asked the same supplier
      if he has more. They didn't have any on stock, but mentioned they
      can order some. A few weeks later I got them. They have been
      labelled EC8010/EC8020/8556. Since I have some Siemens EC8010s
      I realized that they are just that a EC8010. I had a discussion
      with a person from that supplier who was their tube expert.
      He said that since certain types are scarce or no longer manufactured,
      current manufactueres tend to use the same tube and label it
      with different types as long as their specs are close enough.
      The EC8010 might work well in many applications which have been
      designed around the EC8020. They are pin compatible and both have
      a rather high transconductance. The EC8010 is about half a EC8020
      in terms of transconductance and plate dissipation.
      A unique feature of the EC8010 is the fact that cathode, grid
      and plate are assembled in a row. The plate does not enclose
      grid and cathode. This leaves the cathode exposed at one side,
      so that you can see it's glow very nicely. If Scott's tubes have
      that feature, I'm pretty sure they are EC8010s. The spave on just
      one side of the cathode would not allow a plate structure big
      enough to dissipate 8W.
      Scott, can you check that ? How thick is the metal of the plate ?
      Similar to the usual miniature tubes ? Or is it a hefty plate
      with metal about 1mm thick?
      The intention of my mail was just to give a warning to carefully
      check what you buy. If these are EC8010s, 50$ would be a hefty price.
      I'm curious what Richardson has to say about this.
      Ciao ... Thomas
      - Re: e-mail from Thomas Mayer about EC8020 Scholl 06:47:49 08/09/00 (0)
        
        In Reply to: Re: e-mail from Thomas Mayer about EC8020 posted by Thomas Mayer on August 09, 2000 at 06:33:43:
        
        Yes the plate structure is as you discribe. I hope to have a responce from Richardson soon. I would like to stick with EC8020s for this design. Could you direct me to a source for 8020s? And thank you for you input even if it did rain on my parade. Honesty IS the best policy and I'll do what I can to correct the misslableing issue. The Nor'Easter is a very good sounding amp that solves a lot of power supply issues very simply, but the EC8010 used is being run at twice the rated plate dissipation but the dang think can really drive (might be time to move on from 5842s) and has been in operation this way for 4-5 months with very good results.

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