Loading ...
Sorry, an error occurred while loading the content.

Re: Mk.20

Expand Messages
  • kyoritsu
    ... Leonard, you often read that low mu triodes make better regenerative detectors, but I think what the parallel triode experiments show is that it is low mu
    Message 1 of 11 , Feb 1, 2012
    • 0 Attachment
      --- In regenrx@yahoogroups.com, "Leonard Meek" <lemeek@...> wrote:
      >

      > I'm interested to hear how you make out with your parallel triodes. That
      > could be a whole new approach to regen detectors. I tried a 12BY7 in my
      > Mk.11 regenodyne because it has a gm of 11000 and rp of 93000. I'll probably
      > have to wind a coil for a different IF freq because the crystals I have are
      > not in a suitable range. Or, I may change to a tunable LO.
      >
      Leonard, you often read that low mu triodes make better regenerative detectors, but I think what the parallel triode experiments show is that it is low mu AND low Rp/high transconductance. Paralleling triodes doubles the transconductance, halves the Rp. I have to find and try a single triode that has those characteristics to test this hypothesis.

      For a GG RF amp, I think the preferred triode has high mu, high Rp/low transconductance.

      A recent thought: a ham band regen with separate detectors for each band, common audio section. Each band would be LC tank and feedback optimized, tuning would be done by a single.main pot controlling a varactor within each detector. Band changing by diode switches. A regenerative detector has only a handful of parts so it's not that crazy. But practically speaking it would have to be solid state (although in the spirit of the original tube computers it could be done).

      Rob
    • Leonard Meek
      Very interesting idea, Rob. A tube version would need to use directly heated types so they could be turned off when not in use. I ve used diode switching in
      Message 2 of 11 , Feb 1, 2012
      • 0 Attachment
        Very interesting idea, Rob. A tube version would need to use directly heated
        types so they could be turned off when not in use. I've used diode switching
        in other circuits. It would solve the layout problem on my next regen. Maybe
        I could use proximity fuze tubes for the individual detectors. I used a
        couple in my Mk.19 and they worked very well. As for low mu tubes, a friend
        offered me a bunch of 6080's. They have a mu of 2 and rp of 280 ohms. The gm
        is 7000. Unfortunately, heater current is 2.5 amps. How about triode
        connecting a 12BY7? It has a gm of 11,000. I have one in my regenodyne but I
        haven't finished it yet.

        Leonard

        ----- Original Message -----
        From: "kyoritsu" <rikkyograsing@...>
        To: <regenrx@yahoogroups.com>
        Sent: Tuesday, January 31, 2012 11:15 PM
        Subject: [regenrx] Re: Mk.20


        >
        >
        > --- In regenrx@yahoogroups.com, "Leonard Meek" <lemeek@...> wrote:
        >>
        >
        >> I'm interested to hear how you make out with your parallel triodes. That
        >> could be a whole new approach to regen detectors. I tried a 12BY7 in my
        >> Mk.11 regenodyne because it has a gm of 11000 and rp of 93000. I'll
        >> probably
        >> have to wind a coil for a different IF freq because the crystals I have
        >> are
        >> not in a suitable range. Or, I may change to a tunable LO.
        >>
        > Leonard, you often read that low mu triodes make better regenerative
        > detectors, but I think what the parallel triode experiments show is that
        > it is low mu AND low Rp/high transconductance. Paralleling triodes doubles
        > the transconductance, halves the Rp. I have to find and try a single
        > triode that has those characteristics to test this hypothesis.
        >
        > For a GG RF amp, I think the preferred triode has high mu, high Rp/low
        > transconductance.
        >
        > A recent thought: a ham band regen with separate detectors for each band,
        > common audio section. Each band would be LC tank and feedback optimized,
        > tuning would be done by a single.main pot controlling a varactor within
        > each detector. Band changing by diode switches. A regenerative detector
        > has only a handful of parts so it's not that crazy. But practically
        > speaking it would have to be solid state (although in the spirit of the
        > original tube computers it could be done).
        >
        > Rob
        >
        >
        >
        >
        >
        >
        >
        > ------------------------------------
        >
        > "In the interest of Regenerating radio's lost art of Regeneration"Yahoo!
        > Groups Links
        >
        >
        >
        >
      • LeonardM
        I just posted a change to my AGC amp to speed up attack and slow down decay. I may have to add another resistor with the switch so as not to load the amp when
        Message 3 of 11 , Feb 3, 2012
        • 0 Attachment
          I just posted a change to my AGC amp to speed up attack and slow down decay. I may have to add another resistor with the switch so as not to load the amp when RF gain is in manual.
        Your message has been successfully submitted and would be delivered to recipients shortly.