The ECH81 triode heptode was designed in for the role of frequency changer mixer in superhet receivers for AM reception. The two valve sections share a common cathode. The triode is to be used as the local oscillator feeding the 13 Volts amplitude sine wave to the heptode mixer. The anode circuit is tuned to enhance one of these signals, normally signal minus LO.

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According to our profound investigations and tests, the tubes ECH81 and ECH83 are equal - not even tested differently, but only stamped differently. They naturally show different values for a different usage volts anode. See this forum article here about that. In recent discussions with Jacob Roschy , it has become apparent how popular and versatile the ECH81 tube is. Jacob has used it in many of his transmitter and receiver designs.

I include here some additional curves that explore the behaviour of G3, which is normally used for local oscillator LO injection. This choice of grid requires a relatively wide p-p input for efficient mixing, but this is easily supplied by the independent triode oscillator.

This leaves G1 independently available for RF input with remote cutoff. The nominal conversion transconductance is specified as uS. In the self-oscillating configuration, the nominal transconductance is uS, and up to uS with a heavy 1mA separate LO injection into G1. Comparing the effect of the control grid G1 on plate current to the effect of the LO injection grid G3. Note the non-inverting voltage gain and negative transconductance from G3 to G2-G4.

This is the nominal recommended screen bias. This is even more so, near 0V bias for either grid. The very modest gm3 has hardly any effect when added to gm1 by driving both grids simultaneously as seen in the next photo. Note how sudden and sharp it's cutoff is with V at the lowest trace.

Note how severe the attenuation is at low control grid G1 voltages at 0V. The third grid G3 retains a high impedance down to zero volts as can be seen in the right-most column. If ever I am having doubts about my lack of knowledge in the area of radio, I simply read one of your articles. Your brain is a scary thing indeed. All joking aside, thank you for yet another informative and interesting article. Please 'keep em coming!

Antique radios, Old Time Radios. Quantity of Models at Radiomuseum. Collection of Jacob Roschy D. Collection of Egon Strampe D. Collection of Christian Schaufelberger CH. Collection of Ekkehard Pfau D. Collection of Roland Biesler D. Collection of Patrice Zeissloff F. Collection of Rudolf Osterkamp D.

Collection of Otto Frosinn D. Collection of Karlheinz Fischer D. Collection of Peter Steffen CH. Collection of Guido Pedrali Noy I.

Collection of Karl - Heinz Bossan D. Collection of Heinz Schmidt D. Collection of Michael Mischke D. Collection of Vitor Oliveira P. Collection of Ulrich Fieseler D. Collection of Alberto Zappacosta I. Collection of Aldo Patriarca CH.

Collection of Lars-G. Lundelin FIN. Collection of Peter Olasz H. Collection of Ottmar Rollmann D. Collection of Giorgio Busletta I. Collection of Emilio Ciardiello I. Collection of Georges Werts B. Collection of Danko Tkalec HR. Collection of Werner Wussow D. Collection of Klemens Rhode D. Collection of Franco Antolini I. Collection of Hermann Fleischanderl A. Collection of Jacky Parmentier F. Collection of Tomasz Szczesniak PL.

Collection of Erich Dorninger A. Collection of Bekir Yurdakul F. Collection of Kazimierz Jarosz S. Collection of Stig Comstedt S. Collection of Emilio Focosi I. Collection of Michael Wenzel D. Collection of Hans- Georg Tenz D. Collection of Reinhard Riek D. Collection of Alexander Hofer A.

Collection of Oskar Elm D. Collection of Marco Lagendijk NL. Collection of Bartosz Szwed GB. Collection of Aires Gomes P. Collection of Marcello Astolfi I. Collection of Ralf Meinke D. Collection of Tor Steinnes N. ECH81Curve traces. Italian Flag. ECH81 End of forum contributions about this tube. You reach this tube or valve page from a search after clicking the "tubes" tab or by clicking a tube on a radio model page.

You will find thousands of tubes or valves with interesting links. You even can look up radio models with a certain tube line up. Country: Europe. Erb Analysis by original leaflets. Text in other languages may differ. Regards, -Joe. Die ECH81 arbeitete jedoch augenscheinlich als Mischer korrekt. Was nun? Das Radio war ausgeschaltet bei der Messung. Nanu, doch alles o. Also, Radio wieder einschalten und Eingangskreise wobbeln. Drehen wir uns im Kreise?? Also Trimmer des Zwischenkreises verdrehen: Keine Wirkung erkennbar!

Kern verdrehen: auch keine Wirkung! Also hat die ECH81 Gas gezogen. Es sieht "ganz normal" aus. Hier arbeitet die ECH81 auch ganz "normal". MfG DR. Many members will probably have opted out articles with some other language flags - or they will not open languages they don't understand.

If you want that your question is seen by more members please go to this thread, click "Edit", change language to English and then click Submit - and your question will have the flag for English.

The right language selection at the Wysiwyg-Editor is only necessary for the first post of a thread since this one shows the language flag for the whole thread.


ECH81 Heptode. Datasheet pdf. Equivalent



ECH81 Datasheet PDF



ECH81 Datasheet


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