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Replace EM11 with EFM11

Ernst Erb Jacob Roschy Martin Renz Bernhard Nagel 
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Forum » Valves / tubes - Semiconductors » Valves / Tubes; practical use and procurement » Replace EM11 with EFM11
Marian Popov
BG  Articles: 4
Schem.: 8
Pict.: 37
08.Dec.12 19:16

Count of Thanks: 8
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I have an old radio Stassfurt 5E63C with EM11, but the tube doesn't work anymore. Can I replace it with EFM11 and if the answer is YES, what changes I have to make to the schematic ?

Thank you.

Michael Watterson
IRL  Articles: 969
Schem.: 650
Pict.: 2497
08.Dec.12 23:34

Count of Thanks: 9
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Replacing with the 6e5s (Cyrillic 6E5C) is a better choice than a EFM11 as it's quite different and also not very available. An Octal to Y8A adaptor can be made. The Russian 6e5s is readily available cheap NOS. There may be Chinese versions too. A consideration may also be the mechanical mount of the tube.

If you want the original eye pattern (See Magic Eye Patterns) then the choice is limited.

Four shadows, but two are more sensitive

EM5, EM11, EM35, UM11, UM35

The UM11 and UM35 are unsuitable filaments, 13V @ 100mA

Because of quite rapid wear, especially of greener rather than blue/green (cyan) eyes, ex-equipment tubes are usually poor. DM70/DM71 wear the least followed by EM84, EM87 etc. The very emerald green end view types are worst life time.

The EFM11 is different structure and patterns, but could be used instead of the EM11, the resistors on pin 1 and pin 8 seem to need to be about 1/3rd in value. But other "eyes" will work with the EM11 resistor values, just with a base adaptor.

Two moving shadows, one control

6X6, 6Z-E1, AM2, AW6, E1180, EFM1, EFM11, EM31, CV1077, V177

This article was edited 08.Dec.12 23:41 by Michael Watterson .

Marian Popov
BG  Articles: 4
Schem.: 8
Pict.: 37
10.Dec.12 19:15

Count of Thanks: 11
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thank you for the information. I'have one EFM11 and no 6E5S. I'll try to find the russian valve and make the replacement. The EFM11 will be waiting for other project. Thank you.