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6M-E5 vs. 6ME5

Jacob Roschy Martin Renz Ernst Erb Bernhard Nagel Eilert Menke 
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Forum » Valves / tubes - Semiconductors » VALVES/TUBES / SEMICONDUCTORS in RADIOMUSEUM » 6M-E5 vs. 6ME5
Joe Sousa
Joe Sousa
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02.Aug.09 21:50

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Dear Radiophiles,

Is there any significance to the dash in the middle of a tube name? I happen to own two examples of the 6M-E5 eye tube. One is labeled 6M-E5, and the other 6ME5. The 6M-E5 came with my GR-21 Heathkig FM radio. The 6ME5 came with a Realistic Radio Shack open real recorder. This recorder is mission a small back cover that may have had a model number.


A related question is what is the meaning of "LOCKED OFF TUBE (CODE 9)" for the 6ME5?




Torbjörn Forsman
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02.Aug.09 22:14

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Typically, japanese tubes that do not have an exact american counterpart, have type designations with a dash. For example, 6R-HH2 (a double triode for television tuners, similar but not identical to the american 6BQ7) or 12G-B3 (a television horizontal output tube, a variant of the PL36 / 25E5 with different heater data).

However, american type designations should never be written with a dash.

May I guess that the 6ME5 might be stamped/branded by a equipment manufacturer that maybe not was so stringent or simply not had a dash in the stamping character set.

Roy Johnson
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02.Aug.09 22:20

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Hello Joe,

The simple answer is that there is almost always no difference. Often it is found that tubes are marked in slightly different ways.

For example we see SP4B written S.P.4B.   Sometimes a "/" is added in some names.    The early tubes tended to have the punctuation marks which were later dropped.

In a similar way we see 6ME5 and 6M-E5 on the tubes and also in the literature. Manufacturers even were not consistent in the naming of the same tube - the price list. box and tube can all be different.

To avoid confusion, and more importantly to make sure that all information goes to ONE place we "lock off" some tube names to force all data to the page with the selected name. 

For example,  we locked off PEN4V in favour of Pen4V  (and all PENxx types).   Both ways are seen, but all data should fall onto the one page!

Best regards,


This article was edited 02.Aug.09 22:28 by Roy Johnson .

Joe Sousa
Joe Sousa
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03.Aug.09 03:02

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Hello Roy and Torbjörn,

Thanks for the clarification, in particular, for the code 9 designation. If memory serves me, "code 9" is also what hospitals in the USA speak over the PA system when some dies suddenly.

There is probably a vast universe of electronic legacy from Japan that has not be explored at RM. I know they made some very interesting and unusual tuning eyes, aside from this minuaturized version of a classic octal round eye. There were some Japanese square target types with the same end view as classic octal eye tube.