[sdiy] Hollow low-pressure ladder filter

[René Schmitz]

Hi all,

Just today I've read in a German Tube forum that somebody tried a ECH81 
(high voltage heptode/triode combination) on his tube tester set for an 
ECH83 (which is a low-voltage heptode/triode). Guess what, the Heptode 
system tested "good", so the plate currents should have been the same. 
Unfortunately he didn't test the triode system as well. 

So this seems to suggest that these low voltage tubes were possibly merely 
selected (maybe for highest emmission) ordinary high-voltage tubes. 
Its interesting that there is no visible difference in the 
geometry of the tube system for both. Also it was found that sometimes the 
low-voltage tubes have production codes that would actually suggest a high 
voltage tube. (I.e. a ECH83 carrying a ECH81 production code.)

I guess a circuit designed for a ECC86 could also work with an ECC88.

Cheers,
 René



At 01:17 30.04.02 +0200, Theo wrote:
>mmm, doesn't sound right.
>
>ECC86 is a low voltage tube, anode voltage 30V max,
>but the nominal anode voltage is only 12V.
>Definitely not "close" to a ECC88.
>
>I have been looking for other tunes like the ECC86 but  could not find them
>nor the US equivalent number.
>From what John Marshall wrote the 12U7 is either similar to ECC86 or the
>same thing.
>
>Theo
>
>
>
>From: Paul Perry <pfperry at melbpc.org.au>
>
>>
>> >> Is 12U7 the same as the ECC86?
>> >>
>> According to a sub book here, ECC86 = 6GM8
>>
>> also 12U7 is 'close' to a 12AE7.
>>
>> If that helps.
>> It might not, because the same book has 6GM8 'close' to
>> our old friend ECC88!
>>
>> paul perry melb aust
>> shall
>
>
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