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09/23/14 at 09:25:10


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Is the EL61 pentode an option for the Rachel? (Read 143 times)
hifitubes
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Posts: 190
Is the EL61 pentode an option for the Rachel?
06/17/14 at 13:05:08
 
I'm not sure what Rachel is running at...

"The EL61s now used in the box have lasted for more than 3000 h without significant degradation in slope and emission - recently I checked them out, and found - within the accuracy of my VCM163 - no change compared to first insertion - operating point was 18W/375V/275V/48mA per valve."
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hifitubes
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Posts: 190
Re: Is the EL61 pentode an option for the Rachel?
Reply #1 - 06/17/14 at 13:06:51
 
Also, the 4689 ...

" The 4689 was used in Cinema amps, PA systems and PTT applications.

It reached the market in the ST shape around 1936, and in the shape
shown around 1947.

It can be used like an EL34, IF you keep Qa below 18W, Ua below 400V
and Ug2 below 300V - the datasheet is a bit conservative wrt voltages
- but power ratings MUST be observed...

Run a 4689 at EL34 operating points and voltages, and you will loose
it fairly quickly. "
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