I have some 4P1S tubes and got round to running some through the tester as triodes . Compared to 4P1L with -22V grid bias for approx. 35mA anode current ~5mA/V , with 4P1S I need to back off the bias to -27V to stay within dissipation limits and get around 4.2mA/V for a 35mA target current . Anyone running these filament bias are going to cook their 4P1S pretty quickly...
It almost seems as if these are different valves in terms of biasing which is hardly subtle . Has anyone got a (preferably translated) datasheet for the 4P1S or run any triode curves ?
316a
It almost seems as if these are different valves in terms of biasing which is hardly subtle . Has anyone got a (preferably translated) datasheet for the 4P1S or run any triode curves ?
316a
Just opened a few from another batch and found a datasheet inside a boxOddly although appear to have been supplied to the Czech military by the Chinese , the datasheet is in English . Ties up with the operating point tables for the 4P1L
316a
Realise this is old. Thanks for sharing the English translated data sheet.
So this is a directly heated pentode.
Is it not interchangeable with the 4p1L /4n1n then? Have you tried this is something?
Thanks for the update.
Interesting. I’ve seen that there are several types of 4p1s available now. One is the usual 4p1s-j, then there are at least 2 types of others that are more expensive, one of which called a 4008 version. And then there’s the 4p1L from Russia (4n1n), which are twice the price again (in China). I believe the 4p1s was supposed to be a copy of the Russian tube.
I’ve read on this forum previously that some were getting arcing or something like that, with the little dot headphone amps. And from what I gather, it appeared to be using the 4p1s-j or the older 4p1s which has a different stamp. Which doesn’t necessarily mean there is something wrong with the tubes, as it could be the design of the circuit.
4p1s def cheaper than 4p1L in China.
Interesting. I’ve seen that there are several types of 4p1s available now. One is the usual 4p1s-j, then there are at least 2 types of others that are more expensive, one of which called a 4008 version. And then there’s the 4p1L from Russia (4n1n), which are twice the price again (in China). I believe the 4p1s was supposed to be a copy of the Russian tube.
I’ve read on this forum previously that some were getting arcing or something like that, with the little dot headphone amps. And from what I gather, it appeared to be using the 4p1s-j or the older 4p1s which has a different stamp. Which doesn’t necessarily mean there is something wrong with the tubes, as it could be the design of the circuit.
4p1s def cheaper than 4p1L in China.
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