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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

6P41s vs 7868

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Are there available any datasheets for these 6P41S? Frank doesn't appear to have them handy...
Best regards!
Original files:

Some curves:
 

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I intend to try the 6P41s some time to see what I can squeeze out of them.

I done some tests with 6P41S as a PP-amplifier. Here are results with 40% UL, triode connected and pentode connected with different operating conditions.
Attached is also the schematic of the test circuit. All measurements were done without GNFB.
 

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Last edited:
Hello Toprepairman,
I am in process of a total restoration to convert Rowe R-4359 amp to use as a stand alone audio amp for my sound system. Am searching for parts list and schematics. I have come across of schematic by secret4mula but not clearly readable. Any info you can assist me with will be greatly appreciated. Would you know the manufacturer of the output trannies? Thanks again .

Regards,
Joe
 
Hi Joe.
Like you I only found a poorish copy on the net and then redrew it by hand.
I really don't know who made the transformers. I have stripped out the surplus wiring with the relay etc, with a view to converting to a straightforward stereo amp.
I got a set of 6P41's but they don't really perform as the originals so I may remove the bases and fit octals to run with 6L6/5881 type valves.
I'm not sure when I'll get round to doing this as I have another, bigger, more pressing project on the go in the shape of a house rebuild. Currently I'm looking at a big hole in the ground with a load of concrete in it. Behind is a huge pile of clay that came out of the hole so this is taking priority just now.
Henry
 
ok,the 6p41s are definitely different to 7591/7868
on my AMI-ROWE r4359, I got to get -70vdc for bias and+ 380vdc for a supply voltage and it's still not good,
the 6p41s do not work long at this voltage.
I start the conversion for 7591.
I keep the 6p41s for a future low voltage amp
end of episode 6p41s
 
i will try on the next r4359. this one serves me as a learning laboratory.
it is possible that you're right but the data of the 6p41s make me think the opposite, moreover, here I have a very high sector voltage, frequently 240vac, suddenly I have a stronger voltage in the secondary, which n is not a good thing for 6p41s.
I have already started the conversion of this one in 7591.
really thank you for the track, I did not even think about it
[ smiley with beer]
 
I got to get -70vdc for bias and+ 380vdc for a supply voltage and it's still not good, the 6p41s do not work long at this voltage.

It would work fine as pentode connected, definitely not as UL.

As you can see from the test results I showed earlier, with 400 V +Ub, 180 V as +Ug2 and -30 V as Ug1, 6P41S works really fine.

Some 55 W is available.
 
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