|
Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
|
Thread Tools |
11th Nov 2019, 2:19 am | #21 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: Pye Empire. Output stage conversion to tetrodes?
A triode connected PEN45 has similar characteristics as the Mazda 6L18 triode which means it's not particularly powerful.
Correction to my previous post. Shouldn't the anode resistance be written as ra? External resistance is written as Ra. DFWB. |
11th Nov 2019, 2:45 am | #22 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
|
Re: Pye Empire. Output stage conversion to tetrodes?
Quote:
|
|
11th Nov 2019, 3:25 pm | #23 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
|
Re: Pye Empire. Output stage conversion to tetrodes?
The 6N7 is not a starter unless I am missing something. It is designed for class B operation and requires a positive grid voltage that will draw grid current to get anything from it.
The datasheet is here http://www.r-type.org/pdfs/6n7.pdf. |
11th Nov 2019, 3:30 pm | #24 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
|
Re: Pye Empire. Output stage conversion to tetrodes?
Triode wired PM24M's might work and that will be almost a drop in replacement.
http://g3ynh.info/valves/old/Data-Bo...G/MVG-p034.pdf |
11th Nov 2019, 4:10 pm | #25 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 7,444
|
Re: Pye Empire. Output stage conversion to tetrodes?
"Triode wired PM24M's might work and that will be almost a drop in replacement."
Actually I was considering the PM24M as a replacement for the PX4s in the Beau Decca TV. But watch the anode voltage. Isn't the PM24M VA max 250V? DFWB. |
11th Nov 2019, 4:42 pm | #26 | |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,902
|
Re: Pye Empire. Output stage conversion to tetrodes?
Quote:
So the output impedance of the PX4s will be modified from the datasheet values. David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
|
11th Nov 2019, 5:51 pm | #27 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 550
|
Re: Pye Empire. Output stage conversion to tetrodes?
I really quite fancy the 6p3p mainly due to them being pence to buy and looking roughly the right size if someone could scribble on the diagram a way of sorting that I'd be elated obviously ignoring the heater requirement .
|
11th Nov 2019, 6:46 pm | #28 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
|
Re: Pye Empire. Output stage conversion to tetrodes?
Quote:
So biasing each triode to a low anode current of around a few mA you can still get a good anode current swing out of them in push pull before there is any substantial grid current. It has been some years since I used one as a class A output amplifier, but it produced good output with minimal drive requirements, I would have to set one up again to determine the exact power and also try them in push pull and the ideal bias setting. But I agree that to get anything like the power out that PX4's could deliver the driver transformer would have to be changed most likely to a step down type to support the grid currents. Last edited by Argus25; 11th Nov 2019 at 6:52 pm. |
|