Search found 137 matches
- Thu Apr 18, 2024 5:03 pm
- Forum: Valves
- Topic: MAZDA AC/P4
- Replies: 0
- Views: 221
MAZDA AC/P4
I wonder if anyone has pressed these early 4v triodes into use - at first sight a use for them might seem hard to imagine. They were intended as drivers for electrostatically scanned 405 line tv receivers before electromagnetic scanning became the norm. I've had a couple for some years but have only...
- Sat Jan 13, 2024 7:28 pm
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
How do you power them? I've used ac from a transformer or full wave dc doubler from 7.5v transformer. Neither caused hum problems.
- Sat Jan 13, 2024 5:33 pm
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Await resultswith interest- never tried doubling up with PP3521.
I see Langrex still have some ( unless you've just bought them up!)
I see Langrex still have some ( unless you've just bought them up!)
- Sun Jan 07, 2024 7:46 am
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Hi Paul
See you're back onto this ( disguised as GM70)
Just to say I persevered with it and via trying AC/SP3's, settled on the later SP61's as a good option, being MAZDA and good spec.
270 R bias, 50k load. 105v screen.
Worth a try...and very cheap - £4.00 @ Langrex!
See you're back onto this ( disguised as GM70)
Just to say I persevered with it and via trying AC/SP3's, settled on the later SP61's as a good option, being MAZDA and good spec.
270 R bias, 50k load. 105v screen.
Worth a try...and very cheap - £4.00 @ Langrex!
- Sat Sep 23, 2023 5:50 pm
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Ooops!
E810F or E180F pin compatible if you leave pin 6 disconnected.
E810F or E180F pin compatible if you leave pin 6 disconnected.
- Sat Sep 23, 2023 5:44 pm
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Just to say that have broken with tradition (my own) and have tried a 'modern' approach as a driver - an E810E ! in pentode mode - 10k load, 150v S.G, 100R bias. 200v ht, runs at approx 14mA - sounds Good, certainly worth a try if anyone is still looking for driver options for the PP3521 triode. To ...
- Sun Aug 27, 2023 4:01 pm
- Forum: Everyones Projects
- Topic: SE output Xfrmr as anode load?
- Replies: 5
- Views: 3077
Re: SE output Xfrmr as anode load?
Thanks Greg,
Didn't know that...
Didn't know that...
- Sun Aug 27, 2023 2:38 pm
- Forum: Everyones Projects
- Topic: SE output Xfrmr as anode load?
- Replies: 5
- Views: 3077
Re: SE output Xfrmr as anode load?
Since the replies to this post I have been playing with a Hammond 20H 20mA choke as anode load for an ML4 driving a KT8c - surprisingly good results but as expected being rather challenged at low audio frequencies.... Wondered if anyone might know of a pair of Hammond 156C chokes looking for a new h...
- Wed Aug 23, 2023 5:57 pm
- Forum: Everyones Projects
- Topic: SE output Xfrmr as anode load?
- Replies: 5
- Views: 3077
Re: SE output Xfrmr as anode load?
Thanks Paul,
Yes of course, I actually checked the inductance after sending the email....
CCS it is then!
Thanks.
Yes of course, I actually checked the inductance after sending the email....
CCS it is then!
Thanks.
- Wed Aug 23, 2023 9:18 am
- Forum: Everyones Projects
- Topic: SE output Xfrmr as anode load?
- Replies: 5
- Views: 3077
SE output Xfrmr as anode load?
Any one tried using Hammond 125BSE output's as load for driver stage at around 20mA.....any practical experience?
Or, waste of time...
Thanks.
Or, waste of time...
Thanks.
- Wed Apr 26, 2023 7:45 am
- Forum: Everyones Projects
- Topic: The Newton 300B
- Replies: 242
- Views: 112724
Re: The Newton 300B
Haven't built a PP amp since 1962 - but have you thought of the 6Y6, a very capable driver......
- Sat Apr 22, 2023 10:09 am
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Yes, I like the PP3521 and have done for some time, also the PEN3520 which although a pentode makes a reasonable sub and can be a direct plug in. I too have used the USA types, UY-227 and UY- 224 (tetrode) but came back to the British types of the same period, MH4 being also from the 30's. Be intere...
- Fri Apr 21, 2023 2:11 pm
- Forum: Valves
- Topic: PP3521 idht
- Replies: 95
- Views: 22696
Re: PP3521 idht
Hi - I too have tried the PP3521 in SE using drivers recommended to drive PX4's but was never happy with the results - these were the H42 and AC/S2PEN types. Since seeing this thread I decided to try again using MH4's as drivers- good, but slightly low gain, I then tried MH4's in mu follower configu...
- Fri Mar 03, 2023 12:25 pm
- Forum: Everyones Projects
- Topic: PT15 se A2 operation
- Replies: 4
- Views: 4661
Re: PT15 se A2 operation
Sketch of cct - told you it wasn't anything special!
Valves are 6SJ7 6Y6 PT15
Valves are 6SJ7 6Y6 PT15
- Thu Mar 02, 2023 4:53 pm
- Forum: Everyones Projects
- Topic: PT15 se A2 operation
- Replies: 4
- Views: 4661
Re: PT15 se A2 operation
Hello Mike It is a long time Tonbridge I think.....Danbury was a loss, still have transformers working! I'll do a sketch (sorry no cgi here!) It's basically just the usual A2 format but using +ve drive to g1 + g2 strapped - works with most transmitter pentodes to varying degrees. Nothing new or spec...