Revised schematic .....
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- Mon Feb 05, 2024 5:53 pm
- Forum: Everyones Projects
- Topic: Fg810 - A Working Title
- Replies: 43
- Views: 20288
- Mon Feb 05, 2024 5:49 pm
- Forum: Everyones Projects
- Topic: Fg810 - A Working Title
- Replies: 43
- Views: 20288
Re: Fg810 - A Working Title
Back onto the main event - I wasn't overly convinced by the double-diode temperature compensation for the bias, (read as, 'not good enough'), for example it would have helped if the diodes were closer to the heatsink end maybe? :oops: So I changed the design slightly, and opted for the adjustable te...
- Mon Feb 05, 2024 5:21 pm
- Forum: Everyones Projects
- Topic: Side Projects
- Replies: 108
- Views: 52155
Re: Side Projects
Had to recalibrate the Voltmeter. For the 10V scale this is done by adding a low value resistor in series. I don't know where I got the idea from that it should be 20 Ω. :oops: More like 100 Ω. Actually, it IS 100 Ω. That being done, the 50V scale was reset (twiddle preset), and readings are a lot m...
- Mon Feb 05, 2024 5:10 pm
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 9449
Re: 6550 SE Amplifier
That will be the the result of inselbildung, or the island effect, where the field from the grid gets to a large enough size to reach the cathode and crate "shadows" on the cathode reducing its effective size, so breaking away from the 3/2 law that normally governs triodes. http://livingi...
- Sun Feb 04, 2024 9:36 pm
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 9449
Re: 6550 SE Amplifier
Gotcha.Paul Barker wrote: ↑Sun Feb 04, 2024 3:56 pm No left, but Ive just realised its pinched up whin it transitions positive. So its a non issue as it wont need to go positive.
As you were .....
- Sun Feb 04, 2024 9:34 pm
- Forum: Assorted Stuff
- Topic: The Quackery Thread
- Replies: 360
- Views: 190492
Re: The Quackery Thread
Sounds like them. Some had like a lightning bolt symbol printed on, I remember.
- Sun Feb 04, 2024 9:33 pm
- Forum: Everyones Projects
- Topic: Pass Sony VFET Project
- Replies: 21
- Views: 3104
Re: Pass Sony VFET Project
Ta muchly. I was curious what the 6-legged thing is, now we know.
- Sun Feb 04, 2024 2:20 pm
- Forum: Assorted Stuff
- Topic: The Quackery Thread
- Replies: 360
- Views: 190492
Re: The Quackery Thread
Anyone remember the conductive straps you could hang from your car? Dangled down behind the rear wheels or something like that. It was a 'thing' quite a few years ago.
- Sun Feb 04, 2024 2:15 pm
- Forum: Jokes
- Topic: A little light humour
- Replies: 2698
- Views: 1174747
- Sun Feb 04, 2024 2:05 pm
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 9449
Re: 6550 SE Amplifier
I cant get my head round the way from -5 to 0 the grid line spacing is smaller. So introducing 2nd distortion which wont mitigate the high 2nd distortion of the 6550. Do you mean at the righthand end of the graph? This might be on purpose to reduce gain at large negative grid - ergo, AGC may be app...
- Sun Feb 04, 2024 1:49 pm
- Forum: Everyones Projects
- Topic: Pass Sony VFET Project
- Replies: 21
- Views: 3104
Re: Pass Sony VFET Project
Any chance of a schematic or is it copyright? Just curious.
Tried a Google but so many confusing variations or things with the same name, apparently!
Tried a Google but so many confusing variations or things with the same name, apparently!
- Sat Feb 03, 2024 9:27 pm
- Forum: Assorted Stuff
- Topic: The Quackery Thread
- Replies: 360
- Views: 190492
- Sat Feb 03, 2024 9:25 pm
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 9449
Re: 6550 SE Amplifier
You might have misunderstood me - it's not the cascode operation aspect that's the possible issue, it's that ECC88 is a radio valve and may want to ocillate at RF. To be honest I've never used it for audio, as I can remember, but I have for radio.
- Fri Feb 02, 2024 12:40 am
- Forum: Everyones Projects
- Topic: 6550 SE Amplifier
- Replies: 110
- Views: 9449
Re: 6550 SE Amplifier
In case you weren't already aware - "The ECC88 is a VHF double triode with separate cathodes. The ECC88 was designed for service as a cascode amplifier in the front ends of VHF radio receivers. One triode acted as the local oscillator and the other as the mixer (frequency changer)." - (The...
- Tue Jan 30, 2024 8:29 pm
- Forum: Valves
- Topic: Valve amplifier service
- Replies: 176
- Views: 84963
Re: Valve amplifier service
Well, there you go. (Weren't the words I actually used...)