700 Watt 810 Triode Vacuum Tube Audio Amplifier Completion & Testing
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- Опубліковано 16 вер 2024
- This is a pretty loose collection of videos made quickly during the testing of the 810 amplifier. There are still improvements to be made in the way of cosmetics but it actually worked with only one simple wiring error. It was a marathon to get it completed in two days but if the plate is driven to 500 mA will provide more than 700 watts into 4 or 8 ohms. Sorry for the out of tune toy guitar we used to test it. :-)
I've seen a machine that looks like your amp. It also had two 810's behind a screen. It was a wood welder. Made in the USA. It fully cured wood glue using RF in a couple of seconds.
OMG! That took me back looking at those old stencils. I started out the same way but in the late 1970s. I was an early PC based CAD adopter about 1985 and never looked back.
A pink pearl eraser. I like those and the Staedtler Mars-plastic. I have my pencil pointers. The are wonderful!
The eraser shield and the mechanical pencil sharper bring back memories of my industrial design drafting courses back in the 70's. Does anyone still use Vellum? Thanks for the memories! 👍
Vellum gave way to Mylar in the late 70’s. Followed shortly by plotters printing on either paper or Mylar in the 80’s. When I first learned drafting in the ‘60’s I used ink on waxed linen.
I took mech. drawing in high school. Loved it. Played with Cadkey 6 for DOS and ACAD 10? 12? for DOS. Heady times! Could run it on an old 386 with 2 megs. memory. Wish I'd save that old PC just for the fun of it.
Could not stop watching.
I was sure there was about to be a giant puff of smoke.
Actually, a gigantic... Bang ... when the HV arcs and blows pieces of the fuse-resistor all over the room and scares everyone out of their wits. Amazingly, it turned out great and not even one blown fuse... It performed extremely well delivering over 700 watts when the drive power was raised and plate current went just over 500mA at 2200 volts and an efficiency of about 64%. I may have to build another one. :-)
Your real world demonstrations help greatly. Keep it up.
OUI!!! Handling the 100 ohm power resistor with the AC line still connected!!!!!
Also, worried me with all your meters on the wall above the 810's! I hope the meters are secure and will not fall! POP the tubes!
This is like having a window looking into the Mad Scientists Lab..............I love this stuff...........
I Love Your Enthusiasm, Good Idea to have a sacrificial guitar player to test with.
You got balls to make a amp like this. I say it maybe again for you be very carefull you won't survive a 2800Vdc.
I admire your work, my father made amps for his radio in the 80ties
2,5 K watts at 10Meter band he made a savety build in in case of electrocution. When switched on the lights went a little flickering hahaha
Just watching that video caused me an adrenalin rush. No joke. Maybe I am a bit jumpy because I just recently managed to blow one 10A fuse with a shorted 230VAC and that bang was loud enough. I cannot imagine how loud a bang that 2.5 kV+ would cause. I hope there won't be one. 🤞
It is cool what you can do with transformers. I've used extra windings on the second run in series with the primary to buck that voltage on the secondary windings being used. Mainly to lower the HV . Also, I came across a 20 watt decade box a while back. Comes in handy. I like drawing schematics by hand also and have some templates. Never seen the drawing pencil sharpener. Cool!
That's some heat! Enjoyed watching.
Great work it’s coming out beautiful
It's very nerve racking powering something like that up for the first time. Normal I have it connected to my current limiter, but kinda hard to do that with such high wattage.
Using resistance in the primary is by far the best, but in situations like mine (where the power line voltage constantly changes), it would probably be better to offer resistance in the secondary. Jim WA5WRE
Nice warmers
The filaments sure came up fast!
Virtually no warm up time on the high power tubes. Kind of like solid state from the 1930's... :-)
Yeah you need a camera operator, a dolly driver, boom operator, maybe some tracks, and of course a lighting director.
I was wondering if you could make like the ceiling fan speed controllers and use a capacitor instead of a resistor in series with the primary. 137uf gives 20R at 60Hz. Then you wouldn't have to worry about dissipation. Current probably an issue though, and rating.
Great show.
EJP
Years ago I built a bunch of SCR voltage controller sand they work great into steady loads like a light bulb but I think I tried one into something like this and it did not work very well. I remember looking at the voltage across the load and it had some pretty sharp voltage waveforms where the SCR turns on so I suspect it could have a good bit of noise in it. Nothing like a huge Variac to control voltage. Anytime I need bias voltage that will have to supply grid current, I tend to go overboard in the size just to keep the bias stable. Now that you have me thinking about it, I may have Tommy add a bleeder resistor to the bias supply to stabilize it a bit more.
Good morning, I am in a project with 813, it is difficult for me to find the output transformers, which you recommend, I want to make them based on triodes, two modules with only one 813 each. Thank you and your channel is very interesting, I always see you.
Within %2 of the rated voltage! Great!
Wow, its crazy!
Very nice! What was the voltage and current going into the 8 ohm dummy load @ 600+ watts?
At 29:28 I can see the volt meter at 72.28 volts across the 8 ohms which comes out to be 653 watts on the meter. Current would be 9 amps... the resistors drop in resistance as they get hot so we are probably working into something less than 8 ohms and actual power is over 700 watts.
Can you try making pp Amp with GU81?
I have never had any GU81 tubes. looks about the size of the 833A but it is a pentode. If I ever get any, I will give it a shot.
Thanks for your comments.
A bit of the bubbly?
We figured it was worthy of a little celebration afterwards - but not too much... we still had work to do.
Do u build and sale amps
Shame you it cost you some tubes, though. 😞
These tubes are probably from the 1940's and one of them just happened to be bad. We tested another six out of twelve that I have and they worked OK. Even the Chinese 810's worked OK.