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GeordieBoy

Wed Nov 11 2009, 02:23PM

Registered Member #1232 Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881

Looks good! How many BPS?

Fabio

Wed Nov 11 2009, 05:27PM

Registered Member #122 Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148

Looks good! How many BPS?

So far 100 BPS (230Vac, 50Hz, 3000RPM, two pole motor with two electrodes), but i have made another two blank holes so i can test even the 200BPS operation, this gap is not intended to be used with this coil but with a future bigger coil instead.

anyhow, this is a "Post Your Cool Pic Here!" so i imediately post some other pics.......
.....an 1200CÂ° electric furnace isn't exactly "cool"......... but who cares???

i bought it few months ago for 8 euros, this pic is relative to his first test, before the massive cleanup

another "HOT" items...... an old smoke detector containing 72 microcuries of Americium 241 (!!!!)

Ciao!
Fabio

Hazmatt_(The Underdog)

Sat Nov 14 2009, 03:59AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

FRIDAY the 13th Milestone for Turkey9

BROKE 100W Barrier at 200KHz with improved phase splitter amp, driving output pair in Class B at 100V.

I've been playing with a single pair as a 20W amp in Class A and I was going to use it to drive the phase splitting matching torid that I have setup as a distribution box, but I decided to do a quick setup and make a step-up driver so I could study I/O power gain, and it looks like that has really paid off here.

The first box is the small phase splitter with output maybe .75W max, so I had output power limitations due to finite gain. I could see the need for boosting that signal, so I lashed together the push pull booster that cranks that signal to 4.5W. That seemed to be a good answer to my power problem.

The final stage is just 2 high current transistors at 100V supply Crankin' into a 70W core. It's class B with switching distortion, but this is the next step to 400W, and an amp to drool over. Next is to check out if it will handle 500KHz. I know there are some people here who would really like to have an amp for their research. And I could really use the money because I'm laid off... so we'll see how things go, and maybe I'll be in the Amp business soon ^^. 200W is around the corner!

aonomus

Sat Nov 14 2009, 04:30AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

I see you finally got your meter fixed hazmatt, darn USPS...

Hazmatt_(The Underdog)

Sat Nov 14 2009, 04:44AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Yea, they really do suck! It was really important to have this one work so I could validate low AND high power, but it works now and is doing a good job for me.

Here's a pic. of the amp driving a coupling loop to fire the coil. Had to shut down because the corona was tracking on the PVC and causing it to burn. This is the largest and most cumbersom flyback ever invented! hehe. Now my room smells of PVC and ozone, which I mind less then burnt expensive transistors! The little white star is where it started burning.

Steve Conner

Sat Nov 14 2009, 11:46AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Nice work Matt! \o/

Have you tried adding a little bias voltage to bias your final transistors into Class-AB? I bet the crossover notches would go away and the waveform would look just about perfect.

Hazmatt_(The Underdog)

Sat Nov 14 2009, 06:21PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Yea, I'm looking into that. I will have to sacrifice some power with gain leveling circuitry, and I need thermal tracking for the finals, which also means active bias.

The 5W booster amp needs some work too, the outputs were not amplitude symmetrical, but were good enough for testing.

I really want to get a 200W module going, and get the artwork setup for a really sweet board. If I can do that, then I can go into a small production run and hopefully make some money.

Hon1nbo

Sun Nov 15 2009, 02:36AM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

Some goodies I picked up at the Hamfest in Azle today (more than this, but I figure I'll post before and after pics of those when I restore/"modify" them)

The top image is an overview of the three items. The first is an Adjustable Vacuum Spark Gap, with the Vacuum still intact (even if it weren't, I could easily re-evacuate it). The second item is a 872-A Vacuum Tube Rectifier rated at 10,000 Volts max - I plan to use it with a neon sign transformer, a capacitor, and more of the tubes (the vendor only had one left, but he says he will get more soon) to make a CW DC supply - very simple, but should be effective as a starter High voltage tube project.
The third device is a High Voltage Probe I got from the same vendor as the spark gap.

Myke

Sun Nov 15 2009, 03:19AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Very nice tubes

I have an 872A also but it doesn't look as clean because it's been used. Be careful with the UV output from it (mercury generates some pretty short wavelengths of light).

Hon1nbo

Sun Nov 15 2009, 03:33AM

Registered Member #902 Joined: Sun Jul 15 2007, 08:17PM
Location: Pacific Northwest USA
Posts: 1042

Myke wrote ...

Very nice tubes

I have an 872A also but it doesn't look as clean because it's been used. Be careful with the UV output from it (mercury generates some pretty short wavelengths of light).

I plan to put some kind of UV protective shield around the tubes, as such a device I plan to have run for long periods of time and I might have to monitor it while I do.

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