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Mads Barnkob

Mon Sept 22 2008, 07:06PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Thats a nice brick!

Here is some parts from a 50-60 year old b/w television set i got from a friend, I only recieved the frame with the electronics on. It was in a non-working condition, so took it apart to be able to bring it home on my bike.

The coolest thing about the components are the danish made capacitors, resistors and switches. Only tubes and a few other things are from mostly Germany :)

Abit of a related question, will I be able to drive a PL36 tube at 1.5MHz? I cant find any values in its datasheet except its a line output tube for televisions.

datasheet:

Hazmatt_(The Underdog)

Tue Sept 23 2008, 07:45AM

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

I finally got my 100MHz Op Amps for the DC - 10MHz preamp ( for driving these power amps ) YAY! so Im happy. They are LM6181IN amps.

The amp to the right is a class B amp that I was playing with for initial testing purposes and I think it will push 20W, I have yet to really characterize it but I will do that after full integration with the preamp.

The amp to the left is my power brick, and I do mean power brick! It has 6 200W Motorola power transistors capable of 20MHz operation and I want to get these guys really pushing the power hard. I was trying to get it going with a CCS and all that stuff ( with some 30MHz transistors ) but I ran into bandwidth problems above 1MHz. Emitter degeneration and compensation are haunting me!

I'll just have to see how many stages it takes me to get 100W out at up to 5MHz. I know some of you guys would laugh at this "audio amp" approach, but I seriously can't get this thing's gain stable from DC to 10MHz with a class AB setup. What I've tried on the brick would be awsome as an audio amp with the CCS and all, but it really won't work above the 1MHz range. So I'm just going to try some more class B configurations and see where I end up. If all else fails I'll buy some real RF parts and go from there. This is my first real RF amp after all.

Steve Conner

Tue Sept 23 2008, 11:25AM

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

wrote ...
I seriously can't get this thing's gain stable from DC to 10MHz

I'm not surprised, I think you are crazy for even trying

If you want power at 10MHz from cheap plastic-packaged thingies, you need to follow the kinds of approaches that these guys use:

BTW, nice brick c4r0! I bet somewhere in Poland there is a train driver wondering why his electric train won't start this morning

Dr. Dark Current

Tue Sept 23 2008, 01:28PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

The first time holding a minibrick in my hand

1222176508 152 FT6000 Flameeffecttransistor

Hazmatt_(The Underdog)

Tue Sept 23 2008, 06:16PM

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

I'm still buying books on RF amps and I haven't gotten the book on switchmode RF amps just yet, but the main goal of this amp (and I don't know if the switchmode one will do this ) is to preserve the waveform. I have a GR tube amp here capable of ~15W of power but it still needs work. The original design assumes that the phase splitter output is balanced and its not even close, so I'm having to redesign the front end.
Other then that, I have a few more books to buy, and probably a bunch of MRF parts.
I know the preamp will go to 10MHz so that's a start, I just don't know where the power amp will crap out at yet.

aonomus

Wed Sept 24 2008, 01:55AM

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

Oh Hai There.

Halfbridge Complete (Sans Caps)

Team Fortress 2 Buttons of awesome.

Dragon64

Thu Sept 25 2008, 01:34AM

Registered Member #1438 Joined: Sat Apr 12 2008, 12:57AM
Location: Canada
Posts: 218

Damn, I want the companion cube button x_X.

Fabio

Sat Sept 27 2008, 11:05PM

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

The tube is huge and weight more than 30kg, unfortunately, the BIG tube can be used only as giant paperweight because the filaments are broken! :-/

Typical coiler's dress!

Arcstarter

Sun Sept 28 2008, 12:49AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Ike was a a real pain in the ass...

Parents bedroom ceiling collapsed.

One of the two bathrooms:

parents bedroom's closet has alot of mold at the top:

And bottom:

We are going to have 75% of our walls torn out in the house because they are all wet.

aonomus

Sun Sept 28 2008, 03:56AM

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

Ouch. Hope you guys can recover from that Arcstarter....

On another note, now would be the *perfect* time to get that 30-60A 240V service installed to whereever you do all your HV stuff.

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