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Linas

Fri Oct 03 2008, 05:05PM

Registered Member #1143 Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721

here is my new project, large DRSSTC, for it i have 600V 400A ultrafast igbt (4 times greater than CM300 ) so here is my new power supply for IGBT driving (+15 0 -15V )*3

Hazmatt_(The Underdog)

Mon Oct 06 2008, 06:17AM

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

I'm trying to get my test set going so I can do more transmission line analysis, but the thing is the rack mounting stuff is so expensive I have to go cheap for now. I got the handles for the synth and the adapters for the analyzer ( $270 and that was with a savings mind you! @.@ )
But I'll need another $80/unit for the rack rails, and probably another $400 for the rack box, man why does this stuff have to be so expensive!
I would probably modify the cart I have here if it could handle the extra weight, but I doubt it could, the analyzer wieghs 120lbs by itself.

I'm trying to get it to talk to the GPIB interface here, which I dunno if its being totally successful. I have some doubts as to the worthiness of the card in the analyzer, but I'll play more with the plotting tool and hopefully get somewhere.

Steve Conner

Mon Oct 06 2008, 09:41AM

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

Did you buy that thing Hazmatt O___o

WaveRider

Mon Oct 06 2008, 06:03PM

Registered Member #29 Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500

Wow Hazmatt. I am impressed.. You are getting seriously into the RF world.. Bravo!!!! Be careful not to burn out the front end of that spec. an. (invest in a collection of attenuators and always keep one connected to the input.)

With your wide-band op amps: be careful to terminate them so that they see a good resistive load on thier inputs and outputs and be very careful to keep all connections _short_!

Also...good luck with the GPIB. It can be a headache, altho' it can be done using a parallel port and some clever software... It's pretty much been superceded in modern instruments with built in network and USB capability.

Drop me a line if you want to talk RF amps!

Hazmatt_(The Underdog)

Mon Oct 06 2008, 06:23PM

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

Yea that is a good point, I'll have to get some attenuators soon! I could really use some dust boots too but I don't think I should snag those from work, I'll have to ask.

The real GPIB problem I'm having right now is communication errors. I have to play with it more because I don't know if the instrument's GPIB card is really operating properly. Also the older SA's don't support a lot of the GPIB commands so its going to be more difficult to talk to it. I need to sit down with the manual and read some things over. I hope to get some comm. confirmation soon, right now I get some funky noise floor plots, so I may have to dump the window into memory somehow first then send the plot request, dunno yet, I have to figure that out.

Steve, you could get a 494 for about $3K, stuff really isn't all that expensive now. The SA cost $1800 and the synth cost $600, so its really not that bad now. Of course ... concerning the credit card I'm kinda done for a long time which is a problem because I could really use a new DSO.. heh. (2430A is kinda flaky right now).

But yes I'm really serious about RF, really really serious. See:

What I really want right now is to build some lab amps for myself and the forum so they have test bench equipment.

When I started out with electronics I was always thinking "how can I build that myself for a fraction of the cost", and the end goal was always to have a piece of test equipment for the bench that I could use again. Stuff like small ammeters, or a little RF volt meter, or freq. counter. A lot of times I just didn't have the time to really build the project so I bought the majority of my stuff. Some was even donated if it could help me get closer to answering my questions.

After some of my goals are met right now, one of my future goals is a counter/meter (a frequency counter and RF volt meter in one little package). I would like the meter to be autoranging, but we'll have to see.

Anyway, when its all said and done, I am very serious about questions and answers, I invest heavily in finding out what something really is, but you know it kinda pays off because I learn something from it, and then I try to post as much as possible here so others can learn too (if they can understand what im talking about.. not always the case.. but I try to make it understandable).

RF Amps! hell yea.. I'm all for that, I just need to get that sine wave current booster finished and post all that for the time being.

Dr. Drone

Tue Oct 07 2008, 04:07AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

aonomus

Tue Oct 07 2008, 04:41AM

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

Wow Dr. Spark, what are the specs on that battery bank/inverter setup? What do you use to charge the bank?

Dr. Drone

Tue Oct 07 2008, 05:02AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Steve Conner

Tue Oct 07 2008, 09:35AM

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

Wow, yup you're definitely "committed" to RF :D

I never bought a spectrum analyzer, since I figure I always have access to one through my work.

For an RF "power amp" I just bought an old HF ham transceiver off Ebay and modified it for general coverage transmit. It gives 100W anywhere from 1.8 to 30MHz, and using a ham antenna tuner, that RF power can be forced into all sorts of places that it was never intended to go

You might want to study the broadband PAs used in these transceivers, they typically use two BJTs like the 66 dollar one you have there.

Backyard Skunkworks

Tue Oct 07 2008, 09:59PM

Registered Member #1262 Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451

New coilgun carbine body. I'll be filling it with around 400J of flashcaps and hopefully getting over 10J ballistic.

Edit: Hosted with imageshack, my new 110mb account seems to be down ATM.

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