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My class E xmtr




 
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Author Topic: My class E xmtr  (Read 9951 times)
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w1vtp
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« on: March 01, 2016, 06:04:56 PM »

Here's my 8 FET xmtr.  Wayne, WA1SSJ built it.  It's a work of art.  Works perfectly

I'll put up the RF deck pics and then PWM / PS on the next post

Al


* CLASS E AMPLIFIER (2).jpg (564.26 KB, 2560x1920 - viewed 1209 times.)

* DSCN3050.JPG (549.34 KB, 2560x1920 - viewed 1107 times.)
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w1vtp
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« Reply #1 on: March 01, 2016, 06:30:58 PM »

Here's the PWM / PS  First pic is without the shelf installed showing the power supply section.  Then the top shelf with the PWM / control circuitry then the front panel

Check QRZ for the transmitter in place


* E PS.JPG (870.1 KB, 4928x3264 - viewed 1141 times.)

* DSCN3042.JPG (492.17 KB, 2560x1920 - viewed 1241 times.)

* DSCN3050.JPG (549.34 KB, 2560x1920 - viewed 964 times.)
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Patrick J. / KD5OEI
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« Reply #2 on: March 02, 2016, 09:27:53 PM »

That's pretty nice. A lot of professional looking boards in there.
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steve_qix
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« Reply #3 on: March 02, 2016, 10:41:43 PM »

The boards are from the "Class E PWM board set".

These three boards comprise the guts of a pulse width modulator.  The boards will work with transmitters from low power to a kW (carrier).

I make them available, including all of the parts that go on the boards (except for the modulator MOSFETs and damper diodes), to the ham community at my cost.  There are about 100 of these board sets in circulation.  Unfortunately, there aren't 100 class E transmitters on the air, but there are quite a few.

The boards make it a WHOLE lot simpler to build a pulse width modulator for class E RF amplifiers than trying to build all of that low level circuitry breadboard style.

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KD6VXI
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« Reply #4 on: March 03, 2016, 12:27:24 AM »

I'll second what Steve said.

I breadboarded my first pwm.   Pc Boards made up for my final rendition and those made it a LOT easier.   I have boards for audio proc,  assy control,  pwm,  AA filter and pwm filter.   Cut assembly time from a week plus (perfboard style)  to hours.

And looks a lot better.

--Shane
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n1ps
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« Reply #5 on: March 03, 2016, 08:13:51 PM »

The boards are a piece of the Class E puzzle....a nice piece using the QIX design, which is bulletproof.  As one can see from the nice posts by Al, building an E TX is a significant endeavor.   The mechanical aspects of an E build are really the biggest challenge.  Its not a coincidence that some of the more successful builds have been by guys with machinist talents like Wayne WA1SSJ and Bob K1KBW.  These guys and idiots like me are lucky to be in close proximity to Steve  Grin Grin Grin

I personally love E designs.  Super efficient, no high voltage and they have excellent audio.  The bad rap on solid state has historically been the lack of forgiveness.  But Steve has got that conquered too with a simple sensing PCB that senses over voltage and current, the former being the critical item.  But even then blowing up an 11n90 has not been a big deal as they are only a couple bucks each (I just bought some more C versions at $1.50 each). 

Back to the mechanical challenges, I think this is what gives most people pause when considering building one.  The place to start is the RF deck.  And the key there is the heatsink.  I found a heatsink and basically built the RF deck around it.  The other big part in the RF deck is the tuning cap....it takes a pretty big bread slicer OR a high voltage Vac variable.  In my case, armed with these key components, the rest was easy.

But my work is "ugly".  At least compared to Wayne and Bobs museum quality work. Shocked Shocked

The mod deck is where Steve's boards come in.  If not for the boards, the mod deck would be 10X the work of the RF deck.  It still is a lot of components and wiring, but made easier with the boards. 

The new SiC FETs offer a significant change in the RF deck mechanics with 1/4 the FETS required.  But they are still in R&D by several people.  They can be a game changer.  Time will tell....and I look forward to the telling!

~ps


BTW...Nice to have an E site again.  I wish we could get access to the original posts as there was a lot of great info there. 

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« Reply #6 on: March 03, 2016, 10:18:32 PM »

Quote
There are about 100 of these board sets in circulation.

Unfortunately, there aren't 100 class E transmitters on the air, but there are quite a few.

Guilty as charged. Shocked

I have two sets of boards I populated three years ago but boat anchor repair and rebuilds kinda put my ClassE on hold.

Phil - Ac0OB
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wa1knx
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« Reply #7 on: March 06, 2016, 04:06:16 AM »

Al, that transmitter is sweet!  Very nice layout of it all ta boot!

Deano
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