The latest from Clip Lead Alley !

[WA4JK]

Hummmm I wonder if a isolation transformer can be shoe horned into the box... Well if I could figure out how to reduct the size of a Class E into one box, I'd just try that.

[steve_qix]

Hummmm I wonder if a isolation transformer can be shoe horned into the box... Well if I could figure out how to reduct the size of a Class E into one box, I'd just try that.

Yes, it's been done a number of times     The goal of this project is to do a compact, one box transmitter.  I did it with the 500 watt "class E ranger" transmitter - and that included EVERYTHING, power supply, VFO, etc!

[WA4JK]

Steve you would not have a pic of the insides of such a beast to share would you. If I can find a case the size of a ranger and the big parts I know where I can get the boards and small components. By the way I'm real corfused on wether to use H moders or PWM for 350W and above.

[steve_qix]

Steve you would not have a pic of the insides of such a beast to share would you. If I can find a case the size of a ranger and the big parts I know where I can get the boards and small components. By the way I'm real corfused on wether to use H moders or PWM for 350W and above.

There are a couple of ways to go.   For the ultimate compact transmitter, I used PWM (and still do).  It is MUCH smaller if you use the correct design.  I have a complete power supply - modulator 450 watts modulated DC that fits in a 7 inch high, 7 inch deep 19 inch space.  That's the complete modulator-power supply.  No power transformer.  This one uses a direct line rectification (and it is isolated using pulse transformers) design.  This is what was done with the class E ranger.  There was no space for a power transformer!

If you have a little extra space, you can add a power transformer and use a much simpler PWM design.  This modulator is well documented on the class E web site and has been reproduced a number of times.  Also talk with Bruce KF1Z, as he has built a number of PWM class E transmitters.

For class H, you will need CONSIDERABLY more heat sink area, and a much larger power supply - both with respect to the transformer(s) and the filter capacitors.  For power levels around 300 to 400 watts, class H generally takes up about twice as much space, and weighs more than twice as much as similar power pulse width modulators.  At higher power levels, class H gets even larger because the power supply requirements become quite large, and everything else grows as well.

Hope this helps 

Regards,

Steve

[KF1Z]

For 250-300 watts and up, use PWM...

Class H requires a larger heatsink, larger power supply (much more "stout")

PWM much more efficient.

They both preform equally well, but PWM wins out at high power for ease of construction etc...


Well, I see Steve has chimed in while I'm typing this.....

My PWM is in a 3RU (5" high)   12" deep , 17" wide (inside space)  box.
That's power supply and all. WITH a transformer  
It's good for approx 320 watts out to the RF deck.. Limited by my too-small toroid power transformer,,, could be 400-450 with a bigger one in there...


With Steve's new "Easy-H", The modulator/power supply, AND a class-E RF output stage for about 120-200 watts will EASILY fit in a  box the same size as my modulator alone.
Though maybe needs to be a 4RU box, just due to the heatsink mounted board's "circumference" with devices installed, and the height of the inexpensive power transformer that Steve has made available....

Haven't actually built one YET, because I don't have a board    

[WA4JK]

So as I digest this I should for a 300-400w class E plan on the PWM moder and possibly plan on using a transformer. That would put the moder powersupply and all components in a single box. From that point I would then have to build the powersupply and rf deck into the same box. That puts both powersupplies into the same box. Would I need to shield the RF side from the moder side? Starting to look like maybe a VKII size box to do this.

[WA4JK]

What is a good source for the box? Thanks

[KF1Z]

There is only one "large" power supply, and then a couple low-voltage supplies.
(think of the modulator as a modulated power supply)

Yes, you will need a transformer, but a toroid doesn't take up too much room (3" tall, 6" diameter MAX)

Yes, a shield between the RF side, and the modulator side will be needed.

[KF1Z]

What is a good source for the box? Thanks

Try here..... lots of options... cheapest I've found..

http://par-metal.com/

[WA4JK]

I bet a VKII case with a new front panel painted Johnson Purple would look kewl with the metering VFO and flashie lights on the front and I bet it would fit as well. Just have to find some metal to make a front panel and cover the bottom of a carcus. Cut the back out for the heat plate and heat sink. Hummm I'm going hunting.

Might become the VKIV. I have never worked with solid state and my layout ability has alot to be desired. We'll see