New Class E transmitter

[AB2EZ]

I've been thinking about some of the new Class E rigs that have appeared in the AM window here in the Northeast... and how pathetically my 4-FET, 75 meter Class E transmitter "stacks up" against those newer, "headroom enhanced", rigs..

So, I am going to build a new rig over the next several months. Suggestions with respect to the electrical and physical design are, of course, welcome.

I have an existing double hung window in my radio room, facing north. I'm going to remove the existing 32" x 28" (window area) sashes; and I am going to replace them with a pair of custom made sashes... each of which will contain a 32" x 28" heat sink. [Cooling fins facing outside and flat surface facing into the shack].

The top heat sink/sash will contain the FETs (and associated components) for the RF deck, and the bottom heat sink/sash will contain the FETs (and associated components) for the modulator.

I'm 5'4" tall, but I will be able to work on the RF deck by simply sliding up the modulator deck and pulling down the RF deck.

With 896 square inches of surface on each of the two heat sinks. I can allocate approximately 2" x 2" per FET, and still easily accommodate as many as 160 FETs on each deck (plus room for other components)

I'm placing an order for an additional 240 volt 200 Amp service drop, so I'll have 48KVA that will be dedicated to this rig.

In the winter, cooling the heat sinks will be no problem. In the summer, I'm going to use a copper tubing heat exchanger to circulate cooling water, from my neighbor's pond, through the heat sinks.

The RF deck will employ 4" x 8"  plug-in modules, each containing 8 FETs (2 balanced quads). There will be up to 4 modules in a "row" and up to 5 rows (sort of like the "header" of an IPv4 datagram) ... for a total of 20 modules.

I'm looking forward to getting this new rig on the air!

Stu

[WA1GFZ]

Stu, How do you plan to combine all the modules?
How about heating the house in the winter?

[AB2EZ]

Frank

Thanks for asking...

I plan to use diode-switched, phased-flipped, coherent 2 x 1 combiners (see attachment)... so each combiner will introduce 3dB of loss in the path from either input to the output.

That way I will be able to stay within legal limit, while still having the biggest Class E-transmitter in the AM window.

The losses associated with the combiners will provide sufficient heating... so that the excess heat can be directed into the plenum in the winter; or taken away by the external water cooling system in the summer.

Best regards
Stu

[KF1Z]

Is the legal limit important in the window?

or

OUT the window in your case.

[AB2EZ]

I can't speak to that without first checking with my lawyer

Stu

[WA1GFZ]

It should probuce perfect audio quality with that level of inverse feedback

[Superhet66]

Please photo document well, this should be fun.

The EPA will request an aquatic thermal impact study in triplicate....

                                                           Think big.
                                                                          D.

[WBear2GCR]

Stu obviously has his tongue in his cheek, or something else somewhere else...?? 

I think he is making an "observational statement" of some sort...

Or maybe he has "rig envy"?? 

                    _-_-bear

[Superhet66]

A dummy load / hydronic base board heater hybrid will earn a tax break under the new green initiative also. With some tuning I think you might reach an "over unity" state and be able to sell excess juice back to the grid.  

[KF1Z]

With some tuning I think you might reach an "over unity" state and be able to sell excess juice back to the marconi net  

[Ed/KB1HYS]

Hmmm,  I don't know why, but I had an image of mounting the heat sink in a "George Forman" type grill enclosure...  great for summer use.

[Superhet66]

Hmmm,  I don't know why, but I had an image of mounting the heat sink in a "George Forman" type grill enclosure...  great for summer use.

Tasty, low fat strapping.....

With some tuning I think you might reach an "over unity" state and be able to sell excess juice back to the marconi net 

The "Over unity" "Zero point" zombies drive me nuts.....
Youtube is the over unity ground zero.....

[W1ATR]

Sweet. If you want to use it in the summer time, perhaps I can help you by spec'ing out a nice small 50 ton (600,000Btu or 150kW) hybrid absorption chiller utilizing a plate system to pump the water around all those fets. Its a win-win, because if there's any headroom left in the leaving water temp, then we can use a nice water to air exchanger to cool some nitrogen gas and pump that down your 4" Andrew spiral core coax going out to the array.

Piece of cake.

[WA1GFZ]

Gee then Stu could do copper tubing antenna elements and send the cold nitrogen down them  for minimum resistance. The only problem is when the birds freeze their little piggies to the wire whenever the rig is in TX.

[Jim KF2SY]

"Shurely you can't be serious...."

[Ed/KB1HYS]

"I'm Dead serious... and don't call me Shirley".