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Author Topic: My Super-JS 300 watt carrier output 40 meter rig - Clip leads abound!  (Read 1640 times)
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steve_qix
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« on: December 29, 2023, 06:13:18 PM »
I have been hearing that 40 meters has been good, so I got a 40 meter transmitter on the air.  This RF amplifier is actually a prototype of a 6.78 mHz ISM band transmitter that I designed for a client.

This setup puts out 300 watts carrier when running 45V @ 7.5A.  The rig is VERY efficient.

This design uses 4 FQA11N90 MOSFETs, and each MOSFET has its own driver IC (IXDD614).

40 was REALLY good today - lots of activity, and strong signals.  We were mostly on 7280.

* 40_meter_class_e.jpg (327.24 KB, 675x900 - viewed 133 times.)
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w9jsw
Two shots of Whisky
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« Reply #1 on: December 30, 2023, 08:30:24 AM »
Can you describe the schematic vs your posted 400W 80M example.

http://www.classeradio.com/8_fet.htm

My guess is it is almost identical except dropping 4 of the mosfets to get a 1:1 driver to mosfet ratio? Anything else change?

How agile is the design. Can the output be re-tuned to 80M or will that require some switching/relays to change key component values?

Can this be built with readily available mosfets - say 16n50s or FQA13N80-F109?
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wa1sth
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« Reply #2 on: January 02, 2024, 08:00:39 PM »
Now that is an inspiring piece of work. VERY colorful...Hope your pies look better
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WA2SQQ
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« Reply #3 on: January 03, 2024, 11:02:37 AM »
My guess is if he meeting things up, it probably would not work as well. It demonstrates the magic of all those clip leads!
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Patrick J. / KD5OEI
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« Reply #4 on: January 05, 2024, 01:28:16 AM »
Showed that JS picture to a 'radio buff' friend of mine and he lost his mind!

me: Check out this 1000 watt ham radio transmitter!

he: I don't see it. Yoiu sent a picture of parts on a desk.

me: That's the transmitter.

he: Naw, I know better than that. What are you trying to pull, man??!??

THIS is one reason I love electronics.

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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #5 on: January 05, 2024, 10:03:53 AM »
I don't know if he was using this particular lash up when I talked to him on 40M yesterday, but it certainly put the sloppbucketeers at bay while he was transmitting. It definitely cut a nice hole in the aether!
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Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
steve_qix
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« Reply #6 on: January 06, 2024, 01:35:30 AM »
Yes, that is the transmitter I was using :-)  It is the only 40 Meter transmitter I have (well, I could put the Flex 5000 on the air, and run it into an SB-200 linear I have), but I haven't done that....

That little JS rig really works very well.  It is AMAZINGLY efficient, and puts out a lot of power for 4 MOSFETs (315 watts carrier).
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« Reply #7 on: January 06, 2024, 10:11:21 AM »
Excellent Steve! Please have a safe trip down here to NEPA. Us along with State College is supposed to get dumped on!
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Mike(y)/W3SLK
Invisible airwaves crackle with life, bright antenna bristle with the energy. Emotional feedback, on timeless wavelength, bearing a gift beyond lights, almost free.... Spirit of Radio/Rush
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