200 Watt Class E Transmitter kit from K7DYY

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200 Watt Class E Transmitter kit from K7DYY

Postby KC3OL » Fri Nov 25, 2005 11:36 am

I would be interested in any comments about this transmitter. The link to his site is http://www.w7jhs.com/wst_page10.html
The transmitter is 5 x 5 x 7.5 inches and only weighs 2.5 pounds. It uses pulse width modulation.

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Postby frank carcia » Fri Nov 25, 2005 11:34 pm

It is interesting to see this design claiming 200 watts from a single fet.
Both Steve and I found 50 watts carrier per fet is about right. More than that and the RDS on hurts efficiency. Also single ended design will have higher harmonics. I does look nice but 800 watts peak sounds like the fet will be begging for mercey.
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K7 Class E TX

Postby flintstone mop » Sun Dec 11, 2005 1:45 pm

Hi guys,
I am a newbie to Class E and was disappointed to read the comment about the 200 watt Tx that is offered from K7DYY. I do not have a Junque box for a solid state project like this or even something bigger. I commend someone like K7DYY, Bruce to make something availabe for someone like me, who doesn't have the funds or ambition to search down all of the components needed for a little more juice (RF power), so that one device is not pleading for mercy.
Is anyone out there offering a "kit" with a little more guts and headroom for the devices used? I can understand why he has a fan on that heat sink!!!
Fred MOP radio
It's difficult to switch my equipment to SSB, for some reason
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Postby KC3OL » Sun Dec 11, 2005 2:23 pm

Here is another link with info about the K7DYY transmitter:
http://hightechham.com/

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200 Watt

Postby flintstone mop » Sun Dec 11, 2005 3:38 pm

Thanks Ted
for the link, but that's where I found the 200 watt Tx and my comments here previously were asking if there is anything else available out there???
More "kits" with a little more power and/ or headroom, instead of one device screaming for 'mercy' :shock:


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Postby frank carcia » Mon Dec 12, 2005 8:07 am

I rate that transmitter at 50 watts carrier 200 watts peak.
I heard a guy on the air over the weekend who blew one up. I think he has S/N 001. 1 FET in the final 50 watts carrier. A number of us have proven that is the best way to have long life.
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200Watts ??

Postby flintstone mop » Mon Dec 12, 2005 10:49 am

THanks for the reply,
I think with your comment I'll wait on some other way to build a kit type Class E Tx that's a little more conservative than the one from K7DYY.
I think the person who owns SN - 001 was W8ER. He mentions on his web page that he had that serial number. http://WWW.W8ER.com, Larry. And a link to e-mail or order these transmitters.
I'll stay tuned to the Class E forum for any developments. Maybe some dude will sell a built high power Class E on E-Pay!! (hi)
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Postby frank carcia » Mon Dec 12, 2005 12:15 pm

Fred,
I think it is a cool kit just needs more FETs in the final. Steve and I came to the same conclusion.
Yes, I think it was Larry. He said he had it sitting on the bench pumping out 200 watts. It blew when he modulated it.
These parts need to be derated when used at RF.
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Postby frank carcia » Mon Dec 12, 2005 12:16 pm

Fred,
Go to ARRL / QEX and down load the sample article for November. fc
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Good Job

Postby N9NEO » Mon Dec 12, 2005 5:18 pm

A very nice compact design. If carrier has to be derated a tad to increase reliability then that is ok, no big deal, only a few db on S meter. I have had very good reports on just 50w carrier. Good to see people putting in effort to make mosfet technology available to more people. It is a difficult job to put it all together and I'm sure a lot of work went into the project. I would ask why not buy the kit and wind it up to 50w of carrier if that gives you a reliable signal.


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K7DYY

Postby flintstone mop » Wed Dec 14, 2005 10:28 am

Hello all,
Larry W8ER claims his K7DYY mosfet Tx is running FB with a slightly warm heat sink at 200 watts carrier and close to 800 Watts PEP. A lot of dummy load testing claimed and no problems. The designer is using a different device, "Advanced Technology type ARF-460" which he claims has more dissapation.
I ordered the 80M version. Bruce says he is designing a heavier design, more mosfets and higher power. THat will be the one I buy for 160M.
G'day

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Postby frank carcia » Wed Dec 14, 2005 10:35 am

well that is a horse of a different color. APT part is an RF FET rated for that power and frequency.
I heard Larry say he blew his up and returned it for repair. This was over last weekend.
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Postby WD8BIL » Thu Dec 15, 2005 7:53 am

Hi Frank, et al....

The first problem Larry had was the 12VDC regulator was dropping out of regulation on moderate modulation peaks.
Turned out to be the load resistor on the reference diode. He sounded real gud last nite.

It did not "blow-up" !!

Hell, we use the Fairchild FETS in our supplies here at Emerson. A pair runs the bank regulator in our 2900 watt recitfiers. They get warm but then again, this is business !! Make'em sing for their supper !!!!
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Postby frank carcia » Thu Dec 15, 2005 8:30 am

I heard Larry last night and he sounded great.!
They are using an rF fet to get higher power. Looks like a nice design.
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Postby WD8BIL » Thu Dec 15, 2005 9:29 am

A pair should make a nice "near legal limit" little box !!
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