[CQ-Contest] Sell My Acom for a Tokyo?
Dick Frey - K4XU
k4xu at arrl.net
Thu Mar 26 22:53:34 PDT 2009
The largest Tokyo Hy-Power amp at 1500W output, uses two ARF1500s in
push-pull at 100V. These are very large 500V MOSFETs, easily capable of
750W output. I quite am familiar with the devices in amp and its PA
circuit. In case you're wondering, they cost $226 each in small quantity.
These MOSFETs were designed for the industrial semiconductor capital
equipment market where 13.56 and 27.12 MHz RF plasma is used for
various operations in the manufacture of transistors, IC's, LCD panels
and solar cells. The user's tolerance for failure in this market is nil.
There are many millions of device-hours on these parts without any
Due to the ballasting of the individual MOSFET die inside the package,
the linearity of these parts just happens to be spectacular. Check out
patent 6,939,743 to see what's inside. They are close to being a solid
state version of a 3CX800. You can see a prototype schematic of the THP
amp in the QEX article available at
THP's next amp down puts out 1kW, and uses four THP2933s. This is a more
robust version of a similar part, SD2933 made by STMicro. Theirs has a
higher breakdown voltage which enables THP to use an unregulated 50V
supply, saving cost and improving over-all efficiency. There is also a
23 lb version with a SMPS supply.
I am still trying to wear out Titan #1, Alpha 86 #0, and a homebrew p-p
pair of ARF1500s. But I hear good things about both THP amps and the
level of service they provide. JA1DJW -- Nobuki Wakabayashi is THP's
founder and president. He speaks excellent English and is very
attentive. The big amp's price is less than the several auto-tuning tube
amps it competes with. They are both well built, smart enough to protect
themselves from hams, and they do flawless QSK if you want it.
I don't have any connection with THP or its representatives but I would
not be unhappy to see more high power MOSFETs in use out there. They
Don't forget - *7QP* is coming to a band near you -- May 2!
Richard Frey - K4XU
61255 Ferguson Rd.
Bend, OR 97702
Email: k4xu at arrl.net
Web page: www.codxc.org
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