There are at least two or more designs using IRF510s in push
pull form. The power out was in the 30-45 watt range for two devices
running at 24V through 10M. This is reasonable for the class of
device. The real trick is as you go up in frequency (above 5mhz) you
need to pay attention to input and output matching. Failure to do so
will result in less power than expected. Also insure the driver is
both properly loaded and can deliver the required power.
Also testing these devices at RF find they exhibit poor IMD at 12V.
At 20-24V they perform much better.
Also to drive these properly the driver stage should easily be good
for 1watt. If any stage before the final amplifer or drivers cannot
deliver sufficient drive not only will power out suffer the signal
quality and bandwidth will be poor.
One of many articles using two IRF510:
home.cnham.com/pdf/amp/irf510/HF_use_FET_1.pdf
Allison
KB1GMX
--- In BITX20@..., Arv Evans <arvevans@e...> wrote:
Chris
My BITX40 uses 24 volts on the IRF510 for a power output of 11
watts. It
required the addition of separate sheilding, 2 ferrite beads on the
gate
lead, and a paracitic suppressor (2 ohm 2 watt carbon resistor wound
with 4
turns of #16 AWG) between drain and output filter to tame it.
If you have a variable power supply, try bringing the voltage up
slowly once
you have it working properly with 12 volts. I did not do this the
first time
and it cooked an IRF510! 8-(
My IRF510 is mounted on the heat sink for a computer CPU. The
original CPU
fan is mounted on the other side of the heat sink and turns on with
the PTT
controlled voltage for the IRF510. I bolted the IRF510 directly to
the heat
sink, which is mounted to the chassis via 1/2 inch (1.3 cm) nylon
standoffs.
The fan housing is plastic so this isolates it from RF on the heat sink.
Next step might be to replace the IRF510 with push-pull IRF510s or
IRF630s and
a 48 volt supply!
Arv K7HKL
_._
On Wednesday 20 July 2005 03:17 am, vdberghak wrote:
Hi all,
did anyone tried to put higher voltage on the IRF stage?
If so, I am interrested about the results like:
- stability,
- increase of output power.
If the output power is not much higher and other problems will
show up,
I will not try it...
Thanks,
Chris.
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