There is a 45w amp kit sold rather cheap on ebay and aliexpress both.
On Sat, Apr 29, 2017 at 6:40 AM, John Backo via Groups.Io
<iam74@...> wrote:
Jorge:
Note that you cannot directly substitute a IRF530 for a IRF510.
That is because the input gate capacitance of the 510 is ~180 pF.
and the gate capacitance of the 530 is ~620 pF. That means the input impedance is
considerably different and needs compensation. There is also a difference in
the drain capacitance which will affect the LPF match.
If these are compensated for, with 20v on the drain, the Pk-Pk AC output voltage can be about
36-40v. (The maximum wattage handling ability of the 530 is about 85W.) Note that the heat sink
must be considerably increased in size.
If you want to increase the wattage that much, you should probably opt for a drain voltage of ~36v.
With a suitable matching network and heat sink, that should allow a Pk-Pk voltage of about 70v.
Note that heat is still the biggest enemy and consideration, as it is in any MOSFET PA.
If you are opting for that much power, you probably would be better off designing or building a dual
IRF530 PA. The BITX3B PA would have to be considerably modified, even if the drain voltage were kept low.
You could probably get away with the current design (modified for impedance) with a IRF520, but
probably not a IRF530.
Check the internet; there are many designs out there.
john
AD5YE
