Showing posts from August 17, 2017


Still struggling to make a "simple" 5Watt PA for the 1.8 - 50MHz range
The QRP-LABS IRF510 5W PA  will not deliver more then 1W at 28MHz
not to speak of 50 MHz there it is an attenuator.
The U3S LPF needs to be terminated with real load to keep the signal a bit decent.
Using the RD15HVF1 Mitsubishi did bring just a little more.
3-4 W at 28  and 1.5 W at 50MHz
The QRP-LABS PCB has extra pads for the  RD15HVF1 that have crossed drain and source.
The RD15HVF1  source the middle pin and cooling flange direct screwed a heathsink.
The cheap eBay RD15HVF1  are fake  IRF510  stamped as RD15HVF1
The real RD15  has low Gate capacity  approx 83pF   while the IRF510 has 400pF or more and the source and drain are crossed.
eBay is poisoned with  fake transistor sellers.
Like  5 pcs RD15HVF1 5$  good quality ...

The specs of the ( REAL) RD15 look perfect, too good  to be true!
FEATURES High power and High Gain:
Pout>15W, Gp>14dB @Vds=12.5V,f=175MHz
High Efficiency: 60%typ. on VHF Ba…