On 5/6/2012 12:42 PM, Tom Thompson wrote:
> I have two home brew solid state amplifiers, one at a kilowatt and
> one at 600 watts. You can see details at http://www.tomthompson.com
> Both of those amps are promoted by Communications Concepts and are
> Helge Granberg designs.
I am honestly surprised that nobody has updated the Grandberg 4 x
MFR150 design (EB 104) for the VRF-2933. That would make a "single
board KW" for 90% Plus of all amateurs ... something within 0.5 dB
of the US "legal limit" and capable of handling SWR < 1.5:1 without
a tuner.
The only "real" work would be in optimizing the transformers for the
proper (lower) impedance.
73,
... Joe, W4TV
On 5/6/2012 12:42 PM, Tom Thompson wrote:
> Bob,
>
> I am using the Freescale 300 W part. The part number is MRFE6VP6300H.
> I will probably not build this into an amplifier. I have two home brew
> solid state amplifiers, one at a kilowatt and one at 600 watts. You can
> see details at http://www.tomthompson.com Both of those amps are
> promoted by Communications Concepts and are Helge Granberg designs. The
> transistors were so expensive that I did not feel comfortable really
> playing around with them. When the LDMOS transistors came out, the
> ruggedness and price were right for experimentation. I built a test jig
> on a copper spreader and aluminum heat sink with a good fan. The traces
> on the PC board are made with copper tape, so I can change the circuit
> easily. I have thermistors mounted on the transistor flange, the copper
> spreader and the heat sink so I can see what the thermal resistance is
> between each interface. The bias is easily adjusted so I can easily
> bias the transistors between Class B and Class A. My Vdd supply is also
> adjustable so I can change the output impedance of the amp and look at
> various efficiencies. You get the idea...it is just a learning platform.
>
> 73, Tom W0IVJ
>
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