Re: IRF510 amplifier failures

Jerry Gaffke

Or build the wa2eby amp with two IRF510's in push pull.
Which works great and is pretty much flat through 30mhz

On Sat, Jan 27, 2018 at 09:53 am, K9HZ wrote:
Well it’s this way.  You can either spend a little more on the transistor (with the nice input characteristics) and design with minimal parts (e.g. one set of broad band impedance matching transformers and bias network) to work over a large frequency range (1-54 MHz)…. Or you use a cheap motor switch like the 510 and live with the gain roll-off from mismatch (large del C / del Freq) with a fixed set of broad band I/O transformers…. OR you spend more $$$ to build band switchable compensation networks to improve the matching (Can be bulky and expensive but not always).  Pay me now of pay me later.  Many commercial SS Amps that cover 1-54 MHz complete still utilize some sort of compensation network in them to cover the large frequency range and it’s not apparent to the user… even with very good RF transistors (sometimes driven by the transformer material).   All depends on the part.  Best to Simulate from the S params first.  It will tell you a lot.

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