Re: Searching for IMD

Warren Allgyer
 

I have tested the MMIC based wideband amplifier board from SV1AFN ( https://www.sv1afn.com/wideband-mini-amplifier.html ) as a replacement for the 45 MHz transmit amp comprised of Q20 - Q22. I removed C20 and C22 and used two short lengths of miniature coax to take the signal off board to a 7 dB attenuator and then the amplifier, then back onto the board. Resulting MMIC amplifier gain was +16 dB.

The yellow trace is before the amplifier board was inserted and the purple trace after. 3rd order IMD was reduced by nearly 10 dB using the MMIC amp.

WA8TOD

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