A Microphone Pre-Amp For Heil and other Microphones
By Mike, N0MF


This is the mike pre-amp I'm using with the Heil HC4. It is an ICOM design that another ham sent me... Of the four I've tried (both bipolar and FET), it seems to work the best for me. It operates the VOX well and drives the transmitter to full output on 160 M.

R2 is mounted at the K2's front panel microphone jumper block to supply power to the pre-amp from the 5V supply in the K2. C2 and C3 can also be 0.01uF caps.