This has to be one the most fun kits to build where the finished product is something you just can’t buy easily – the KK7UQ IMD PSK meter.
Clint KK7UQ is a wonderful person to deal with, and I’ve had the pleasure to work him as well. His meter concept is simple:
The RF signal is picked up by a short whip antenna on the meter, fed into an AGC controlled RF amplifier, the signal is detected, sampled with an A/D converter under the control of a micro controller. The signal is analyzed by firmware on the micro controller and the equivalent IMD is calculated and displayed on a 3 digit LED array built into the IMD Meter. (from Clint KK7UQ’s website)
Since not all of us are up on the jargon, let’s run it down.
PSK – Phase Shift Keying – One of the Most Popular Digital Modes (usually PSK31 or PSK63 – the numbers indicate speed) – Full write up at: http://en.wikipedia.org/wiki/Phase-shift_keying
IMD – Intermodulation distortion – The “noise” sub-optimally tuned up PSK transmissions are prone to. – Again a fuller nice write up is at the Wiki: http://en.wikipedia.org/wiki/Intermodulation_distortion
A/D – Analog to Digital converter – basically this circuit digitizes for processing an analogue signal – see: http://en.wikipedia.org/wiki/A/D
AGC controlled RF amp – A radio Frequency Amplifier with Automatic Gain Control
The IMD Meter Building Experience is one of great fun and an outstanding product when you’ve finished.
The Kit version had been available directly from Clint KK7UQ or the recently added Fully Assembled version from RigExpert
Either has my Recommendation, and are a welcome addition to any shack with digital operations.