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Meter Meter on the Wall, Who has the Fairest PSK Signal of Them All? The Clint Hurd KK7UQ PSK Meter Kit 29 - January - 2007

Posted by k9zw in Amateur Radio, K9ZW Built.
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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:

KK7UQ IMD Meter

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.

73
Steve
K9ZW

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Comments»

1. k9zw - 31 - January - 2007

A nice checklist for a PSK station setup can be found at: http://www.psb-info.net/Station-Setup-Checklist.html

73

Steve
K9ZW

2. Clint Hurd KK7UQ - 2 - December - 2008

Hi Steve – I enjoyed our QSO yesterday on 20m PSK. You asked for comments on the IMD Meter page. I have 2 comments:
1) The reference to “RigExpert” with accompanying URL is no longer valid. It should be changed to: “USInterface” with the URL of http://www.USInterface.com
2) The IMD Meter is only available in fully assembled form from US Interface. I no longer provide kits.

Thanks for the nice writeup.
Clint KK7UQ


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