KA7OEI's blog

Random musings - usually on a technical (nerdy) subject - perhaps related to amateur radio and things found at ka7oei.com and modulatedlight.org

Monday, July 27, 2026

A new push-pull switch/potentiometer for the Heathkit HM-102 VSWR/Wattmeter

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Figure 1: The Heathkit HM-102 HF VSWR/Power meter. This meter - often found at swap meets and hamfests for low cost - is still as useful as...

Sunday, July 12, 2026

Making LED headlights RF-quiet

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TL;DR If you have LED headlights that are causing RF interference, ferrites alone will probably not be enough to completely solve the prob...

Wednesday, May 27, 2026

Replacing the relays in the Yaesu FT-480R (FT-280)

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tl:dr: Figure 1: The front panel of my "FT-280R" all-mode 2 meter transceiver including paper labels showing the "new" m...

Saturday, April 11, 2026

A (simple) WWVB loop amplifier for radio-controlled clocks

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Note: The techniques described below should work - with only minor adaptation - for any "Longwave" time signal used by these radio...

Wednesday, March 18, 2026

Repairing a ("smoked") MFJ-998 1.5kW automatic antenna tuner

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Figure 1: The (repaired) MFJ-998 front, now working, sitting atop my Heathkit SA-2060 manual tuner and underneath my homebrew neon bar-graph...

Wednesday, March 4, 2026

Modifying the MFJ-5008 parabolic ultrasonic receiver for better sensitivity and wider frequency response

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Figure 1: Front view MFJ-5008 parabolic dish with integrated microphone and receiver (located on the back side). Click on the image for a la...

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