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. No AI is used to generate this content.

Friday, May 31, 2019

Revisiting the 20 meter "helical resonator" band-pass/notch filters

In my June 30, 2014 blog entry ( linked here ) I described simple band-pass and band-stop filters that could offer a degree of isolation b...

Monday, April 15, 2019

Applying outboard AGC and filtering to RTL-SDR dongles to maximize usable dynamic range on HF

An AGC system for RTL-SDR "wideband" receivers operating in "Direct...

Monday, March 11, 2019

Quieting an insanely (RFI) noisy LED floodlight

A friend of mine recently installed some inexpensive Chinese-made floodlights to illuminate his backyard, but was dismayed to discover that ...

Thursday, February 14, 2019

A 2 meter and 222 MHz low-pass filter for the SocoTran ST-7900D

In an earlier post (link) I described a "hilariously bad" radio - the Socotran ST-7900D (a.k.a. the QYT "KT-7900D") . ...

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