Nearly every radio project needs a low pass filter at some point, the QRP-Labs LPF kit is a quick and easy build that can knock out harmonics for nearly any low power HF radio. This is a compact, modular kit implementing a 7-element low pass filter which can handle 10 watts safely. Variants are available […]

The QRP-Labs Ultimate Relay Switched LPF Kit was developed by Hans Summers, G0UPL, as an extension to the Ultimate 3 and Ultimate 3S transceivers. It allows switching between six different Low Pass Filters (LPFs) and so operating the transceiver on six different bands instead of one. I’ve used these relay-switched filter boards in several projects […]