Finding impedance and velocity factor of an unknown Coaxial cable using nanoVNA
I needed some 75ohm cable to make impedance transformer harness for my VHF/UHF cross yagi setup. Found a 20m roll of RG179 which was procured from China long ago. I…
RF Sampler
A DIY RF sampler with -50db sampling out, most beneficial for measuring the output of HF radio PA section using Spectrum Analyzer. Also can be used for Pure Signal transmission.
K9AY Receive loop antenna
In 2022 I made one 200m long beverage antenna for our IOTA (S21DX, 2022) which was around 2m high from ground. For some reason (most probably very high conductive wet…
5 Band LPF for HF Amplifier (up to 200W)
As many wish to make the cheap PA-70, PA-100 type Chinese SSPA using IRF530 based MOSFET. I always advise them to never operate a SSPA without final LPF. We do…
Homebrew 3 elements 10m Yagi antenna
When S21DW heard that I am planning to make an 3 elements short beam for 10m to replace my 2 elements 10m antenna he immediately jumped to make it asap.…
S21RC Digital Interface Rev 3.0 (Ham Radio – Computer)
Fully isolated interface between Radio and Computer for various digital mode.Radio Side connection:Gnd (isolated from Computer ground)Audio IN/OUT (Isolated by audio transformer)CAT RX-TX and/or CIV: (Isolated optically)PTT and COS (Isolated…
SSPA Controller V2.1.x LITE
Update Log: 7 Jul 2024: 2.1.14 Lite released. Bug fix for PEP hold, and gradual decay added for watt graph.14 March 2024: 2.1.13 Lite released, Exponentially Weighted Moving Average used…