Antenna switching - controller

In spring 2019 I broke my finger on left hand and I can't switching antenna with my mechanical switching, for this I developed electronics switching controller with microcontroller ATMEGA328P, with many buttons, LEDs, relays and controller. Now I can switch all my antenna between three transceiver and chose the right one. Down you can see few pictures of this controller. 

All configuration are stored all the time, and after power on I can use previous configuration. From controller I can switch all remote relay switch by antenna position. Please see also my topic "Principle of antenna switching". I tested this controller during contests and OL700CO operation, it's very good help for antenna switching. Complete controller use 4 PCB with electronics, and from another two PCB I made front and rear panel.

Front panel without button


Rear panel without connectors


New controller and old mechanical controller


Output relays PCBs


Assembled front panel


New and old controller


New controller during operation


Dummy load 2kW+  - under development (without thermostat)

For many experiments I need very good dummy load for high RF power. After different things I chose easy solution. I use 3x50ohm dummy load and 6 resistors with 50ohm, all on nominal power 250W, together 2.25kW. The configuration is one dummy load 50ohm with 2 pieces 50ohm resistor in series, it's 150 together and this all 3x paralel with final resistance 50ohm. I tested it with 1.5kW on all HF bands with switched on both blower and for 1 minute it was enough. After 1 minute was the temperature rising up to 50°C. The cooler is 50*100*200mm aluminium, under all resistors I used thermal foil from the manufacturer KERAFOL, material S900 thickness 0.15mm. SWR on all bands (1.8 to 50MHz) under 1:1.1,  tested with antenna analyzer AA-200.

More you can see from picture.

Antenna switch 3:1 for HF 1kW

For my ham radio use I need to switch more antenna to one output cable. This project show one from more possibility how to do it. All three input are connected to ground if are not use and when is one from this three input connected to output then is connected thru relay. I used relays with two 8A contacts from Finder series 40.52, but is not important (I bought this for good price).

Few pictures for motivation



Top side



Bottom side


Side view

 Antenna switch installed by 40m vertical


Transmitter ICOM IC-746Pro. All-band, all-mode transceiver for 1,8 to 144MHz. Output power 100Watts.

Antenna of me and OK1KQI : 2x10el. vertical stacking DK7ZB 6m long on rotator, 4x4 el. vertical stacking DK7ZB to west, 2x7el. vertical stacking to south, 2x4 el. vertical stacking DK7ZB to east and 4el. DK7ZB to north. I use this antenna on portable QTH. All antennas with LNA.

USB Interface mikroKEYER from microHAM

PC - notebook Fujitsu AmiloPro Core2Duo T5550, 1GB RAM, HDD 160GB