The hobby of Amateur Radio has many distractions. One rabbit hole you may choose to explore is microwave communication. If you’ve never really thought about this aspect of our hobby, then it would pay to do a little research before you dive in. On this page, I’ll share some tips on where to start with amateur microwave. Chances are you already have some gear in your shack such as a QRP radio that’s capable of operating on the popular two IF (intermediate Frequency) 2m and 7cm bands. The IC-705 and FT-818 are two radios perfect for microwave operation.
The five most popular bands in VK are 23cm (1.2 GHz), 13cm (2.4 GHz), 9cm (3.4 GHz), 6cm (5.7 GHz) and 3cm (10 GHz). Once you’ve mastered these, the challenges continue with 12mm, 6mm, 4mm and even higher. Before you go any further, have a look at the video below, then read on…
So you’ve watched the video above? Good. There’s a point in the video where I suggest finding a radio club to see who’s active in your area. It’s OK to see amateur microwave in action on Youtube, but it’s something else to push the button on a radio and have a QSO. I can’t recommend more that you try before you buy. If you’re keen after that, and chances are you will be, find a microwave operator who can be your mentor. Like everything in ham radio, experience is everything and what you’ll learn on that first encounter with microwave, is more than you’ll get watching Youtube videos for hours. It’s real-world stuff!
Microwave bands as far as the amateur radio community go, start at 1.2 GHz or 23cm. Although technically speaking this isn’t really microwave, It is the limit of the commercial ‘black box’ or radio you can buy from the toy shop. Some operators stop here and don’t go above this band for many reasons, but mainly equipment related. Yes it’s true you have to build things, and yes, it can be more plumbing than cabling, but the reality is, it’s a part of the spectrum that has its own unique rewards.
If you’re keen to get into amateur microwave, then the recommendation is small steps. Master one band at a time and find a mentor. This is so important. This can be someone from your local radio club or someone from one of the microwave groups on Facebook such as the VHF UHF Microwave – VK ZL Amateur ham radio. Chances are your mentor or local club will have the test gear you need to get your first project off the ground, and they’ll know how to use it.
Unless you can buy a built transverter from another microwaver, you’re going to have to get building. Knowledge of RF practices for RF cabling is essential, but it’s not complicated. Keep your cables as short as possible and use good quality cable. Semi-rigid coax such as RG402 and the ability to solder up SMA connects is a skill you’ll need. To build sequencers such as the Minikits EME166, you’ll need a fine tip quality soldering iron and equipment to hand SMDs or Surface Mount Devices. They’re small. If you have a steady hand and a good workstation, you’ll be fine after a little bit of practice.
Building transverters into small portable kits of an indestructible nature is straightforward and rewarding to build. The transverter below is just that. It consists of an SG Laboratory 9cm transverter housed in an IP65 aluminium case. The batteries are LiPo 18650s. The SG Lab transverters come with PCB antennas which work well for their size and weight which is handy for minimising gear when you’re walking up a hill.
The photo below is the 9cm transverter in action. As you can see, it’s lightweight, easy and quick to set up. The internal battery means you won’t forget a DC cable.
The last thing you want to do is destroy a transverter with too much RF as an IF stage. Most transverters use 2 or 3 watts drive as a maximum. Hi power rigs are a bit of a no-no too as they can have ALC overshoot transient at the beginning of transmission which can also take out a transverter. If you can, get yourself a Yaesu FT-817 or FT-818 qrp rig. These are the rig of choice by most microwaves today. Just have a look at the videos on Youtube. They also have 2m and 70cm. Most transverters use these bands as IF.
The Icom IC-705 is perfect for a microwave IF radio. It has a waterfall display which makes finding stations that are off frequency easy to find. The higher you go in frequency the more chance there is for multiplication errors. Frequency drift can also be challenging. Both Kuhne and SG Laboratory transverters have optional 10MHz external references which can help stabilise local oscillators.
The layout above shows the elements of a microwave station. Low noise amps, PAs and coaxial relays are optional. Most transverters have a built in sequencer so if you choose to run a basic transverter system, chances are you’ll just need an IF radio, transverter and an antenna.
In this video, the iPad is connected to the IC-705 via Bluetooth. Rob VK3KTD was trying out his brand new 3cm Kuhne PA. The path is about 70km over water from Mt Martha to Glenroy on a cold winter’s evening. All in all, a successful first contact using new gear.
The graphic above highlights the microwave part of the radio spectrum.
The five most popular bands in VK are 23cm (1.2 GHz), 13cm (2.4 GHz), 9cm (3.4 GHz), 6cm (5.7 GHz) and 3cm (10 GHz). Once you’ve mastered these, the challenges continue with 12mm, 6mm, 4mm and even higher.
The calling channels on the microwave bands follows the structure of the lower bands. For example, the 2m and 70cm call channels are 144.1 MHZ and 432.1 MHz. This extends up the band so 1296.1 MHz, 2403.1 MHz and 3398.1 MHz etc are the call frequencies for SSB. During contests and Microwave Activity Days, the trend is to use .15 as a calling frequency. 3398.150 MHz for example.
SSB Call: 1296.100 MHz
SSB Contest Call: 1296.150 MHz
Standard and Advanced Licences
SSB Call: 2403.100 MHz
SSB Contest Call: 2403.150 MHz
Standard and Advanced Licences
This band can suffer from severe WiFi interference in densely populated urban areas.
SSB Call: 5760.100 MHz
SSB Contest Call: 5760.150 MHz
Standard and Advanced Licences
SSB Call: 10368.100 MHz
SSB Contest Call: 10368.150 MHz
This list isn’t a complete list by any stretch of the imagination nor is it an endorsement. I’m adding and subtracting links as I find them. Use these as a starting point. As a general word of advice, anything you find on eBay may not be as good as what you’d probably by from a reputable dealer. Having said that, there are eBay bargains to be had, but do your research and keep in mind you do tend to get what you pay for. Maybe ask in a Facebook group and see if others can share their experiences.
Kuhne make very popular transverters amongst other things. There are products that cover most amateur bands that you need a transverter for. They are pricy and have very expensive shipping. Kuhne is located in Berg, Germany.
The Mini-Kits Microwave Transverter Kits are ideal for getting on the higher microwave bands. They are all available as a basic Kit, or fully optioned including local oscillator, sequencer, RF Amplifier, and hardware etc. Mini-Kits is a South Australian company.
Based in Florida, Down East Microwave have a range of LNAs, transverter and amplifiers. They also stock antennas and components.
Mini-Circuits design, manufacture, and distribution of RF and microwave components and integrated assemblies. With design, manufacturing and sales locations in over 30 countries, Mini-Circuits offers 27 product lines comprising over 10,000 active models. Mini-Circuits products are used widely in commercial, industrial, and military applications.
The Mini-Kits EME166 Sequencer is very popular. It makes connection to other circuitry much easier due to a single 10 way header connector on the board. The Sequencer can be used to control Transverters with various component like antenna relays, power amplifier, or receive pre-amplifiers. It is also suitable for sequencing the switching of high power RF amplifiers with a transceiver. The circuitry incorporates both DC and RF sensed inputs that can be used to control the switching of the sequencer from RX to TX mode. The sequencer suits Transverters with either a single, or dual I/F connections. The circuitry uses a PIC micro-controller and MosFET switches, and has over voltage and current protection.