Getting active on the 6cm microwave band is no more difficult than any other microwave band. The 6cm or 5.7 GHz amateur radio band is accessible to standard and advanced licensees in Australia. It’s the higher of the two WiFi bands but doesn’t seem to suffer the noise problem like its poor 2.4 GHz or 13cm cousin. Antennas are cheap and readily available in the form of dishes and panels. So if you’re keen to dip your toe into the microwave bands check out the video above.

Microwave bands, like HF and VHF bands, have their own unique set of characteristics and 6cm is no different. It’s a band that seems to play second fiddle to 3cm or 10 GHz, but as I recently found out, it’s very much a band to have in the kit, especially if you like going portable.

5.7 GHz is also a band that will be available in Icom’s IC-905 SHF transceiver.

In VK3, 6cm is more by appointment than on the lower bands. There’s virtually no activity outside of SSB on 5670.1 MHz so if you choose to go down this path, it’s best to find a friend who wants to join you, or reach out to others who are already active on this band. There are several Facebook and email groups where you can introduce yourself.

Antennas

Antennas for 6cm are readily available. Dishes and panels are the best as gridpacks are too porous at this frequency. You’ll find them anywhere and everywhere online upwards of $80

Kuhne Electronics, based in Germany, are probably the most well-known supplier of microwave transverters for amateur radio. This is the Kuhne 6cm transverter. Down East Microwave in the US, is another supplier of ready-to-use transverters. The Kuhn transverter has a user-configurable IF using internal jumpers in the 2m or 70cm band and can be driven with up to 5w of RF power for 250mW out.

250mW is more than capable of going the distance at this frequency providing conditions are good, you’re in an elevated location, and your cabling is up to scratch for microwave. A couple of watts is nice though.  Check out the new 5.7 GHz 10w PA from SG Lab that is a well-priced power amplifier for the 6cm amateur band.

Coax for 6cm Microwave Band

Your choice of coax, and length, is also critical at this frequency. Keeping in mind that 3dB loss is halving your power, LMR-400, which is also known as LL-400 and CNT-400, loses 3.5dB every 10 meters at 5.8 GHz

LMR-400 is a semi rigid coax in an RG8 form factor and isn’t really that flexible.

Your interconnecting cables also need consideration as to coax type and length and avoid right angle coax adapters.

Transverters for the 6cm microwave band

Transverters are used in conjunction with transceivers to change the range of frequencies over which the transceiver can communicate. Getting a 6cm transverter can be a challenge. Your choices are buying one from a very limited number of manufacturers, building one, or finding a second hand one.

Kuhne Electronics, based in Germany, are probably the most well-known supplier of microwave transverters for amateur radio. This is the Kuhne 6cm transverter. Down East Microwave in the US, is another supplier of ready-to-use transverters. The Kuhn transverter has a user-configurable IF using internal jumpers in the 2m or 70cm band and can be driven with up to 5w of RF power for 250mW out.

250mW is more than capable of going the distance at this frequency providing conditions are good, you’re in an elevated location, and your cabling is up to scratch for microwave. A couple of watts is nice though.

Building a transverter into a portable box

You’ll need to find a coaxial relay capable of switching 5.7 GHz for this purpose. Try and find a failsafe relay as there’s less work involved in getting these going compared to a latching relay.

The Kuhne transverters have a TX +12v output which is ideal for switching a relay and will negate the need to build a sequencer. The image above is Kuhne’s recommended configuration for a basic transverter system.

You’ll notice a 10MHz input. This is an option 10 MHz external reference source for locking the local oscillator inside the transverter. From experience, the internal Kuhne oscillators are solid and reliable. Next is the 12v power source. Under 1 amp is required during transmission. A monitor provision allows you to connect a meter to give you a visual reference of transmit power. This is optional but recommended.

The PTT connector, when grounded will switch the transverter into transmit. Alternatively, +12v on the IF cable will also set the unit to TX. Most IF radios offer a TX ground via an accessory jack.

Connect your QRP radio to the IF input on the transverter. This can be a radio such as an IC-705 or FT-818. Avoid radios capable of high power outputs as ALC overshoot may spike the transverter with more than 5 watts damaging the transverter.

Separate TX and RX SMAs are provided on the transverter, hence the reason for a coaxial relay. Finally, a +12v TX is provided for powering a relay. This output is capable of up to 400mA and most relays are rated at 200mA so there’s a bit of headroom.

As mentioned earlier, choose a QRP radio as an IF. A radio such as the IC-705 is ideal as it has a waterfall which is super handy for finding wayward signals up and down the band. You can also configure it to be a beeper which will save you from building one which essentially caused the radio to transmit a series of ‘beeps’ ideally used in path alignment.

The call frequency in Australia is 5670.1 MHz.

SG Laboratory also makes quality microwave transverters and at the time of making this video, a 6cm transverter is being designed and prototypes made. No date has been given for its general availability.

Getting active on the 6cm microwave band is now up to you. All that’s left to do now is to build your transverter into a rugged, go-anywhere box. This can be half the fun of getting onto the microwave bands. Remember, use quality components, good RF connection techniques, and keep your cable lengths as short as possible.