The G0MJW Pages

Most of my very limited operating is now on the microwave bands. Over the last couple of years I have been building up a set of transverters to a common design so that I can swap them easily on the mast. These so far cover 2320 MHz, (13cms), 3400 MHz (9cms), 5760 MHz (6cms) and 10368 MHz (3cms). I also have equipment for 24048 MHz, the first system is a converted Nortel unit with integral 30cm dish and the second is a DB6NT based unit with a 2W amplifier and a 48cm Procom dish.

3400 MHz (9cm) Station

The 3400 MHz band is a very popular microwave band in the UK with a lot of home based activity. This is the lowest band where dish antennas are more convinient than Yagis and where the rainscatter mode becomes important. It is relatively easy to generate high power on the band owing to the availability of affordable LDMOS RF power transistors.

The system I use is lightweight and can be mast mounted. It is based on a DB6NT transverter which has a noise figure of 0.9 dB and an output of 250mW at 3400 MHz. This is complemented by an HP ex Ionica 3400 MHz amplifier that gives about 12-15W of output power. I use a dish antenna with a home made feed horn mounted at 10m AGL on my Tennamast.

5760 MHz (6cm) Station

This is also lightweight and can be mast mounted. It is based on a DB6NT transverter which has a noise figure of 0.9 dB and an output of 250mW. I have added a power amplifier based on a 7 GHz surplus unit which gets up to 4W or so of RF. The antenna is a dish, (I have several) with various feeds. Frequently 6cms and 3cms are co-mounted and share a dish.

10368 MHz (3cm) Station

I have three 3 cm transverters. The first one I built from the UK design by Charlie, G3WDG. This has a commercial 1 W SSPA purchased for £20 at a microwave round table. It has a 144 MHz IF and works most of the time. The second transverter is based on the Qualcomm boards from the USA. This uses the 1W Qualcomm SSPA, again with a 144 MHz IF. The third is based on a DB6NT MK3 transverter with a 500mW commercial PA driving a DownEast Microwave 8W PA. This is built to be lightweight and mounts on my mast, it has a 432 MHz IF, a 1.2 dB noise figure and produces around 3W of RF. I need to improve the drive to the final amplifier to get the full 8W. I have several dishes for 3cms, one 50cm offset shown below plus a 60cm prime focus with a home made scalar feed.


Best DX from the home site is around 300 km. I mainly use the equipment as a portable station. Here is a picture of a portable setup on my Navara with 6cms and 3cms sharing a dish during a test. I don't drive it like this! The Yagi is for the 144MHz talkback. I have since improved the system with lower loss feeder for 6cms and a quick to joint together join pole with a rotator.

24 GHz Station

My 24 GHz station is based on a microwave link transceiver. This is only used portable as it has a miserly 250mW of output and 4 dB NF. The antenna has 35 dBi gain and is integral with the transverter. Here it is in action at Hackpen IO91CL - and although you can't see it, it is receiving G3PHO from Wales. This unit also fits on the Navara mast as above.

I am working on upgrading this system to 2W with a 45cm dish and 2 dB NF.


Last Modified 9 November, 2009