G4HUP and DL4MUP EME History on 2m 23cm and 13cm

G4HUP EME on 2m

Having assembled a station with good Auroral and MS operation capabilities at my new location in the early 1990's, I started to listen for signals on setting and rising moons. Because of a very long feeder run (70m) I had installed an MGF1302 preamp at masthead, and this enabled me to hear the larger US EME stations. Very shortly after this, in 1991, I made my first 2m EME QSO with K2GAL, closely followed by W5UN! Over the next 3 years I extended the station up to 4 yagis, with full elevation, MGF1801 pre-amp and a Tempo 2002 PA. I enjoyed the EME operation, until the antenna was destroyed by strong winds - thus proving that it was large enough!

MGF1801 Preamp information written by G4SWX and WA5VJB from VHF/UHF DX'er (defunct UK specialist magazine) is here. These are scanned pages from the magazine, - I lay no claim to the contents, but wish to ensure the information is not lost!

My initial list for 2m is here.. If anyone still needs a QSL card, please contact me!

Due to pressure of work that had been building up, I never did get round to re-building the array. This was also partly because I wanted to do other things as well, and the 4 x 18 array did not give much room for other antennas on the tower!

DL4MUP EME on 23cm and 13cm


Thanks to Guenter, DL4MEA, I was able to use his 3m dish and TH347 PA for 23cm EME activity. Using this excellent facility, I have made over 50 initials.

The system has a single stage cavity preamp based on metalwork from KB2AH, with an NE 32484 - currently this is giving abt 0.4dB NF - not as good as can be achieved with this device, and not as good as we have previously measured. Evolution of this pre-amp can be seen in the gallery pages. This is followed by a DJ9BV type second stage with an FXH35, both preamps mounted behind the feed.

An old R&S weather satellite tracking system provides the dish mount and mechanism, with added optical encoders for feedback. The tracking software used is Nova, with the control interface being designed and built by Guenter. Resolution in both az and el is 0.1 degree.

The prime mover is my FT847, followed by a DD9DU transverter, and a modified ex-GSM PA giving 80W drive to the TH347. We experienced a lot of frequency stability problems initially, spending the first 15-20 seconds after any TR changeover tracking the freq drift! This was solved by replacing the internal xvtr LO with a DF9LN external LO. Spectran is the 'DSP of choice' for observing signals on the band - currently in use with a Toshiba Tecra laptop. Experiences with this and with Fujitsu-Siemens machines are OK, but I was not happy with the performance of the previous Tosh Satellite Pro on the audio front.

2003 ARRL EME contest log is here.

2002 ARRL EME contest log is here.

2002 REF/Dubus contest log is here.

2001 ARRL EME contest log is here.

Dish Feeds

We have used circular polarisation on 23cm from the beginning, using the N7ART Diagonal Waveguide Feed. This feed remains on the dish for 23cm. More recently we have found a method of simplifying the way of launching RF in this feed by using probes (like VE4MA) in place of the very critical crossed dipoles, as published by K9BCT - this makes the set-up much easier, as was proven by our attempts to set up a scaled DW feed for 13cm. Using the cross-dipole arrangement as per N7ART simply would not align on this band, and after investigation on a network analyser it was realised that the slots used to allow the dipoles to be mounted through the back plate were actually resonant, and seriously degrading the performance.

At EME 2002, OK1KIR group presented a septum polariser feed for 23 (and higher bands) at EME 2002. The OK1DFC article is to be recommended, and I have a set of metalwork ready to assemble and try out. The big advantage of this variant is that there are no polariser screws to set up. See Rectangular Waveguide Septum Transformer Circular Polarised Feed

With the addition of the 13cm feed, the positioning of the feeds at the focus of the dish has been mechanised, using a satellite screw-jack actuator. The mechanism can be seen in the picture below, with the 23cm feed above the 13cm feed. A simple pulse counter is used in the shack to indicate where the feed is pointing.

2320 MHz EME

The scaled version of the N7ART Diagonal Waveguide feed, with signals launched by monopole probes rather than the crossed dipoles is now installed on the dish. So far testing is taking place Rx only. The preamp is a DJ9BV 2 stage, giving approx 0.55dB NF at 2320, and 40dB gain at 2304 and 2320, falling to 38dB at 2424Mhz A G3WDG transverter shares a common enclosure with my DB6NT 23cm transverter - see the picture below for details. The 2320 LO is a DF9LN osc, inside the xvtr enclosure, and the 2304 LO is provided by an external Adret synthesiser - a front panel switch selects internal/external LO. I had hoped to cover 2424 in the same manner, but have found that the LO strip tuning is too narrow to cope with it! A revised LO is under design.

On the left side of the case is the switching - RF at the front and DC at the rear. Next to that is the DB6NT xvtr for 23cm, with an M57762 PA behind it - a cheap computer fan sends enough air through the heatsink to keep it cool.

Towards the right side of the case is the 13cm G3WDG xvtr with a G4DDK LO strip 'piggy-backed' on top. In front of them is the DF9LN osc for 90.66667 (2320), and the LO relay is just behind it. On the rear panel are 1W and 10W PA's from G3WDG.

There is a single Rx input to the box, switched between the 2 bands, and each band has a separate Tx output. External LO input is also switched between the bands. When the Band select switch (front panel, left) is in the center position, the IF input is routed out to another socket on the back panel so more transverters can be fed from a single IF rig without having to change cables over, etc.

A power amplifier using MRF21120 modules is currently being assembled.

Page created: 02.12.2004

Last updated: 29.032012