EME94 13cm Transverter Kit

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EME94 Description:

The complete High Performance 2.4GHz Transverter is suitable for Satellite operation on 2401MHz, and SSB on 2403MHz. It is constructed on a professionally etched 90x65mm Teflon PC Board, and uses a number of SMD components, Mini-Circuits Mixer, MMIC amplifiers, and a 5 Section Hairpin Filter to make the design compact and predictable in performance. The 5 Section Hairpin Coupled line filter has a sharp 3dB roll off at around 2350MHz, with a response at 2250MHz of less than –20dB thereby providing a good SSB noise figure for a 144MHz I/F. The filter is quite critical in design and relies on consistent PC board material, so Arlon 572B has been used along with a professional PC board manufacturer that allows us to get the best performance from this design. The Transverter comes standard with a 144MHz I/F, but can be used with a 432MHz I/F. For 2401MHz Satellite operation it is suggested that a 432MHz I/F be used to leave 144MHz free for a 23cm uplink Transverter. The receive converter was designed to have a reasonable noise figure for general purpose terrestrial use, and it is expected that many will fit an external low noise preamplifier at the antenna. The power and I/F switching of the Transverter is best controlled by a Transverter Sequencer e.g., EME166 Kit which will give the correct RF drive level on TX, and will allow other options to be added later, including preamplifiers, power amplifiers, or coaxial relays etc. The Basic Transverter requires a suitable local oscillator, and more information on what is required can be found on the 13cm Transverter block diagram.

Kit Constructors Alert:

1/ The MGA86576 MMIC is now obsolete from Avago and there is no replacement so it was decided to discontinue this Kit. The MGA86563 SMD version can be used as a replacement and details are available in the Kit mod section.

EME94 Kit Notes:

For extra strength tinplate was fitted around the prototype Kit to make it easier to fit the SMA connectors. This can be avoided by soldering SMA09 PCB mount SMA connectors directly to the board. Break the 4 pins off the connectors using pliers and file the rear flange flat, then solder to the board aligning the connector to the at right angles to the board. When aligned solder the flange to the bottom edge of the board for a good earth connection and strength. If you are concerned with the board flexing, then you can solder some 5mm wide strips of blank PCB or tinplate under the board.

EME94-3A Top View
The Image shows how the tinplate and SMA connectors are fitted to the board. There is around 2 - 3 hours work to get to this stage, but it needs to be done to strengthen the board and for good RF connection of the SMA connectors. After this is completed the fitting of the components to the board takes much less time.
EME94-3A Bottom View
The Image shows how holes need to be drilled into the tinplate to accommodate the SMA connectors. This needs to be done very carefully as it is very easy to damage the board if the drill bit grabs onto the tinplate.
Fitting of the MGA86576 Amplifier and the input inductor
How the MGA86576 is soldered to the bottom ground plane
Modification shows how to use a MGA86563 as a replacement to the MGA86576
The MGA86563 mounted to the bottom of the board
Top View of the completed 13cm Transverter
Bottom View of the completed 13cm Transverter

EME94 Kit Tests:

Plot of the TX Output Spectrum of the 13cm Transverter
Plot of the RX Gain and Noise Figure of the 13cm Transverter

What Other Components Are Required:

A number of other Kits and Components are required to construct a complete transverter. For the 564MHz Local Oscillator, the EME175 Kit can be used. The EME177 Heater Kit is high recommended when used with the 60 degree C Crystals from Mini-Kits For more information on the EME175 oscillator, and EME177 Heater Kits please see the EME175 Kit web page.

For sequencing and switching of the RF and power supply voltages the EME166 Sequencer Kit is highly recommended. The EME166 can handle the dual I/F connection on the EME94.

For low power Antenna switching, the EME144 Relay Kit is ideal and will handle a few watts of RF at 2400MHz.

For a Power Amplifier search the auction sites as surplus amplifiers are readily available.

RF Cable and SMA connectors are not supplied with Kits and can be found on the website. The SMA PCB mount connectors used on the EME94 Kit are part number SMA09.

Changes and Modifications:

1/ Damage to the MGA86576 amplifier is normally due to static or lightning damage. The MGA86576 MMIC is obsolete and there has unfortunately been no replacement made available by Avago. With some work, it is possible to make a MGA86563 SMD version fit. Carefully remove the damaged MGA86576, and drill a 0.9mm hole at the end of the strip line and carefully countersink the copper with a 3mm drill bit on the bottom of the board. Fit a 1mm PCB pin through the board from the top side and solder it to the strip line, and flush cut the PCB pin on both sides of the board. Fit a MGA86563 tack soldering the output connection to the PCB pin on the bottom of the board as shown in the construction pictures. The amplifier needs to the positioned so that the 4 ground leads can be soldered to the ground plane, with the input lead access able through the hole from the top side of the board. The input inductor used is the same 10mm length of wire wrap wire that will only just reach between the input capacitor, and the input of the MGA amplifier through the hole in the board.

2/ Low output power could be due to L2 150nH in the 2M I/F version being open circuit. Check with a multimeter.

3/ For any other faults check the voltages on the board.