EME223 630m Band Transverter

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EME223-630M KIT Description:

The complete high performance 472 to 479kHz ( 630m Band ) Transverter Kit makes it very easy to get onto the 630m band especially with weak signal digital modes, but being linear it will work with all modes including SSB if it is allowed in your country. Construction takes around 6 hours to fully built and test. The Transverter is designed as a transmit down, and a receive up converter, with a fixed frequency range of 472 to 479kHz, and produces up to 5 Watts of linear output when used with a suitable low power < 5 Watt Yaesu FT817 or similar 3.6MHz 80M Band Transceiver.  The design incorporates a 500kHz low pass filter that is used on the receiver for broadcast band rejection, and on transmit as a low pass filter to effectively reject the second and 3rd harmonics. There is further filtering in both the RX and TX paths using a tuned 472 to 479kHz band pass filter to effectively remove remaining out of band signals.   The design incorporates a RF sensing circuit for automatic switching from RX to TX mode. For a higher performance station the board has the option to disconnect the low pass filter from the PA so that the Transverter can drive a higher power RF amplifier, and then the receive converter with low pass filter can be used on a separate receive antenna.

Kit Constructors Alert:


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EME223-630M Kit Construction Notes:

The pictures below show the basic constructed Transverter and the Kit construction notes and overlay diagrams should be carefully followed when constructing. For larger pictures to check orientation of some components click the images below. Construction is quite straight forward with although the bifilar and tri-filar transformers can be a bit tricky to wind correctly. The alignment of the band pass filter and local oscillator are quite easy to do without test equipment. BUY THIS PRODUCT

EME223-630m Top View
Top view of the EME223-630m. The picture shows the basic EME223-630m Kit with SMA connectors that have been used for easier enclosure mounting.
EME223-630m Bottom View
Bottom view of the EME223-630m. The picture shows the minor SMD components on the bottom side of the board
Winding of the bi-filar Transformer TF1, 10 Turns of the 0.3mm wire twisted bi-filar on the FT37-43 core
How Transformer TF1 is mounted onto the board, Be sure to get the polarity of the windings correct.
Winding of the tri-filar Transformer TF2, 5 Turns of the 0.4mm wire twisted tri-filar on the FT50-N49 Toroid. Note picture is incorrect and should be 5 turns not 6
How the windings of TF2 are twisted for correct phasing before mounting to the board, Note picture is incorrect and should be 5 turns not 6
How Transformer TF2 is mounted onto the board, Be sure to get the polarity of the windings correct.
How Inductors L9, L10 and L11 are wound, 28 Turns 0.5mm ECW on T50-3 Toroids
How the winding is wound and spaced for the 120uH inductor L8, 15 Turns 0.5mm ECW on the FT40-N49 Toroid
How the 50deg C PTC Crystal Heater is fitted to the 3.2MHz Crystal

EME223-630M Performance Tests:

EME223-630M Lower gain is a 15R degen resistor and 2K7 feedback. the +26dB gain is the final design and uses a 3.3R degen and 2K7 feedback resistors. Overall RX Transverter gain is 0dB
EME223-630M Plot showing the Band pass filter response of the 472 to 479kHz filter FL1 which has a 6dB loss to get the sharp response.
EME223-630m Gali-84 TX driver Gain
EME223-630m IRF510 Gain with the bias set correctly to just being turned on.
EME223-630m 500kHz Low Pass Filter Response showing the high attenuation at 1MHz
EME223-630m harmonic output from the 500kHz Low Pass Filter when driving the IRF510 to +37dBm 5 Watts. Both the second and third harmonics are 50dBc or greater.
EME223-630M 4MHz Cheby Chev Low Pass Filter on the output of the 3.2MHz Oscillator

Mounting into a Hammond Die cast Enclosure:

It is recommended that the Transverter board is mounted inside a Hammond 1590BBS Die cast enclosure for RF shielding and to provide heatsink cooling for the IRF510. The heat-sinking seems ample when the Transverter is used with a 2 minute transmit cycle on WSPR mode. It is suggested that the mounting holes for the board are made before the components are fitted to the board. Some care needs to be made when measuring the holes that need to be drilled, as any inaccuracy could result in the holes on the front of the enclosure being out of alignment. The 6.5mm holes for the SMA connectors may need to be enlarged to 7mm as the board is fitted into the enclosure at an angle as extra clearance may be required.

How the 3mm holes need to be drilled to suit the mounting of the PC board into the Hammond 1590BBS enclosure. Mark the position of the upper left hole and place the PC board onto the enclosure to mark the other holes. The hole for the IRF510 can be marked as the centre of the hole in the board.
How the holes need to be drilled to suit the SMA connectors and DC socket on the front of the enclosure. You need to be careful and double check after marking the positions before drilling the holes.

Kit Changes and Repairs:


1/ There are no current changes to this Kit.