Pimping Elecraft KX3 for VHF and up

Long wait is over, the 144 MHz transverter module for my Elecraft KX3 has arrived!

KX3-2M transverter module shipment kit

The transverter module came in the way all Elecraft users have got used to; well packed, all small bits and pieces in ziplock bags and  with very detailed installation manual.

The transverter board is a very high-tech piece of electronics not only due to the physical size constraints, but the RF performance is quite outstanding, merely required as the sole RF performance of KX3 is so outstanding.

Looks like the KX3 has been originally designed quite well having optional internal transverter modules in mind as, even it is a tight sandwich, the transverter module has its well-planned position in the radio. Also the antenna connector hole already exists in the radio body, so does the LO signal output connector on the main board.

I have the optional antenna tuner board and the roofing filter installed in the KX3, both needed to be removed during the installation to access the LO signal output connector and to install the SMA antenna connector.

 The SMA connector for 144 MHz antenna fits just in between the toroidal coils of the filter part of the main board. I had to move the closest coils so the connector body would not make contact with them. This was mentioned in the installation manual too, so I'm not probably the only one needing to make some space for the connector.

The LO signal for the transverter is available next to the roofing filter connector on the other end of the main board.

Both the antenna cable and the LO signal cables use UMC (Ultra Miniature Coaxial) connectors which are small but tough.

Mating the contacts first time requires impressive amount of force comparing the connector size. The LO cable connector is below the roofing filter board, which was required to be removed during the cable installation.

The transverter board fits directly on top of the optional antenna tuner board, utilizing the same connections the tuner board uses.

The power transistor of the transverter is attached to the side wall of the radio body between the antenna connectors, and there's also a screwhole ready for that.

The sandwich consisting only the optional tuner board was already a tight fit, and even more tight it got with the transverter module installed! There is still some clearance between the modules and the cables run freely.

I noticed later when getting the radio back to one piece that the transverter antenna cable is bit on the way of the loudspeaker and extra care needs to be taken when closing the lid so the cable won't get squeezed between the metal sheets.



Finalizing the installation required me to upgrade the firmware of the radio, which was no pain using the KX3 utility. The installation manual clearly went through step by step the required parameters to be entered so that the transverter module would be recognized and available.

 
I briefly tested both FM and narrowband operations and everything looks good. Getting FM to work was bit tricky but thanks to the manual again I was able to get both repeater offset and PL to work :) I'm getting old as I need to read manuals!

When I get a chance I will do some basic measurements on the performance of the transverter module to proof the sensitivity and output power. According to the manual it should put out 3 W on 12V, and about 1 W on 10V which is the case when running on batteries.

144 MHz is a nice addition to the KX3. The module supports also +5 V bias voltage on transmit for switching transverters to TX, which makes me want to try KX3 as the IF radio for microwave stuff too :)