Installing the Elecraft KX3 2m Module 4

Transverter ready for installation

Transverter ready for installation

I’d lusted after the 2m module for my Elecraft KX3 for some time now and finally succumbed after good reports from Michael (G0POT). I wanted the transverter for two main reasons; one for VHF SOTA activations and two for 2m contests. The receive performance on the Elecraft KX3 blows my Yaesu 857 and 817 out of the water and I wanted to make use of this better performance during contests.

This post won’t outline all of the steps to install the module but will talk about my experiences during installation. Elecraft have already written an excellent installation guide.

The first step was to fit the SMA connector, the KX3 uses the existing BNC connector for 160m-6m and the SMA for 2m. To do this I had to remove the ATU module and then struggle for some time to make space for the connector. The location of the toroids was right next to where the connector comes in and I had to move these as carefully as I could to make some room:

SMA Connector fitted - notice how tight it is to the toroid!

SMA Connector fitted – notice how tight it is to the toroid!

The 2m module comes with ultra-miniature coax (UMC) cable to take the signal from the SMA connector to the main KX3 board and another one to connect the module to the main board. I’d never worked with these UMC SMA connectors before and they are difficult to line up properly, so that you can snap them into place. The make a distinctive snapping noise once fitted correctly, but this requires a worrying amount of force employing the use of the flat end of a pen, as they’re too small to use your fingers!

Ultra Miniature Coaxial (UMC) cable connected

Ultra Miniature Coaxial (UMC) cable connected

Snap On Ultra Miniature Coaxial (UMC) connectors

Snap On Ultra Miniature Coaxial (UMC) connectors

The next step was to refit the ATU module and then fit the 2m Module on top of this. If you have an Elecraft KX3 you’ll know it packs a lot of performance for such a small portable rig, this means there’s very little space to work with inside. I found the fit to be extremely tight when I added the 2m module and it took some getting right to ensure everything was correctly aligned.

2m Transverter sits on top of the ATU - it's a tight fit!

2m Transverter sits on top of the ATU – it’s a tight fit!

2m Transverter Installed!

2m Transverter Installed!

Once I had finished the installation I needed to setup the transverter options in the KX3 menu system. The installation guide takes you through all of this and I found it easy enough. With this I had completed the installation and my KX3 is now ready for 2m… I just need to test it in anger now!

2M Ready to Rock & Roll on the KX3

2M Ready to Rock & Roll on the KX3

In conclusion the installation was harder than expected. I had built my KX3 from a kit and found this quite straight forward, but I did have difficulty with this module due to the tight fitting components and the UMC coax connectors. In hindsight I should have had it installed by Water Stantons for a couple of quid, but instead sweated for about an hour!

4 thoughts on “Installing the Elecraft KX3 2m Module

  1. Reply RandomFan Jul 2,2015 05:55

    Do you think it would be possible to change the SMA connector to BNC? I consider the SMA connector to be a design flaw, because it’s completely indefensible in a device that will NEVER have the antenna permanently mounted. I can understand it in handhelds, but its only purpose there is for mil-spec/JIS dust and water ingress feature lists.

    For the KX3 where the SMA connector will need to be able to endure being mounted and dismounted every time the radio gets used, the short life of SMA is ridiculous, and it will need to be replaced anyway.

    • Reply James Stevens Jul 3,2015 08:15

      I’m not sure the BNC would be possible due to the very limited space inside the case. It was very very tight with the standard SMA connector and I had to move some of toroids to make space.

      I do agree that a BNC connector would be more robust than an SMA, I plan to get a pigtail SMA to BNC 😉

      Thanks, James M0JCQ

      • Reply RandomFan Jul 3,2015 08:27

        The next best thing would be to put a low profile SMA to BNC adapter on the SMA connector, like I do with my handheld radios. Do you know if that will work OK? Can you try it, if you have an adapter handy? For “little” 2 meter antennas, I may want to mount the antenna directly on the KX3, or with a right-angle adapter. That SMA might be too weak for a direct mounted antenna. Is that why you said you would try to use a pigtail?

        I’m going to email Elecraft and ask them if they could change the SMA connector to a BNC. Maybe if enough people ask them about this, they’ll take the hint and just get rid of the SMA. Elecraft’s email to ask about that change is

        • Reply James Stevens Jul 3,2015 09:35

          I think that will work, I have ordered a small SMA to BNC adaptor as well as the pig tail (actually SMA to N-Type). The idea with the pig tail is indeed to take the strain off the small SMA connector, I use EcoFlex 10 coax with quality N-Type connectors for VHF portable contesting and think the stress would be too much on the little SMA connector. But the pig tail and additional connectors are all adding losses into the setup 🙁

          I’d be interested to see what Elecraft say about your request, they usually have good reasons for their design choices, so we’ll see 😉

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