MX-P50 INTERFACE LEADS

Having got my IC-705 working with the MX-P50 amplifier, I thought it was time to do the same with my Elecraft KX3 and my ELAD FDM DUO. In theory, there should be no problems interfacing them, but I did of course have to sort out connecting leads.

The MX-P50 has a rather odd connector for the PTT signal and because I want the option of using a few different radios with the amp, I decided to cut it off and replace it with Anderson PowerPoles for the sake of uniformity (plus I've got loads spare). With that job done, it was easy to start making up interface cables. To remove the risk of me connecting power to the amp’s signal lead by mistake, I fitted blue heatshrink tubing to the amp’s signal lead and the interface cables.

I already had a generic KX3 amp-lead which was terminated with a male phono connector (RCA). At first I was going to snip off the phono and fit powerpoles, but I thought the phono connector might come in handy at some point in the future with another amp, so instead I kept it and made up a short patch lead to convert it from phono to powerpoles (as seen in the photo above).

At the other end, the KX3 lead has a 2.5mm TRS jack-plug which connects to the phono-plug thus...

TIP : not used

RING : Centre-Pin (PTT)

SLEEVE: Shield

Once the lead was made up, it was time to connect the amp and radio together and test it. I set the KX3 to a power output less than 2W and switched to DATA mode for a constant carrier.

I attached a power-meter fitted with a dummy load, set the band selector to match the radio and transmitted. With 1.5W in, the amp put out around 25W. Perfect for Foundation License holders!

Brief video showing it in action

 

The next job was to test the lead I’d made up for my ELAD FDM DUO. This went slightly different to the other radios in that the output was around 23W no matter what the output power of the Elad was! Still, pretty much on the money for a Foundation Licensee.

 

TIP : PTT

RING : Not Used

SLEEVE: Ground

 

73, Tom, M7MCQ.