QRP End Fed Antenna Common Mode

LDG includes great instructions for the beginner

As it turns out – the smoke detector had a weak battery and was beeping at a timed interval. However, I made sure the counterpoise wire was moved away from the coax feed because you don’t want coax right next to the transmitting wire antenna if you can avoid it.

The Balun Designs 4130 QRP 4:1 unun

It still is a good idea to use a 1:1 current choke on the coax before it enters your shack / tent / RV / cabin or other radio room. I haven’t experienced any common mode noise on receive, so separating the counterpoise away from the coax is a great idea. This is one time where adding beads to the coax would be as good as purchasing a 1:1 current choke. Several coils of the coax and a snap on choke or two would most likely take care of any common mode – especially at QRP levels.

I do know that with QRO – you can’t get away with such an antenna. I remember trying off center fed dipoles and probably an end fed antenna – and even with just 100 watts, I do remember having such bad RF in the shck that I swore “never again.

But I’m still amazed at what 10 watts is doing up and down the West Coast with the local nets on 75M – I was able to check into another net this morning – with net control in BC – at the boarder with US and Canada – about 375 miles away.

OK – I will check out the LDG 4:1 and 9:1 unun’s today – after lunch and before we get dumped on with a foot of snow and drifts.

2 Comments on “QRP End Fed Antenna Common Mode

  1. Hi Rich,
    Let me know if you want to try a sked tonight or tomorrow(CW/SSB), I prefer CW 🙂
    Enjoy the PNW and Thanksgiving.
    Jim. K6JS


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