An Easy All Band Dipole for Elecraft Owners September 16th, 2013
I have been a long time fan of open wire feeder, not so much because it has a very low loss even over extremely long lengths, but also because it is a great way to make an all-band dipole. Take any random length of top section, and provided that it measures more than around 3/8th of a wave or so on the lowest band, you can make it work on all other higher bands. The snag, if you can call it a snag, is that you need an ATU in order to match it to your radio’s preferred 50 Ohm unbalanced antenna output. And the traditional way to do this is to use an ATU that will handle balanced line. It is another item to adjust unless you use an auto ATU such as one of the MFJ models. However there is an alternative way if you are fortunate enough to own an Elecraft transceiver.
Elecraft provide the option of an internal auto ATU in all of their transceivers. But it is not a normal ATU that you find in the majority of commercial transceivers. The Elecraft models have the ability to match a much wider range than any other internal auto ATU that I know off. This offers the possibility of doing a lot more with it.
At my station I run a balanced wire feeder back from my dipole into the radio room via a velux window. The balanced line I use is 450 Ohm ladder line and I simply trap it in the Velux window. I have used this method for several years and had no problem with the feeder being broken. My little KX3 transceiver has an internal auto ATU and that leaves me with the problem of having to terminate my balanced line with the KX3. This I do with the aid of a Watson 4:1 balun. Then I take a very short length of coax cable from the balun back to the KX3 and the ATU does the rest.
My antenna is around 35ft long for each leg and it works fine on all bands from 40m to 6m. The radiation pattern is something that you would need to model in order to see what it looks like, not that there is much you can do about it. However, as my antenna is only 20ft high and I live in a typical heavily populated suburban road, there is not too much point in worrying about this aspect. On the lower bands there is good high angle radiation for short distance sky wave, and it gets lower as the frequency of operation is raised. What more could you want for a small garden? Some would say an Elecraft transceiver. I would be delighted to oblige an introduce you into the world of Elecraft. Peter G3OJV.