Tag Archives: atu

How to use dual coax feeders as ladder line

palstar-at4kHaving recently taken delivery of a Palstar AT4K manual tuner, I was keen to get her into production to replace my CG5000 in the attic.

Problem: the route to the attic from the shack is complex but I have a number of spare coax runs going that way including a couple of RG58 cables that I installed about 10 years ago as backups. Actually I originally installed three RG58 lines but I’ve been using one of them to send 12V up the line to the ATU.

parallel-cox-to-ladder-lineAfter MUCH research, I finally used about 20 feet of parallel coax feeders, connecting ladder line to both ends. To clarify, I run about 12 feet of ladder line from the ATU to the parallel RG58 cables. I soldered the ladder line to the inner core of the RG58 coax and shorted the braid-to-braid. My 20 feet of RG58 runs to the attic, through walls, up ceilings etc and in reverse, I connected the ladder line to the RG58. Again, I shorted the braids of each line to each other with a solder blob. My ladder line then has another run to the feedpoint of a large 60m loop that runs through the attic and around the garden.

The results have been quite amazing. Comparing my 40m reference dipole to the the CG5000 (SG230 type) ATU feeding the 60m loop has always shown that the loop was about an S point lower than my reference dipole for most stations.

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Antenna -v- High Wind

Movie IconWas I QSB this afternoon on PSK31? Probably!

(Can’t get video to play? Right-click and save it to disk first! Don’t ask :)

In the main, we’ve all heard that wind normally beats antennas when it comes to staying up. In case you haven’t ever seen a cheap fishing rod blank in high winds, have a look at this. I call it a 10m vertical, in fact this one is only 8m. The matching is done at the feedpoint with an SG230 and 9 raised radials. It’s a temporary antenna. I’m just testing it out for fun. The 12m beats this by a fair margin on the 40m band.Anyway, enjoy the little film!

By the way, don’t be fooled by the helically wound look. It is hardly that. Here’s a real helically wound vertical from a couple of years ago – and this one does tune on the 40m band without help from an SG230. It is directly fed with coax:

73

Callum.