Saturday, August 1, 2015

A coaxial air-core balun

Today I posted a video describing an air core balun I built:

I wanted to post it here so that you guys could see it as well in case you don't subscribe to my Youtube channel (you should be!).

It is made of 25 feet of RG-6 coiled around a 5 1/8" form.  The form is a 4" PVC pipe coupling (it measures 5.125" on the outer diameter) and the coax is the "fancy" quad shielded coax.  I got both at Lowes but you can find them at Home Depot or whatever your local big home improvement store is.  The coax was from bulk and 25 feet was only $7.25 (29 cents a foot) and the coupling was $2.10.  Of course cost to put it together depends on your junk box - I had a pair of Amphenol PL-259s on hand so that's what I put on.  I followed the method I showed in a previous post for connectorizing RG-6.

Initial results seem to show a reduction of RF in the shack but I'm still having problems with my powered Logitech speakers making thumping noises when I key and unkey the radio.  It must be coming from the mixer board because when I have the speaker input unplugged, there's no noise.  Tackling RFI is no fun.

So if you guys have any suggestions aside from ferrite beads - already have those everywhere - let me know!