Tuesday, July 16, 2013

Building the AlexLoop Clone

I am one of those guys that would rather strike out and try to build something myself - it is actually part of the hobby I enjoy the most.  Plus the idea of dropping $$'s on an antenna just kinda turns my stomach!

The first thing I did was gather the parts.  I used LNR-400 coax for the main loop.  Some 10 gauge wire for the small loop and some RG8 for the coax to the rig.

I also purchased a variable capacitor from Midnight Science - it is a single gang.  I probably should have purchased the dual gang - and probably will - more on that later.  I also picked up the reduction drive from them.

Here is how it looks right now all set up:

It is a really slick setup - the grey pipe is simply plastic electrical conduit - everything is simply attached using wire ties.

Inside the "black box" - the air variable capacitor, reduction drive and coax connectors for the loop coax.  If you look closely you will see that I ran a short wire from the center to the ground on the coax connectors.

It is all fine and dandy BUT I can't get the darn thing to tune!  At first I thought it was the feed loop not being built correctly - and I was right!  However, after rebuilding the feed loop the thing still won't tune.

I can almost get it tuned on 10 meters - down to about 3:1 - but the capacitance introduced by my hand turning the capacitor is horrible.  I have read that if you use a 2 section capacitor this problem is reduced.  Once I can get it working with this capacitor I might invest in a 2 gang.

I really think it comes down to the feed coax at this point.  There is just not much else that could keep it from working.  I am going to rework the connector and see if that fixes it.

Right now I have it all set up looking really cool - but it does absolutely nothing! :)