Saturday, May 16, 2020

Townhouse antennas

My first antenna in the rental townhouse was a dipole for 20m which has been working pretty well. The challenge here is that the windows seal tightly and it's not possible to run coax through them so I had the balun inside and the two legs of the dipole stuffed through the window seal.

One leg ran straight out and the other around the corner to the left. The KX3 tuner is excellent and could match this quite well.

Today I visited Jaycar and purchased some iron powder toroids, some wire and a soldering iron (all my electronics is still in storage). I constructed a QRP 9:1 Unun. (Three turns to 9 turns).

The end fed wire goes out through the window, around the corner, over a citrus tree and is held on the side of the clothes line. This now tunes up well on 20m, 30m and 40m.

Compared to the dipole WSPR reception has worse signal to noise but the addition of extra bands, particularly 40m, makes it a much better option. I'm receiving well and transmissions on 40m are getting out quite well.

I did notice that a ceiling fan turned itself on after I'd been transmitting and I'm worried about affecting TV reception so I'll be receiving mostly until I test that. Amazing what WSPR can do even in very challenging circumstances.

It's Sunday morning and I've been able to listen to the 40m broadcast from South Australia and also from Dural near Sydney. Here's a snippet. It does fade up and down but is mostly audible.


Dick said...

Have you considered the Comet window pass through? It is a flat patch cord with PL connectors...about a foot or so long. I had one for years. Works reasonably well though it should be used in a window that remains shut. No constant open-close. No drilling required It will break down if abused. Not cheap but worth it.

Peter Marks said...

Thanks Dick, I wasn't aware of those. I have been thinking about making the glass the dielectric in two large capacitors with thin copper on each side. Perhaps passing copper tape through the rubber seal would be better.