Indoor magnetic loop experiments – March 2009

 

Together with Wouter PA3WEG I started building a magnetic loop. Main goal is to be QRV on 80 and 40m SSB from my present QTH, where I cannot put up a 4 square hi…

 PA3WEG’s magloop experiments can be found here

 

The experiment started with a trip to the local DIY store, where we bought all available 22mm diameter copper tubing, and took it home by bike.

As usual, the first (QRP!) trials were done in the living room.

 

The loop blends in nicely with the living roomJ

 

Coupling loop detail

 

Tuning capacitor detail

I got this nice split stator tuning cap from Gert PG5D (formerly PA0NZH)

Range is 13-85pF

 

Before this cap, I used a small normal variable cap, which resulted in arcing at power levels of 10W and up. PA3WEG made a small movie of this which you can find here.

 

After these encouraging results, and after getting annoyed with the large amounts of copper in the living room, I moved the loop to the bedroom.

There’s a loop in the bedroom… with a nice scenic view over the city of The Hague.

 

Since the tuning capacitor has a relatively low maximum capacitance (not enough to resonate the loop on 80m) I made a parallel capacitor out of Aircell-7 coaxial cable. Furthermore, I improved the connection to the copper tubing

Low resistance tuning capacitor mount.

 

The loop is now used to make QSO’s mostly on 80m SSB using modest (<50W) power levels, which allows QSO’s all over The Netherlands and parts of Europe.