31 Jan 2013

TXing with a ferrite rod antenna on 7MHz

Just for fun this morning I tried WSPRing on 7MHz using JUST a ferrite rod wound coil and a 365pF tuning capacitor as a tiny loop antenna sitting on the desk. All other antennas and grounds were disconnected fully. I used one of the low tap positions to find a 1:1 SWR position and put the FT817 on 2.5W (3 blobs). The rod did not get warm. The wire used is around 0.5mm enamelled copper with around 60 turns, tapped at every few turns at the cold end.

The ERP was very small, although I have not yet measured it. To my total amazement, I got an immediate -24dB S/N WSPR report from OZ7IT in Denmark at 853km. Just proves how incredible WSPR is and what a powerful tool it is for simple experiments like this.

Ferrite rod TX antenna on 7MHz WSPR - it worked!


Anonymous said...

Very good, Roger.

ERP?? :)

'73 de Ik7FMO - Richard
SE Italy

Julian Moss said...

That's incredible, Roger.

Julian, G4ILO

PE4BAS, Bas said...

Ever tried to TX on a dummyload Roger? This is absolute amazing. 73, Bas

Steve L said...

Now that's interesting.. you may have started a ball rolling here...


Anonymous said...

You may be coupling into the local wiring around you and thats helping things along,