Saturday, October 24, 2009

First 500KHz WSPR spots

This evening I received my first WSPR signals on the 500KHz band. Strong traces were regularly received from SM6BHZ 1000km away, while G0NBD 135km away in Cheshire was also received several times at around the limit of readability. Just at the moment of publishing this post a trace from OR7T, 679km away, appeared. Perhaps I'll catch fellow blogger Roger G3XBM soon!

The receiver was my Elecraft K3. The antenna that made this possible was the latest addition to the G4ILO shack, a PA0RDT Mini-Whip.

This remarkable active receive-only antenna is small enough to hold in your hand, and is currently suspended from its feeder hooked over the curtain rod above the shack window. I shall probably write more about this antenna later.


GW0KIG said...

Hi Julian

That PA0RDT antenna sounds really interesting. Was it a home brew or a commercial unit? I tried Googling it but didn't get much info.

73 de Kevin

Unknown said...

It's made by PA0RDT (roelof [at] ndb [dot] demon [dot] nl). He doesn't have a website, I don't know if he has an information file he can send you if you contact him. It cost 45 Euro post paid to UK.

It covers VLF to 30MHz and the performance seems pretty amazing for its size. I really want to spend more time with it though before making any more comments on it.

Anonymous said...

This PA0RDT mini-whip antenna sounds great. With its flat response from LF to 20+ MHz it appears it would work well as a noise antenna for your MFJ noise cancelling box. It would be one less knob to adjust with your present tuneable noise antenna. It obviously works fine with your WSPR test on 500kHz and with such a small pick up aerial built in.

This seems a worthwhile project for home construction, yet another one for me to add to the list Hi Hi.

I look forward to seeing your further experiments with this device.

73 de Maurice G4DVM.

Unknown said...

I did think the mini-whip might be an alternative to the MFJ noise canceler, if I could put it in a place where it did not receive the noise. However after some wandering about with the FT-817 and the mini-whip running from a battery I could not find any place within the boundaries of my property where the noise was not present to some extent.

I did also consider the possibility of using it as a noise antenna but the small loaded vertical I use as a noise antenna receives more noise and less signal than the mini-whip which is really what you want. Tuning the antenna isn't difficult, fiddling with the gain and phasing is, and you can't eliminate that.