Thursday, 28 January 2010

Short Distance 500kHz Success

After a bit of discussion on 70 cm this morning, we talked through Spectran and WSPR settings and use. I was convinced that any wire antenna in an FT817 would produce some signals on 500kHz. With 6Km between us G3KAN had just got to see more than just a 30 second burst of my QRSS.

At 14.22 we made it, using just the wire in the rig, the signal -15dB.

2010-01-2814:42 G3ZJO 0.503820 -15 0 IO92ng +17 0.050 G3KAN IO9226

A run of 4 Spots followed, then some screen shots by e-mail. It will be interesting to find out how long the RX was on for when we talk again. I am intrigued by the possibility that short periods of enhanced propagation bring signals up to a usable level on a poor antenna at short range.

Activity on 500kHz Increasing

500kHz (600m) Activity is increasing slowly as more stations in more countries get active. Once your Antenna efficiency RX or TX reaches a certain level the circle of possible contacts expands. The number of of stations logged quickly get to a level and new ones are slow to come in.

I am pleased to have a report overnight from the POLICE, well the call always looks like that and makes it memorable, I think, let me try, PA0LCE, yes that's right at 423Km and -33dB on WSPR so right on the edge of de-code-ability.

There are several more bridges to cross. Local stations at 5 to 6 Km and 15 Km who report, no see, although there may have been an odd 30 seconds of good signal at 6Km the other night, not enough QRSS to be sure. These local distances intrigue me.

Wednesday, 27 January 2010

500kHz QRP Sucessful Station

After much experimentation I have settled on a set up for 500kHz that is giving me some good success.

The Antenna is an Inverted L, 6m Vertical and 8m Horizontal. The more Top Loading wire the better, however I don't have the space for several top wires. I added a lumped capacitance in the form of a disk 270mm dia and wire spokes.

The Loading coil is quite a large diameter wound with Silver Plated PTFE Insulated wire.

The PNP NPN pair PA produces some 500 or 600mW of RF at 50 Ohms. This gives an ERP of 200 to 275uW.

Results mainly using WSPR has brought reports from 32 different stations in 7 Countries.