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

IO92

26

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.

Some preliminary results on 500kHz with Litz Loading Coil

It is early days yet and only one station that is known to receive me, G7NKS has been active.
G7NKS is equidistant from G3ZJO and G3XBM and at reciprocal angles.


This is useful in theory. Previously I had compared the only available reports from signals not received at precisely the same time, this one is from 06:16 this morning thanks to WSPR net.

2009-12-12 06:16 G3ZJO 0.503810 -24 0 IO92ng 0.05 G7NKS IO92ub 46 120
2009-12-12 06:16 G3XBM 0.503865 -6 0 JO02dg 0.001 G7NKS IO92ub 46 240

Indicated Power levels should be disregarded G3XBM quotes an Estimated Radiated Power, I quote a QRPp Input, neither can be taken as exact. G3XBM runs 5Watts of RF, I run 160mW, this is 15dB less. The signal at G7NKS shows 18dB difference. I shall work more on my Antenna to see if I can eliminate the 3dB now apparent.

500kHz QRPp

I decided to try QRPp on 500KHz. I have run my Low Power MEPT's with WSPR on HF and VHF / UHF with good results.
I then developed the XORgan which uses 2 Crystals and an XOR mixer to produce WSPR code at Audio frequency for PC Less and thus lower power consumption WSPR.

The XORgan led me to try the Hypersonic XORgan using the same method to directly generate WSPR, QRSS and Hellschriber at a very very high Audio frequency :-) 500KHz in fact.

I added a one chip Buffer / PA stage so that in just 2 chips I have a complete LF Transmitter with an RF Otput of 160mW. Existing stations on 500kHz were geting good results using 5Watts from their TX's and WSPR. I reconned I could get usable results with my 160 mW (15dB less power) so that was the basis for my Experimental Permit.

Quite rightly some advice said that on LF if you have a little Antenna Loss it is no great problem as you can just use a little more power to compensate. On the RX side there is little need for a super efficient Antenna. At my QTH I dont have the possibility for a very good Antenna so I have to make the small set up I have as efficient as possible. With QRPp there is nothing available to waste.
Up to now results have been quite encouraging. Antenna tests continue, more on that and the results later.