More countries on 472kHz

Last night I left my 472kHz WSPR system running through the night and was very pleased to receive SM6BHZ and DF6NM at good S/N at times.

477kHz WSPR DX last night

FT817 speech processor built and working - brilliantly!

DYC-8x7 speech processor tucked under the FT817

This morning I built the Funk Amateur DYC-8x7 speech processor kit that came last week. Total assembly time, taking it slowly, was just 30 minutes with no problems at all. Testing and set-up was easy in the end and the results so far are spectacular.

VHF NFD is running - I'd forgotten this - so this is an ideal time to test the rig with the processor in circuit. Using just my 10m halo - feeder loss is such that it is a good match, if not an efficient antenna, on both 2m and 70cm! - I went on and gave a few points away on 2m and 70cms. Whereas before I would be struggling, contacts came easily. The little speech processor makes a LOT of difference and is an excellent product.

Conclusion: at 34 euros delivered to the UK this represents excellent value for such an effective product.

FT817 speech compressor kit arrives

My Funkamateur BX-8x7 audio speech compressor kit (also known as the DYC-8x7) has now arrived. I was impressed by the speed of delivery and the packaging. The kit looks ideal and straightforward to build. One problem with this design was the RJ45 connector lead, but the latest version has 2 RJ45 sockets already fitted on the module and a ready made lead (with plugs on) to connect between the unit and the FT817. The MH-31 mic simply plugs into the other socket. The actual building should only take about 20-30 minutes.

My only difficulty is in the instructions which is a copy of the original Funk Amateur article  in German. I am hoping someone can translate this for me, or give me a precis with setting up instructions.

Ceramic filters on 472-479kHz?

An eBay seller from Hong Kong has 100 off 472kHz DIP ceramic filters on sale for £5.31 delivered to the UK. See item number 400305093888.

Some filters similar to this have useful bandpass characteristics and acceptably low insertion loss (around 3dB), so may be seriously useful for 472-479kHz rigs and transverters. For example, as a roofing filter to protect a RX after a small gain stage, or as a filter to clean up the output of a transverter at low level before applying a signal to a driver and PA. I guess they must also be useful in a ceramic stabilised oscillator.  Anyone used these in similar applications?

WSPR on the new 472-479kHz band

For the first time I've been monitoring 477kHz USB dial for WSPR signals, hoping to copy some of the Germans now allocated the band. SM6BHZ is on too, but not yet seen.

At 2058z DF0WD was copied at -27dB S/N for my first German WSPR signal on 477kHz at a distance of 556km. I have also heard a couple of other stations from elsewhere in W.Europe who appear to be testing at very low power before the band is officially released in their countries.

500kHz WSPR and OPERA compared

Today I've been comparing OPERA OP4 and WSPR performance by running my QRP beacon in daylight in both modes for several hours each on 500kHz. Theoretically OP4 should outperform WSPR by a few dB, but I am getting roughly similar reports from stations 126 and 210 km away in both modes.

Personally I prefer WSPR because of the neater on-line reporting system and user interface, shorter TX period (2 mins rather than 4 mins) and the fact that more data is being transmitted (call, power, location). Unfortunately only a couple of UK stations have been looking for my 500kHz WSPR signals, so the test is a bit limited.

SAQ VLF tests today

SAQ, the very old alternator TX on 17.2kHz VLF, was transmitting today and was copied as far away a North America. Here are some recordings made in Germany by Stefan DK7FC.

Dear VLF group,

Today the S/N of SAQ was much weaker here in Heidelberg/JN49IK, probably due to the high QRN levels.

I extracted a wav file containing the full message and tests. Can be used for reprocessing if of interest for someone: https://dl.dropbox.com/u/19882028/VLF/SAQ/SAQ_afternoon01Jul2012.WAV (117 MB)

And here is a mp3 file for listening in a normal player (first 2/3 is a test procedure, then the mesage comes): https://dl.dropbox.com/u/19882028/VLF/SAQ/SAQ_afternoon01Jul2012.mp3 (24 MB)

73, Stefan/DK7FC

MF bands and local comms

This morning with my 20mW ERP on 500kHz I worked G3XIZ around 45km away on CW. Chris gave me 569 (on his meter) when using his loop antenna on RX. He was a very good signal here. Earlier I copied the other stations in his net M0JXM and G3DXZ. Yesterday G3KEV was a good CW signal and PA0A was copied later today.

500kHz QRP transverter with ferrite rod ATU on bench

The new 472-479kHz will be an ideal band for local area CW nets: as my far less than ideal set-up here proves, one can work up to around 45-50km without any problem even with very low ERPs. Running 6dB more power from the PA (I currently have just 5W out) will help further.

This afternoon my 500kHz OPERA has reached yet another new station: G8ALS in Coventry 126km away. My maximum daytime range on OPERA OP4 mode seems to be around 220km, although a few more stations reporting may increase this.

500kHz ERP

Using the coax feed to my 10m/6m halo as a vertical I've worked out the ERP currently on 500kHz OPERA. The RF power from the transverter is around 5W from an IRF510.

The 10m and 6m halo lengths correspond to a horizontal capacitance of around 35pF. Some of the feed from the shack to the bottom of the vertical section is horizontal through the loft and this has not been included (I think it may add loss though). The vertical section outside is 6m long, equivalent to a vertical capacitance of 36pF. Using standard formula this means my effective height is around 4.48m.

Radiation resistance then works out as 0.088 ohms.

Measured antenna current is 0.48A (using a current transformer and detector)

ERP = 0.48 x0.48 x 0.088 = 20mW (or lower if the losses are higher).


 

First 500kHz OPERA reports

Having managed to match my 6m long coax feed line (as a Marconi vertical) up to the 10/6m halo antenna on 500kHz by adding some inductance wound on a ferrite rod in the shack, I've just received my first OPERA beacon reports on the band from ON6EO at a distance of 220km and G0KTN at 210km. Reports were -30dB and -29dB S/N which is marginal.