USB powered direct conversion RX

G1INF has a neat idea on his blog for a simple direct conversion RX that is powered from the USB connection of a PC. His application was for LF reception but it would work equally well as the front end of a simple SDR for any HF band, replacing the loop with a bandpass filter. The audio output from the NE602 is connected to the PC's mic connector. Simples!

UK on-line VLF Receiver

There is an on-line VLF receiver on which you can hear natural emissions such as sferics, tweeks and whistlers located at Todmorden in the north of England. As well as a real-time audio stream, it has an interesting way of plotting received signals so you can see the direction of arrival of sferics.

Fivehead QRP SSB transceiver kit

This afternoon Ted G4NUA came around to test the receiver section of his Fivehead 20m SSB transceiver kit from Walford kits in Somerset. I was surprised how small the transceiver was. We checked the RX with a signal generator and re-did the alignment. We then tried it on an external antenna and it was about the same sensitivity as the FT817 and was copying plenty of stations on 20m SSB. Ted has still to finish the TX part. When done it should put out about 1.5W pep.

Warm sunshine and G3XBM up a tree

Today the sun has been shining and it's quite warm so I've been up the neighbour's tree lopping branches so that they don't obstruct the light. It is a field maple and it grows so fast. I took down branches about 4 metres long and these have grown in the last 3-4years. There is also a method in my madness: there's a sturdy branch just the right height to act as a support for the end of my longwire. It's twice as high as the original on the clothes line support. So, when the job is done I'll string out some black PVC covered wire. Also, for the first time this year I managed a cup of tea on the patio: maybe spring really is almost here at long last.

11th country on 500kHz

Just had a 500kHz WSPR report from MW0CVT 250kms to the west of me. This is now my 11th country from which I've had reports on the band. This is also my 83rd unique report on the band.

Amateur DXing below 9kHz (VLF)

Some recent discussion on the LF Reflector is suggesting that distances of >100kms should be workable with amateur stations below 9kHz, albeit running QRO exciters. This would be possible with optimised stations and antennas and very slow QRSS modes. As an example, see the email posted this evening by RA9MB:

I was wonder if it is posible to use a loop on 9 kHz. Serious problem to radiate 9 kHz is high voltage we saw. Loop has that advantage that voltage is not too high. Then i do some estimations. Let's assume vertical loop 15m x 50 m with 20 mm diameter coper tube as a wire. Then effectivity of such a loop on 9 kHz is about -65 dB. It is adequate to radiate 1 mW
on 9kHz (I=250A, TX power about 4 kW). We saw such a radiation should give abt 100 km  distance in QRSS. Besides such a loop is well suited for 136 kHz. On 136 kHz it effectivity should be about -25 dB. Not too bad: 1 W radiation with 400 W TX :-)

QRP transatlantic on 80m

Just got a report from W1XP on 80m WSPR when running just 1W into the 5m long vertical. DX is 5280kms. Report suggests that 500mW would also have crossed the pond.

New Zealand gets 500kHz (for now)

From March, New Zealand amateurs will be allowed to use 505-515kHz. The number of administrations making temporary allocations is increasing all the time now. Expect some ZL-USA (and maybe Europe?)  tests before long on the band. I wonder who will be the first to receive some 500kHz WSPR beacons from the Antipodes?

Australia on 40m QRP tonight

It really is too easy with WSPR on HF.  Last night some reports from Antarctica and tonight a brief 5W transmission on 40m got me another report from VK6POP in Australia. One of my projects is a micropower WSPR beacon for 10m, but it will have to be something like 10mW to be anything like a challenge :-)

First sub-9kHz NoV application with OFCOM

G7NKS has already submitted his application for an NoV to operate below 9kHz. Mine will be prepared in the next few days. Approval (or rejection) may take some time as OFCOM has to consult with the Met Office first. The Met Office monitors <9kHz for sferic activity to track storms and lightning.