10m QRP (2W) AM DX QSO

The excellent conditions on HF today

Just worked K1IED in Connecticut when using 2W AM to my halo antenna. The 10m AM segment is busy with some good signals from the US and Canada. When 10m AM is like this you just know 10m is wide open.

Although K1KW was an excellent AM signal I was unable to get through the pileup on AM to work him.

The very poor quality video below shows K1IED's 10m AM signal a few minutes after I worked him.

Simple 10m AM transceiver?

Yesterday, someone suggested that I build a simple 10m AM rig. Now clearly the best option would be a DSB transceiver for which I have many of the ideas clear in my head and implemented in my WISPY transceiver for WSPR.

However, I think it would be fun to make a 10m version of my Fredbox and Sixbox QRP AM transceivers. These are to be described in an article in Practical Wireless. For local nattering I think more output is needed on 10m, probably 1-2W AM. A low level series modulator followed by a single stage linear amplifier is a simple way to go on TX. For receive, a super-regen receiver would be fine for local use when the band is not busy. This is 75% of the time at least and almost 100% of the time in the evenings, most times of the year. It would be unsuitable when the band is very active, as currently during the day. A better AM receiver could be built, but nothing beats a super-regen for elegant simplicity, as long as it has an RF amp to isolate it from the antenna.

Maybe this is a quick project for a few autumn afternoons. A few watts of AM on 10m should span several miles locally with a vertical or a dipole.

472kHz Transverter Updated

A few people have now successfully copied the transverter design. I have just updated the webpage describing it and corrected a few errors on the schematic. Also, I have shown an additional low pass filter on the output which is prudent. It should not be necessary with a sharply tuned short Marconi or loop antenna.

See https://sites.google.com/site/g3xbmqrp/Home/472khz-transverter for the updates.

Rev H 472/500kHz Transverter Schematic (click to enlarge)

Petrol from air and water???

The BBC Business page carried a story this week about a company in NE England that is developing a technique to produce petrol from air and water. This sounds like something too good to be true, but if scaled up to production levels could be something remarkable.

"A British firm based on Teesside says it's designed revolutionary new technology that can produce petrol using air and water. Air Fuel Synthesis in Stockton-on-Tees has produced five litres of petrol since August, but hopes to be in production by 2015 making synthetic fuel targeted at the motor sports sector. The company believes the technique could help solve energy supply problems and curb global warming."

See http://www.bbc.co.uk/news/business-20003704 .

Another 472kHz transverter copy

LA5VNA's version of the G3XBM 472/500kHz transverter

Steinar LA5VNA has built a copy of my 472/500kHz 10W transverter and showed a copy of the design on the RSGB LF reflector today. Like G3ZJO, Steinar's is giving over 10W (more like 15W) output. To my knowledge there are now 3 copies of this design built and working. I recommend the addition of a second low pass filter to improve the harmonic content. The one from GW3UEP's QTX transmitter would be ideal (2 x 6n8 caps and a 15uH inductor).

IC7100

As yet, I have not heard any more firm news on price and availability of the IC7100.  There was a rumour that the US price was going to be around $1875, but I have no idea where this figure came from. If correct, it sounds far far too much.

Although I am a QRP person, this rig does appeal to me: the very comprehensive band coverage (including 4m) would make it a good main station radio. With the IC7000 being just over £1100 I would expect the IC7100 to be somewhat more than this, at least at first, but not as high as the figure above which would translate to around £1875 with import duties, VAT and dealer mark-ups.

IC7100 - will there be a QRP version available in the USA and Europe?

What would be really nice would be an "IC703 version" of the IC7100 i.e. a 10W pep version. Now if Icom  produced one of these a lot of QRP enthusiasts would sit up.

10m comes to life big time

This afternoon I took a look on 28/29MHz and the band was WIDE open. We are close to the sunspot peak - some would argue just past it - and at this time of the year conditions on the higher HF bands are at their very best. If you have never worked on 10m get on now (especially for the CQWW DX SSB contest next weekend!) and enjoy it whilst it is so very good. In 5 years from now the band will be very very different with just the occasional African and South American openings and Es propagation.

K1IED who worked many QRP AM stations on 10m today

When conditions really are this good, I recommend listening 29.0-29.1MHz for DX AM stations. Today there were some excellent AM amateur signals to be heard from the USA and Russia. K1IED was S9+ with his 250W to a big beam and he managed to work several QRP stations from Europe. In the past I have worked the USA with a few watts of AM but time prevented me having a decent try today. Andy G0FTD managed to work him with just 1W. You can see his video here.

Listening to 29.0-29.1MHz AM when the band is in good shape is like entering a time warp taking you back to how amateur radio sounded in the 1950s and early 60s. Wonderful.

Just maybe DX on 8.9755kHz?

Last week G3WCD, who is 32km from me, monitored my very long carrier VLF transmission to see if he could detect anything. I transmitted a continuous carrier for a day with a 1 hour break during the period. On his 45uHz bandwidth VLF grabber he noticed a signal (me?) very close to my stated frequency that disappeared the day after, when I was not transmitting. So, starting late tonight, I am repeating the test with an even longer continuous transmission (days if need be) to see if the carrier re-appears on his screen. Should the signal appear, I will drop carrier for a day or so and then re-key the TX to see if the signal re-appears.  At this distance I would be very surprised if anything would be detectable, but this is certainly worth this second, longer, try. Chris G3WCD has a VLF grabber at http://g3wcd.bplaced.net/.

Mixed result on 8.9775kHz today

Earth-mode test results. Distance to "best DX" location 6km NW of TX

Today I tried a few new things:

(a) A larger coil for RX: 12 turns on a loop with a diameter of approximately 3m, that could be placed on the ground.
(b) Transmitting a callsign in 10wpm CW followed by a 60 second carrier.
(c) Trying to pick up the signal at new locations.

Results were mixed:

The larger coil is really no better than the 80cm 30t coil placed on the ground. I was hoping it might be better. Failure!

Although I tried several locations in a new direction (SW) I only managed to copy my beacon signal at one new test location 4.4km away in the village of Swaffham Bulbeck. Tests at a closer location in that direction gave no copy at all. Also tests at 3 more distant locations (max 7.5km) were complete failures with not the slightest hint of anything there.

Much weaker signal copied at 4.4km SW today (nowhere near strong enough for QRSS3)

The trick of sending 10wpm CW followed by a long carrier worked: when the signal was weak it could be copied on Spectrum Lab in narrower bandwidths than I use for QRSS3 as the dash is 20 times longer. This helped me positively ID the signal in Swaffham Bulbeck. On QRSS3 the signal would have been lost in the noise. Best signals appear to be out in the Fens to the NW and to the south (on the chalk hills). I have still to try NE with sensitive kit.

I am still totally puzzled by how the signal propagates through the ground. Placing the loop right over water pipes in the road failed to detect anything where I expected copy at about 4km SW, and the one successful location at 4.4km  SW was on a corner of a road close to some overhead (11kV?) lines but not near water pipes as far as I know. So, I tried other places close to these overhead cables and copied nothing! There must be something that is common to all successful places that is not there helping the signal at other places. I am still trying to think how to find what this is!

I am extremely doubtful of success on these DX tests we are running over the next 24 hours judging by the mixed bag of result very locally. Certainly it will require the very narrow bandwidths to see anything at all from the miniscule radiated component.

KX3 in stock at Waters and Stanton

I read that W&S now has the Elecraft KX3 in stock for immediate delivery. This is a far cry from the 8 month lead-time when deliveries first started.  The supplier is  taking a profit from selling the units, but at least you know the price. My experience when importing kits and parts from the USA into the UK is that the import duty and VAT and Parcel Force "handling charge" (a rip off!) can add a significant amount to the final price, and a degree of uncertainty.

I am still tempted by the KX3. It is many years since I last bought a commercial rig and this one, although expensive, does tick all the boxes: small, 10W, excellent SDR receiver, coverage to 6m (soon 2m), auto ATU, speech processor., etc.

Maybe?