Amateur VLF DXing

Operating an amateur station at VLF is a very specialised area of experimentation. There are basically 2 different threads (1) earth-mode or utilities assisted earth-mode with propagation mainly along or close to roads and (2) radiated DXing in which a VLF signal is actually radiated and propagated to great distances. With (1) I have managed 6km with QRSS3 with 5W from a TDA2003 audio IC at 8.97kHz. Earth-mode gear can be low powered and simple to build.

VLF amateur signals

With (2) the Atlantic Ocean has now been crossed, i.e. quite remarkable distances with amateur powers and antennas. Usually very large loading coils are needed and making these can be "challenging". As high voltages are likely, great care is needed. Of course, most DXing is done with very long stable transmissions in very narrow bandwidths. Most amateur VLF gear is home made with free PC software to allow signals to be seen. Casual listening is not effective.  Most operation is now around 8.300kHz as this is unallocated in many countries.

News of VLF activity may be found at https://sites.google.com/site/sub9khz/ .

6m tropo?

G8EPQ (77km) and I continue to exchange 6m WSPR spots today. Although there is evidence of aircraft reflection, this is probably mainly tropo at this range.   About 1Hz of the drift is due to my rig. When there is a large drift I suspect this is aircraft Doppler shift, so the dominant signal then (that being decoded) is via aircraft. So, probably tropo, but also via planes.

G4BRK (134km) was spotted on 6m WSPR yesterday but not seen him yet today.

Sunspots and 10m - Tuesday May 19th 2015

Sunspot number has dropped back to single figures standing at 83 today.  K=4 suggesting reasonably disturbed conditions. 10m is expected to be "poor" today. I am not expecting great things of 10m today, although some single hop F2 is possible and Es across Europe is always possible at this time of year.

UPDATE 0910z:  So far, the only 10m spots have been from local G4IKZ (18km). No 10m Es and no 10m F2 yet.

UPDATE 1046z:  Still just being spotted by local G4IKZ (18km) and nobody else on 10m.  I see the Southgate News is reporting a moderate geomagnetic storm.   See http://www.southgatearc.org/news/2015/may/geomagnetic_storm_on_may_19th.htm#.VVsVTkZQqPc .

UPDATE 1535z:  Still only G4IKZ (18km) spotting my 10m WSPR beacon. This is a bad day. Otherwise a total blank!

UPDATE 1600z:   K has reduced to 2 (was 4) suggesting conditions are improving. I wonder if we will see any DX this evening on 10m?

UPDATE 1755z:   Indeed a totally dire day, so far, on 10m WSPR with just local spots: no F2, no Es, nothing DXwise at all.

Miracle Whips and derivatives/copies

A 56 inch long whip can only behave like a 56 inch whip. This is a basic law of physics. What the Miracle Whip (MW) and its derivatives do is match this whip on the HF and VHF bands. With a decent ground or counterpoise wire the MW may be only a couple of S-points down on a "decent" antenna on the higher HF bands. They work reasonably well and, in the past, I used my MW quite a bit, even from indoors.  They are definitely NOT a miracle antenna, although they are not too bad.  Since the owner, a Canadian called Robert, died there have been a few newcomers in the market.

Would I buy one today? Probably not. I have had better results with small loops.  As a simply deployed mainly RX antenna they make an ideal companion for an FT817 or similar. Their beauty is their simplicity. If you want optimum performance in a small antenna there are better solutions.  Small loops seem to work better, but then bandwidth becomes very narrow although loops don't need grounds or counterpoises to work well. Personally, at QRP levels I'd use a loop every time.

As Wheeler showed years ago, efficient small antennas are reactive and unless losses are minimised, efficiency suffers. This is a fundamental limitation. Although high permeability ferrites and high permittivity ceramics can help to alter the size of space near an antenna and "magnify" the effective size of small antennas, the effect is small unless there is a lot of ferrite with high permeability or a lot of ceramic with a high permittivity. In theory, a tiny antenna can be very efficient but you'd need superconductors and lossless capacitors!  At the moment, sadly, neither are practical for mortals!

See https://sites.google.com/site/g3xbmqrp3/antennas/mwhip .

10m Es this teatime, but no luck on 6m WSPR Es

It is currently 4.35pm local time and I see that my 500mW 10m WSPR beacon has already been spotted 3 times by IK3JBR (1146km) by Es. I expect several more Es reports on 10m over teatime. Around lunch and teatimes are often good times for Es.

As yet today, no sign of 6m Es, here at least, although I continue to be on both 10m (500mW, 100% TX) and 6m (1W, 20% TX, 80% RX).  At this time of year, arguably, 6m is the more interesting band.  Both are good fun though and filled with surprises.

UPDATE 1800z:  Plenty of 10m Es about and EA8BVP (2986km) has spotted me 26 times today so far by F2 on 10m WSPR, but so far today just G stations spotting me and being spotted on 6m WSPR.

UPDATE 2128z:  Late 10m Es in the form of CT1JTQ (1843km) at 2108z and EA8BVP (2986km) has been copying me all day by F2. However, no sign at all of 10m WSPR spots by USA stations either by F2 or multi-hop Es.  I think it is getting too late, although I shall be on 10m and 6m all night again.

Wallflowers - NOT amateur radio

Wallflowers at Cley, North Norfolk

Last week we were in North Norfolk visiting various churches and the rhododendrons at Sheringham Park. We ate at a pub called "The Three Swallows" in Cley-next-the-Sea. These wallflowers were just outside a house between the pub and the church. At the right temperature these smell wonderful.

Yaesu FT7 HF transceiver

Yaesu FT7 - a true classic

Way back in about 1979 I owned a Yaesu FT7. This was a 10W HF rig using a modular construction.  It was a beautiful radio with a lovely, quiet receiver.  It is probably the best radio I have ever owned and used. It predates WARC bands and only covered one 500kHz part of the 10m band and the non-WARC bands from 80m-10m. Today, it looks large. It was an analogue radio - no memories, no synthesisers - just a very good HF radio transceiver.  I worked all over the world with mine using QRP SSB and simple, low, wire antennas and no beams, mainly on 10m. In those days, most (all?) USA SSB was above 28.5MHz. Canadians were mainly below 28.5MHz.

My little FT817 has more bands and modes and is about 1/10th of the size.

I can thoroughly recommend the FT7, but they are very hard to find.  A later version was 50W pep and had full 10m coverage in 4 x 500kHz sections. The FT7 was a "real" radio - no gimmicks, just a truly amazing rig. Many who owned them and sold them (like me) later regretted selling them. As they say, these rigs are "keepers".  If you find one you are unlikely to be disappointed.  Also, the handbook was complete so you could service it and not an SMA component in sight!

See https://sites.google.com/site/g3xbmqrp3/hf/ft7 .

Jackdaws - NOT amateur radio

Jackdaw

At the QTH we moved to a couple of years back, just before I was taken seriously ill, we see far fewer smaller birds. They are around but don't seem to be attracted to the bird table or nut feeders. We get a reasonable number of small birds in the garden and nearby such as dunnocks (hedge sparrows), great tits and blue tits, robins etc. Maybe they visit other bird tables or find food naturally very locally?

Our nut feeders seem to attract larger birds in the main like pigeons and collared doves. We have lots of trees and other cover. Every morning at much the same time we get jackdaws on the bird table. We have red legged partridges in the road most days and we have even had mallard ducks in the garden.

See http://www.rspb.org.uk/discoverandenjoynature/discoverandlearn/birdguide/name/j/jackdaw/ .

Sunspots and 10m - May 18th 2015

Sunspot number has fallen again to 75 (K=2) and 10m propagation is expected to be "poor". I think a 10m USA opening is less probable today.

UPDATE 0748z:   Early Es on 10m this morning with a spots from OE (Austria) and I (Italy) before breakfast.  EA8BVP has already spotted me many times today. I think this is single hop F2.

6m WSPR and aircraft

Just checked my early spots of G8EPQ (77km) and notice 3 Doppler shifted traces suggesting the involvement of aircraft reflection in the path between us. The path is so regular that pure tropo may support propagation but signals may well be enhanced by well positioned planes on the path with sufficiently low Doppler to allow WSPR decodes.

UPDATE 1058z:  G0OQK (98km) was spotted at 1028z, presumably helped by aircraft.