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/ .

CB to ham

From Steve G7VFY:

Good use for old CB's.

There is a Yahoo group, CB to ham.

https://www.youtube.com/watch?v=oYoI2Q7O3zU

Stephen Walters

G7VFY

VLF amateur radio

Being involved in VLF amateur radio is a very specialised activity requiring special (but low cost) kit to be successful. Casual listening is highly unlikely to be successful. Long distance reception of amateur VLF signals usually involves looking for signals using Spectrum Laboratory software locked to a VLF MSK signal so that very narrow bandwidths can be looked at for hours or days on end.

Most amateur VLF tests are done on 8.27kHz as this is unallocated spectrum in many countries.

News about amateur VLF activity can be found at https://sites.google.com/site/sub9khz/ . There has been very little amateur VLF work done this year but amateur VLF signals have crossed the Atlantic.

Tests using utilities assisted earth-mode do not involve big loading coils. Just under 6km has been achieved with just 5W using this mode, before I had my stroke! The kit was simple too. See https://sites.google.com/site/sub9khz/earthmode .

One of the things I am really looking forward to, when fit again, is some more field work with VLF using earth-mode.

My 1990s station ...and clearing out

Whilst sorting through my collection of SPRAT magazines to give to a local amateur G4NUA - I recently bought the SPRATbook and have most on DVD - I came across this photo inside one of them. It must have been taken around 1992 I think and shows the amateur radio station I had then. What is interesting  is that I actually had a 100W radio (FT747) at that time, although it was hardly ever used at that power because of the problems with RF feedback into the rig. The shack then consisted of a table by the window in our main bedroom. My wife must have been very tolerant!

The 10m Lincoln President, derived from a CB radio, was actually a very nice radio: I recall working mobile with it and having a solid SSB QSO with a station in India early one evening around the 1990 solar maximum whilst driving near Cambridge. It was sold long ago though. The little Mizuho MX2 (I still have one) was used to drive a 10m transverter and I worked plenty of 10m DX with it and around 1W pep to a vertical CB halfwave. The Standard handheld rigs came from my workplace: at one time we were considering OEM-in of PMR radios from Standard (before they joined with Yaesu)  and one of my colleagues got a pile of samples on a trip to Japan. Guess who got some of them after they had been "evaluated"? In the end we got some portable PMR radios from a source in South Korea and that was a disaster.

Today I have far fewer transceivers - all QRP - but get just as much fun. There are no homebrew rigs in this 1990s picture although I did have some. Today quite a lot of my kit is home made, although not all rigs remain in their cases for too long as I tend to note the schematic and take a few photos, then reuse parts and enclosures.

Some ham books of mine on eBay

Today I've put a few of my books for sale on eBay. They include RSGB and ARRL handbooks. If you are interested do take a look. If you live in the Cambridge area and want to pick them up locally then there will be no postage to pay. See http://myworld.ebay.co.uk/rlapthorn