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Fun With Amateur Radio

Roger Lapthorn

G3XBM�

Feb 8th 2023

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Topics to cover

After effects of my stroke on experiments
Amateur radio is what you make it
QRP in general
8m
23cm
4m
10m WSPR
630m WSPR
VLF
Optical 481 THz

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That Darned Stroke

Up until Sept 2013 used to enjoy “in the field” experiments.
Still enjoy the hobby, but mainly from home.
Do what gives you fun.
Very diverse hobby.

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QRP

Usually taken as 5W, 10W PEP SSB
Rarely run more than 10W PEP
10m DXCC with 10W PEP SSB achieved in the 1980s with very simple antennas.
Each to their own - QRP is not for everyone!

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8m (40 MHz)

Why?

Boundary between HF and VHF.
Most propagation modes.
Antennas small.
QRP capable of really working, although QRO helps!

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8m (40 MHz)

NOT amateur radio - why?
Military veto?
RSGB against?
OFCOM and FCC seem anti. Why?
Official Secrets Act?

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8m (40 MHz) Proposals

Digital only (WSPR, FT8, QRSS, CW, no speech)
40.680-40.685 MHz (just 5 kHz)
By NoV only
Time limited
Strictly no interference
Definitely not “more of the same”
OFCOM, RSGB, and FCC against - military veto?

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8m without a licence?

Legal in UK?
10mW WSPR beaconing.
ISM band 40.66 - 40.70 MHz.
Technical requirements and IR 2030 must be met.
Not a legal expert.
Proved locally with WSPR.
Es in spring/summer 1500km.
Amateur Radio, not the Amateur Radio Service
OFCOM’s position.

Following discussions with OFCOM, there may be a way around. It look like operation in the ISM 8m band (40.66-40.70 MHz) is legal without a licence for beacons, but not for communications as long as the technical requirements and IR 2030 are met. In the UK, this means 10mW ERP which does not sound much. Local tests (thank you) have proved that even with this power on WSPR then local ranges can be covered. In Australia a 5mW 8m WSPR beacon has been copied over 5000km away! This suggests anyone at all could put on an 8m WSPR beacon and be copied by sporadic-E in Europe or by F2 even further! This is not the Amateur Radio Service, but very much amateur radio. Callsigns can be made up. For my local tests I used 8M3ISM. You must use a callsign that will be recognised by WSPRnet so you can see where you are getting.

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8m (40 MHz) - what is possible?

3 continents and 18 countries so far with 2.5W (or less) and a low dipole
People with better ERPs copied in South America and South Africa
Mods to rigs can be simple

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23cm

SG labs (Bulgaria) 2W transverter

2 element test antenna
First QSOs
UKAC
Aircraft scatter
Serious DX?

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23cm Transverter

The SG Labs transverter is highly rated.
2W PEP.
Comes with 2 element test antenna.

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23cm Test Antenna

Test antenna supplied with transverter.
Made from PCB material.
2 element
SMA connector.

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10m WSPR TX 500mW

Totally self contained WSPR TX smaller than a pack of cards.
No PC needed.
Use when 10m antenna available.
WSPRnet +WSPR rocks.
More 10m WSPR activity than expected.

One of the things I have had for many years is a small 10m WSPR beacon made by W5OLF. This is about the size of a pack of cards and puts out 500mW. This has been copied on every continent including Antarctica. No PC is needed. I just sync time with an atomic clock. The radio pips would do at the start of the day. Whenever the 10m antenna is free, I tend to use it. With a package like WSPRnet, you can see who is getting you. At the moment, stations in the USA copy me most afternoons. Many stations prefer FT8 these days, although over 20 unique stations copy me most days on 10m WSPR. WSPR signals only need 6Hz of bandwidth and work with very weak signals, far weaker than CW. Just 200 Hz of spectrum can fit in a lot of signals! FT8 needs about 50Hz bandwidth and is not as sensitive, although it will still decode signals much weaker than CW.

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10m FT8

More popular than WSPR now.
Wordwide DX QSOs veen with QRP
Better than CW
No chatting
DX chasing
Small antennas

FT8 is like Marmite in that some love it and some hate it. As my voice is poor, I quite like FT8. It allows very basic contacts to be made even with simple antennas and low power. With tools like PSKreporter, available free on the Internet, you can see who is receiving you, even if they go back to someone else. It is not a mode for chatting although JS8 allows this. Some people think it is just PCs talking with PCs. On order is a QDX transceiver from QRP Labs. This covers 20-10m with QRP. With it, I am sure the whole world can be worked. The photo shows my 10FT8R FT8 receiver. It uses very low cost 14.060 MHz crystals. The whole RX is very low cost and simple. It would make a nice club project on a simple PCB. It would surprise me if it cost more than £10 buying all parts new. Frees up main rig so you can monitor 10m FT8 in the background.

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10m AM

What is possible?

29.0 -29.1 MHz.
Old AM rigs - beautifully modulated.
AM on modern rigs.
High sunspot count.
Different.

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4m

Homebrew transverter - QRP
No antenna yet
European countries now
Range good within UK
FT8
Halo?

My first outing on 4m was at university in 1969 working ZB2VHF with 4W AM with a modified WW2 rig. Later, I went /P with work friends in April 1971 when it was freezing. In those days it was all AM. Until recently, my only access to 4m was with my homebrew QRP transverter. With just a wire dipole some quite interesting UK contacts were made. Now there are many European countries on the band (it used to be just UK, Eire and a few “British” places abroad). Recently I tried again on FT8 RX with my 6m vertical, but managed all over the UK and a few stations in Europe by sporadic-E. Now I have an FT-710 and I hope to erect a halo and take part in some UKAC activity sessions on 4m. Even my big-wheel antenna and coax will match to the rig on 4m with the auto ATU in the FT-710, so I can access the band for now. I have no idea of the gain, polarisation or directionality of this “ad hoc” arrangement.

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630m WSPR

Earth rods in ground typically 10-50m apart.

or

One earth rod at a distance + connection to house metal water pipes (depends on earthing system).

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630m WSPR results

Amazed at results with earth-electrode antenna.
10mW ERP .
DX to Norway most nights on QRP TX.

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SM6LKM’s VLF Receiver

Runs on PC.
Just needs input from antenna/preamp.
Tunes 0-22 kHz with mouse.
Others available now - check internet”

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Spectran

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Spectrum Laboratory

Complex and powerful program.

Plots spectrum view of signals received.

Allows reception for days in very narrow bandwidths.

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What is “Earth-mode”?

Communicating through the ground via conduction/induction

Signals attenuate very rapidly (inverse cube law)

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Earth-mode Concept

VLF signal injected into the ground or water

Detected as a weak potential difference (or H field) at a distant point

Conduction or induction?

Some question theoretical explanations

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Earth-mode Transmitter

HF crystal/divider

K1EL keyer IC

TDA2003 5W PA

VLF ATU

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My Earth-mode Test Method

Set TX running at home in CW or QRSS beacon mode into earth electrode antenna

Check current in earth-electrode “antenna”

Go out with /P antenna and PC

Spectran or Spectrum Lab software used to find signal

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2.5km on 0.838kHz

0.838kHz ULF signal at 2.5km – strong!

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5.1km on 8.76kHz

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How far can you get?

6km so far with 5W QRP TX at 8.76kHz in 11mHz DSP filter
River and sea coast DX tests were planned

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WSPR on 8.97kHz

G6ALB received at 3km by WSPR (40W)

Reception was possible with handheld E-field probe in upstairs shack

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Optical Tests

My thing was over the horizon beaconing. This is sometimes known as NLOS (non line of sight)
Ranges of almost 9km were achieved.
Simple gear.
No signal in the sky and inaudible by ear.
481 THz red LEDs
100mm lenses.

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Optical Line of Site

One QSO on 481 THz over 11km.
With Bernie G4HJW.
AM TX

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Optical Line of Site

This was the gear used for the 11km line of sight QSO.

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In conclusion

Have fun.
Do what YOU enjoy.
Remember, this is just a hobby!

Sorry, I cannot answer questions!