UK amateur license changes

Whilst I understand recent OFCOM changes to the UK amateur radio licenses, I am disappointed that power levels have been increased. Having worked all over the world with 10W pep SSB many years ago and now with even better modes like FT8 available, why do we need more power? 1kW linears are VERY expensive, re-enforcing the message that amateur radio needs deep pockets for rigs, linears, towers and beams. 

As I hope I have shown, deep pockets and high power are definitely NOT needed to have fun or work the world. I hope more stick with foundation licenses!! You can work the world, and have far more fun, for the cost of a few pints of beer or a good night out.  

You definitely do not need to spend much money or run loads of power!!

People power - NOT amateur radio

We often have more power than we think as individuals. As an example, a private company slipped in an application for a large gas power station on unused land on the edge of the village. The village council "quietly" nodded it through. It was about a month before most of us found out. Locals were up in arms and very many letters were sent to the district planners. We also found out that some of the data used in support of the application were wrong.

Since the protest, the applicant has reportedly withdrawn the application. The applicant was out to make a quick buck (allegedly) but this was thwarted by people power.

Power to the people!

Power on 10m WSPR

There seems to be an advantage on 10m WSPR with a little more power. VK2KRR was using 10W when I copied him earlier. VK5MR who copied me just once today at -24dB S/N when I was using 2W probably would not have copied me at 500mW. When conditions are good, more power does not make sense as 500mW is enough. When conditions are "just" there, it seems more power helps. So far today I have been spotted just once even at 2W TX. With 500mW I would probably not have been seen by anyone.

UPDATE 2052z:  After a promising start 10m WSPR was a disappointment today with just G spots since this morning.  It looked very promising early on.

A novel QRP power source

FreeCharge 12V is a small, portable generator, similar to that used in portable hand-cranked torches. The output is regulated to give 12-14.2V DC although the product datasheet does not state the available current. I suspect it is in the low milliamps as its main use appears to be to power/charge mobile phones in an emergency.

This could make a novel power source for low power QRP transceivers as no batteries would be required, just a few seconds or minutes of cranking.  Figures given are 360 turns (approx. 3 min wind) gives 9-11 minutes of mobile phone talk time and a 60 second wind gives 2-4 minutes of talk time. Price is £19.99 and it is available from Freeplay or via Amazon UK.

The sales blurb says:

"The Freecharge 12V provides emergency power to a mobile phone, PDA, iPod, GPS receiver, or any other electronic device for which you have (or can get) a cigarette-lighter adapter. Wind its hand crank to generate electricity and put power straight into your device. Never be unable to use your mobile phone, or other important device, just because its battery has run down."

Power harvesting IC - runs off 20mV produces 5V

This week's Electronics Weekly has a link to Linear Technologies new power converter IC (LTC3108) that can run from 20mV and deliver 5V. It is designed to be used with Peltier effect devices and similar sources of low voltages, but it could be used with the DC power derived from a crystal set.

Free power QRPp transceiver or beacon?

The idea of powering a low power receiver, or even a transceiver or QRPp beacon, from free, otherwise wasted, RF energy that is all around us appeals to me. A few people have been toying with this idea and there are even some commercial ICs likely to appear which "harvest" energy from stray RF and even vibrations. The circuit shown here is from the excellent site by KE3IJ (R.Andersen) and shows how to use 50 or 60Hz mains "fog" and stray RF to power a simple receiver. See http://www.tricountyi.net/~randerse/nopower.htm .

See also Ben Tongue's crystal set pages for a circuit using a supercap to store harvested energy which is then used to power a micropower op-amp.

A "harvester" QRPp transceiver or beacon which derives its energy from stray RF, storing this is in a supercap and allowing brief periods of transmission at very low power is worth developing I think. I have not seen such "harvesting" circuits used to power a transceiver or beacon before but for a uW level beacon this should be feasible.

IC703 TX failure

After many years of excellent service my IC703 decided to expire on TX last night: power started to drop when running 5W on 30m then 80m (good matched load), then nothing, although I could detect a signal on the FT817, probably at mW levels.

I believe this is a common IC703 issue. Does anyone have data on how to fix this and where I get the spare parts? I believe it is either a driver or PA failure.

Incidentally Martyn Lynch quoted £45/hr plus parts and shipping to do a repair. I don't expect I'd see any change from £100.

This is the first time in 42 years of operating that I have had ANY piece of amateur gear fail, confirming that generally equipment is reliable if used carefully, so I cannot complain.

ERP estimates on 500kHz

Just got this letter from M0BMU who has estimated my ERP on 500kHz currently .

Dear Roger, LF Group,

It is interesting to make an estimate of what G3XBM's ERP might be...

The noise level at M0BMU during relatively quiet daytime conditions I estimate to be of the order of 3uV/m in the 2.5kHz WSPR reference bandwidth. The reported SNR gets up to about -25dB, making the signal level from G3XBM about 0.18uV/m.

ERP = (Ed)^2 / 49; with E = 0.18 x 10e-6, d = 69000m , ERP is about 3uW with only "geometric spreading" propagation losses. But there is some additional reduction in field strength due to ground wave propagation losses, perhaps 3dB with "good" ground, so the ERP would then become about 6uW. Diffraction losses due to the curvature of the earth are negligible at this distance.

Obviously, this could be +/- several dB due to various uncertainties, but should be of the right order of magnitude. Plenty of potential for improvement then!

Cheers, Jim Moritz
73 de M0BMU

Even lower power success on 500kHz

This afternoon I fired up my 700mW 500kHz WSPR beacon and wet string antenna (ERP microwatts) and got 3 reports from G3XVL at 61kms. So, I tried putting a 6dB then a 10dB attenuator between the PA and the ATU. Even with a power from the PA of just 70mW (never mind what that would be as ERP from the antenna!) he still gave me a -25dB S/N report! These were the three reports in reverse order:

2009-09-14 14:42	G3XBM	0.503829	-25	1	JO02dg	0.001	G3XVL	JO02nb	61	112
2009-09-14 14:40	G3XBM	0.503827	-23	1	JO02dg	0.001	G3XVL	JO02nb	61	112
2009-09-14 14:36	G3XBM	0.503823	-18	1	JO02dg	0.001	G3XVL	JO02nb	61	112

This suggests that just 35mW from the PA would have been enough to span this distance, even with my tiny antenna and poor ground.