Peterborough Talk - Wed July 22nd

This Wednesday I am giving my "Kitchen Sink Radio" talk at the Peterborough Radio Club. I will put the presentation on my website after the event. At the moment I am hoping my wife's WinXP PC survives as it has two keys which packed up last week. I need this PC for the slideshow. Arghhh!!

6m Super DX

For the last few days I have been in South Devon on holiday. Some evenings I have been out looking for skeds with the SixBox 6m QRP AM transceiver but two tests failed even with 2W AM from the FT817 and the 1/4wave magmount, so no QSOs with the baby rig yet. However, I managed several European DX QSOs with 6m QRP SSB, all with good reports.

Last night was exceptional on 6m: YV4DDK, FM5AA and 9Y4D all coming through at good strength (at times) on 6m SSB with just a 1/4wave magmount antenna! Although I tried calling the YV4 at one point I knew it was pointless with all the super-QRO stations with big beams calling them. Still, it was good to HEAR such super-DX on 6m (8000kms) with such a simple portable station.

6m AM and noise

Two local tests with stations on 6m AM have shown just how noisy the band can be when using this mode. M1KTA was 18kms away and M1MAJ around 15kms yet both were not strong on the vertical V2000 antenna on 6m AM even when they were using FT817 rigs at 2W AM. We were going to try the SixBox but signals would have been too weak. Switching to USB made a lot of difference (better) unsurprisingly, as the noise level reduces with the bandwidth.

This goes to show how AM signals do need to be strong to overcome the band noise: when signals are a decent level AM is a fine mode, but it can be hard work when they are very marginal with lots of noise in the background.

6m QRP AM tests - Cambridge area

Anyone around near Cambridge/Newmarket/Ely with a 6m vertical antenna who can help me range-test my very simple homebrew 6m QRP AM rig in the next couple of days? SixBox details on this blog and my website. It is working OK but I want to find out how far it gets locally.

Freq: 51.125MHz (sorry only xtal I have at the moment)
Power: 50mW AM
Ant: V2000 vertical
Loc: Burwell, 10m NE of Cambridge, JO02DG

Grandson 2

Our second grandson,  is on holiday with in-laws in Australia. We've just been sent this nice picture of him. He is clearly enjoying himself.

SixBox QSO 3 - sensitivity testing

This evening I had a third QSO with G6ALB using the SixBox 6m 50mW AM transceiver. The main aim was to test the receiver sensitivity since fixing an issue last evening. Andrew first called me using his FT817 on the lowest AM power setting and he was good copy. He then switched over to a modulated AM signal generator at 7dBm level (5mW). This was easily copied on the superregen RX. Even with a 10dB pad in at my end I could still copy the signal i.e. at an equivalent of 0.5mW from Andrew 2 miles away. So, without accurate test equipment I can safely assume the RX is detecting low uV level signals. I must work out the path loss.

Having got the SixBox working pretty well it now remains to see how far it can reach. I am really pleased with this simple project. It is very satisfying to work people on AM using really simple homemade equipment built with minimal test equipment and using parts which cost very little.

The current TX frequency is 51.125MHz. I need to buy a crystal for the 6m AM working frequency (50.57MHz in the UK or 50.4MHz in the USA).

Sunspots creeping up

Noticed the sunspot numbers trend recently? Whereas a few months ago there were weeks and weeks without a spot, now there are spots on a high proportion of days and the general level of active cycle 24 spots is creeping upwards. All this bodes well for this autumn when I hope we'll see some F2 transatlantic propagation on 10m again on many days, with plenty of US and Canadian stations workable with QRP - a sure sign that the old sun is waking up.

6m Sixbox AM QSO No 2

RS59 from G6ALB this evening with the SixBox 50mW AM transceiver. In putting the transceiver in its box and adding the RX tuning I inadvertently removed the coupling cap between the RF and and detector stage so the RX was a little bit deaf. I will add this back tomorrow and expect sensitivity to be back to low uVs level. Even without it, I could hear signals of 2-3mW out from Andrew.

Next week I am in Devon on holiday, so will be looking for some 50MHz AM QSOs with the SixBox from clifftop highspots. I will set up some 6m AM skeds using the local VHF and UHF repeaters.

10m AM Net in S.London (Wednesdays)

A 10m AM net has been started in South London, UK by Gary G7IRG. It meets on 29.05MHz (AM mode) on Wednesdays at 9pm local time. Last week the net had 3 people on: G7IRG, G0KRT and M0GPG. If you live in this area, or indeed anywhere, why not see if you can hear the net and give them a call?

When 10m is wide open, as it will be in a couple of years time, the band between 29.00 and 29.1 MHz will be filled with AM stations from around the world.

6m when the band is quiet

6m is a band ripe for exploitation when there is no DX around. When there is sporadic-E or F2 DX about, people use the band in thousands and some have worked DXCC. However, when conditions are not good, it is left to a few dedicated enthusiasts to work random MS and tropo and ionospheric scatter mode QSOs using QRO with modes like JT6m. The amount of LOCAL 6m activity, at least here in the UK, is very low indeed.

We have 2MHz of band in the UK (4MHz in the USA) and it is a pity more use is not made of this fine band for local QSOs using simple QRP homebrewed equipment. It is an ideal band for QSOs up to around 20 miles or so and much quieter than 160m or 80m, which can be very noisy these days.