VLF earth mode

Many years ago I did quite a bit of experimenting below 10kHz. This was reception of G6ALB at 3km on 8.97kHz. I think he was running about 40W. This was 2011.

See https://sites.google.com/site/sub9khz/vlf-using-earth-mode.

Pixie testing

About 6 years ago, I managed to construct a 40m Pixie kit. Doubt if I could do it now, although perhaps I could with care. 

It must have been tested it at the QTH of G6ALB, although I do not remember this. The photo shows these tests.

4m reception

A local amateur has set up a personal beacon on 4m. He is about 3km away. I have no 4m antenna, so I tried reception with the V2000 vertical omni antenna and the 2m big-wheel omni antenna. Good copy was possible despite the power being only 10mW.

See https://soundcloud.com/user-250132188-848737928/g6alb-4m-beacon?si=94cf74a951194d67a176bca91d1caab9&utm_source=clipboard&utm_medium=text&utm_campaign=social_sharing

Valve site

Confession time....    In all my time I have never ever built a valve circuit!  

Maybe low voltage HTs might have persuaded me, but all my circuit ideas and projects have been semi-conductor based. If you are interested in valved circuits you may want to visit Andrew G6ALB's site.

See http://www.tetrode.co.uk/

Valve site

G8ALB has a site that is mostly about valves. I arrived on the scene just after transistors came in and I never got to build anything with valves. The nearest I got was a stroboscope.  A VHF RX based on the 955 acorn valve, was on the drawing board, but was never made.

See http://www.tetrode.co.uk/

G6ALB's (mainly valve) website

For years I had regular QSOs each week with G6ALB in the next village. It looks like his website has not been updated since 2009! If you are "into" valves, you may find some ideas here.

See http://www.tetrode.co.uk/

Not amateur radio again

Today we visited the next village, Swaffham Prior, 3km west of here, home to G6ALB where there are 2 churches and 2 windmills. Andrew G6ALB and I are testing low cost AM modules on 70cm. As yet these tests have only been partially successful. Tomorrow I need to check the sensitivity of my receivers.

After our visit, I have updated our blog http://eachurches.blogspot.co.uk/ where you can follow our visits around East Anglia.

2m/70cm yagi erection

Andrew G6ALB is erecting my new VHF/UHF yagi for me as my health is still too poor. He hopes to return later today. Andrew is hoping to fit a decent N connector to the failed Moonraker patch lead. With luck, the whole installation may be done this weekend depending on Andrew's time and the weather.

I am so grateful for Andrew's help - amateur radio spirit at its best.

V2000 erected and first QSOs on 6, 2 and 70cms from new QTH

On Tuesday I completed the erection of my tri-band colinear at the new QTH and carried out some tests over a 3km path to G6ALB to see how results compared between my old and new QTH on 6, 2 and 70cms. I was expecting results "on the hill" to be somewhat better, but in actual fact over this short path the results were identical within the limits of experimental error. Andrew put in various levels of attenuation to see how low he could go and still copy me. On 2m for example he could put in 43dB attenuation and still just copy me. 43dB is an attenuation of 20000 times suggesting just a few uW is enough to cover this distance.

Yesterday morning I was able to work through the Welwyn Garden City 70cm repeater, although conditions were up a bit. Last night I worked several I and HA stations on 6m SSB and CW during an unexpected Es opening, getting good reports with my 5W.  Conclusion so far: the antenna works fine.

I am now considering that big-wheel for 2m on the same mast. I am looking forward to working some SSB/CW stations again on 2m.

80m FETer outing

This evening I came on 80m to listen for G6ALB who was taking part in the valve QRP day. Using my  18mW output FETer transceiver (18 parts total) I was able to hear almost all of the stations active around 3.56MHz using QRP.  G6ALB was worked (599 each way, but we are only 3km apart). I had forgotten how effective this little transceiver was and it was a pleasure to use it once again.

10m Chirpy Measurements

Last week G6ALB made a copy of my Chirpy 14 component transceiver for 28MHz CW. Andrew had access to some better calibrated test equipment and carried out some RF power and sensitivity measurements both on his version and on my second original unit - the first was just a rat's nest on the bench.

Both on my version and G6ALB's version the measured RF power out was in excess of 200mW, which is around 2-3dB more than I had crudely measured. The RX sensitivity on both was such that below -100dBm (around 2uV) was audible in our earpieces in a quiet room. Backwave carrier on TX was rather too high at around -10dBm. Second harmonic was also only around -6dB, so a low pass filter is really a necessity apart from casual short tests.

It does seem that the simple design is reproducible and its performance not at all bad for something this simple. The only major shortcoming is the chirp.

Sputnik valve TX tests

This afternoon G6ALB and I got together to build a 2 valve 21MHz transmitter using a couple of Russian valves of the same types used in the original Sputnik 1 satellite in 1957. Surprisingly I've never built a valve transmitter before. Even today, Andrew did most of the building. My input was to wind a toroid and to help sort out the wire ends of the two valves. The valves were kindly supplied by Mike AA1TJ.  The breadboarded TX is shown in the picture. On a test this evening over the 3km path between our QTHs the 400mW TX was copied fine on my IC703 and 10m halo antenna.  Even at the lowest HT voltage (around 30V) his signal was still solid copy on the "Sputnik". Our aim is to have a pair of these units ready for Sputnik Day (Oct 4th) and to work each other and other more distant stations who are using similar rigs.  See also http://aa1tj.blogspot.com/2011/07/sputnik-qso-party-transmitter-prototype.html

136kHz WSPR - first report received

Well, it is no great DX at 3km away in the next village, but I've now received my first WSPR report on 136kHz from G6ALB. He gave me -21dB S/N when I was running 20uW ERP from the earth electrode antenna.

SixBox 6m AM QSO

A solid QSO this evening with G6ALB (2 miles away) on 6m AM using the 50mW SixBox rig with vertical antennas at each end. In the other direction, using the super-regen RX at my end, we did some sensitivity tests with Andrew putting a signal generator on and gradually dropping his AM modulated carrier. I was able to copy his signal when it was reduced to 0.5mW.

I also tried to receive a 7dBm carrier from Andy on 70.26MHz AM using the retuned super-regen RX, but was unable to hear it, although we were both using 6m antennas which were not resonant on 4m.

Currently I am putting a rebuilt SixBox in a real box. Later, I will make a breadboarded DSB version.

More details on the SixBox page of my website.