16 Apr 2014
PY2RN WSPR analysis
Bert PA1B has analysed my recent reception on WSPR by PY2RN to see just how little power could have been used and still be successfully decoded in Brazil - the answer is very little for a lot of the time! Most times even 1mW should have been enough. This of course assumes local noise levels allow decoding to the lowest levels for WSPR at around -30dB S/N. In some cases this may not be possible because of local QRN/QRM.
Late evening reports on 10m
Before my program stopped running, 10m WSPR was in good shape up to (at least) 2200z last night. TI3/AB4AW (Costa Rica, Central America) was last reported (by me) at 2200z.
It may well have been open later still, but my WSPR program decided to close! This morning, I have re-opened the WSPR software and reset the clock to internet time. This morning, sunspot count is 149 with "stable/good" propagation forecast. 10m should be good today.
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| 10m 2W WSPR spots last evening until very late |
15 Apr 2014
Some building in the shack!
For the first time since my stroke last year I decided to build and test something in the shack (other than a loading coil). For my very wobbly self, this is a major step. I decided to have a go at the Petitico 10 parts rig from PY2OHH shown a few posts back.
Somewhere I have a 7MHz crystal, but I could not locate it, so I built a bench version, for 3.560MHz instead. I still haven't managed to optimise values yet.
On RX the sensitivity with 600 ohm headphones was, at best -70dBm, so a strong signal is needed to hear anything. It was less sensitive with a crystal earpiece. It is possible that further optimisation might yield a few dB more, but this level I expected. The RX-TX offset seems ideal. The only real operating technique, with this sort of sensitivity, is LISTEN (for a good, strong signal) and then POUNCE. I have yet to check TX output power.
I'd like to try it on 7MHz really and may buy some 7.030MHz crystals from GQRP club sales. On 7MHz I have an antenna and can listen for my signal on the Twente SDR RX in Holland.
The actual results are almost academic. What mattered was that I actually built something with my soldering iron, didn't burn holes in the carpet and, sort of managed, despite my severe balance problems.
I am wondering if I should open the Ultimate 3 Beacon kit box and build it or wait a few more weeks. At the moment I think I should wait. My confidence levels are still low.
The 481THz NLOS test I had planned will have to wait until I feel less giddy I have decided. Everything for now will be shack based.
Somewhere I have a 7MHz crystal, but I could not locate it, so I built a bench version, for 3.560MHz instead. I still haven't managed to optimise values yet.
On RX the sensitivity with 600 ohm headphones was, at best -70dBm, so a strong signal is needed to hear anything. It was less sensitive with a crystal earpiece. It is possible that further optimisation might yield a few dB more, but this level I expected. The RX-TX offset seems ideal. The only real operating technique, with this sort of sensitivity, is LISTEN (for a good, strong signal) and then POUNCE. I have yet to check TX output power.
I'd like to try it on 7MHz really and may buy some 7.030MHz crystals from GQRP club sales. On 7MHz I have an antenna and can listen for my signal on the Twente SDR RX in Holland.
The actual results are almost academic. What mattered was that I actually built something with my soldering iron, didn't burn holes in the carpet and, sort of managed, despite my severe balance problems.
I am wondering if I should open the Ultimate 3 Beacon kit box and build it or wait a few more weeks. At the moment I think I should wait. My confidence levels are still low.
The 481THz NLOS test I had planned will have to wait until I feel less giddy I have decided. Everything for now will be shack based.
Slow start on 10m this morning
Time now is 1030z and so far only DK3SML (733km) at 0854z has been spotted on 10m WSPR. Sunspot count is 105 with "normal" HF conditions, so hopeful of improvements as the day progresses, but signs are not encouraging: it was better at this time yesterday and yesterday was not a very good day.
UPDATE 1148z: spots exchanged with PY2RN, also CX2ABP (11127km) spotted here. The band is livening up on N-S paths only so far here. No transatlantic stations yet copied.
UPDATE 1950z: transatlantic spots, 2-way spots by exchanged with CX2ABP (11127km) into S.America with 2W, and a TJ3 - in all a good day on 10m, despite the slow start.
UPDATE 2042z: still being spotted by K1OF (5500km).
UPDATE 1950z: transatlantic spots, 2-way spots by exchanged with CX2ABP (11127km) into S.America with 2W, and a TJ3 - in all a good day on 10m, despite the slow start.
UPDATE 2042z: still being spotted by K1OF (5500km).
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| Unique 10m WSPR spots of my 2W signal today |
481THz RX issue - now fixed
As mentioned in an earlier post, my sensitive non line-of-sight NLOS optical (red LED at about 481THz) RX packed up when I clumsily dropped it yesterday when out in the field at the test site. An investigation this morning revealed a wire had dropped off the battery feed and this was easily fixed. The RX now works as before.
I shall have to try the NLOS test again when my wife can drive me out there. I shall have to do it soon as tree leaves will soon obscure the path at the home QTH end. Just wish I was not so clumsy still following the stroke last year. In the field I feel so much less able than last year. I feel really disabled and hate being so useless and clumsy.
UPDATE 2050z: for now, all my tests will be shack-based because of my poor health, so no immediate plans to repeat NLOS tests until I feel a lot less wobbly.
I shall have to try the NLOS test again when my wife can drive me out there. I shall have to do it soon as tree leaves will soon obscure the path at the home QTH end. Just wish I was not so clumsy still following the stroke last year. In the field I feel so much less able than last year. I feel really disabled and hate being so useless and clumsy.
UPDATE 2050z: for now, all my tests will be shack-based because of my poor health, so no immediate plans to repeat NLOS tests until I feel a lot less wobbly.
14 Apr 2014
10m - mixed fortunes
Today was an odd day on 10m WSPR - some good propagation N-S but very marginal indeed transatlantic. The band did open up but hardly any transatlantic spots.
I think we are now moving towards summertime conditions and are gradually starting the slide down towards the next minimum. We will have a very long journey downwards and some days conditions will be excellent. On many days, the band will be closed. On some days propagation will be mainly N-S only.
With luck, Es will help to liven up the band in summertime. Just occasionally, mutli-hop Es will support transatlantic 10m and 6m propagation as well as propagation into the Middle East. Also, sometimes the first hop is Es then linking up with F layer propagation further to the south. Even in the quiet years, 10m has surprises.
At 2142z NA4U (6533km) was spotting my 2W still. Surprise!
I think we are now moving towards summertime conditions and are gradually starting the slide down towards the next minimum. We will have a very long journey downwards and some days conditions will be excellent. On many days, the band will be closed. On some days propagation will be mainly N-S only.
With luck, Es will help to liven up the band in summertime. Just occasionally, mutli-hop Es will support transatlantic 10m and 6m propagation as well as propagation into the Middle East. Also, sometimes the first hop is Es then linking up with F layer propagation further to the south. Even in the quiet years, 10m has surprises.
At 2142z NA4U (6533km) was spotting my 2W still. Surprise!
Aborted 481THz NLOS test
I am beginning to think that ALL tests outside the house should stop until I am a lot better (stroke). The best description is I feel, all the time when on my feet, as if I have drunk 8 pints of beer and am very drunk and clumsy.
This evening, my wife drove me out to an NLOS test site where I managed to drop the RX head hard on the ground. The head immediately stopped working even before I started hunting for my signal! I could hear no hiss at all. There was no sign of the very visible moon noise in the RX.
The test would have been marginal anyway, especially with a bright full moon, but to be unable to carry out the test at all was a great shame. It is just that everything is SO hard for me at present and setting up optical kit is stretching the limits of my current abilities. Feeling clumsy nearly all the time is tiring too.
Even getting my VHF/UHF beam up at home will require help. Andrew G6ALB has kindly offered to erect it for me. This should be an easy task for me - normally it would be - but not at present. At least, when erected, VHF and UHF activity should be straightforward at home in UKAC sessions on Tuesday evenings. Sitting down my balance is fine. I just hope this soon improves. Walking is getting better but balance/giddiness are still big issues.
This evening, my wife drove me out to an NLOS test site where I managed to drop the RX head hard on the ground. The head immediately stopped working even before I started hunting for my signal! I could hear no hiss at all. There was no sign of the very visible moon noise in the RX.
The test would have been marginal anyway, especially with a bright full moon, but to be unable to carry out the test at all was a great shame. It is just that everything is SO hard for me at present and setting up optical kit is stretching the limits of my current abilities. Feeling clumsy nearly all the time is tiring too.
Even getting my VHF/UHF beam up at home will require help. Andrew G6ALB has kindly offered to erect it for me. This should be an easy task for me - normally it would be - but not at present. At least, when erected, VHF and UHF activity should be straightforward at home in UKAC sessions on Tuesday evenings. Sitting down my balance is fine. I just hope this soon improves. Walking is getting better but balance/giddiness are still big issues.
Simple audio filter designs
The PY2OHH pages contain a useful link to a TI paper on active filters. In my experience, virtually any audio or RF transistor (e.g. 2N3904 NPN) can replace the op-amps with little effect. Some prefer "perfect" op-amps whereas I find transistors easier to work with and place. The performance difference is very very small.
2N3906 is a ubiquitous PNP equivalent. The 2N3904 and 2N3906 devices are available from a range of suppliers for just a few pence each only. A few 2N3904s in parallel with small emitter resistors make a good HF/LF QRP PA replacement for a 2N3866 too. My recommendation is buy 100 of each (2N3904 and 2N3906) and stock your junk-box. Less than £10 and it will be a long time before you run short! Think of all those projects.
See http://py2ohh.w2c.com.br/trx/filtroativo/filter%20design%20in%20thirty%20seconds.pdf for the active AF filter paper.
2N3906 is a ubiquitous PNP equivalent. The 2N3904 and 2N3906 devices are available from a range of suppliers for just a few pence each only. A few 2N3904s in parallel with small emitter resistors make a good HF/LF QRP PA replacement for a 2N3866 too. My recommendation is buy 100 of each (2N3904 and 2N3906) and stock your junk-box. Less than £10 and it will be a long time before you run short! Think of all those projects.
See http://py2ohh.w2c.com.br/trx/filtroativo/filter%20design%20in%20thirty%20seconds.pdf for the active AF filter paper.
Good start on 10m this morning
EA8/LA3JJ has already spotted my 2W WSPR 3 times and it is only just after 0800z. Sunspot count is 95 and the forecast is for "stable/normal" HF conditions. Perhaps this will be a good day on 10m?
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| 10m WSPR spots with 2W to 1130z today (basically N-S) |
PY2OHH's Pititico 10 parts transceiver for 40m
Andy Cutland has sent me this link. It is from, Miguel, PY2OHH's excellent site which is full of ideas for QRP and QRPp enthusiasts. I can thoroughly recommend it for ideas. I would expect this RX to hear signals, but be quite deaf as there is no audio gain apart from that in Q1.
Apparently the headphones were around 500 ohms impedance. I guess a crystal earpiece might work as audio is derived across R2. Maybe then C5 could be deleted?
Q1 must act as a (crystal controlled) regenerative detector on RX with the level of oscillation set by R2. Not sure of RX-TX shift as this will depend on RX and TX current. There is no low pass filter either, as shown. This means harmonics will also be detected and emitted. Still, this is meant to be VERY simple. I must try it.
Apparently the headphones were around 500 ohms impedance. I guess a crystal earpiece might work as audio is derived across R2. Maybe then C5 could be deleted?
Q1 must act as a (crystal controlled) regenerative detector on RX with the level of oscillation set by R2. Not sure of RX-TX shift as this will depend on RX and TX current. There is no low pass filter either, as shown. This means harmonics will also be detected and emitted. Still, this is meant to be VERY simple. I must try it.
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