Author Archive
Changing propagation
March 16th, 2015 | 
Author: If proof were needed that we are now on the way down to the next minimum then take a look at the sunspot number graphs at http://www.solen.info/solar/ .
Although conditions are sliding, do not abandon the higher HF bands like 10m. There is (usually) quite a lot of good DX around still. In the last solar minimum I was still able to work well into southern South America on 10m with QRP SSB. WSPR should be even more reliable when conditions are edgy.
I really do hope a strong core of WSPR operators stick with 10m as, in many ways, in the poorer times are when WSPR will be most valuable as a tool. I am hoping that when not on traditional modes like SSB or CW people will still WSPR so we can catch fleeting openings, which are probably far more common than people expect on 10m. Remember, the F2 or transequatorial propagation has only to go above 28.126MHz for 120 seconds and someone on WSPR may spot it!
Over 1000km on 472kHz TX with earth-electrodes
Last night LA4ANA (1047km) copied my 5mW ERP from the earth-electrode “antenna” on 472kHz WSPR. This is my best DX yet on the non-antenna, nearly 300km further than my best previous TX record. I was also spotted by DL4YHF (556km) for the first time on the earth-electrode “antenna”. My PC decided to crash some time after midnight last night, so I missed any DX overnight. These spots were during the evening period.
In the last 2 weeks alone I have been spotted by 28 different stations when I’ve been using 5mW ERP from the earth-electrode “antenna” on 472kHz WSPR. Let no-one say 472kHz is out because they cannot fit an antenna! If my signal can span over 1000km with WSPR then you can surely do better. I make no claims for the earth-electrode “antenna” but if you are unable to erect a proper antenna give it a go.
I have still to try it at this QTH on 136kHz but at my old QTH I managed to be spotted at 250km with very low ERP.
RSGB Wortley-Talbot Trophy
Well, I was delighted, honoured and surprised, to get a nice letter from the RSGB today. In it, it said I’d been awarded the Wortley-Talbot trophy for my experimental work on over the horizon work at 481THz and the article on this published in RadCom last year.
Sadly my continued ill health means I’ll be unable to pick up the award at the RSGB’s AGM in London in April. I just wish my health was better so I could do some field work again soon! Both VLF and optical field work are on hold until I feel better. This year I really really hope I’ll manage it.
To be honest this award came as a complete surprise, but I’d happily trade these lovely awards to be back to my old healthy self.
UK Activity Contests
Every Tuesday evening the RSGB organises a VHF/UHF activity contest. I have just in time submitted my entry for the low power section of last Tuesday evenings 50MHz contest. With just 3 QSOs logged there is no way on this earth that I’ll be anywhere but near the bottom! Having a V2000 omni vertical antenna, 5W, and a stroke damaged voice is no way to enter a 50MHz, UK based, contest! The V2000 and even 2.5W is great in the Es season (I work most that is around), but it is far from ideal working inter-G on 6m SSB.
Tonight is the 144MHz (2m) March leg of the UKAC. My small 3el beam should turn again now (manually) so I’ll see how long my voice holds out. 45 minutes to 60 minutes is usually my limit. Last week I was on very little time. My best DX seems to be around 200km with 5W on 2m in “normal” conditions.
At this time of the year there are fewer portable stations active but activity (SSB and CW) is usually very high so this is a good opportunity to work some new squares. People have been very friendly. If in the UK or nearby join the fun 2000-2230z on 2m. I usually go QRT by 2100z because of the strain on my voice.
Just checked where I sit in the Jan 2015 AL section of the 50MHz UKAC. You guessed? Bottom! Well someone has to be!
10GHz WBFM transceivers
The modern way of getting (simply) into 10GHz WBFM appears to be using very low cost 10GHz Doppler radar modules with a 100MHz FM receiver. Whilst with G6ALB for my Pixie tests Andrew demonstrated a working 10GHz link based on these low cost modules. These are useful links Andrew sent me.
Hi Roger,These are the units I found when I was looking for [definitions of] the 10.525 GHz ISM band.It looks like 3cm Doppler radar is alive and well,I’d assumed it had disappeared in favour of PIR.Some data here:These are very good pages (for wideband FM on 10 GHz).
Andrew G6ALB
40m Pixie measurements
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| Pixie harmonic measurements |
This afternoon I visited G6ALB to do some more accurate measurements of my completed 40m Pixie kit. Power out with the 12V battery was 400mW and with a fresh PP3 9V battery 200mW. On the 12V battery TX current is around 129mA and at 9V around 83mA. 2nd harmonic rejection was about 20dB. Even the 9V output is a useful level. Maybe the cased unit should include an internal 9V battery pack which is switched off when an external 12V pack is available?
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| Pixie on the bench |
To be more useful, I should add a 7.030MHz crystal and have a switch to select this or the original 7.023MHz one. 7.030MHz is the QRP frequency. My experience is this can be quite busy.
I should also case the unit! Drilling the case could be a challenge in my current state of health! Just doing the building and testing was exhausting.
First 40m Pixie QSO
At 1000z this morning I exchanged RST 579 reports with G6ALB who is 3km from me on my 40m Pixie on 7.023MHz CW. This was my first on-air QSO. Netting was perfect and I used the rig directly into my low Par triband antenna. An ATU might have helped. Andrew G6ALB said the channel was pretty busy but that I was a good RST579 with no hint of chirp. This afternoon we’ll put the rig on his spectrum analyser. I gave Andrew 579 probably reflecting the poorer MDS of the Pixie. I have no idea of his power or antenna.
My initial goals have been met: I built the kit and have managed a QSO on the air with it. With the fatigue associated with my brain bleed still very apparent (I am well and truly shattered currently), I was well pleased. A few more QSOs with the 40m Pixie would be good, HI.
$10 well spent. Excellent little kit. FB little transceiver. Works surprisingly well.
