7 Dec 2011
You Kits SSB transceivers
For some reason I have missed the news that YouKits are producing (or about to) 2 band and 4 band HF SSB/CW transceiver kits at very reasonable prices. See http://www.youkits.com/ . One is a backpack and one a handheld. Quite interesting. See TJ2A and TJ4A code numbers on their website.
Micropower generation/power harvesting
Labels:
linear technology,
power harvesting
Elecraft KX3 internal photos
Elecraft KX3 rear view inside |
5 Dec 2011
481THz progress update
TX beacon optics |
4 Dec 2011
LF tests with the earth electrode "antenna"
Following the great success on 160m with the 20m spaced earth electrodes yesterday, I fired up the WSPR transverter into the same "antenna" today on 137.5kHz. Although I managed to decode G8IMR at 188km several times, no reports of my signal were received. This ties up with tests last year which suggested the earth electrode system was around 8dB down on my 80sq m vertical wire loop. With results on 137.5kHz hard to get with 500uW ERP it was perhaps not surprising that no-one managed to decode me on the earth electrodes.
I now have a choice on 137kHz: either re-erect the wire loop, but double the wire thickness when I do so, or change to a Marconi vertical with a large loading coil. The thicker loop will increase ERP by up to 6dB but I suspect more is to be had with the vertical. It would be daft of me not to give the Marconi a try both on 137.5kHz and on 500kHz. Even with my limited space I can still manage around 8m of vertical with around 20m of top section.
I now have a choice on 137kHz: either re-erect the wire loop, but double the wire thickness when I do so, or change to a Marconi vertical with a large loading coil. The thicker loop will increase ERP by up to 6dB but I suspect more is to be had with the vertical. It would be daft of me not to give the Marconi a try both on 137.5kHz and on 500kHz. Even with my limited space I can still manage around 8m of vertical with around 20m of top section.
Labels:
137.5khz,
earth electrodes
3 Dec 2011
Amazing evening on 160m ...without an antenna
160m WSPR reports - using 5W to 20m spaced earth electrodes |
Sunday I intend to try 137kHz with the earth electrodes as I now have some 6dB more power than the last time this was attempted.
Labels:
160m,
earth electrodes,
wspr
Earth electrode "antenna" on HF
Today I had to prune the tree to which my 80m sq wire loop is attached, so the loop had to come down for a while. Instead I connected up my 20m spaced earth electrode pair "antenna" with the connecting wire about 1.5m off the ground coming back along the garden fence. This is the antenna I use on VLF earth mode tests with the best DX reception of my signal being 6km away when using 5W at 8.76kHz.
I have been amazed how well this works on 160-40m this afternoon. This is the log this evening on 160m with 5W WSPR - best DX report so far from OZ7IT at 853km. On 40m I reached over 2000km with a report from the north of Norway.
I have been amazed how well this works on 160-40m this afternoon. This is the log this evening on 160m with 5W WSPR - best DX report so far from OZ7IT at 853km. On 40m I reached over 2000km with a report from the north of Norway.
Labels:
160m,
earth electrodes
10m - still WIDE open
A small wire halo antenna, 5W from an FT817 and WSPR software and these are the loggings of my 28MHz QRP signal in just a few minutes this morning. Best DX report 16964km from VK2ALC.
30 Nov 2011
481THz (light communication) progress
This afternoon I did a bit more on the optical front. I repeated my outdoor range tests using a low-cost high brightness LED as both a baseband optical transmitter and receive detector. With around 10mA TX current into the LED I was able to copy a 1kHz tone at 20m with another high brightness LED as the detector, without any additional optics other than the LED's built-in lenses at each end.
A 100mm lens properly focussed has a gain of >24dB (nearer 30dB if correctly adjusted). Assume 24dB "antenna" gain at each end of the link and we will have 48dB system gain over the simple LEDs on their own. Based on these calculations my optical transceiver should have a range of at least 5km. If the gain of the lens is 30dB then the range could be as great as 20km. This is without using high power LEDs as the TX or using larger Fresnel lenses which would have even higher gain.
I now have the 100mm lenses I intend to use as well as 2 gun sights bought off eBay. The next step is to buy some drain pipe to house the optics. I have still to decide whether to build fully self-contained FM transceivers (simpler) or to build the optical transceive heads with separate transverters to use with the FT817.
A 100mm lens properly focussed has a gain of >24dB (nearer 30dB if correctly adjusted). Assume 24dB "antenna" gain at each end of the link and we will have 48dB system gain over the simple LEDs on their own. Based on these calculations my optical transceiver should have a range of at least 5km. If the gain of the lens is 30dB then the range could be as great as 20km. This is without using high power LEDs as the TX or using larger Fresnel lenses which would have even higher gain.
I now have the 100mm lenses I intend to use as well as 2 gun sights bought off eBay. The next step is to buy some drain pipe to house the optics. I have still to decide whether to build fully self-contained FM transceivers (simpler) or to build the optical transceive heads with separate transverters to use with the FT817.
RF skill levels
In my professional life I interviewed many graduates aspiring to become RF engineers. Very few, in recent years, had what I would call "the knowledge". By this I mean a "gut instinct" for RF that does not come from an academic course, important though this aspect is. Rather, this "jizz" comes by living and breathing RF through building RF things yourself, however simple. A great many 2:1 graduates in communications electronics knew almost nothing about RF, had never touched a soldering iron ever and were rejected. In all honesty I believe I could sense who would make a good RF engineer within 2 minutes of the interviews starting.
Today I received a request from a Spanish amateur who professed (more or less), "I`ve a problem. I know nothing about electronics and would be unable to build the SAQ converter on your website." He then offered to pay me to build and ship the converter to him. Surely, a radio amateur in ANY country should have learnt basic RF skills as part of his training in preparation for his licence? At the most basic level the understanding may not be deep, but how can a radio amateur really not know how to put together a basic circuit?
In the UK we have a growing, and very serious, issue with poorly educated science and engineering graduates who are simply not coming out of universities with the skills needed to start work in industry. One answer was the sandwich course in which young A-level students were accepted on a company training scheme that married "on the job" skills training with educational training, usually to HND or degree level. People spotted young, with real RF "jizz" (easily judged in interviews) usually went on to become the best engineers we had.
Today I received a request from a Spanish amateur who professed (more or less), "I`ve a problem. I know nothing about electronics and would be unable to build the SAQ converter on your website." He then offered to pay me to build and ship the converter to him. Surely, a radio amateur in ANY country should have learnt basic RF skills as part of his training in preparation for his licence? At the most basic level the understanding may not be deep, but how can a radio amateur really not know how to put together a basic circuit?
In the UK we have a growing, and very serious, issue with poorly educated science and engineering graduates who are simply not coming out of universities with the skills needed to start work in industry. One answer was the sandwich course in which young A-level students were accepted on a company training scheme that married "on the job" skills training with educational training, usually to HND or degree level. People spotted young, with real RF "jizz" (easily judged in interviews) usually went on to become the best engineers we had.
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