http://images.4channel.org/f/src/589217_scale_of_universe_enhanced.swf
This quite wonderful website brings to life the scale of things in our
incredible universe from the smallest strings and branes to the largest
galaxies and nebulae in the cosmos. And we are somewhere in the middle
of all this. Zoom in both directions (smaller and larger) and be
amazed.
12 Feb 2012
Successful non line-of-sight 481THz test tonight by cloudbounce
QRSS3 signal at 3.6km by non line-of-sight cloudbounce |
With the beacon aiming out through the double glazed shack window at nearby Burwell windmill (as an aiming point) I set off for a road at Landwade which was 3.6km away "over the hill" and on a NLOS path from here. At Landwade I set up the 100mm optics and my variation of the KA7OEI head feeding into my laptop running Spectran. Immediately I got a good signal from the beacon 3.6km away. Signal was around 10dB S/N in 0.67Hz bandwidth. The signal was neither visible as a red glow nor audible in the earpiece despite listening quite hard and panning around for best signal.
This was my first proper NLOS test and it is extremely encouraging. I did try to elevate the RX to higher points in the sky but best reception was with the optics aiming at the lights of Burwell village in the distance i.e. as low as was possible in elevation. At the TX end I was aiming to just clear the slight rise in ground to the east of me near Burwell windmill.
Weather conditions were light patchy low cloud with pretty decent visibility. I did notice QSB as cloud cover varied.
I'm really lucky finding this test path as I can put the TX beacon on the bedroom shack windowsill and fire towards the windmill. In daytime I would be able to align the RX better as I was having to guess the best direction with only Burwell church visible. I had to tweek the alignment to what I thought was the right direction. I did not spend a lot of time trying to peak the signal and better copy is possible. In all honestly I did not expect this test to be successful.
Simpler 481THz beacon TX
11 Feb 2012
Homemade 45rpm disc recording
Handmade disc recording made on a coffee tin plastic lid |
Labels:
45rpm,
francis wood,
homebrew,
homemade,
recording
10 Feb 2012
Cambridge Club Talk - a good turn-out
This evening I gave my talk "VLF Amateur Radio" to the CDARC in Cambridge. The turn-out was excellent, especially considering the very cold weather here at the moment. It was -10deg C coming home in the car. At the end of the talk there were plenty of interesting questions. It was fun to share my enthusiasm for VLF things with such an appreciative audience. Click on the link if you'd like to see a copy of the slides I used this evening.
Labels:
amateur radio,
cambridge,
cdarc,
radio club,
vlf
9 Feb 2012
Reliability of radio gear
Tin Whiskers on an IC contact |
One thing many people agreed on was this: if you want to be sure of the reliability of your amateur radio equipment then build your own. A simple QRP transceiver, easy to make from many published designs in QRP books, should last a lifetime and will be easy to fix in the unlikely event of something going wrong. There is also nothing quite as satisfying as making contacts with something you have built. Even a simple crystal controlled TX and direct conversion receiver are likely to give FAR more satisfaction than a rig costing £1000 with all the bells and whistles. I still recall the thrill of my first ever hombrew contact across the Atlantic with 800mW CW on 15m using my little Pipit transceiver with 7 transistors total and a handful of parts. This rig was so effective that it was my main station rig for many months. Every QSO, and there were lots, meant something special.
Labels:
kiss,
qrp,
reliability,
simple
8 Feb 2012
KX3 review on eHam
http://www.eham.net/reviews/detail/10271
This is the first ever review of the Elecraft KX3 by one of the field testers using SN-0006 sample fitted with internal batteries and the optional roofing filter. The field tester was mightily impressed.
This is the first ever review of the Elecraft KX3 by one of the field testers using SN-0006 sample fitted with internal batteries and the optional roofing filter. The field tester was mightily impressed.
Optical cloudbounce propagation theory
Bernie G4HJW and I are interested in carrying out some "cloudbounce" tests using our 481THz optical kit and we both are none to clear about the physics of scattering of signals from water droplets and dust in clouds or the sky. However, today a new tool to help our understanding was shown to us on the UKNanowaves Yahoo Group in a posting by Barry Chambers.
The free software is available at http://www.philiplaven.com/mieplot.htm and allows us to work out the intensity of a scattered optical signal as a function of scattering angle, droplet size and wavelength. Scattering is best when the angle of incidence is at grazing incidence and the droplet size is small. If I've understood the results correctly, aiming at the underside of a cloud at 45 degrees would result in a scattered signal some 50dB weaker than if at grazing incidence. So, depending on how far apart the 2 stations are and the angle at which the optical signal hits the underside of a cloud then signals can be quite strong or extremely weak. This is why weak signal modes like QRSS60 may be needed to work a given path by cloudbounce.
The free software is available at http://www.philiplaven.com/mieplot.htm and allows us to work out the intensity of a scattered optical signal as a function of scattering angle, droplet size and wavelength. Scattering is best when the angle of incidence is at grazing incidence and the droplet size is small. If I've understood the results correctly, aiming at the underside of a cloud at 45 degrees would result in a scattered signal some 50dB weaker than if at grazing incidence. So, depending on how far apart the 2 stations are and the angle at which the optical signal hits the underside of a cloud then signals can be quite strong or extremely weak. This is why weak signal modes like QRSS60 may be needed to work a given path by cloudbounce.
Labels:
cloudbounce,
diffraction,
scattering
A novel QRP power source
FreeCharge 12V is a small, portable generator, similar to that used in portable hand-cranked torches. The output is regulated to give 12-14.2V DC although the product datasheet does not state the available current. I suspect it is in the low milliamps as its main use appears to be to power/charge mobile phones in an emergency.
This could make a novel power source for low power QRP transceivers as no batteries would be required, just a few seconds or minutes of cranking. Figures given are 360 turns (approx. 3 min wind) gives 9-11 minutes of mobile phone talk time and a 60 second wind gives 2-4 minutes of talk time. Price is £19.99 and it is available from Freeplay or via Amazon UK.
The sales blurb says:
This could make a novel power source for low power QRP transceivers as no batteries would be required, just a few seconds or minutes of cranking. Figures given are 360 turns (approx. 3 min wind) gives 9-11 minutes of mobile phone talk time and a 60 second wind gives 2-4 minutes of talk time. Price is £19.99 and it is available from Freeplay or via Amazon UK.
The sales blurb says:
"The Freecharge 12V provides emergency power to a mobile phone, PDA, iPod, GPS receiver, or any other electronic device for which you have (or can get) a cigarette-lighter adapter. Wind its hand crank to generate electricity and put power straight into your device. Never be unable to use your mobile phone, or other important device, just because its battery has run down."
Labels:
emergency,
energy,
freecharger 12v,
portable,
power
Weak signal modes compared
There has been quite a bit of debate recently about just how good certain weak signal modes are when compared against similar modes. So, ON7YD has done some research and straw polling to compare them and published the results on his wonderfully informative website. He asked people to try to decode some weak QRSS signals by eye - these were at defined S/N ratios and compared the results against OPERA at various speeds and WSPR.
Amongst his conclusions is that "Opera8, QRSS10 (or DFCW10) and WSPR should have a more or less equal performance." This is very much as I have found from practical experience on 136kHz where QRSS3 does not perform as well as QRSS30 which is somewhat better than WSPR. So, WSPR being much the same as QRSS10 seems spot on. The advantage of WSPR is of course the internet database reporting which allows you to see where you have been received. QRSS reports depend on someone decoding the signals by eye and then manually sending you a report, which rarely happens. So, WSPR remains my favourite weak signal beaconing mode.
Amongst his conclusions is that "Opera8, QRSS10 (or DFCW10) and WSPR should have a more or less equal performance." This is very much as I have found from practical experience on 136kHz where QRSS3 does not perform as well as QRSS30 which is somewhat better than WSPR. So, WSPR being much the same as QRSS10 seems spot on. The advantage of WSPR is of course the internet database reporting which allows you to see where you have been received. QRSS reports depend on someone decoding the signals by eye and then manually sending you a report, which rarely happens. So, WSPR remains my favourite weak signal beaconing mode.
ON7YD's graph showing the effectiveness of various weak signal modes |
Labels:
opera,
qrss,
weak signals,
wspr
472-479kHz secondary allocation
From the RSGB's website today comes the latest news from WRC-2012 about an amateur secondary allocation to replace 500kHz with something more permanent. It needs ratifying but it does now look very likely indeed to happen.
Agenda Item 1.23 – 500kHz
Progress through Committee 4 (COM4) was a little easier than expected and the frequency band 472-479kHz will be allocated to the amateur service, on a Secondary basis. This is subject to no further objections being received during the two final readings through the plenary meetings, of which the first ‘blue’ reading is expected to be during the plenary this coming Friday, late afternoon.
7 Feb 2012
Free power radios
KE3IJ's always excellent website has a novel receiver circuit that derives its DC power from AC mains hum and noise it picks up on its antenna. It uses a single 2N3904 in a regenerative circuit. Ideally the circuit would be better with a lower Vbe device i.e. a germanium transistor.
Taking this one stage further, I know from my experiments at VLF that the AC mains hum between a pair of grounded electrodes can be pretty high. There is certainly enough 50(or 60)Hz energy going free in the ground to power something useful. I keep wondering if I could get a few uWs of HF RF power from a low voltage crystal oscillator that would be enough to work some local stations on CW? My nearest station is 0.3km and the next nearest 3km. Now having a QSO using free power from my back garden would be rather fun.
Taking this one stage further, I know from my experiments at VLF that the AC mains hum between a pair of grounded electrodes can be pretty high. There is certainly enough 50(or 60)Hz energy going free in the ground to power something useful. I keep wondering if I could get a few uWs of HF RF power from a low voltage crystal oscillator that would be enough to work some local stations on CW? My nearest station is 0.3km and the next nearest 3km. Now having a QSO using free power from my back garden would be rather fun.
Labels:
50hz,
free power,
ke3ij,
mains hum
6 Feb 2012
New Elecraft KX3 Photo
The new KX3 HF-6m 0-10W Elecraft All-mode transceiver |
5 Feb 2012
Remarkable "all diode" transceiver QSO
DL3PB's "all diode" transceiver |
Hi folks,I'd like to share with you a long-cherished dream, that recently came true, fourty years after I came to read about hams using tunneldiodes to make QSOs when I was aged twelve or so:
Finally I managed a first skywave QSO with my PARASAKI-transceiver, an 'all diode' rig: Christophe/F8DZY replied to my very first call on 20m band in REF-contest last weekend. I was running 2mW into a temporary vertical dipole on my balcony. Distance between us is 918km - obviously OM Christophe has excellent ears.Those interested in the cruel details of my circuit, please find attached a schematic and a photo of the pretty ugly setup. The circuit is designed straight-forward with exception of the parametric VXO, derived from Mike/AA1TJ's famous Paraceiver design. (see http://fhs-consulting.com/aa1tj/paraceiver.html)
The low impedance of the high peak-current tunneldiodes make it very difficult to built a really crystal controlled oscillatorrather than an LC-oscillator, synchronized by the crystal more or less, at least on the higher SW-bands. The Parametric VXO provides a crystal-stable, chirp-free signal on expense of an output power of two milliwatts only instead of ten, but with an amazing spectral purity, no need for a low pass filter or such. Of course it sounds pretty cool making a QSO with a 'bunch of diodes' and a parametrically excited crystal, but believe me or not, I'd preferred to bring that full ten milliwatt into the air - on the other hand that approach allowed to tune the rig a bit ( ~ 5kHz/per xtal ), which turned out to be much more valuable than a few milliwatts more while being 'rock-bound'.The receiver in its 'gain-less' version works fine for strong signals - while listening to QRP(p) stations, the moderate gain of the audio amplifier helps a lot. A comfortable frequency shift between receive and transmit is realized by the 5µH inductor at the LO-port of the mixer, with little effect on sensitivity.
Thanks for the bandwidth, OMs, won't bother again you with such mails, unless I make a cross-pond QSO with that rig ( not that likely ) or any skywave QSO with homemade semiconductors ( probably impossible )...72!Peter/DL3PB"
Labels:
dl3pb,
tunnel diode
481THz optical treebounce and skyscatter
Optical treebounce (0.3km total path) 10wpm CW 0.501kHz 35dB S/N |
First test was 10wpm CW off the tree (0.3km path length total) with strong signals received 35dB S/N in 5.4Hz bandwidth. Signal v.clear in the earpiece too. I could just make out the red light glow in the distant tree branches. Aiming critical.
Weak QRSS60 signal received by aiming at clear sky |
just aimed at what I thought was roughly the same patch of sky. Now I can't be sure whether the signal is purely from scattering off mist/dust particles or what, but I think it is unlikely signals are coming off other objects as I am aiming quite high into the sky (about 45 degrees up) clearing nearby stuff.
These tests suggest that with very slow QRSS I may be able to get a non line-of-sight optical signal to G6ALB in the next village 3km away. When the weather improves I'll go out /P with the PC and RX and see if I can detect the "forward" scattered optical baseband signal at much greater range (1-3km). With proper cloudbounce it should be better I think.
This reference looks like it should be interesting (about scattering) http://en.wikipedia.org/wiki/Rayleigh_scattering
Labels:
cloudbounce,
rayleigh scattering,
skyscatter
A 472-479kHz band?
Latest reports from the WRC2012 conference suggest the possibility of a secondary amateur allocation between 472-479kHz look "promising" although this hinges on a crucial meeting on Tuesday Feb 7th. Some countries remain against an amateur allocation, but the majority do support one, with caveats. A 7kHz wide worldwide allocation would be a good outcome, so keep fingers crossed for a few more days.
Labels:
472-479khz,
500kHz,
wrc2012
4 Feb 2012
QRP and S Points
This very useful little diagram was posted on Wim PC4T's blog today showing how little effect going QRP usually has on operating effectiveness. Going from 100W to 500mW is just 4 S-points, so if your signal is strong you'd still be a decent signal. Of course, when conditions are marginal 100W may be helpful, but QRP is so much more fun.
Optical receiver noise floor measurements
A PC with some simple free software makes a very useful piece of test gear.
For example, today I wanted to check the noise floor of my optical receiver head between 0-20kHz in total darkness and in daylight and compare this with the noisefloor of the PC with the head turned off. SM6LKM's excellent little software receiver designed to listen to SAQ's transmissions on 17.2kHz was ideal. This tunes from 0-22kHz. Here are the results (see plots) which show noise goes up by about 5dB in the daylight, although noise at 0-2kHz seems to go down in sunlight. By connecting the optical receiver head to the PC I was able to use this little package to see the noise floor changes. G4JNT thinks the FET is possibly being biassed to a less optimum position, or it is saturating, in daylight. By changing the bias I may be able to get a lower noisefloor and better sensitivity. That I shall try tomorrow.
For example, today I wanted to check the noise floor of my optical receiver head between 0-20kHz in total darkness and in daylight and compare this with the noisefloor of the PC with the head turned off. SM6LKM's excellent little software receiver designed to listen to SAQ's transmissions on 17.2kHz was ideal. This tunes from 0-22kHz. Here are the results (see plots) which show noise goes up by about 5dB in the daylight, although noise at 0-2kHz seems to go down in sunlight. By connecting the optical receiver head to the PC I was able to use this little package to see the noise floor changes. G4JNT thinks the FET is possibly being biassed to a less optimum position, or it is saturating, in daylight. By changing the bias I may be able to get a lower noisefloor and better sensitivity. That I shall try tomorrow.
481THz update: 1.6km test
Today I did my first test beyond the end of my street and in daylight. I set up my 1.082kHz subcarrier CW beacon and 100mm optics pointing out through my double glazed bedroom window and aimed it at a local feature called the Devil's Dyke which is 1.6km (1mile) exactly from home. This is the furtherest line-of-sight (LOS) path I have from home.
Then I went up to the Devil's Dyke and started looking with my handheld 100mm optics receiver. Much to my joy and surprise I heard the beacon before I spotted it by eye. The beacon could be copied over a stretch about 50m along the path. S/N I'd guess at around 20dB (by ear) in speech bandwidth in daylight. Next time I'll take the laptop and measure S/N with Spectran. 1.6km is my best distance so far. I'm using a BPW34 detector with some reverse bias with the PIN diode's anode connected directly to the FET gate in a KA7OEI optical head. This feeds into a feedback biased common emitter stage into a crystal earpiece. Recovered audio was a bit low in the wind.
Some progress in the right direction.
Then I went up to the Devil's Dyke and started looking with my handheld 100mm optics receiver. Much to my joy and surprise I heard the beacon before I spotted it by eye. The beacon could be copied over a stretch about 50m along the path. S/N I'd guess at around 20dB (by ear) in speech bandwidth in daylight. Next time I'll take the laptop and measure S/N with Spectran. 1.6km is my best distance so far. I'm using a BPW34 detector with some reverse bias with the PIN diode's anode connected directly to the FET gate in a KA7OEI optical head. This feeds into a feedback biased common emitter stage into a crystal earpiece. Recovered audio was a bit low in the wind.
Some progress in the right direction.
Labels:
481thz,
daylight,
devil's dyke,
light,
light beam,
optics
2 Feb 2012
More Sixboxes and Fredboxes
Then I noticed a version of my 2m AM Fredbox on a Romanian website. See http://www.garajuluimike.ro/electrice/emitator-receptor-144mhz.htm . This version also uses an LM386 audio amp to drive a loudspeaker.
Labels:
6m,
AM,
fredbox,
joe milbourn,
lm386,
sixbox,
transceiver
Latest Solar Data
Jan Alvastad's excellent page on solar data shows that for the last couple of months the trend in solar activity is downwards, not upwards. Now it is not uncommon for solar cycles to show more than one peak, with the second being greater than the first, but I hope that was not "it" and that we are now sliding down to the next minimum already! The image below is on Jan's site and I hope he does not mind me linking it here.
Labels:
jan alvastad,
solar,
sunspots
More on the German "Chirpy"
Today I got this email from Martin about his build of Chirpy:
Hi Roger,
Somehow the text of my email got lost when I send it from my phone. I like your blog very much, especially your homebrew projects. Yesterday I took the time to get the chirpy from the breadboard into a nic enclosure. I have plenty of this tins since my xyl likes to eat some paste that comes in them. My rebuild of chirpy puts out 210 mW and has a lot of chirp. Perhaps we can have a chirpy qso when the band is open.
Thank you very much for the design and your nice blog.
73 de Martin, DL8MAR
Labels:
chirpy
Slight progress towards a new 500kHz band
The latest reports from WRC2012 about a possible new allocation just below 500kHz sound slightly more hopeful than a few days ago with China and Russia softening their positions, but unfortunately the Arab group seems dead set against an allocation at all. We'll have to wait until Working Group 4C (next level up) discusses it. In the meantime let's keep our fingers crossed.
1 Feb 2012
VLF Talk - Cambridge Club Feb 10th
On Feb 10th I have been invited to talk to the Cambridge and District Amateur Radio Club on VLF through the ground although I intend to widen the scope to include all aspects of amateur radio communications experiments below 9kHz. In the last year or so this aspect of our hobby has come on leaps and bounds and what was once thought of as impossible being achieved. Surprisingly, this is a very accessible part of the spectrum in which to experiment. If you want to come along and are not a CDARC member I am sure you'd be made welcome by club members.
Labels:
cdarc,
earth mode,
vlf
Another 10m Chirpy
Martin Spreemann (callsign not known) in Berlin has sent me a picture of his version of Chirpy, the minimal component transceiver for 28MHz CW. I wonder what results people who have made this (rather chirpy) transceiver have obtained? Please let me know if you have built and used one. Remember the design uses a fundamental crystal for 28MHz, not a 3rd overtone. The design should work equally well on 24MHz (slightly less chirp too) and 21MHz, although I suspect broadcast breakthough will start to become more of an issue.
Labels:
10m,
28mhz,
chirpy,
transceiver
31 Jan 2012
Optical "tree bounce" tests
Spectran screenshot of 481THz "treebounce" test 30.1.12 |
Yesterday my 1W ultra-bright LEDs arrived from Hong Kong. When fitted to the beacon these will be VERY bright and will extend the range possible on 481THz yet further. All good fun!
Labels:
481thz,
spectran,
treebounce
30 Jan 2012
A Czech Chirpy from OK1CDJ
Ondra OK1CDJ kindly sent me some photos of his version of my 10m chirpy transceiver. Currently he is getting around 50mW out, a little lower than on samples made here. I have suggested some things to check and possibly change. I really must find a way of making it chirp less, HI.
See http://translate.google.com/translate?client=tmpg&hl=en&u=http%3A%2F%2Fblog.ok1cdj.com%2F&langpair=cs|en for an English translation of Ondra's blog.
See http://translate.google.com/translate?client=tmpg&hl=en&u=http%3A%2F%2Fblog.ok1cdj.com%2F&langpair=cs|en for an English translation of Ondra's blog.
29 Jan 2012
Optical CW beacon TX now ready
Today I completed my first keyed optical beacon transmitter (with 100mm optics) which I'll be
using for tests at greater range than hitherto. The 481THz
(red light) beacon sends my callsign in either 10wpm CW, QRSS30 or
QRSS60 as well as a continuous carrier or a 30sec on/off sequence. The TX uses a sub-carrier of 1.082kHz or 8.659kHz, the frequency being derived from an HF crystal divided down in a 4060. The message comes from a K1EL K-ID2 programmed PIC. Initial tests this afternoon at dusk allowed me to copy the 1.082kHz 10wpm CW sub-carrier signal by reflection off a wall across the street at decent strength.
My next challenges are to find some local paths of a few kilometres to check the beacon and the receiver. I'd also like to try some non line-of-sight paths, possibly including cloud-bounce.
My next challenges are to find some local paths of a few kilometres to check the beacon and the receiver. I'd also like to try some non line-of-sight paths, possibly including cloud-bounce.
27 Jan 2012
How sensitive can headphones be?
Having made several short-wave crystal sets in my time I have nearly always used the little "deaf aid" very high impedance crystal earpieces as the acoustic transducer. I thought these were very sensitive being able to copy HF AM signals down to around -55dBm to -60dBm. However I recently read somewhere that with the old WW2 DLR5 low impedance headsets one could hear an applied audio signal as low as 2uV (-101dBm), which is remarkably low.
So, I began to wonder just what ARE the best headsets to use if one is after the maximum efficiency converting an audio frequency electrical signal into sound pressure in the ear?
This graph (from Wikipedia) shows the sensitivitity of typical humans at different ages. Someone of my age (63) is likely to be less able to hear as low as someone aged 30 years.
As some of these old military surplus headphones can be hard to find nowadays in good condition, I wonder what is the most sensitive headset/earpiece that can be bought new "off the shelf". Any ideas please?
So, I began to wonder just what ARE the best headsets to use if one is after the maximum efficiency converting an audio frequency electrical signal into sound pressure in the ear?
This graph (from Wikipedia) shows the sensitivitity of typical humans at different ages. Someone of my age (63) is likely to be less able to hear as low as someone aged 30 years.
As some of these old military surplus headphones can be hard to find nowadays in good condition, I wonder what is the most sensitive headset/earpiece that can be bought new "off the shelf". Any ideas please?
26 Jan 2012
Dropbox Problem
When my grabber is running I use Dropbox to automatically upload the captured image to a location on the net where anyone can see the image. Recently Dropbox has been doing something wrong and when I try to launch the program I get an error message (see image). I have tried EVERYTHING to fix this, to no avail so far. Has anyone else had this issue? I looked on the Dropbox website (not too helpful), tried running Ccleaner to see if the registry entries were faulty (no luck), reinstalled the software (about 10 times now in different release versions) and deleted each when the same darn message appeared.
Help!
Help!
25 Jan 2012
New beacon chips arrive
Today my new KID2 pre-programmed beacon ICs arrived from www.k1el.com . These are for use in my VLF, 136kHz, 500kHz and 481THz beacons. With 7 pre-programmed messages in 10wpm CW, and various QRSS speeds these are ideal. I have used these before and been very satisfied. See http://k1el.tripod.com/files/kid2man.pdf for more details of the ICs.
Laptop/Netbook Reliability
Investing in a new laptop or netbook can be a tricky decision: getting the right price, spec, performance and reliability. My Dell laptop failed a year or so ago (keyboard) but I was able to repair it by buying a new keyboard via eBay and following some good fitting instructions found on YouTube. My wife's school laptop LCD screen just failed suddenly when it was in use on her lap with black "cracks" appearing as if the whole thing had been dropped. This was repaired under warranty thankfully. Then you hear of hard-drives failing.
Today I came across an interesting page giving some reliability statistics for laptops and netbooks. Apparently Asus and Toshiba make the most reliable ones. The paper is by a company selling extended warranties, so they will be keen to show that it is worth buying one. Nonetheless I think the stats are fair.
Today I came across an interesting page giving some reliability statistics for laptops and netbooks. Apparently Asus and Toshiba make the most reliable ones. The paper is by a company selling extended warranties, so they will be keen to show that it is worth buying one. Nonetheless I think the stats are fair.
Labels:
laptop,
netbook,
reliability
24 Jan 2012
FT-450D hum: a good response from Yaesu
I will paraphrase Paul's reply below.
He went on to say,
"Please rest assured that Yaesu does care about its products, their reliability and performance. We certainly look to resolve any problems as soon as they become known to us. The FT450D is a splendid radio, having done excellently at the T32C DXpedition last year when over 200K QSOs were made with no reports to us of any hum problems."I thought this was an excellent and totally professional response. Yaesu is a first class manufacturer and it is reassuring to see they have taken on board the hum issue in this otherwise excellent little radio and have now taken steps to properly fix it on new build units.
20 Jan 2012
137kHz transverter bites the dust
Having re-erected my 80m loop antenna I was about to reload OPERA and give it a try now it appears more stable. I ran up the transverter on WSPR to check all was well only to have the power supply suddenly take around 20A and shut itself down. I think the MOSFET PA died on me. All being well I will get this fixed next week when my grandson goes back home again and have another try.
Labels:
137khz,
transverter
Netbooks
For many years I used a little Asus EEE PC701 (7 inch screen) netbook running a pre-loaded Linux OS. This was ideal for basic net surfing and emails, but it lacked the flexibility of a Windows OS when looking for ham radio software. At the moment I am looking at a possible replacement that I can use for general web browsing and also to run WSPR, OPERA and hopefully Spectran and Spectrum Lab freeing up the main PC. Such a small netbook would also be useful for field use with VLF tests, lightbeam experiments etc.
It is quite amazing what £200-250 will buy today. My first laptop cost me £1499 back in 1998 and the performance was nowhere near that of even my little Asus EE PC701!
My inclination is to buy another Asus machine unless someone can give me good reasons to choose another make.
It is quite amazing what £200-250 will buy today. My first laptop cost me £1499 back in 1998 and the performance was nowhere near that of even my little Asus EE PC701!
My inclination is to buy another Asus machine unless someone can give me good reasons to choose another make.
A new meteor scatter mode
http://www.dk5ew.de/2012/01/13/psk2k-a-new-meteorscatter-mode-by-dj5hg/
This webpage gives details of an interesting high speed MS mode from DK5EW. There is also a Yahoo group to discuss this: see http://uk.groups.yahoo.com/group/psk2k/
This webpage gives details of an interesting high speed MS mode from DK5EW. There is also a Yahoo group to discuss this: see http://uk.groups.yahoo.com/group/psk2k/
"PSK2k is high speed meteor scatter software written by Klaus DJ5HG (Prof. of Computer Science at University Hamburg). It allows 2 way MS QSO’s to be conducted with any suitable transceiver/PC/soundcard combination.PSK2k is fully error correcting and call specific in operation so you will only see the QSO in progress and any non-QSO CQ or QST text. All other transmissions (other people also in QSO) are discarded. This allows multiple QSO’s to take place on a single frequency.
PSK2k can be operated in fully automatic mode if required. This enables QSO’s to be completed fully automatically without user intervention. Important advantages are that long term testing can be done, on QRP power for instance, without having to sit an monitor every period."
Labels:
dk5ew,
meteor scatter,
psk2k
18 Jan 2012
Philips FM321 70cm mobile
The very first FM synthesised 70cm rig in the UK was made by Philips in Australia and was called the FM321. This 4W mobile was based on the very similar FM320 designed for the Australian UHF CB band. I owned an FM321 for a couple of years back in the early 1980s and really enjoyed using it on the UHF simplex channels and repeaters. Ergonomically it was excellent with simple up-down channel change and a decent volume control. It is a pity rigs are not made as simple as this today. No memories, no fuss.
From the home QTH and with just a hand rotated small vertical yagi I could work some impressive DX on FM on some days. That's the thing about 70cms: propagation changes within hours and often in very localised directions. When there was plenty of simplex activity it was very interesting watching propagation change and the maximum range change from maybe 30 miles to over 100.
From the home QTH and with just a hand rotated small vertical yagi I could work some impressive DX on FM on some days. That's the thing about 70cms: propagation changes within hours and often in very localised directions. When there was plenty of simplex activity it was very interesting watching propagation change and the maximum range change from maybe 30 miles to over 100.
Labels:
fm321,
philips. 70cm
WRC-12 Radio Conference (Jan 23 - Feb 17)
This most important international frequency revision conference takes place Jan 23th - Feb 17th. As always, the amateur service can never be certain of the outcome with a possibility of precious spectrum being lost to other services. However, this time there is a good chance that we will GAIN a new amateur MF band somewhere between 415 and 526.5kHz. The most likely outcome is a band near 480kHz around 8kHz wide. 8kHz of spectrum would allow much more experimentation, especially if this allocation was world-wide. This would supersede the special permits around 500kHz allocated in some countries.
Labels:
500kHz
Nice antenna for 80m QRP?
13 Jan 2012
Optical RX improvements
G8CYW Optical head (April 2011 RadCom) |
In the first instance I need to remeasure the noise floor with the optical head in total darkness to see if the changes indeed make it better than the current discrete component circuit. My first quantitative noise measurements suggest far higher noise floor than I expected.
Assuming this gives improved performance over my 0.4km local "up the road" test range, my next step is to attempt a longer path, so I am looking for a path of around 2-3km to test with my baseband beacon. If this works with decent S/N then I'll retry looking for the GB3CAM optical beacon. At 32km this is a good test of system performance. At the test site at Nine Mile Hill the traffic noise was high (optically and audibly) so I also need to increase the signal level in the earpiece used to align the RX.
There is also soon to be a second optical beacon near Cambridge and this should be a little closer and an easier signal to find. However, I need to do tests before this is installed at Dry Drayton.
Incidentally, I managed to overcome the parallax issue in the optics alignment so now a distant street light is spot on in the cross-hairs of the spotting scope.
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