AmateurRadio.com

This evening I managed to hear signals bounced off the moon using an FT-817 and an antenna made from a stick and a few bits of wire.

I took the battery out of the clock / weather station to silence its interference and went down to the bottom of the garden with the home made antenna and the FT-817. I couldn’t see the moon this evening as it was cloudy – in fact, attempting to drizzle – but I pointed the beam in the same general direction as last time, turned it vertical to minimize the QRN and started tuning around 432.045MHz. After a minute or so I heard some weak CW.

If I had to give a signal report it would have been 319, the signal was about equal to the noise. Sometimes it would pop up a few dB above the noise for a second or two, and I heard the call KP4AO (though not all in one go), reports being sent, R, 73 and BK, but I couldn’t make out any other calls.

I had the computer interface plugged in to the FT-817 so I brought down the Samsung NC10 netbook which I have been using for my Echolink node and tried to make recordings of what I heard using Sound Recorder in order to listen to them again and even put some samples here. But for some reason when I played them back on my shack PC all I could hear was noise – the CW had all but disappeared. What a disappointment, to have no record of this rare event.

Then, on a sudden stroke of inspiration, I changed my computer sound card settings so that I was using the Realtek internal sound card – normally used for HF digital modes – to play back the audio in place of the cheap USB “dongle” I normally use for computer sound. What a difference! Instead of just hiss with a barely detectable hint that a CW signal might have been there, I now heard the KP4AO signal via the moon just as I heard it live off-air. I have converted a couple of samples to MP3 format without much loss of fidelity so you can hear for yourself what I heard:

• Here is a short sound clip from KP4AO recorded at 1937 UTC
• And here is a slightly longer one recorded around 1945 UTC

The CW certainly is weak but you can pick out letters now and again. If you manage to pick any calls out of those samples then you have better ears than me (which is certainly possible.)

An interesting evening’s experiment. Not just because I heard signals bounced off the moon for the first time ever but also for the unexpected demonstration of how weak signals get lost when you use a cheap sound card. I had been planning on using one of those USB dongles to make my own SignalLink interface. I think it’s back to the drawing board on that one.

I heard nothing during my attempt last night to receive signals from KP4AO bounced off the moon. Nothing, that is, except a lot of noise. Sitting at the bottom of the garden with my newly constructed hand-held 6 element 70cm beam, the Moon was above and just to the left of the roof of our house. And the nearer I moved the beam to the house, the greater the noise. This house is truly a disaster area for radio reception!

This afternoon I thought I would try to see where the noise was coming from. With the beam horizontally polarized the noise was a broadband hash, white noise, indistinguishable from band noise except that its level is much greater with the beam pointing towards the house. If I turned the beam vertical then the white noise faded out almost to receiver noise, but another pulsing noise came up. It went kerchunk chunk chunk chunk, kerchunk chunk chunk chunk, ad nauseum. And the level of this noise peaked up with the beam pointing right at the shack window!

I switched everything off in the house and it made no impact on the noise whatever. I decided that it must be something battery powered. There is a radio controlled alarm system in the house that has a built-in backup battery. Nothing I can do about that. However I could not hear any noise increase when I went near it with the TH-F7E and a whip antenna. The noise level goes up and down as you walk about the house, as does the kerchunk chunk chunk noise, as if the noise source is invisible.

Eventually I did locate the source of the kerchunk chunk chunk noise. It was coming from an Ascot radio controlled clock sitting on the shelf in the shack just above my radios. I removed the batteries and after a few seconds the noise stopped. I walked about the house some more and in places I heard it again! This sort of thing can make you start to doubt your sanity.

Eventually I found that exactly the same noise was coming from another clock / weather station in our conservatory. It’s a different brand, not radio controlled, and (probably not coincidentally) it receives temperature and humidity readings from the same external sensor. Presumably they have some electronics in common and this is transmitting a signal in the 432MHz band.

But I haven’t found the source of the broadband hash, which may or may not be related to the crackly S9 noise that plagues most of the HF bands. I think the noise problems at this QTH are beyond solution. I haven’t logged an HF band contact from here since 13th March. It isn’t that I can’t work anything on HF from here, it’s just the demoralizing effect of hearing this dreadful noise as soon as you switch on and knowing that there are interesting signals buried under it that I have no chance of hearing.

Flights in or out of the UK are banned for a fourth day due to the alleged effects of dust from the Icelandic volcano. Flight restrictions have been just been extended until midnight tonight, with suggestions that they could extend for “several more days”. Britain is virtually cut off, with the Channel Tunnel and ferries to and from continental Europe fully booked. There is talk of an economic disaster, with some European airlines in serious financial difficulties as a result. Tens of thousands of people are stranded, unable to get home from their Easter holidays and facing financial ruin, loss of pay and even the loss of their job as a result. Travel insurance companies in most cases are refusing to pay out for additional accommodation or the cost of returning by alternative means.

However, the Dunkirk spirit is not dead. Just as in 1940 when Brits with small boats went across the Channel to bring our defeated troops back, TV presenter Dan Snow is today mounting an operation with inflatable craft to bring stranded Britons back from Calais to Dover. You couldn’t make it up. (Postscript: The attempt was halted by authorities, presumably for health and safety reasons. Oh well. Nice try.)

It is reported that the Dutch airline KLM has flown a Boeing 737 to 13km over Dutch skies with no adverse effects, whilst Germany’s Lufthansa has flown several planes from Frankfurt to Munich without any harm being caused to the windows, fuselage or engines. But Dutch and German airspace are also closed for the time being. However the Ukrainian International airline – which coincidentally Olga used on her recent trip to Ukraine – is to recommence flights at 0900 UTC today as it believes the skies are safe. Hooray for the Ukrainians! At least someone has some sense.

According to some aviation experts, the only time aircraft have suffered from volcanic ash is when they flew right through a plume of it as the volcano was erupting. The ash here is so thin that you can see the moon and stars when the sky is clear. Isn’t this just another case of out-of-control safety mania, with bureaucrats being afraid to make any decision that just might lead to them being blamed later on, regardless of the probability of risk? Isn’t it time for someone to use some common sense?

This morning I made a 6 element Yagi for 70cm using some 25A copper mains wire with the insulation stripped off and a length of wooden dowel. I copied the design from CT2GQV’s blog. The object is to see if I can hear radio signals bounced off the moon.

If you didn’t know, a bunch of guys that include Joe Taylor K1JT of WSPR fame have got permission to use the 1000-foot dish of the Arecibo Radio Telescope (shown above) for a couple of hours each day over this weekend to make radio contacts via EME. Using full power their signals should be strong enough to be heard using a hand held yagi and it should be possible to work them using just 100W with the same antenna.

I only have the FT-817 with 5W so it isn’t possible to try to work them, but I thought I would try to hear them, which is why I made the antenna. I think you’ll agree that their antenna is more impressive than mine! There are, of course, no 70cm signals to test it on, but there are plenty of noises and the yagi seems quite directional. The SWR is about 1.7:1 at 432MHz and falls gently as you go lower in frequency, but I’m not sure how to adjust it so I’ll leave it as it is for the moment.

The first session was yesterday. Unfortunately their PA blew up so they were only able to run 25W of power. Some contacts were made, but obviously not with people using low power and hand held antennas. Hopefully they will have got a PA working in time for the remaining two sessions, otherwise I am not going to hear a thing.

This evening they should be on between 1740 and 2020 UTC – that’s 1840 to 2120 BST. They will be transmitting on 432.045MHz using SSB or CW. Their call is KP4AO. The moon is only showing quite a thin crescent at the moment so it may not be easy to spot during daylight, even assuming the sky is clear as it is here. If you are in the UK the moon will be at an elevation of about 45 degrees to the south-west at the start of the session, declining to about 25 degrees due west by the end of it. If your QTH is elsewhere you can use this web site to locate it.

Tomorrow’s session is scheduled for 1840 to 2125 UTC – 1940 to 2225 BST. The moon will be in the same position relative to the start of the session.

Fingers crossed that they get the PA going so we can have a chance to hear something. If not, the antenna won’t be wasted as I’ve been meaning to have a try at satellite communications.

One of the greatest uses of WSPR is to get accurate, real-world comparative reports on antennas. When comparing antennas in the past I have used two computers and two radios on two different frequencies using the same power and manually set the WSPR programs to both transmit on the next cycle so that they send their beacon signals simultaneously. During the transmission I set both programs back to “no transmit”. This way I get directly comparable reports from both antennas at the same time and I don’t have to worry about one transmission being received and reported by the other system.

Now, this is no longer possible. The WSPRnet website has implemented a “data scrubber” which will filter out invalid spots including bad calls (bogus decodes), bad timestamps, wrong band reports and duplicate reports. The latter are apparently the most common type of error, accounting for 1.7% of spots. I wasn’t aware this was that common, though it can happen due to reciprocal mixing in the receiver or the computer sound card. But one result of this is that you can no longer intentionally transmit two beacons at the same time using the same call, locator and power level, because if you do all but the strongest report will be filtered out.

I think this is an ill thought out move that will result in deleting valid spots just because they can’t be distinguished from invalid ones. The WSPR software does report the transmit frequency being used by each instance of the software so it should be possible in some cases to determine whether duplicate spots in the same timeslot are genuine or not. This won’t help those using hardware based WSPR transmitters that don’t connect to the website though.

Troubled car maker Toyota has suspended sales of its Lexus GX 460 worldwide after the US consumer magazine Consumer Reports claimed that the vehicle could roll over.

“When pushed to its limits on our track’s handling course, the rear of the GX we bought slid out until the vehicle was almost sideways before the electronic stability control system was able to regain control,” the magazine claims. “We believe that in real-world driving, that situation could lead to a roll-over accident, which could cause serious injury or death.”

Let me get this straight. If you drive like an idiot, the vehicle is supposed to prevent you from suffering the consequences of your stupidity?

I think the nanny state safety obsession in the western world has got totally out of hand. I don’t know how we put the genie back in the bottle (or even whether the population as a whole feels the same way and would want to) but any political party that would repeal the health and safety legislation, outlaw the compensation culture and put the emphasis back on common sense, personal responsibility and the need to prove criminal negligence in order to win a claim in the event of an accident would get my vote.

It has been a glorious day today. After lunch I set off for Tallentire Hill armed with the TH-205E and three antennas: a 2m telescopic quarter wave, a 45″ 2m 5/8 wave Black Whip telescopic from eBay seller jeepbangkok and the SOTA Beams MFD.

I set up the MFD in the vertical position strapped to a fence post and put out some calls. Despite my high elevation the 2m band was quiet and I only managed to raise “the usual suspects”. Richard MM1BHO/M heard me calling through the GB3DG repeater and we had a short QSO. Then Keith G0EMM heard me call on 145.500 MHz and was willing to spend a bit of time doing some antenna tests.

Prior to this I had heard a contact on the GB3CS repeater and had quickly swapped all three antennas to see what the difference was on receive. There was no noticeable difference between the MFD and the Black Whip but both were significantly superior to the 1/4 wave telescopic (which is itself an improvement over the short whips and “duckies” normally used with 2m handhelds.) However the signal was steady on the MFD whereas it varied depending on the position in which I was holding the TH-205E with the BNC mounted antenna. When using the MFD I was sitting on the ground so it was above my head and my body wasn’t interfering with reception. When using rig-mounted antennas it is best to stand up as an extra couple of feet above ground make a noticeable improvement. But it is also worth turning around and moving a short distance as the direction you are facing can make a big difference to signal strength.

Keith confirmed that there was no difference in my signal between the MFD and the 5/8 telescopic. I was 59 on both of them, whereas I was only 4 by 3 on the quarter wave. Keith also gave me my second unsolicited complimentary report on the TH-205E audio, saying it was “just like my voice.” I was using one of the cheap Kenwood speaker mikes which I bought on eBay originally for the TH-F7E.

We were then joined by Colin 2E0XSD who again said that I was the same strength, 59+ on both the MFD and the 5/8 wave. I was only 4 by 7 on the quarter wave.

After I finished the contact with Keith and Colin I tried some more calls. I was able to access the GB3CS repeater using the MFD and the 5/8 – when in the right position – but not with the quarter wave. Some repeaters I could hear but not access even with 3W, which is what the TH-205E appears to put out on “high power” with the 7.2V battery pack, but perhaps they don’t respond to 1750Hz tone-bursts.

When I bought the Black Whip a few weeks ago I put it on the antenna analyzer and got this SWR curve. I seem to remember that I had to collapse the topmost section to get the SWR null spot on 145.000 MHz but I don’t suppose it makes any difference in practise.

I think the Black Whip 5/8 telescopic is a superb antenna for 2m FM use and well worth the few pounds it costs, as long as you have a radio that can handle it. The base is sprung to absorb any shocks but even with the HT Saver SMA to BNC adapter I was a little uncomfortable using it on the tiny TH-F7E. The big old TH-205E has no such problems with a large antenna, although its lower power output with the battery pack I have is a slight disadvantage.

Is it worth carrying the MFD instead of the 5/8, which telescopes down to the same length as a quarter wave telescopic antenna? Well, if you are using a modern hand-held radio then the MFD’s coaxial connection will avoid putting undue strain on the SMA connector. You can secure the MFD to a fence post or stuff the support mast in your rucksack allowing you to operate sitting down and even let go of the radio when receiving. The MFD is also convertible to a horizontal dipole for SSB use. So it still has several benefits. But I expect I will be taking the Black Whip on most of my hilltop outings.