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#1
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On Sat, 05 Jan 2013 04:02:59 -0800, JIMMIE wrote:
The beer got flowing the other day and some of my friends and I got to BSing about the possibility of transmitting a microwave pulse and reciving it reflected off the moon. Plans are to use a microwave oven magnetron for the transmitter. We were wondering if this would be legal. No, it would not be legal to do it as you described. However, there are lots of ways to do it legally: http://en.wikipedia.org/wiki/EME_%28communications%29 http://www.electronics-radio.com/art...r-propagation/ moonbounce-propagation-eme.php etc. Google is your friend. |
#2
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David wrote:
On Sat, 05 Jan 2013 04:02:59 -0800, JIMMIE wrote: The beer got flowing the other day and some of my friends and I got to BSing about the possibility of transmitting a microwave pulse and reciving it reflected off the moon. Plans are to use a microwave oven magnetron for the transmitter. We were wondering if this would be legal. No, it would not be legal to do it as you described. However, there are lots of ways to do it legally: And why not in the USA? Microwave oven mangetrons operate at 2.45 GHz, which is the top of the 2.39 to 2.45 GHz band and should be trivial to pull down a little bit. All modes are allowed in the band. All licencess other than Novice can use the band. |
#3
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On Mon, 07 Jan 2013 02:15:09 +0000, jimp wrote:
David wrote: On Sat, 05 Jan 2013 04:02:59 -0800, JIMMIE wrote: The beer got flowing the other day and some of my friends and I got to BSing about the possibility of transmitting a microwave pulse and reciving it reflected off the moon. Plans are to use a microwave oven magnetron for the transmitter. We were wondering if this would be legal. No, it would not be legal to do it as you described. However, there are lots of ways to do it legally: And why not in the USA? Microwave oven mangetrons operate at 2.45 GHz, which is the top of the 2.39 to 2.45 GHz band and should be trivial to pull down a little bit. All modes are allowed in the band. All licencess other than Novice can use the band. Microwave magnetrons would likely have unacceptable spurs and sidelobes, as the frequency is not very stable. |
#4
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David wrote:
On Mon, 07 Jan 2013 02:15:09 +0000, jimp wrote: David wrote: On Sat, 05 Jan 2013 04:02:59 -0800, JIMMIE wrote: The beer got flowing the other day and some of my friends and I got to BSing about the possibility of transmitting a microwave pulse and reciving it reflected off the moon. Plans are to use a microwave oven magnetron for the transmitter. We were wondering if this would be legal. No, it would not be legal to do it as you described. However, there are lots of ways to do it legally: And why not in the USA? Microwave oven mangetrons operate at 2.45 GHz, which is the top of the 2.39 to 2.45 GHz band and should be trivial to pull down a little bit. All modes are allowed in the band. All licencess other than Novice can use the band. Microwave magnetrons would likely have unacceptable spurs and sidelobes, as the frequency is not very stable. Spurs are highly unlikely with a cavity based device like a magnetron. Sidelobes are an artifact of antennas, not oscillators, unless you are talking about modulation sidelobes which are pretty trivially dealt with in a pulse device. The frequency stability of a magnetron is highly correlated to the power supply, i.e. the anode voltage. The power supply and pulse control of an oven would be useless for any sort of communications, so one would need to build one that pulled the frequency down into the amateur band and provided for some sort of modulation scheme. The simplest modulation would be very high speed CW. |
#5
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Jef wrote:
Spurs are highly unlikely with a cavity based device like a magnetron. Sidelobes are an artifact of antennas, not oscillators, unless you are talking about modulation sidelobes which are pretty trivially dealt with in a pulse device. The frequency stability of a magnetron is highly correlated to the power supply, i.e. the anode voltage. The power supply and pulse control of an oven would be useless for any sort of communications, so one would need to build one that pulled the frequency down into the amateur band and provided for some sort of modulation scheme. The simplest modulation would be very high speed CW. Some years ago a local ham injection locked his microwave oven and produced a pretty stable source in the 2.4GHZ band. Jeff That would be the smart thing to do if one wants frequency stability and these days it is pretty easy to do. |
#6
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#7
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Ian Jackson wrote:
While these technical discussions are very interesting, I can't help feeling that most of it will go over the head of the OP. Even if he knows nothing about amateur radio, he will by now have realised that moonbounce is quite a specialist subject, and not something that the ordinary man-in-the-street would be able to suddenly decide to have a go at. If he does know about amateur radio, he probably knows this already! Well, I have not personally used moonbounce but I have visited a moonbounce station back in the late seventies and I sometimes read about moonbounce as it is today, and I get the impression that it has become a lot easier for the average ham to build a moonbounce station. It may not be for the ordinary man-in-the-street and probably also not for the ordinary novice radio amateur, but someone who can read and think and is not without money should be able to assemble a JT65 moonbounce station. Back in the seventies it required you to be a lunatic, have a suitable location, and a real lot of money. |
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