Love the idea !

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Love the idea !

Postby Harry Dalek » Sun Apr 11, 2021 12:57 am

Now isn't this a project and a half !

youtu.be/90ij3rzH5wg

youtu.be/NNxKNUrCqNY
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: Love the idea !

Postby Steve Anderson » Sun Apr 11, 2021 1:00 pm

...reminds me of the days when I worked in radar at Decca in New Malden and Chessington in/near London in the 70s. By chance I have a couple of exactly the same CRTs, 5ADP7s, and a couple of 5ADP1s.

All kudos to the guy in getting this far...not sure what use he may have for it, but certainly educational!

As he mentions, his biggest hurdle is going to be the receiver. The Klystron he's using as a transmitter was usually used as a local oscillator for the receiver, they were eventually displaced by Gunn diodes as the power required is only 20mW or so. The 10GHz [1] antenna input was mixed with the Gunn diode's output to produce an I.F. of around 70MHz.

The receiver had to be logarithmic as the reflected power goes down with the square of the distance to the target. In other words the receiver needs to have a large dynamic range. A target 100km away, in marine terms - over the horizon, returns a very weak signal, but when the vessel is berthing the crew want to have a resolution better than 15m or so and hence a very strong return signal.

Typically a radar uses a Magnetron as the transmitter, the frequency and power output is set by its design and can only be varied over a very small range. A microwave oven Magnetron is a somewhat different device, its power can be varied, but it's frequency stability is rubbish!..no good for radar. But your meat pie doesn't really care...

Steve A.

[1] 10GHz (X-band, 3cm wavelength) is the most often used marine radar frequency, the other other common frequency is 3GHz (C-band, 10cm wavelength), the advantage is it's less reflected by rainfall where an X-band radar would be effectively blind. Large vessels will typically have both, often duplicated too.

The same problem as Ku-band satellite TV (12-18GHz), during heavy rain - no TV.
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Re: Love the idea !

Postby Steve Anderson » Sun Apr 11, 2021 8:54 pm

Not being familiar with you-tube, is there any way to get in contact with the poster of these items? I can suggest a few ideas to get rid of his 'quadrant flashes' by linearising the circuitry used for deflection...

Steve A.
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Steve Anderson
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Re: Love the idea !

Postby Harry Dalek » Mon Apr 12, 2021 7:30 pm

Steve Anderson wrote:Not being familiar with you-tube, is there any way to get in contact with the poster of these items? I can suggest a few ideas to get rid of his 'quadrant flashes' by linearising the circuitry used for deflection...

Steve A.


You can can reply in the comments under the videos Steve ,it should show up on he's account as a message .
I think its a great project he has taken on interesting indeed .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 4612
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: Love the idea !

Postby Steve Anderson » Tue Apr 13, 2021 11:57 am

Thanks Harry, I'll give it a blast...

Steve A.
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Steve Anderson
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