21cm without preamp is it posible???

[Raydel Abreu (CM2ESP)]

Hello,

Quick question here. Is it posible to do some amateur radio-astronomy on 21cm or shorter wavelenght **without** a LNA or pre-amp. If there is the chance what could be the minimum dish diameter required.

Thanks,

Raydel
---

[Marcus D. Leech]

You need an LNA, you really do. Or you need to integrate over very long
time periods, with absolutely-rock-steady gain.

I use a 95cm offset-fed dish for 21cm radio astronomy. It's close to
the bare-minimum to give you some chance of success.

I'm still working on the write-up of my experiments, but I hope to
publish soon.




--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

[Raydel Abreu (CM2ESP)]

Oh, that's a bad news...

Build or buy a LNA for higher than UHF frequencies is very dificult here in Cuba due to the lack of components. VHF is an option but it is a very noise populated band as I live just in the middle of the city.

Raydel

2013/5/17 Marcus D. Leech <patchv...@gmail.com>

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[Marcus D. Leech]

Oh, that's a bad news...

Build or buy a LNA for higher than UHF frequencies is very dificult here in Cuba due to the lack of components. VHF is an option but it is a very noise populated band as I live just in the middle of the city.

Raydel

Indeed, and the trade embargo from the U.S. doesn't help, I imagine.

The G4DDK pre-amp may be a good choice for you:

http://www.g4ddk.com/SPFAMP.pdf

Even 21cm will be a significant challenge in the middle of an urban environment.

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[Raydel Abreu (CM2ESP)]

That's so true Marcus,

I downloaded the PDF file and it is very interesting, finding the SPF5043 could be challenging but i will try to have some hope on this...

Raydel