[amsat-bb] Re: Pre-amps
kc6uqh at cox.net
Sat Dec 22 22:30:13 PST 2007
Here is a link to a noise figure meter project. Even if it is not
calibrated it can be used for comparitive measurments.
Art , KC6UQH
----- Original Message -----
From: "Tony Langdon" <vk3jed at gmail.com>
To: <vk4tec at people.net.au>; "Amsat-Bb at Amsat. Org" <amsat-bb at amsat.org>
Sent: Saturday, December 22, 2007 5:56 PM
Subject: [amsat-bb] Re: Pre-amps
> At 11:38 AM 12/23/2007, Andrew Rich wrote:
>>So I took a gamble and put in the VHF parts instead.
>>Bingo S1 to S9 improvement.
> OK, but the important thing is what is the improvement in S/N? If
> the preamp has too high a noise figure, all you'll end up doing is
> moving the S meter a bit more... What you're aiming to do is
> improve the S/N of the received signal.
> If the S/N doesn't change, you will still gain an improvement by
> siting the preamp at the masthead. If it does improve with the
> preamp at the radio, the improvement will be even more with the
> amplifier correctly installed at the antenna.
> 73 de VK3JED
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