I think the theory is that the atmospheric noise is below the receiver's
detection level so the noise you hear is generated inside the rig. Add a
preamp and both the antenna noise and signal come up by the same amount
bringing the antenna noise up to the detection floor and boosting the
signal at
Doug, the preamp does not discriminate between signal and noise. It does not
bring the signal out of the noise. It will raise the level of the signal and
the noise if the noise level is very low such as happens frequently on VHF,
sometimes on ten meters and occasionally on 15 meters. Preamps
DOUGLAS ZWIEBEL wrote:
Hi...
The following request for information is not specific to the K3 (or
even to Elecraft). Please craft your response to be generic.
Despite being an active ham/contester for over 40 continuous years
(but not being an ee), I just do not understand how a
Keith is quite right.
All receivers generate internal noise in their amplifiers. The goal is to
make sure this internal noise does not compete with the received signal so
the only thing that limits the ability to hear weak signals is the
unavoidable atmospheric or antenna noise.
Of course, the
Hello Doug,
Here some basics about preamps. I will try to make it short, but I could
expand to pages
A preamp only makes sense if the noise-figure (NF) of the preamp is better
than the NF of the normal input stage (usually the normal frontend input).
Each stage in a receiver (frontend,
...@gmail.com; 'Elecraft Reflector'
elecraft@mailman.qth.net
Sent: Monday, December 15, 2008 11:14 AM
Subject: RE: [Elecraft] K3 sensitivity + preamp: looking for wisdom
Keith is quite right.
All receivers generate internal noise in their amplifiers. The goal is to
make sure this internal noise
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