Posted by
G3VVT on
Dec 22, 2004; 3:41am
URL: http://elecraft.85.s1.nabble.com/K2-AGC-versus-RF-Gain-versus-AF-gain-tp372777p372781.html
Micheal,
The so called RF gain in the K2 is actually IF gain, which is the same as
used in the JRC NRD-515 RX. The difference is the K2 has fixed RF front end
gain before the RX mixer with a switchable preamp or attenuator in addition. The
NRD-515 has no RF amplifier only a switchable RF attenuator in front of the
1st RX mixer. Not familiar with what the Kenwood RF gain does in the TS-530S
or the TS-930S.
The K2 has a slightly strange action in that a strong signal goes to a
higher S meter reading pretty much as soon as the RF gain is reduced and when the
S meter reading goes higher the RX volume does go down as you say. Not a lot
but perceptible. It is possible to set the S meter with no signal in to the
level required, say S9, though when a station is tuned in that was S9 with full
RF gain it now reads higher and the audio volume is less.
The JRC NRD-515 volume stays constant until a point is reached that the S
meter reading rises with reduced RF gain and becomes greater than the reading
for the incoming signal. The RX audio volume then begins to fall beyond that
point
Looks like a quirk with the K2 AGC action or design.
My K2 has had the AGC threshold set to the point where switching the AGC on
and off has no effect on the no signal background noise. Came out in my case
at 3.70V, though apparently varies slightly from K2 to K2
Bob, G3VVT
K2 #4168
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