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Old February 3rd 04, 04:33 AM
Pete KE9OA
 
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Every solid state Drake receiver that I have had, except the R7/TR7 seems to
have that problem. I am not sure if it is because some of the AGC control
voltage is being derived ahead of the final I.F. system. I don't notice this
problem with the 7030. I don't think I would replace the R8 with the
7030....the R8 is a good receiver.

Pete

"phil " wrote in message
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hi Ron:

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?


yes, not via "suppression" [filter] but by its first mixer [SD5400] being
able to handle the energy.

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.


the AGC can be turned off, what cannot be fixed is close-in dynamic range.

It's not a question of being any good (the R8B is good) but whether the
7030 is any better. Some slight edge.


yes. 7030 2-kHz DR is 82-dB; R8B 5-kHz DR is 75-dB. 5-kHz IP3 is +1 dBm
[7030] versus -20 dBm [R8B].

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.


at that spacing it would be difficult but you might try a series-resonant
trap.

regards,
phil



 
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