Topband: Re:

[Maurizio Panicara]

A receiver system needs the bests possible dynamic range within a good NF.
Between two receivers with same blocking level, that one with better NF is
definitely the best or, reversing the point, stated what's the required NF
the best receiver is that with the bigger dynamic range
Passive hi level mixer have an high intercept point but their NF is poor.
Active hi level mixers can have an high intercept but the active devices are
then polarized in a way that developes a poor NF.
Most of the (serious) antennas used for 160m reception are 30/40 dB(i)
unefficient and the receiver sensitivity has to be accordingly increased.
A sensitivity  of  0.316 uV with a 30 dB unefficient antenna equals a 10 uV
sensitivity  in a dipole.
A sensitivity  of  0.1 uV with a 40 dB unefficient antenna equals a 10 uV
sensitivity  in a dipole.
Unless planning to use a very directional antenna with gain and no losses at
useful angles, the overall 160m receiver sensitivity must be good, fair
isn't enough.

73,
Mauri I4JMY









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