"Geoffrey S. Mendelson" wrote in message
...
William Sommerwerck wrote:

What does this have to do with the perceived need
for an RF stage at the receiver?

Read the rest of the posting, it explains why.

I did. It was even more confusing.

Ok, maybe this will make more sense.

Hams either use resonant antennas or antenna tuners.
Resonant antennas by virtue of the fact they are resonant in-band, are not
resonant out of band and therefore reduce out of band signals.
Antenna tuners (for reception) act as preselectors which reduce out of
band
signals. In practice and design, they are TRF stages.
So if you buy a ham radio with an antenna tuner, it may not have a tuned
front end as specfied, but in reality it does.

I'm not sure that's correct. My Yaesu ("joy of ham's desiring") has a
switchable antenna tuner and switchable RF stage, and they're not
interlocked in any way. No engineer would design a ham transceiver that
depended on an antenna to provide adequate selectivity.

Besides, the RF stage is also there to improve sensitivity (when needed). As
for selectivity... image rejection is more-important than selectivity, and
this is a triple-conversion receiver.