"Telamon" wrote in message
...
In article ,
"Pete KE9OA" wrote:

How do you figure that this is nonsense?

Well let's quote the the statement that I responded to OK?

In article , BDK
wrote: You can't even be sure identical
radios will have the same S-Meter readings, in most cases. The
reading is pretty meaningless, except to compare antennas, or if a
preselector is used, to adjust for max reading.

You already answered one exception to this blanket statement about
radios calibrated in an absolute scale.

Here is another exception, you can be reasonably sure that the same
model radio will have similar readings.

Typically, SWL radios would have their S-Meter calibrated at 14MHz,
so that S9 would equal 50uV. You are correct when you mention
S-Meters that are calibrated in dBm as being absolute, as long as the
system in in calibration for gain distribution, etc. Receivers that
have this function do provide for setting up the gain distribution.
Now, the mystery continues.................what exactly do you mean
by the following statement?

"The RF gain control just sets maximum sensitivity of the radio and
does not change the gain of the radio so by turning all the way down
you are at the radios published maximum sensitivity. As you turn it
up you are desensitizing the radio."

The above statement, in quotes, is a new one to me. Could be showing
my young 54 year old age. The RF gain control only sets the maximum
sensitivity of the radio when it is controlling the bias to the RF
stage in addition to the I.F. stages, and this usually isn't the
case, except for some of the older tubed equipment. Most RF gain
controls USUALLY only set the gain of the I.F. stage. This has
nothing to do with the sensitivity of the system, if we are talking
about noise figure (I realize that you didn't mention that, so I
won't put words in you mouth on this one). When you turn up the RF
gain control, you don't desense the radio, but you do give the AGC
loop more gain. Maybe this is what you meant.

Man, you are ancient.

How did you know? Have you looked at the service manuals of the more recent
equipment? I don't think so.


No I pretty much meant what the user would experience using the radio.
Looking at the radio as a black box and not understanding how all the
circuits inside actually operate I described what would happen as the
RF gain control is operated with the AGC circuit on.

The perspective here is what to expect from the operation of the RF
gain control not unlike what to expect from the S-meter, which is the
subject of the thread.

--
Telamon
Ventura, California

That still doesn't make sense. As you advance the setting on the RF gain
control, the S-Meter reading will increase, unless you are talking about
some of the older tubed units that used a negative AGC and had the S-Meter
at full-scale when the receiver was powered down. Now, about being
ancient........................................... ....

Pete