[Collins] Odd symptom and S meter reading

[Glen Zook]

I set my "S" meters to read S-9 with a terminated 50
microvolt signal (this is equal to the 100 microvolts
across the resistor network that many receivers use). 
This is the old "standard".

Most of the newer equipment have "S" meters that read
as little as 10 microvolts for S-9 and increasing that
by 10 dB, or so, results in a "40 over S-9" reading! 
The lower number of microvolts to produce an S-9
reading is a "ploy" by the manufacturers to make their
equipment seem more sensitive.  One manufacturer sets
their equipment around 15 microvolts for S-9 then the
next one at 10 microvolts for S-9 and so on.

As a result, none of my "S" meters read as high as
most of the newer equipment.  However, they are much
more accurate.  On my 75S-3A and both 75S-1 receivers,
going from 50 microvolts for S-9 to about 500
microvolts produces a 20 dB above S-9 reading which is
what it is supposed to read.  Going to about 5000
microvolts produces a 40 dB over S-9 reading.

I have found that if I really look at my "S" meter and
give the other station what it really reads often
seems to insult them because they are used to getting
a reading from newer equipment where you can almost
drop a crystal on the other side of town and get an
S-9 reading!

The newer equipment is not usually any more sensitive
than the older equipment.  In fact I have found that
the minimum detectable signal is often of a weaker
signal than in the solid-state equipment because of
the fact that transistors tend to be noiser and tubes
are not.  But, in the vast majority of cases the noise
level on the bands is such that it requires a
significantly greater signal (in microvolts) to be
able to receive that signal in most receivers.

Glen, K9STH


--- jkoneal@comcast.net wrote:

I have the same problem with my 75S3B s-meter.  It is
very stingy indeed!

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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