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[AMPS] True Or Not True #2

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Subject: [AMPS] True Or Not True #2
From: (
Date: Fri, 7 Sep 2001 11:00:16 +0200

> How many db increase for every one S-unit, using as factory
> standard ??.
> de YD1BIH

Hi Firson,

it depends by each factory....

Following conventions (traditions) it should be 6 db per S unit and 50 
uV for S-9 in HF. Someone had 5 db per division (Drake, for example, if 
I remember correctly) likewise most Japanese RX float and read S9 
already with less than 10 uV.
Actually, the majority of S meters do not work well, in the range 
between S1 and S-5 they are mostly linear (i.e. 1 dB per division), 
between S5 and S9 they start to indicate something that's anyway not 
constant and vary between 3 and 6 dBs per division, over S9 they *show* 
their best that's often a *poor best*.
Knowing that's not easy to deal with an AGC voltage in the way to 
produce a constant S-meter movement, in the digital era it's easy to 
correct the readings associating the correct offset to different AGC 
voltages and also taking in account for attenuators or preamplifiers.
It seems design engineers still do not consider this opportunity that's 
instead widely used in other equipments.

Mauri I4JMY

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