Topband: Received Signal Strengths
4cx250b at miamioh.edu
Sat Jan 9 12:10:06 EST 2016
Agree with Tom. My Flex 6300 calibrates signal strength directly in
dbm, which makes a lot more sense to me than S-units. I've checked it
with a switched attenuator, and it's quite accurate. The log scale of
the display makes it's very easy to see the effects of attenuators,
preamplifiers, RX antennas, etc.
Sent from my iPhone
On Jan 9, 2016, at 8:38 AM, Tom W8JI <w8ji at w8ji.com> wrote:
>> Typically, on 160M, I leave the preamp off for my beverages. The received
>> noise floor for my N/S beverage (on CW) is usually S2 - 3 and for my phased
>> EU beverages is S0 to S1. I have found the signal strengths of the received
>> stations to be 1 to 2 S units down on the beverage and equal or stronger on
>> the beverage if I turn the preamp on - with usually a rise in the noise
>> floor by a 1 or 2 S units. Interestingly, on 80M CW, I usually use the
>> beverage preamp. The signal often comes up 3 - 4 S units and the noise only
>> 1 to 2 S units. I often drop in some attenuation to make the noise floor
>> "just" go away.
> If the signal comes up 3-4 S units and the noise 1-2 S units, the meter is nonlinear. This is typical for many receivers. Some are as little as 1 dB per S unit down low on the scale. Most meters (it was years ago I looked) were 3 to 5 dB per S unit up at the high scale end.
> The entire idea of S readings is for many uncontrollable reasons...... meaningless.
> There have been various campaigns over the years to correct reports, but none can ever mean anything.
> It is silly getting all worked up because we **think** S meters and S reports are like precision dial calipers, when they are really like marks on a rubber band.
> Topband Reflector Archives - http://www.contesting.com/_topband
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