I like the Flex calibrated meter that tells me the signal level at the antenna terminal and seems to be unaffected by frequency and is unaffected by the preamp. Absolute accuracy, compared to what, I don't know, but it is repeatable.
On the other hand, S-meters have been somewhat controversial for signal reports for as long as I can remember and the "live" or "liberal" S-meter is important to some.
Your proposal is not one I would request, but for others it may be important.
You have legitimately posted your request fir a switch to convert the accurate Flex S-Meter into a more traditional innacurate Relative S-Meter similar to the approximations of signal strength derived from Legacy AGC Loops. Since Flex does not use Legacy AGC loops it might be hard to implement
I can understand that many people would gain comfort from the fiction of those readings WHERE no antenna attached implies S0 even though the Minimum Discernable signal is not -127dBm but rather something like -110dBm or S4.
Anyways I Always thought all DX and contest signal reports were 5/9 whatever. Hi. Hi.
While I personally applauded the demise of legacy S-Meters Let’s see how many likes you get.
If you receive a S9 or -73dBm signal and add 30dB gain in the preamp. A Legacy AGC loop will read S9+30dB. But your signal really is still -73dBm at the antenna and all the preamp should have done is reduced your noise floor by 30dB.
But again I can understand how people can prefer to enjoy the comfort of the fiction that a preamp makes a received signal at the antenna stronger because lowering the relative noise floor makes it seem so.
Just for the heck of it, I switched on my IC 7300 which currently sits with no antenna connected. It does show S-0. I'm not asking Flex to change their S-Meter. Apparently, Icom, probably as a cave in to the knob and dial operators, made the decision to carry over the "inaccurate" S-meter tradition to their version of the direct sampling world.
Who needs an S-meter anyway. The important thing is that you can hear/copy the other station, right?
AFIK none of the Legacy Radios actually use a calibrated RF Voltmeter at the antenna to measure the true received signal voltage. (There might be some that I do not know about)
Instead S-Meter readings are derived from the AGC Loop, hence when one adds 30dB preamp gain to the radio, the S-Meter jumps 30dB even though the actually received signal voltage at the antenna has no changed and when one removes the antenna, there is no AGC hence it reads S0 even though the radio cannot read a signal below S4 or -103dBm
But heck if it makes you happy to have a fictitious number give you comfort that your preamp in working or your radio is not hearing anything with the antenna disconnected then by all means vote for this idea.
Here is a link to the Woodbox Radio ANALOG S-Meter
Looks and feels like one of the Legacy Meters but unfortunately unlike legacy meters it still gives you an accurate reading rather than an AGC Loop Approximation so 30dB Preamp gain does NOT increase the reading at the antenna
- My Analog Flex S-Meter is working perfectly.. Calibration is exact, and I love to see the meter move back and forth when receiving SSB signals.. It is very easy to install!! You need two parts.
- One part is a Label Maker to print out the work FLEX
- The second part is the radio to place the FLEX sticker on it
- The result is a FLEX radio with a precision S-Meter!!!
My analog radios like the FT2000 and FT 847 and quite quite when the antenna terminals are shorted and, of course, the S meter reads zero since there is no AGC voltage generated.
Respectfully, Jim KD1I
And that shorted input was intended to have a 50 ohm load across it, so may not be near as accurate when reading a short. A 50 ohm short will probably give you a different measurement.
But neither reading, will be a signal measurement.
Noise just IS, it's never 0.
For real-time discussions
73, Jay - NO5J
I set a 500 Hz RX filter width.
And all I got was this crazy picture showing SmartSDR reading S-0.
No internal noise visible. No signals either.
Hard to argue with reality.
BTW when I switch it to read as dBm it reads as low as -135 dBm. There is always noise in this reality. It can be measured.
The level varies 2-3 dBm very slowly, but it won't read any lower than S-0.
When I turn off the 20 dB preamp it does read S-1 @ -120 dBm.
For real-time discussions
73, Jay - NO5J
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