S-Meter Accuracy of FLex and Others - Rob Sherwood

Bill -VA3WTB

Your noise floor is hight Burt,,what did Flex say when you opened a help ticket?

Ria

I did some investigation of my own on my 6700 and this is what I ended up with. All measurements are CW at 500Hz passband, no antenna connected.

160m - S2 - -114dBm
80m - S1 - -118dBm
40m - S1 - -119dBm
20m - S1 - -119dBm
17m - S1 - -119dBm
15m - S0 - -142dBm
12m - S1 - -119dBm
10m - S1 - -118dBm
6m - S0 - -143dBm

I do have to wonder why the 6400 reads so high? 

With that said I have no real complaints. I nearly never give real signal reports anyway, unless it's dBm. Far more objective. 

Burt Fisher

Not worth bothering them with an S meter issue, I did bother them with my 6400M crashing they tried like **** to help but I decided to live with it, for now.  I wish they had an idiot setup I could download for idiots like me to set parameters to a "normal" setting for "Global" etc.

Ria

Burt, am I the only one here seeing the irony, in that your YouTube videos repeatedly scold contesters for not giving “real” signal reports, yet you’re asking for Flex to give you a fake reading of zero on their S meters?

Ria

“if I short the inputs to any other type meter it reads zero. A digital VOM does not have a reading above zero even though active circuits inside it may have electrons flying around inside. Zero ought to be zero.“ Actually, it doesn’t. Nearly every VOM I’ve used measures the resistance of the test leads in addition to the resistance of the load under test. Usually you see something like 0.05 of an ohm or similar when you short the leads of a VOM. It’s true for most every meter, from a high end fluke to a free harbor freight one.

Ria

“if I short the inputs to any other type meter it reads zero. A digital VOM does not have a reading above zero even though active circuits inside it may have electrons flying around inside. Zero ought to be zero.“ Actually, it doesn’t. Nearly every VOM I’ve used measures the resistance of the test leads in addition to the resistance of the load under test. Usually you see something like 0.05 of an ohm or similar when you short the leads of a VOM. It’s true for most every meter, from a high end fluke to a free harbor freight one.

Craig Williams

All mine except my Waveteck DM27XT. Actually reads 0.0 with the test leads shorted. And, it's probably a Beckman as Waveteck bought Beckman from Emerson Electric after I left their Doric Scientific Division around 1988. Now no Beckman or Waveteck.

Burt Fisher

Ria this is not the forum discuss an opinion on contests. If you are trying to bait me, I will pass. My comment on zero being zero need not be rehashed. Beta was technically superior to VHS but the market went to VHS. Thus the S-meter purity issue may be won by Flex but the market will determine whether my opinion has any merit.  The talent expressed in this thread humbles me as I cannot hold a candle to the science demonstrated here. 

Ria

Except that zero is not zero as has been repeatedly explained. I support flex in having an accurate S meter rather than a feel good one. As an owner for the past few years, three time award winner and former alpha team member and being friends with the senior staff in the company I fully understand and support their reasoning. 100%.

Gerald-K5SDR

Burt,

I hear your desire to have the S-meter read zero but to do so would render the S-meter to be totally worthless for any purpose other than to watch it squiggle.  An accurate S-meter actually serves a useful purpose for properly setting the preamp gain or attenuation for best dynamic range of the receiver given the antenna and operating conditions.  I described this in another thread.  Therefore; we have no intention of changing the S-meter to render it useless.  An accurate S-meter also gives you a true RMS power measurement of the received signal at your antenna port, which may a novel idea in ham radio.

Thanks for your comments but this subject is now respectfully closed.

73,
Gerald

dwcolvin

I realize this thread is six years old, but if, e.g., the 6400 is so accurate (and I certainly find it acceptable), why does the 8400 report about 11 dBm higher (dummy load OR antenna)?

ka9ees

@dwcolvin You took the words right out of my mouth!

WX7Y

dwcolvin,

The Flex S Meters samples the signal within the bandwidth of your RX filters so when comparing the 6400 and 8400 make sure the RX filters are set identically between the two radios.

ka9ees

@WX7Y Morning Bret, I have my 8400 setup the same way as my 6600M. What I have casually observed is, the meter is about two S-units higher than the 6600. That is with signal or no.

Mike-VA3MW

GM Guys

I had a conversation with engineering to confirm if this is an RF problem or a numbers/calibration issue.

They confirmed that the there is nothing wrong with the radio and if you can do an MDS test, you'll see they are both the same value. Now, the S meter might not be correctly calibrated. Several of us checked radios and our noise floor readings were spot on.

All radios are also calibrated for -73dBm is equal to S9 before being shipped.

If you have a concern with the S Meter calibration, you may wish to open a support ticket, but it is only a meter reading issue, not an operational or impact your ability to hear a weak signal.

Mike

dwcolvin

We understand it's "only a meter reading issue," but now at least two of us have reported seeing 2 S-units (11 dBm, to be precise) higher (exactly same settings, same antenna (or dummy load, or grounded)), A/B-ing a 6400 (or 6600) and an 8400, and I HAVE opened a support ticket. Instead of the noise floor (reported as) S-5 to 6, it's S-7 to 8 (2.9 KHz LSB, 40M, -8 "RF Gain"). I chased around trying to find what I did wrong...

Now, if "several of us checked..." and there's no problem, and some of us have a problem, THAT is a problem with SOMETHING.

dwcolvin

> @ka9ees said:
> @WX7Y Morning Bret, I have my 8400 setup the same way as my 6600M. What I have casually observed is, the meter is about two S-units higher than the 6600. That is with signal or no.

Just curious, did you import profiles from your old radio? I did.

ka9ees

@dwcolvin I did at first, but had to reset the rig after this problem showed up. I'm now using profiles I built just for the 8400.

Butch

Sounds like it's bug swatting time again.

KF4HR

dwcolvin

@ka9ess Do you still see the same "+2 S-unit" anomaly after reset?

I saved all the original 8400 settings before loading 6400 profiles.

73,

Denny, W4DWC

ka9ees

Yes, I sure do.

dwcolvin

@ka9ess Then I won't bother trying it. I was hoping there was something about loading "old" profiles that affected S-Meter calibration.

It would be nice if Flex posted "we understand what's happening, and it will be fixed by ______________."

ka9ees

My call is KA9EES not KA9ESS. ;-) I don't think that they are ever gonna do that.

Butch

I wonder if it would be possible to have a built-in S-Meter Calibration routine built into the SmartSDR? Click on a S-CAL button and the antenna relay could temporarily disconnect, then an internal signal at -73 dbm gets injected and the operator adjusts a slider to show S-9.