8400M Sensitivity vs. Noise

Maxejb

Afternoon to all;

I reposted this because I wanted to hears some comments / opinions.

I have owned 2 Flex Radios: 8400 and then a 8400M (which I currently use and enjoy). I still own an Icom 7300. The Sherwood report, while useful is not a measure of transceiver usability…

Now having said this, I was disappointed to see that the new Flex 8400 baseline sensitivity is 5.0-uVolts versus IC-7300 of 0.30-uVolts. If this is true, then this would explain why Flex radios are perceived as being so "quite"…. Now, if I adjust the preamp setting to +32dB then the Flex achieves a measure sensitivity of 0.45-uVolts. Even an Apache-G2 has a baseline sensitivity of 0.40-uVolts (I only mentioned this because it is another example of a competitive SDR). I suspect that Flex decided to raise the baseline sensitivity level to make it easier for Flex's noise algorithms ability to process lower noise levels. The trade off without turning on the pre-amps is a greater potential to miss weak signals. So to say that a new Flex 8400 or 8600 transceiver is superior to other radios (based on a hardware) would be erroneous. I would love for Flex to "readjust" their baseline sensitivity to a much lower level and still offer the same levels of noise reduction…Then, that would truly make Flex the clear winner.

Since I'm not a DX chaser, I can live with the current radio specifications. But for the radio's cost, I believe the radio specs should fall in line with radios in it's class….

Mike

KG5EJG

P.S. If Rob Sherwood's data is a typo, someone needs to reach out to him…

Trucker

Probably a typo. My Flex radios can hear anything that the 7300 I had could hear. Given today's environment, the numbers posted by Rob, ( no disrespect intended) are all but meaningless with all of the man made noise that surrounds us. Just about any modern radio today will work as well on basic reception as any others. It's the ability to fight that noise when you have no control over the source that makes the difference. Without modern noise reduction features that are available to us, some of us would not be able to operate from our homes at all. I feel like the most important thing is how well the noise fighting tools in a given radio and it's implementation, is more important than numbers on a chart. Those only tell a very small part of a much larger story.

James

WD5GWY

Gord-VA7GP

Must be a typo.

My HW-101 is spec'd at 0.3uV for 10dB S+N/N, and this was >50yrs ago.

Maxejb

James,

Nope it isn't a typo. Sherwood had tested another Flex model much earlier... it too had a low baseline sensitivity level. While it's true that man-made noise is the primary problem in hearing weak stations; a low baseline sensitivity is a poor start to even trying to copy / detect weak stations. Addressing high level mademade noise is not the same as dealing with low level noise (man-made or otherwise). I suspect that Flex elected to have a low baseline sensitivity so that the development of noise reduction algorithms would be easier with more apparent results in reduction! Well Bravo, but Flex should raise the baseline sensitivity to mirror their competitors and then readjust their noise reduction algorithms.

Any Flex claims to superior noise reduction need to be Apples-to-Apples with respect to a consistent noise - sensitivity baseline.

Rob should developed a noise reduction testing methodology.... These results might really upset alot of Apple carts!!

Mike

KG5EJB

Trucker

Mike, thanks for your comments. I have compared my Flex radios to several others I have ( and have had) in the past with no noise reduction being used with any of them. Honestly, I could not tell any difference in sensitivity between them doing an A/B test using the same antenna. What one radio could hear the others did just as well. I currently own a Flex 6600, Aurora AU-520M, Anan G2 Saturn Ultra ( which has much better numbers than the Flex), Anan 8000DLE, Kenwood TS-890, Kenwood TS-450S, Hallicrafters SR-400A Cyclone III, Hermes Lite 2, and a QMX +.

Until not too long ago, I had several Kenwood hybrids. But, I have been steadily downsizing ( don't want to leave my family a bunch of stuff to deal with if I can help it) using the same antenna, and no noise reduction, ( with those radios that had it) I have never been able to discern much difference reception wise. What one could hear, the others could as well. Some were more noisy which I always attributed to the design of the receiver. That's why my main criteria is how well the radio's noise reduction works ( if it has any) in combating my local noise environment. The Anan radios using Thetis with Warren Pratt's WDSP library tops them all. Followed closely by Flex with their new noise reduction features, and AetherSDR surpasses Flex Radio's implementation ( currently) because they are using open source code to power their noise reduction features. Then, after that Yaesu's latest generation of radios noise reduction is extremely effective as well. ( I forgot that I have a Yaesu FTDX-101D ..... old age strikes again!)

Those, firsthand observations without consulting a test chart have helped me find what is most effective for my operating conditions. I have found that some of the radios listed in Rob's chart didn't hold up well in actual use with my antenna system and location. But, it is always fun trying different radios. ( a hard habit to break. )

James

WD5GWY

Mike-VA3MW

Having spent a day testing minimum descernable signal on my FLEX-8600 for 1296Mhz EME operations and wanting to compare it, I can tell you that the 8600 was about 4dB better than the IC-7300 and IC-705.

Regardless, for HF operation, none of us (except a few) are in a quiet enough location where it will make a difference.

And, we don't know the last time Mr. Sherwood's test equipment was actually calibrated, so you need to take that into consideration as well. Given the cost to make this happen, I bet it has been quite a while.