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Author Topic: Flex 6400/6600 - New User Reports/Impressions?  (Read 51408 times)
K9ZW
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Posts: 309


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« Reply #105 on: April 16, 2018, 09:17:08 AM »

I’ve been traveling for weeks, returning a few days ago (just before the big snow storm), and have operated my main QTH’s Flex-6600M with Flex-PGXL amp from a handful of different states.

Operated remote from my hotel in Chicago Illinois.

Operated from several locations in Arizona.

Ran QSO's between meetings in Omaha Nebraska.

One morning I was checking the bands while on the treadmill in a fitness room in Iowa, again by remote to my home station. (That was from an iPhone running SmartSDR for iOS).

I can do all of this easily with my FlexRadio System gear.

And to be certain, I am sure I was one a many - many - operators remoting.

While stuck inside during the big snow storm, I was running QSO's using "SmartSDR for iOS" from an iPad.  The reports I got from stations like VP9KK with his 59+20 & crystal-clear audio with nothing more than an iPad for my station's GUI, Microphone and Speakers, was frosting on the cake.

Did in all this remoting were their glitches?  Yeah - flaky internet connections mostly.  But I still made contacts!

It is a neat state of the hobby where with a handful of gear one can remote, and among the easily remotable gear the FRS Flex-6000 serieshardware & SmartSDR software sure make it easy.

I'm appreciative of being on the air remotely, rather than being off-air for three weeks just because I was on the move.

YMMV, and there are a lot of great radios out there, and as long as you have fun it's worth while regardless!  I know I had fun because my FlexRadio Systems Flex-6600M, PowerGenius XL Amp, and SmartSDR/SmartLink software all played well.  

73

Steve
K9ZW
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KA4DPO
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Posts: 1143




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« Reply #106 on: April 16, 2018, 09:35:41 AM »

I’ve been traveling for weeks, returning a few days ago (just before the big snow storm), and have operated my main QTH’s Flex-6600M with Flex-PGXL amp from a handful of different states.

Operated remote from my hotel in Chicago Illinois.

Operated from several locations in Arizona.

Ran QSO's between meetings in Omaha Nebraska.

One morning I was checking the bands while on the treadmill in a fitness room in Iowa, again by remote to my home station. (That was from an iPhone running SmartSDR for iOS).

I can do all of this easily with my FlexRadio System gear.

And to be certain, I am sure I was one a many - many - operators remoting.

While stuck inside during the big snow storm, I was running QSO's using "SmartSDR for iOS" from an iPad.  The reports I got from stations like VP9KK with his 59+20 & crystal-clear audio with nothing more than an iPad for my station's GUI, Microphone and Speakers, was frosting on the cake.

Did in all this remoting were their glitches?  Yeah - flaky internet connections mostly.  But I still made contacts!

It is a neat state of the hobby where with a handful of gear one can remote, and among the easily remotable gear the FRS Flex-6000 serieshardware & SmartSDR software sure make it easy.

I'm appreciative of being on the air remotely, rather than being off-air for three weeks just because I was on the move.

YMMV, and there are a lot of great radios out there, and as long as you have fun it's worth while regardless!  I know I had fun because my FlexRadio Systems Flex-6600M, PowerGenius XL Amp, and SmartSDR/SmartLink software all played well.  

73

Steve
K9ZW

That's cool Steve but you do know that you can remotely operate a whole bunch of the newer radios with a simple internet connection.  The main thing is that you had fun doing it, that's what counts.
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K9ZW
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« Reply #107 on: April 16, 2018, 12:19:00 PM »


It is a neat state of the hobby where with a handful of gear one can remote, and among the easily remotable gear the FRS Flex-6000 series hardware & SmartSDR software sure make it easy.



That's cool Steve but you do know that you can remotely operate a whole bunch of the newer radios with a simple internet connection.  The main thing is that you had fun doing it, that's what counts.

Think we all know there are ways to remote several radios, and I kind of sort of thought had that clearly covered.

Lots of nice stuff out there, and I can first hand report the plug-n-play of the FlexRadio System works for me - DX heard & worked. 

As for some detail, the new FRS PGXL Amp works great!  Being able to control it remotely was a real boon.

The FlexRadio Systems option sure makes remote easy?

73

Steve
K9ZW

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KA4DPO
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« Reply #108 on: April 17, 2018, 10:35:44 AM »

Still have not seen anything from Sherwood or ARRL on the 6400 or the 6600.  I am more interested in the M models since they are supposed to operate stand alone without any computer assist.  The manufacturer specs are good but realistically not better enough to warrant additional cost for casual hamming since most of the top 15 or 20 rigs on the Sherwood Engineering site are practically brick wall anyway under normal conditions. 

I guess the little Elecraft rig is the one to beat for weak signal work, I don't think any other radio can touch it right now.  The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.
I am also hoping that at some point the ARRL, or someone, will chime in with an article about eye candy and at what point does it become overkill (like it hasn't already).  Seems like all of the SDR folks are far more concerned about the display than the actual radio performance.  I don't know about you but the only time I ever worked anyone on a screen was either RTTY or PSK, aside from those modes the display is actually kind of useless.
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W1PJE
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« Reply #109 on: April 17, 2018, 03:18:00 PM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.
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KA4DPO
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Posts: 1143




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« Reply #110 on: April 17, 2018, 08:32:48 PM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window so the noise is somewhat band limited which gives an improved signal to noise ratio.  Also, the analog input is continuous while the Direct Digital Sample is granular.  There is some signal resolution lost in the granularity.

A direct sampling front end works at some sample rate.  Each sample is a stream of bits that first are subjected to several statistical algorithms that determine what is signal and what is noise.  Only problem is that in very high noise conditions some noise gets through as signal and some signal gets canned as noise.  This happens more when there is high amplitude Gaussian noise like we encounter on the lower bands and very low signal levels.  Software is good but it can't quite replicate an analog and that is why the Elecraft is so good at digging out the weak ones.  Remember, there is no granularity in an analog signal.

 
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AC7CW
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« Reply #111 on: April 18, 2018, 08:20:09 AM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window

SDR radios can be, and often are, equipped with analog band filters. For that matter we can use a high-Q magloop antenna and have very narrow filtering ahead of the first RF stage of any radio. And yes, SDR's do have RF amplifiers even though some have tried to tell me that "direct sampling" means "no RF amplifier".
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Novice 1958, 20WPM Extra now... (and get off my lawn)
N1EU
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Posts: 148




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« Reply #112 on: April 18, 2018, 08:27:14 AM »

Software is good but it can't quite replicate an analog and that is why the Elecraft is so good at digging out the weak ones.  Remember, there is no granularity in an analog signal.

I had a K3S, Flex 6500 and ANAN-100D in the shack at the same time for a couple of years and operated/compared them under a variety of conditions.  The Flex and ANAN gave up nothing to the Elecraft in terms of digging out the weak ones, whether the band was noisy or quiet.  The were very different animals, but they all had superb receivers in that regard. 

73, Barry N1EU
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W1PJE
Member

Posts: 29




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« Reply #113 on: April 18, 2018, 09:07:17 AM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window

SDR radios can be, and often are, equipped with analog band filters. For that matter we can use a high-Q magloop antenna and have very narrow filtering ahead of the first RF stage of any radio. And yes, SDR's do have RF amplifiers even though some have tried to tell me that "direct sampling" means "no RF amplifier".

I agree with all these points.  Any good radio based on digital sampling must deal with using a RF preselector = bandpass filter in its pre-sampling stage, whether in hardware (antenna response) or in an analog filter, etc.  To do otherwise would risk violating the Nyquist criterion by inviting frequency aliasing of an out-of-band signal into an apparent lower frequency.  This is part of the design when one chooses a target bandwidth for the final digitally demodulated signal.

So in this case, saying that the analog front end looks at a 'narrower bandwidth' is comparing apples to oranges.  A proper comparison would use the same target bandwidth for both designs and in that case, you could directly compare analog with digital designs in terms of performance (where you examine other things like linearity and quantization noise - although that is getting much better thanks to modern relatively high bit count ADCs.)
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KA4DPO
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« Reply #114 on: April 18, 2018, 09:49:04 AM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window

SDR radios can be, and often are, equipped with analog band filters. For that matter we can use a high-Q magloop antenna and have very narrow filtering ahead of the first RF stage of any radio. And yes, SDR's do have RF amplifiers even though some have tried to tell me that "direct sampling" means "no RF amplifier".

I agree with all these points.  Any good radio based on digital sampling must deal with using a RF preselector = bandpass filter in its pre-sampling stage, whether in hardware (antenna response) or in an analog filter, etc.  To do otherwise would risk violating the Nyquist criterion by inviting frequency aliasing of an out-of-band signal into an apparent lower frequency.  This is part of the design when one chooses a target bandwidth for the final digitally demodulated signal.

So in this case, saying that the analog front end looks at a 'narrower bandwidth' is comparing apples to oranges.  A proper comparison would use the same target bandwidth for both designs and in that case, you could directly compare analog with digital designs in terms of performance (where you examine other things like linearity and quantization noise - although that is getting much better thanks to modern relatively high bit count ADCs.)

You are correct about equal front end selectivity, I should have stated that as a condition.  Still, even though sample rates are much higher than they used to be, the quantized samples are still a series of snapshots in time and can't replicate an analog signal one hundred percent.  I am still convinced that for signals that are only a couple of db above the noise floor that an analog front end followed by DSP can recover those signals better than a direct sampling system.  Keep in mind that I am talking about very weak CW and using headphones and a gray matter processor to decode.  I realize that in most cases, similar to that pointed out by N1EU, that they will all perform about equally but I suspect those were signals that could have been copied on a good many radios.  This has nothing to do with contests conditions, I'm not talking about weak signals in the presence of strong adjacent signals, I'm talking about very weak signals, almost in the noise, but otherwise unhampered by QRM.  That is where the difference can be seen.
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W1PJE
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« Reply #115 on: April 18, 2018, 12:06:23 PM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window

SDR radios can be, and often are, equipped with analog band filters. For that matter we can use a high-Q magloop antenna and have very narrow filtering ahead of the first RF stage of any radio. And yes, SDR's do have RF amplifiers even though some have tried to tell me that "direct sampling" means "no RF amplifier".

I agree with all these points.  Any good radio based on digital sampling must deal with using a RF preselector = bandpass filter in its pre-sampling stage, whether in hardware (antenna response) or in an analog filter, etc.  To do otherwise would risk violating the Nyquist criterion by inviting frequency aliasing of an out-of-band signal into an apparent lower frequency.  This is part of the design when one chooses a target bandwidth for the final digitally demodulated signal.

So in this case, saying that the analog front end looks at a 'narrower bandwidth' is comparing apples to oranges.  A proper comparison would use the same target bandwidth for both designs and in that case, you could directly compare analog with digital designs in terms of performance (where you examine other things like linearity and quantization noise - although that is getting much better thanks to modern relatively high bit count ADCs.)

You are correct about equal front end selectivity, I should have stated that as a condition.  Still, even though sample rates are much higher than they used to be, the quantized samples are still a series of snapshots in time and can't replicate an analog signal one hundred percent.  I am still convinced that for signals that are only a couple of db above the noise floor that an analog front end followed by DSP can recover those signals better than a direct sampling system.  Keep in mind that I am talking about very weak CW and using headphones and a gray matter processor to decode.  I realize that in most cases, similar to that pointed out by N1EU, that they will all perform about equally but I suspect those were signals that could have been copied on a good many radios.  This has nothing to do with contests conditions, I'm not talking about weak signals in the presence of strong adjacent signals, I'm talking about very weak signals, almost in the noise, but otherwise unhampered by QRM.  That is where the difference can be seen.


Under the conditions that a human is applying their brain's pattern recognition to try and recover a coherent signal (CW) in the presence of non-coherent/random signals (noise), you certainly could be right.  We've now wandered into an area that is very very difficult to quantize since one would have to also consider the hearing of the individual, the fact that even with identical hearing not everyone perceives sound the same way, the expertise in hearing similar patterns previously, and on like that.  Analog could indeed be easier to deal with there for some, but perhaps not all, listeners.  (I suppose similar arguments can be made for vacuum tube amps vs. solid state amps when it comes to "fidelity", whatever that is.)

It's also the case that sampling rate and bit depth are interrelated in some ways.  Providing one has already bandwidth limited the incoming signal, oversampling it would change the number of samples in time before the amplitude changes 1 bit, so it does change the behavior of the digital signal a bit.  But quantization noise is still mostly driven by the bit depth and how much front-end gain is applied to the signal before you try to digitize it.

By the way, radio astronomers provide an interesting case: they deal with noise limited signals all the time and most times near the noise floor of the instrument.  They have been using 1 bit sampling - retaining only the sign of the signal - for decades.  This would seem to be a ridiculously extreme distortion decision - except that all the signal's shape characteristics are in the zero crossings or phase, and almost none of it is in the amplitude domain.  (They then go for max sampling rate at 1 bit.)  Also, in audio, when CD players were being refined, they made similar decisions to oversample but use 1-bit sampling.  Obviously there, audio purity is central to the listening experience, so they were careful to listen for high dynamic range near the noise floor.

So it can work either way - the subject is a complex one and interesting to think about.

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K9ZW
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Posts: 309


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« Reply #116 on: April 18, 2018, 12:40:21 PM »

Back to the Flex-6400/6600 there are quite a few Shack pictures being posted of the new radio:

https://community.flexradio.com/flexradio/topics/show-us-your-flexradio-in-your-shack

Some good 6600M performances in contests:

Contesting with a 6600M in the CQ WW WPX at VP5P - https://community.flexradio.com/flexradio/topics/contesting-with-a-6600m-in-the-cq-ww-wpx-at-vp5p

and another good show:

Feb 2018 NAQP RTTY doing well with a barefoot Flex-6600M - https://community.flexradio.com/flexradio/topics/another-flex-contest-win

73

Steve
K9ZW

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SP5QIP
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Posts: 111




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« Reply #117 on: April 18, 2018, 12:44:36 PM »

It's not radio doing good score. It is location, antennas and operator.
Mike
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AC7CW
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Posts: 1241




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« Reply #118 on: April 18, 2018, 03:28:47 PM »

Quote
The analog front end has an advantage over direct sampling in the high thermal noise on 160, 80, and 40.

Can you explain that in another way?  I'm having trouble understanding why high thermal noise favors an analog front end.

Sure.  The analog front end looks at a narrower window

SDR radios can be, and often are, equipped with analog band filters. For that matter we can use a high-Q magloop antenna and have very narrow filtering ahead of the first RF stage of any radio. And yes, SDR's do have RF amplifiers even though some have tried to tell me that "direct sampling" means "no RF amplifier".

I agree with all these points.  Any good radio based on digital sampling must deal with using a RF preselector = bandpass filter in its pre-sampling stage, whether in hardware (antenna response) or in an analog filter, etc.  To do otherwise would risk violating the Nyquist criterion by inviting frequency aliasing of an out-of-band signal into an apparent lower frequency.  This is part of the design when one chooses a target bandwidth for the final digitally demodulated signal.

So in this case, saying that the analog front end looks at a 'narrower bandwidth' is comparing apples to oranges.  A proper comparison would use the same target bandwidth for both designs and in that case, you could directly compare analog with digital designs in terms of performance (where you examine other things like linearity and quantization noise - although that is getting much better thanks to modern relatively high bit count ADCs.)

I have an SDR that operates all the bands from 80-10. It, by design, has analog LC bandpass filters for each band. A dipole might actually serve as a narrow enough filter to prevent aliasing in some cases, I have to think about that...
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Novice 1958, 20WPM Extra now... (and get off my lawn)
AC7CW
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« Reply #119 on: April 18, 2018, 03:30:23 PM »

It's not radio doing good score. It is location, antennas and operator.
Mike

Try it without the radio some time Smiley
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Novice 1958, 20WPM Extra now... (and get off my lawn)
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