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Author Topic: SDR versus Traditional Transceivers.  (Read 12633 times)

W8JX

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RE: SDR versus Traditional Transceivers.
« Reply #105 on: October 09, 2018, 07:17:40 AM »


I love that kind of thinking as it makes it much easier for me to break DX pileups. The single RX guys are the ones who constantly call at the same time the DX is calling.


The operators skill or "savy" is far more important on bagging DX. If you do not really know what you are doing then I guess you may indeed feel you need those extra receivers. 
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WB8LBZ

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RE: SDR versus Traditional Transceivers.
« Reply #106 on: October 09, 2018, 08:23:44 AM »

In the most recent Texas QSO Party, there was a mobile that used 7.228 when they got close to a county line. I didn't need to be tuned to that frequency when I saw the APRS location getting close to the county line. If you had a traditional transceiver, which I have used in the past, I would need to park one of the frequencies in the band stack on that frequency and hope I cycled through when they came up.

Having another band to look at also lets you know when there is activity on that band (15 meters for the sake of discussion) all the time you are on 20 or 40. I can't do that right now the way my antennas are constructed. Flex has shown this in demos and the Anan will do this in software too (maybe others). It is the difference of looking through a peep hole or looking at a wide angle picture. Look at http://www.radioforeveryone.com/2018/05/about-software-defined-radio-and-rtl-sdr.html for the visual reference.

73, Larry  WB8LBZ
El Paso, TX
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KA4DPO

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RE: SDR versus Traditional Transceivers.
« Reply #107 on: October 09, 2018, 11:11:54 AM »

   I see the multi receiver thing it as a whistle and bell with little real utility. 

I love that kind of thinking as it makes it much easier for me to break DX pileups. The single RX guys are the ones who constantly call at the same time the DX is calling.

Dual RX or Dual watch is a must for the serious DX chasers who do not want to spend hours trying to work rare DX in a pileup. Spilt single RX just does not cut it for working pileups. 2 RXs allow one to constantly monitor the DX while also trying to figure out where the DX station is listening. A nice big panafall also helps.

Please continue to use your split RX to work DX in pileups. Me and many other DX chasers thank you....

Contesting and SO2 are different animals.

Stan K9IUQ



That's just amazing since when I'm working a DX station on split,  I am listening on his transmit frequency so I know when he is transmitting.  That is the weakest justification I have heard yet.  I have a nice big panafall BTW, but I don't use it for DX, I use it for RTTY and digital. 

Also, I know where the DX station is listening because I have been doing this for a very long time, that's called experience.  And besides, the overwhelming majority of DX will tell you where they are listening.  Sorry, can't buy the multiple RX angle except for SO2 and that requires special filtering and careful antenna placement.
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W8JX

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RE: SDR versus Traditional Transceivers.
« Reply #108 on: October 09, 2018, 11:25:33 AM »

Also, I know where the DX station is listening because I have been doing this for a very long time, that's called experience. 

Yes and that experience you cannot buy, you learn it and tou do not need two receivers to do that.
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N6YFM

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RE: SDR versus Traditional Transceivers.
« Reply #109 on: October 09, 2018, 02:52:14 PM »


I love that kind of thinking as it makes it much easier for me to break DX pileups. The single RX guys are the ones who constantly call at the same time the DX is calling.


... If you do not really know what you are doing then I guess you may indeed feel you need those extra receivers. 

So, a couple of observations;

A.  If you have significant experience, yes, you can do more with less.

B.  If you don't have significant experience (like me), we post questions here in
     an attempt to learn from those who do.  Also, if we don't have significant experience,
     more tools and more information make our learning journey easier.

C.  This was one of several responses where your basic message was approx;
     "If you don't know what you're doing...."
     How does that help?   Really?
     Does that provide mentoring and guidance?
     Does that make more rookies want to ask more questions?
     Does that make you feel like you are teaching, or driving potential new hams away?

D.  No argument;   Ansel Adams could take a better photo with a full manual
     80 year old Hasselblad camera than I could with a 2018 Nikon, but for
     a beginner that is learning, that new extra information and automatic modes
     really help us get some results WHILE we are learning, so we don't give up
     altogether.  So that does not make me a moron for preferring to use something
     more modern that shares more information about what is going on.

Try to smile some time.   It really won't kill you my friend...

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KA4WJA

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RE: SDR versus Traditional Transceivers.
« Reply #110 on: October 09, 2018, 04:26:50 PM »

Frank, thanks for starting this thread!  (and, yes I read it all)
Enjoy your new rig!!  :)
(and with the clean AL-800H, not needing 100-watts of drive, so being driven with the 7610 at reduced power, I'm assuming you'll have a nice clean signal!!  Congrats!!)

{And, I appreciate Brian, K6BRN's detailed explanations of ham SDR's....I sent that to a couple friends, cuz you explained it better than I could've....btw, my first exposure to SDR was from a old friend hired to do test/eval of the SDR radios in the B2 Stealth Bomber, that was like 17 years ago, and he couldn't tell me the details, but wow...}
 
I don't have an SDR / direct-sampling / DSP rig, and since I really like radios with knobs (old school, I know) it's doubtful that I will buy a black-box SDR, but have been considering other options....just wish the 7610 had active pre-distortion, or that ANAN would make a radio with knobs...

As some may know, I was thinking of upgrading / spending $$$$ on a new rig....but when I went looking, I found few had as good of transmit spectral purity / transmit IMD as my older legacy rig, and none came close to my maritime HF rig that I primarily use these days...
But, I'm still considering things... :)

I'm not Zenki....and I'm not throwing any IMD grenades... :)  
Just wanted to say that I've been reading this thread a while now, and I wanted to point some of you to some actual transmitter test results that might be helpful...

And, yes, while the TS-990s (with its $7000 price tag) does have a fairly decent transmitter, and certainly better than most modern ham rigs, even it is not that stellar....nor, in my opinion, is it like Ed (VE3WGO) said "fantastic"....
But...


But, let's not deal with opinion....let's look at some facts....
Fact is, while higher-voltage SS PA's allow the devices to operate longer in the linear part of their cycle,  simply having a "50-volt PA" in your ham rig is not the determining factor to having a clean, linear transmitter with lower transmit IMD products....it can help the designer make the PA cheaper while maintaining its linearity, but fact is there ARE current production HF ham rigs (and HF maritime rigs) with 12-vdc PA's (TS-590SG, etc.) that have better transmit IMD than some with 50-vdc PA's (like the 7800, FTdx-5000 etc.)

Please have a look at the ARRL test results....and you can see this...
https://www.eham.net/ehamforum/smf/index.php/topic,97093.105.html


Ed, VE3WGO, I'm not nit-picking here....and please know this is not about you...just that you posted this here, so... :)

Please let me know where you found the Kenwood TS-990 test data that showed "3rd order IMD at -40 dBc"...as that would be -46db (PEP)???

The ARRL Product Review Test showed a best case of -39db (PEP), and worst case of -31db (PEP)....that's 7db to 15db worse than the test results you provided...

Here are the 3rd, 5th, 7th, and 9th order transmit IMD from ARRL product Review Tests....please note these are db(PEP), not dbc...

Kenwood TS-990  (50vdc PA)
-31 / -46 / -52 / -57  (worst case)
-39 / -46 / -54 / -56  (typical)


And, for this discussion's comparison, here are the 12volt PA TS-590SG and Icom IC-7300...
Icom IC-7300  (12vdc PA)
-30 / -37 / -44 / -58

Kenwood TS-590SG  (12vdc PA)
-31 / -38 / -48 / -55 (worst case)
-42 / -38 / -48 / -58 (typical)


Les, there's no way that the IC-7300 Tx is on par with the TS-990.  Your TS-990 has a very linear 200 Watt transmitter.  3rd order IMD at -40 dBc.  Fantastic result due to its high voltage FET power amplifier.

But if you and others think both these radios' transmitters are on par, then Kenwood's effort to make a superior Tx in the 990 was apparently all for naught.

73, Ed

My fellow hams considering spending money on a new rig (as I have been think about doing as well), may wish to actually place some concern into the transmitter and its spectral purity....and actual test results of these transmitters....
And, in particular, please take note that with typical human speech, the "3rd order IMD products" of our SSB transmitters can fall within the transmit passband, or very close to / just outside of the transmit passband edges, and much (except for those with "boosted" bass response transmitters/audio chains) of the immediate adjacent frequency splatter is coming from the 5th order products, with the higher order products causing splatter up/down a few more khz away (sometimes as far as +/- 10 to 12khz away!)...so, while the marketing guys hope all you look at is the 3rd order products, fact is if you desire to improve the airwaves / reduce the splatter on-the-air you should be looking at all the IMD products, especially the higher order products....(oh, and turn down your mic gain, too...)

Please have a look at these pages....the actual facts are there...you can read/analyze them yourself, and make your own choices of rig as you desire....(but, if my fellow hams don't have the facts, most are making uninformed / poorly-informed decisions)

https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647

https://www.eham.net/ehamforum/smf/index.php/topic,97093.255.html

It surprises many that the "12volt PA" TS-590SG has a 2db to 3db better 3rd order and 9th order transmit IMD than the "50-volt PA" TS-990S....with the 590SG about 6 to 8db worse on its 5th and 7th order products....(this is primarily due to the design and tuning of each of these PA's....in that they could be designed/tuning slightly differently and one might produce better lower-order products at a sacrifice for higher-order products, and vice-versa...btw, this is explained in detail in posts, by me and others, in that other thread I reference..)  Not to mention being better than the 50-volt PA IC-7800 and FTdx-5000!!
 

And, some might find the actual spectral scans showing a direct comparison (on the same screen) of a "modern" rig (IC-7600) versus a "legacy" rig (IC-756ProIII), to be helpful...as well as the old FT-1000 MkV in Class A, versus a K3...
Have a look:
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1080308.html#msg1080308


Anyway, I really just wanted to point out a few things:
a)  There is a lot more to what makes a great rig than where it is on Rob's list (and if you don't believe me, why not click on the links I provided and read Rob, NC0B's own words...)

b)  It is a myth that just using a rig that has "50-volt PA" means you necessarily have a clean transmitter...

c)  We hams are getting shafted these days by the slip-shod / half-assed engineering of the transmitters (primarily the PA's) of our modern rigs, and as such the limiting factor in our receivers is not our receiver specs, but rather the transmitter specs / transmit IMD of the other transmitters on-the-air (typically within +/- 20khz to 30khz of you)....and this has been the case now for a long time (a decade or two), and many of the same guys who strived to bring us clean receivers with high dynamic range (NC0B, W6XX, K3LR, W8JI, etc.) have been saying this now for years/decades!!!
Please read what they have written...
(heck Rob, NC0B started talking about this in the mid/late 1970's....from Dec '77, when writing about SSB operations: "Generally speaking, transmitted IMD from an RF power amplifier [transmitter] will be worse than that internally generated in the receiver, with the result that the transmitted IMD may cover up a receiver's shortcomings." as well as many times since then has gone into great detail about how our own transmitters prevent anyone from ever using the best of our receivers' capabilities these days...)


Oh, and one last point...please remember these  IMD products are distortion products that are outside your transmit passband / outside the filter bandwidths, and as such cannot be "heard" by anyone listening to you, they must tune up/down to hear / monitor them (or they can use a spec analyzer, to see them)....so, anyone that thinks because you get complimented on "clean audio", etc., that this means you are transmitting a clean signal, please understand it does not... :)
(now, while really harsh and distorted audio can be an indication of an over-driven rig / too high mic gain, etc....and these can, of course, cause poor transmit IMD, so can a poorly designed PA, improperly adjusted ALC, poor voltage regulation, over-driven PA, even poor swr with SSPA's, etc. etc...and none of these can be "heard" on your frequency...)  
Also, please note that there are no transmit IMD specs/rules for the amateur radio service....not FCC, not EU, UK, etc...it is up to the operator to assure that they are using the minimum bandwidth necessary for the mode of operation and to assure they are not interfering with any other stations....
We should all remember that the manufacturers do not have any IMD spec to meet, other than what we hams are willing to be BS'ed into swallowing!!  :(


Okay, no long rants about IMD today....just trying to provide you all with some links to some actual test results...
So, I will close with what I reopened the other thread with, back in February:
Quote
I suppose that since most never hear themselves on-the-air, and darn few ever hear what their own transmitter does on freqs +/- a few khz (or worse +/- 10 to 20khz), the actual transmit IMD and spectral purity of our signals tend to get over-looked...and that is a shame!


73,
John,  KA4WJA

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KA4DPO

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RE: SDR versus Traditional Transceivers.
« Reply #111 on: October 10, 2018, 09:45:53 AM »

No argument that there is a lot of room for improvement in amateur transmitters but there is also a lot of room for improvement in amateurs as well.  There is a large segment of the ham population that came from the "all knobs to the right"  school of thought who don't understand how a class AB amplifier works.  Too often these hams run too much processing, and far too much audio mic gain, and that is just for starters.  They have no Idea that ALC is not really a good thing but that it can cause flat topping in order to protect the finals.  This manifests itself as third and fifth order crud that can be a substantial level.

As for transmitters, it is not easy to get a clean hundred watts out of a broad band transmitter.  Low pass filters can help a lot but, the only way to get a really clean output would be to operate on one single frequency with a narrow bandpass filter, that is what broadcast stations do.  Of course they also operate in class A and have a very clean signal to start with.  

Two real world things also come into play here.  Transmitter phase noise that shows up all over the radio spectrum is not 100 percent cumulative.  A good example of this is during contests.  If all of the phase noise generated by all of the transmitters accumulated, the noise floor would be raised by 40 or more db.  We all know that is not the case although, there is a small but measurable increase in Gaussian noise across the radio spectrum during contests.  The reason for this is that some percentage of the phase noise cancels, or reduces as signals of different phase angles occupy the same frequencies.  In order for them to cancel completely they would have to be zero beat, identical in power, and 180 degrees out of phase, the chances of that happening are almost non existent.  But there is statistically some attenuation of noise that takes place while slightly more noise occurs that is additive.

In the case of digital predistortion we know that as a class AB stage gets close to the 3 db saturation point intermod products increase rapidly.  Digital predistortion enables the amplifier to operate closer to it's saturation point by correcting the phase angle of the transmitted envelope, thus significantly reduing spurious output products.  The one problem with this is, that while it really cleans up the signal close in, it has an elliptical effect.  Don't believe it?  Run an Apache Labs 8000 DLE at 200 watts using pre distortion.  First, it won't let you, but if you could you would see the unwanted emissions one or two octaves away from the transmit frequency, and at substantial power.

There are no free lunches in anything including radio transmitters.  I can build a transmitter that is clean as a whistle but will only be about eight to ten percent efficient, and at 12 volts will only deliver about twenty five watts PEP.  So Your points regarding current transmitters are valid and can't be argued with except to say the solutions are either too expensive, or not what the majority wants.  Break out the soldering iron, wind some cores, and let the good times roll.
« Last Edit: October 10, 2018, 09:48:05 AM by KA4DPO »
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N6YFM

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RE: SDR versus Traditional Transceivers.
« Reply #112 on: October 11, 2018, 10:30:10 AM »

No argument that there is a lot of room for improvement in amateur transmitters but there is also a lot of room for improvement in amateurs as well.  There is a large segment of the ham population that came from the "all knobs to the right"  school of thought who don't understand how a class AB amplifier works.  Too often these hams run too much processing, and far too much audio mic gain, and that is just for starters.  They have no Idea that ALC is not really a good thing but that it can cause flat topping in order to protect the finals.  This manifests itself as third and fifth order crud that can be a substantial level.

Well said.
Recent "behavior" during the Baker Island Dxpedition on FT-8 mode proves that roughly half the
people "think" (sic) they know everything, don't bother to read the instructions, and clobber the
band segment for everyone else.

"If we could just figure out how to harvest STUPID, we would have more money than Bill Gates".
No shortage, really...     I have no disrespect at all for those of us who are less experienced, or have not
yet learned, or are beginners but are interested in learning (myself included).  But what I can't understand
is those who refuse to read the instructions, refuse to ask questions, refuse to use google, and simply do
"turn all knobs to the right" and blast away.   That's just a "Special Kind of Stupid" {tm}.

I am patient and more than happy to mentor and help anyone with any question (if they bother to ask),
but it was simple fact that too many hams during that baker island event did not care to ask, or bother
to read instructions or band guidelines. They simply blazed away with stupidity and ruined chances for
many other people.

Again, the above is not meant as an insult, but rather a factual observation.

Cheers,

Neal
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KA4WJA

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RE: SDR versus Traditional Transceivers.
« Reply #113 on: October 12, 2018, 12:00:35 PM »

John, KA4DPO,
While I agree we need to encourage education in our ranks, especially in operating practices...I'm not sure this is the thread for that. 


So, onto the subject at hand, "SDR versus Traditional Transceivers"...
I will not turn this into an IMD rant....(remember, I'm not Zenki!  hi hi...)
But, I would like to clarify a few things... :)


1)  Actually it is not difficult at all, and definitively not expensive, to build a clean 100-watt amateur radio HF transmitter...just this summer we've been discussing rigs like the 1960's Collins 32S-3 and the 1980's Kenwood TS-830s (as examples of vacuum tube PA's that are "clean"), the 1990's JRC JST-245 or even an Icom IC-765 (12vdc PA ham rigs that are fairly "clean") also there are many Icom and JRC maritime HF rigs that work wonderfully on the ham bands that are further examples of 12vdc SS PA's that are "clean"...heck even an IC-756ProIII is MUCH cleaner and produces a much narrower signal on-the-air than a "modern" IC-7600...(please have a look at that thread, where you will see the spectral scans of many of these, as well as the actual test results for dozens of rigs, new/modern as well as legacy)

I'm still surprised that so many of my fellow hams buy into the BS from the manufacturers that this is somehow "expensive"....
Plain and simple, it is not expensive at all...
There are discussions here on eham, regarding what can be easily and inexpensively done...

Most that have actually looked see that the "cost" is another amp or so of idling current and a corresponding additional amp or two (at most) of final peak  PA current, at 12vdc....and maybe an addition $25 to $50 in better parts/devices in the 12vdc PA's...this is Class B, not Class A...
{Understand that you can buy today for ~ $1800, a 150-watt HF Ham/Maritime SSB, CW, FSK (100% duty-cycle) Rig, with IF-DSP, with remote head, etc....that is 10db to 15db "cleaner" (better transmit IMD) than most of our other HF ham rigs these days...}


2)  I think you may be mistaking harmonics or "spurs" / spurious emissions, for IMD products, when you're writing about using filters to filter out these products??
Because IMD products from SSB Voice transmissions (or multi-tone digital modes, or even AM-DSB) are produced close-in to the transmit freq / close to the transmitter's IF passband, caused by non-linearity in the transmitter's PA stage(s) at RF....they are not "filterable"...
(I least I'm not aware of any affordable filter that has a 2.8khz bandwidth at say 3.650mhz, that can handle 100 watts of RF thru it...if there are such affordable filters, please let us know...)

Also, I'm not aware of broadcast stations running their PA's in Class A??
Actually most of the newer AM BC (MW) transmitters use "digital modulators" instantly turning on/off various modules, instantly as the audio input calls for them....it's actually quite elegant....but a total red herring to this discussion...
'Cuz we're talking about HF SSB/Digital ham transceivers... :)


3)  Yes, transmit phase noise does produce issues on the air....but this is only applicable / noticeable in CW operations (or other on/off, non-multi-carrier digital modes), where the transmitter is producing one signal at a time....of course this noise is still there in SSB operations, but the transmit IMD products are usually many dozen's of db's higher!! (most ham transceivers' transmit phase noise is down 75db to 85db to 90db, or more, @ 3khz to 5khz away from their carrier freq....so, only when the IMD products are near / below these levels, would the transmit phase noise be noticeable on-the-air from SSB transmissions....


4)  I'm not sure I understand all of what you wrote here??
I'm familiar with IMD products rising sharply as an amplifier is pushed beyond its 1db compression point, and at saturation things get pretty ugly... :)

But, what is a "3db saturation point"??  In my ~ 45 years in communications / RF, I've not heard of this term....perhaps it's just a new way of wording something / some spec, that I'm not familiar with??

As for the ANAN-8000DLE....it's a nice rig (just wish it had "knobs"!)...but I highly doubt Apache Labs runs the PA of the 8000 at saturation....if they did, not only wouldn't it last too long, but its IMD products (w/o pre-distortion) would be worse than a CB radio / CB amp, which they are not...(to be clear, w/o pre-distortion, at 200 watts, the 80000DLE isn't great in the IMD department, about on par with most other modern HF rigs...)

In any case, I looked closely at Adam Farson, VA7OJ/AB4OJ's, detailed test of the ANAN 8000DLE, last summer....and I didn't see any mention of the pre-distortion not working at 200-watts out...and in actuality he showed the spectrum analyzer scan of it operating at 200 watts, with pre-distortion and without (over-layed on top of each other)...

Here are the transmit IMD test results that he published (at 14.1mhz):

-33 / -40 / -54 / -60  (with NO pre-distortion) at 200 watts
-67 / -70 / -70 / -70  (with pre-distortion) at 200 watts

FYI, the ARRL testers had some difficulty getting the pre-distortion to work well, and they found only 3db to 5db improvement in transmit IMD with it turned on, versus off....

Also, to be clear, I'm not sure what you mean by "one or two octaves away"....are you referring one or two octaves of the baseband audio freqs / tone freqs??  'Cuz they are represented there by the IMD products....
Or, are you referring to one or two octaves of the fundamental (harmonics)??  As the 8000DLE's harmonics (at 200 watts out; from 14.1mhz) are down better than 70db (2nd = =71.8db; 3rd = -91.5db; 4th = -95.0; 5th = -94.3db; 6th = -100.2db, etc...) and while the 3.6mhz harmonics are not as good (with an odd anomaly on the 3rd), I cannot quite understand what you are referring to, when you write that
"you would see the unwanted emissions one or two octaves away from the transmit frequency, and at substantial power."
   Could you explain??



In any case, I just wanted to clarify a few things....

73,

John,  KA4WJA
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KA4DPO

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RE: SDR versus Traditional Transceivers.
« Reply #114 on: October 12, 2018, 12:10:28 PM »

Interesting to note the title of this thread is " SDR versus Traditional Transceivers.   The interesting thing is, I don't think anyone has made a "Traditional" transceiver in over 20 years.  The first SDR's came out in the mid 1990's with DSP and of course, computer controlled front panel interface.  So unless we want to compare any modern radio to things like the TS-820, Drake C line, or the original TenTec Omni series, this thread is kind of off the rails.

It all boils down to someone, actually, a lot of someone's, not understanding what SDR really is.  I am very pleased with the direction amateur radio manufacturers are moving in.  They are moving forward like they always have and SDR just keeps getting better all the time.  Radio performance is the best it has ever been and continues to get better.  There really is no comparison between SDR (anything made in the last 20 years) and traditional radios that used real components in discreet circuits for each function.  Nope, no comparison.
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KA4WJA

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RE: SDR versus Traditional Transceivers.
« Reply #115 on: October 15, 2018, 04:24:09 PM »

FYI, here are some updated / corrected transmit IMD figures for the Apache Labs ANAN-8000DLE (form Nov 2018, QST)

As for the ANAN-8000DLE....it's a nice rig (just wish it had "knobs"!)...but I highly doubt Apache Labs runs the PA of the 8000 at saturation....if they did, not only wouldn't it last too long, but its IMD products (w/o pre-distortion) would be worse than a CB radio / CB amp, which they are not...(to be clear, w/o pre-distortion, at 200 watts, the 80000DLE isn't great in the IMD department, about on par with most other modern HF rigs...)

In any case, I looked closely at Adam Farson, VA7OJ/AB4OJ's, detailed test of the ANAN 8000DLE, last summer....and I didn't see any mention of the pre-distortion not working at 200-watts out...and in actuality he showed the spectrum analyzer scan of it operating at 200 watts, with pre-distortion and without (over-layed on top of each other)...

Here are the transmit IMD test results that he published (at 14.1mhz):

-33 / -40 / -54 / -60  (with NO pre-distortion) at 200 watts
-67 / -70 / -70 / -70  (with pre-distortion) at 200 watts

FYI, the ARRL testers had some difficulty getting the pre-distortion to work well, and they found only 3db to 5db improvement in transmit IMD with it turned on, versus off....
The ARRL updated their review of the ANAN-8000DLE, stating that after their original IMD tests, they sent their unit to Apache Labs service center / Doug Wigley, W5WC (in Arkansas), where Doug quickly determined that the RF Coupler output was too high and caused the "pure signal" pre-distortion to become overloaded and seriously effected its functionality because of this overload distortion...
He changed some resistor values, which solved the problem!  (and Apache Labs has also changed these in production models)
He returned this unit to ARRL and they (ARRL) re-did their transmit IND tests and in Nov 2018 issue of QST, published the updated / corrected IMD test results of the ANAN-8000DLE...see pages 63 and 64...


Also, to be clear, I'm not sure what you mean by "one or two octaves away"....are you referring one or two octaves of the baseband audio freqs / tone freqs??  'Cuz they are represented there by the IMD products....
Or, are you referring to one or two octaves of the fundamental (harmonics)??  As the 8000DLE's harmonics (at 200 watts out; from 14.1mhz) are down better than 70db (2nd = =71.8db; 3rd = -91.5db; 4th = -95.0; 5th = -94.3db; 6th = -100.2db, etc...) and while the 3.6mhz harmonics are not as good (with an odd anomaly on the 3rd), I cannot quite understand what you are referring to, when you write that
"you would see the unwanted emissions one or two octaves away from the transmit frequency, and at substantial power."
  Could you explain??


In any case, I just wanted to clarify a few things....

73,

John,  KA4WJA

The ARRL updated their review of the ANAN-8000DLE, stating that after their original IMD tests, they sent their unit to Apache Labs service center / Doug Wigley, W5WC (in Arkansas), where Doug quickly determined that the RF Coupler output was too high and caused the "pure signal" pre-distortion to become overloaded and seriously effected its functionality because of this overload distortion...
He changed some resistor values, which solved the problem! (and Apache Labs has also changed these in production models)

He returned this unit to ARRL and they (ARRL) re-did their transmit IND tests and in Nov 2018 issue of QST, published the updated / corrected IMD test results of the ANAN-8000DLE...see pages 63 and 64...


Here are their results (at 200 watts PEP):




Comparing Adam Farson, VA7OJ/AB4OJ's tests with the new ARRL tests...

ARRL Tests (typical)
-30 / -38 / -47 / -54  (with NO pre-distortion) at 200 watts
-32 / -43 / -54 / -59  (with pre-distortion) at 200 watts, old/defective results
-54 / -64 / -60 / -60  (with pre-distortion) at 200 watts, Updated Results (from 20m for comparison to Adam Farson, VA7OJ/AB4OJ's tests on 20m, but check out the 40m and 80m results which are really nice!)

Adam Farson, VA7OJ/AB4OJ's tests on 20m:
-33 / -40 / -54 / -60  (with NO pre-distortion) at 200 watts
-67 / -70 / -70 / -70  (with pre-distortion) at 200 watts

Comparing Adam Farson, VA7OJ/AB4OJ's tests with the ARRL tests (both their original results and their updated test results)...clearly shows that pre-distortion does work....BUT...

But, in my opinion, this also shows that this is not an "off-the-shelf" / mass-producable feature...yet!!
And, is also shows (again, in my opinion) why Flex and Icom have decided to not incorporate pre-distortion into their units (nothing like marketing a feature, that doesn't work out-of-the-box, to ruin your reputation)...

Just wanted to update / clarify these results for all... :)


Fair winds...
73,
John,  KA4WJA
« Last Edit: October 15, 2018, 04:43:02 PM by KA4WJA »
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