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Author Topic: Ham Xcvrs' and Amps', Transmit Spectral Purity, IMD Products, vs. comm/maritime  (Read 152530 times)
KA4WJA
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Posts: 1098




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« on: May 28, 2014, 02:31:05 PM »

Hello to all....
Instead of piling on and drifting other recent threads (such as the "Alpha/Ten-Tec Merger" and "Filtering Questions", discussions), I thought starting a new topic that is directly on-point might be helpful???

Please remember up front, that I don't have too much spare time (elderly family commitments) to hang out and post messages, so as some of you know, when I do spend the time / make the effort it is probably not frivolous, and well worth the time to read/ponder/comment intelligently on.... Smiley Smiley
(but, I still try to keep a sense of humor about these things....after all it's not like good transmit specs are going to save the world... Smiley

So, here goes...


1)  Over the recent years I've been pleasantly surprised by the well thought-out and somewhat reasoned posts by "Zenki" regarding the lack of concern by hams, radio manufactures, and regulators, of transmitter spectral purity, IMD products, oscil. phase noise, etc. of our radios and amps...

{Aside from his desire for more stringent "gov't regulations" (which I eschew), his thoughts on these matters have paralleled mine....(I'm NOT a convert of his....these are my words / opinions which I've held for years....and the many facts that I'll provide here are all public information available for many, many years...) }

Make no mistake, I also wish that "Zenki" would identify himself/herself, post his/her callsign, etc...
Part of me wishes to ignore/discount anyone who desires to remain anonymous, and I certainly NEVER appreciate "un-named" sources used by media, etc..
I, and many others, are proud of our calls, and have no fear of exposing any of opinions, desires, etc. even our inadequacies, to any/all...
So, I fully understand and accept that "Zenki's" posts are thought of as nuisance to many and as an insult to a few...
Zenki's opinions will mean nothing to me until he mans up and starts posting under his callsign (assuming he has one) like 99+% of the other people here on eHam rather than hiding behind an anonymous screen name.

I totally agree.  I prefer having a conversation with an someone that is not anonymous.  I am proud of my callsign, license and credentials, and wish others were of theirs.

I would think, in an amateur radio forum, having an amateur radio license is a basic credential, and not to much to ask.  

73,

John  W5JON


But, I am NOT him...so maybe my words will be more "appreciated"?? Smiley




2)  The facts are that there currently ARE "12-volt" HF radios made (w/o any DC-DC converters), that are VERY clean, and are FCC type certified under Part 80, Part 87, and Part 90 (maritime, aviation, and land mobile), as well as meeting CE, ITU, specs/certifications....and this radio here, does excellent service on the amateur radio bands, with full IF-DSP,  vfo, 100's of user-programmable memories, back-lit LCD displays w/ both vfo freq and alpha-numeric info, etc. etc. etc...

This is a current production Icom M-802 HF transceiver, which first entered the market in 2003....and sells for about $1800....(yes, that price is LESS than what some hams think of as "normal", for a full-featured, IF-DSP HF rig....and 1/10 the price of the often bandied-around "$20,000 radio"!!!)

Please have a look at its transmit IMD tests (at 150 watts PEP)...the radio is spec'd at 150 watts output 100% duty-cycle, continuous-duty (FSK/SSB/CW)....

Here are the two "worst-case" transmit IMD spectral scans at 150 watts PEP output...(courtesy of the FCC, note the Part 80, "IMD mask" on the screen)






(these are about what the old Yaesu FT-1000 did in Class A....)

You see, there ARE clean "12-volt radios" being made, and they are not that expensive....(oh, and BTW, it meet these specs when operated from 11.5vdc to 15.5vdc....not just at a "nominal" 13.6vdc...)

My problem with Zenki is that he keeps talking about things that are never going to happen.  Yes we would all love a Amplifier or Radio that had a Zenki stamp of approval but that Radio would cost $20,000 and so it will never be made and I so just can't see the point of going on and on about a fantasy radio or amplifier.
 
12-volt based 100w class rigs put out crap on TX. Until buyers start caring about that, nothing will change.

Of course, most won't. The old, what's in it for me deal.


I don't wish to "pick on" anyone in particular (the above quotes are just the most recent ones...sorry), but as you can all see, there ARE clean '12 volt HF radios" being made and selling at "affordable" prices...


And yes, I would also prefer dynamic testing with voice or white noise....but these 2-tone tests are what I have and what are available in the public domain, so that's what I'm stuck with as "facts" here...





3)  And, if any of you are wondering what other specs and design features, this radio has....here are just some of the highlights....
(this is NOT a sales-pitch for this radio, just a run-down of what it is, what it does, and how good the specs are....so that you can all see that this is a REAL radio, that is being used everyday on both the ham and maritime bands, that is NOT outrageously expensive....and has a VERY clean transmitter!!!)

The Icom M-802 is a full IF-DSP based SSB/CW/FSK transceiver (covering 1.6mhz - 30mhz transmit and 500khz - 30mhz rec);   with DSP-based modulation and speech compression;   DBM-input (no rec RF amp);   with full-QSK CW;   a built-in FSK (100-baud) encoder/decoder and simple-display (with adjustable shift spacing and freqs);   AM receive;   secondary/sub-receiver (FSK only);   vfo and memory / channel freq control, as well as direct freq input via the keypad;   DSP-based noise blanker;  Voice Squelch;   DSP-based AGC and DSP-based ALC (no ALC overshoot issues, nor ALC trying to control too much gain, etc.);  memory/channel scan and band scan;  adjustable transmit power level;  adjustable RF Gain;   +/- 150hz RIT;  full computer control capable;  aux outputs and connectors to allow connection/interface to ext. modems, ext. amplifiers, etc.;  full remote control head;   remote automatic antenna tuner interface built-in;   etc. etc.
(yes, it lacks some "features" that some hams desire...and has features that no ham needs.....but I'm NOT advocating that this is a replacement for our ham transceivers, just pointing out all the features/specs this radio has, for the 'affordable" price of $1800...)


--- The M-802's first IF is at 64.455mhz, where there is a first IF crystal filter (nowadays called a "roofing filter") of 15khz wide.

--- The M-802's second IF is at 455khz, and there is a 2nd IF ceramic filter of approx. 12khz wide. (note that ceramic filters at 455khz perform very well)

--- The M-802's third IF is at 12khz, and here is where the DSP module does all the work of mode filtering, demodulating various modes, etc.

From the M-802's serv manual...
Quote
The DSP [Digital Signal Processor] circuit enables digital IF filtering, digital noise reduction, digital PSN [Pulse Shift Network], phase demodulation, digital automatic notch, etc.   As well as does all the "modulating" and "speech compressing" during transmission.

The few receiver tests specs I have, show a wide-spaced IMD3 of 100db, narrow spaced IMD3 of >80db, BDR of 142, and phase noise 134-135dbc/hz....making better than most "ham radios" costing 2 - 3 times as much$$$$....

(The M-802 has a great receiver, which outperforms probably > 99% of the "ham" transceivers out there, including many that cost 2 - 3 times the price!!
It doesn't have phase noise issues like many modern $3000 - $5000 ham rigs have, and hence doesn't suffer from noise-limited IMD...it does not suffer from recip mixing IMD, etc.)


As the M-802 is designed (both hardware and firmware) to conform to the FCC Part 80, 87, and 90 standards, therefore there is no feature for changing any of the transmit filtering....
And, in receiving (all IF-DSP controlled):
--- the SSB voice bandwidth is controlled at 2.4khz wide....
--- the AM voice bandwidth is 6khz (I think??)
--- the CW and FSK-Narrow (F1B) and AFSK-narrow (J2B) bandwidth is 500hz...

--- the AFSK/J2B-middle bandwidth is 1khz...
--- the FSK/F1B-wide bandwidth is 1khz...
--- the AFSK/J2B-wide bandwidth is 2.4khz...

Additionally it furthers has 3 "digital mode" filter bandwidths are:
--- narrow is 500hz...
--- middle is 2.4khz...
--- wide is 2.8khz...

http://www.icomamerica.com/en/products/marine/ssb/m802/

http://www.docksideradio.com/Icom%20SSB%20Radios.htm


And again, this radio is spec'd at 150 watts output, 100% duty-cycle, continuously duty (FSK/SSB/CW).....
And again, here are the transmit spectral scans (from the FCC certification test report)...








Compare those to a brand new, fresh out-the-box, Icom IC-706MkIIG....(courtesy of the ARRL lab)



And, how about the $3500+ Elecraft K3.....anyone wish to agree that this transmitter can be thought of as "total garbage"Huh (courtesy of NC0B, Rob Sherwood)
Sorry guys....I know there are many "militant" K3 supporters here, and I'm not trying to antagonize you...but Rob Sherwood uses this in his regular presentations, so it should not be a surprise, nor is there any controversy here....the K3's transmitter is what it is....(they market / hype the receiver, not the transmitter...)





Without actually seeing the real transmitter IMD test scans of the real commercial/marine "12-volt dc" radio (the Icom M-802), and without reading the specs/features of this same reasonably "affordable" radio ($1800, for the M-802), I understand that some would jump to the conclusion that "it can't be done at 12 volts", and/or "it's too expensive", etc...
But, with all this information I posted here, I think you can all see that these conclusions / reactions are misplaced, and it CAN be done easily and at a relatively low cost...
BUT...

But, even more impressive is the fact (sorry I don't have the scans to "prove" it) that a couple older "12 volt" HF marine transceivers, have even BETTER transmit spectral purity and even lower transmit IMD products....
Such as the Icom M-700Pro (which is a 1990's design, that just ceased production about 7 - 8  years ago, and retailed for ~ $1250...and can be purchased used nowadays for about $500 - $700) had even lower phase noise, and all IMD products down better than 75db...and here again, this is at 150 watts PEP output continuous-duty (FSK/SSB/CW)..
Yes it did have a full vfo as well as 150 channels, etc....but not too many "ham-radio-type features".....but its "12 volt PA" and its entire transmitter was VERY clean...(actually better than a Yaesu FT-1000 in Class A)



....Continued in next post....

73,

John,  KA4WJA
s/v  Annie Laurie,  WDB6927



{P.S.....BTW, I'm not one that thinks someone must disclose their credentials and/or brag about their experiences, in order to present facts....and I don't believe any of us should need to un-zip and break-out a yardstick to see who is "the most qualified"... Smiley
But, just an FYI....yes, I'm a bit younger than many of you (53) and was licensed as a teenager...majored in physics, but have run my own electronics firm for the past 30 some years....but, most importantly I have operated and installed numerous HF maritime radios on-board many vessels since the early 1970's (a few years before becoming a ham, 35 years ago...)
(as I'm NOT an RF engineer by trade or education, I defer to those of you here that are....but, I DO understand the radios, the various circuitry, and most importantly the real-world problems that poor transmit spectral purity is causing!!)
And still to this day, I regularly operate on both the maritime and ham bands on-board, when at sea and/or tied to the dock...so, in addition to the above facts, I have real world, first-hand experience with the best and the worst of HF transmitters... Smiley }
« Last Edit: May 28, 2014, 02:36:43 PM by KA4WJA » Logged
KA4WJA
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« Reply #1 on: May 28, 2014, 02:33:27 PM »

Continued from above...

4)  And, since this IS the "Amplifiers" Forum....in regards to how some (many??) hams might feel an amp with good IMD specs might be wasted money....
(Minor Opinion Alert Here!)
[when discussing average exciter IMD] Anything over that in an amplifier is wasted money. Your amplifier IMD is set by the driver radio. Most tube amplifiers and even tetrodes have an IMD of better than 42 dB. My 8410 measured 43 minimum on all bands.

Now put on your marketing hat and try to market an amplifier with the best IMD possible. Hams want cheap reliable power, and good resale ownership.   Everything else is wasted money.  You are promoting the attributes of a fine Merlot to an audience with a beer budget.
I have great respect for your RF design expertise Mike, but here we disagree!!!

If we say that the radios could be better, but the amps are "good enough"...or vice versa, that the amps need to be better, but the radios are "pretty good"...aren't we just promoting self-fulfilling prophecies???
I think so...but, others may have different (valid) opinions..
(I'm not even going to bring up the "all knobs to the right" / "drive every watt possible out of it", philosophy of so many hams these days....'cause it'll just cloud the main issue here, that we as ham consumers CAN demand better transmit spectral performance from the manufactures, and the manufactures CAN make "affordable" radios and amps that provide these better specs...)

But, back to some facts...
Ever seen the results of a really clean transmitter into a really clean amp???
Here is the result of an FT-1000MkV in Class A, into an Alpha 77, running about 2000 watts PEP....and using a transceiver such as the above mentioned M-802 or M-700Pro, would have similar (or even better) results...
(I know that the FT-1000 has some other issues, such as its ALC-induced issues, but here I'm just using this as an example to show the static transmit IMD results....and I'm limited by the spectral scans that I have and that are out in public domain...)

Have a look...



Anyone have a scan of a K3 into a ALS-600, etc.Huh
Anyone need to see one in order to know how crappy the signal is??  Smiley





5)  Also, I've been confused by the knee-jerk reactions and/or off-the-cuff comments about marine radios not being designed to meet modern ham standards or the needs/desires of the modern ham operator....
As someone who actually operates on the marine bands very regularly (and have for 40 years now), perhaps I can clarify things a bit...

--- I am NOT advocating that all hams should use marine HF radios...
--- But rather pointing out that the same designers, engineers, and factories that are making our HF ham transceivers with truly HORRIBLE transmit spectral purity and "total garbage" transmit IMD specs/tests, are also designing/engineering/manufacturing hi-quality "12 volt" HF transceivers at reasonable prices, that have excellent transmit purity and specs!!
--- And, I'm wondering (and posing the question here), WHY are so many hams accepting this, and not demanding better???





6)  Further, there is some misinformation here...(sorry Mike)....
This is only a problem with HAM radio. We are the only radio users that butt transmissions right up against each other. Marine and Aviation users are on 25 KHz split frequencies. Their radios are not any cleaner but the neighborhood is much more sparse.
Actually the Marine channels DO butt right up against each other...they are 3khz wide...(hence the need for 2K80J3E emissions and VERY clean transmitters!)
And YES these adjacent channels ARE used, so keeping splatter at bay is important here...

Just so we fully understand things, I'm going to give real world, personal examples...
--- Over the years (and as recent as last week), I have run or assisted on Maritime HF Nets and Weather Broadcasts...

--- For long-range offshore weather, I regularly use 12.359mhz for over an hour each day, and always have other weather broadcasts (w/ 1000-watt transmitters) transmitting on 12.362mhz and 12.365mhz simultaneously...(during my broadcasts/net)
(and, occasionally have other traffic on 12.353mhz and/or 12.356mhz, as well...)

--- For more regional offshore weather, I regularly use 8.294mhz...and just as regularly have other traffic on 8.297mhz...(as there are only two worldwide 8mhz simplex maritime Voice channels) BUT....

--- But, even more importantly when using 8.294mhz, we must be conscience of the fact that 8.291mhz is the 8mhz Int'l GMDSS Distress Calling Frequency....and causing interference there just isn't "bad engineering practice", but can actually cost someone their lives!!! (just this past week 4 mariners died/drown in the N. Atlantic, 1000 miles ESE of Cape Cod....while two other groups of 3 each, were successfully rescued in the N. Atlantic all in just the past 7 - 10 days...and this stuff happens all the time....so, NOT causing interference IS very important!!)

--- I immediately know when someone on an adjacent channel is using a "MARS-modified" / "opened-up" ham radio on the marine freqs....as their splatter is truly horrible!!
(I can spot an IC-706, from 1000's of miles and 10khz away!! Smiley )
And, don't forget that many maritime mobile service radios are not supplied with a regulated 13.6 - 13.8vdc...but, rather many are operated at voltages as low as 12 volts, or even lower in some situations (especially in emergencies)....
Anyone ever heard/measured a "modern 12-volt ham transceiver" operated on low voltages such as 11.5 - 12.5 volts???  (once you hear the "fm'ing" and other distortions "in-band", you'll never forget it....and if you tune a few kHz up/down, you'll quickly see just how much crap is being transmitted outside the transmitters passband!!!)

--- In years past (before sat comm became more affordable), there was a tremendous amount of HF voice activity all hours of the day/night on almost all the HF Maritime freqs (both simplex and duplex), especially crowded with "public correspondence" (ship-to-shore radio-telephone calls)...
And, the ITU tried to assigned the coast stations their channels that would have some sort of "buffer" (typically a one or two channel width buffer, of 3khz or 6khz) between stations that would be within single-hop or double-hop range of each other and their primary customers at sea...in order to reduce de-sense and any problems with splatter coming from 1000 watt ship stations and 10,000 watt shore stations...
Even today, with less number of users, there are still 3 - 6khz spaces between the coast stations' assigned channels...)
BUT...
But, this is NOT the case for the simplex ship-to-shore, and ship-to-ship channels that are all stacked right next to one another, ever 3khz....

--- I won't ramble on and on about this, as this is a fairly innocuous point, which distracts from the main issue that ham radio transmit spectral purity and IMD products are truly Horrible and other radio services using the HF bands (such as the HF maritime mobile radio service) requires much stricter specifications, and the radio manufactures comply with these rules, producing "12 volt" radios at reasonably "affordable" prices..


Sorry Mike, but the facts are:
a)  the HF marine radios ARE much cleaner!!!
 ---  and ---
b)  the marine HF channels ARE only 3khz wide, and adjacent channels ARE used quite regularly!!!






7)  How about I leave you all with some good (but sobering) thoughts???
Mike, here I agree with you and can commiserate!!! (still amazes me that even seasoned hams run their RF wide open on every band, at all times!!)
 
Your radio can be as clean as a whistle but due to signal strength, poor receiver design, NB on and operator error at the other end they will perceive that you are splattering. I would guess most hams have no idea what the RF gain control is used for.

About 6 years ago at Dayton, I help set up the special event station. We were at the ICOM booth running a 7800 and an amplifier (1000 watts) to a 4 element SteppIR beam at 80 feet. All day long everyone with a mobile in the parking lot would come in to tell us about our wide signal. I’d ask how strong we were and the regular reply was we were pinning their S meter. As soon as I explained about receiver overload their eyes would glaze over.
The problem is, if all we do is accept the status quo, things will get worse and worse....and we will all have nobody to blame but ourselves...


And, this sums up the REAL point of all my ramblings here today...
In regards to our HF bands, interference, distortions, transmitter spectral purity, etc..
Alternatives DO exist...
--- and ---
They are reasonably "affordable"

Isn't up to US to try to make things better???


How about we all write Icom Kenwood, Yaesu, TenTec, Flex, etc. etc. etc....and request that they actually make HF ham transceivers that meet these specs, and fit inside this "mask"Huh





Okay, enough for now....(I've actually got other things to do..Smiley


73,

John,  KA4WJA
s/v  Annie Laurie,  WDB6927





{P.S.....BTW, I'm not one that thinks someone must disclose their credentials and/or brag about their experiences, in order to present facts....and I don't believe any of us should need to un-zip and break-out a yardstick to see who is "the most qualified"... Smiley
But, just an FYI....yes, I'm a bit younger than many of you (53) and was licensed as a teenager...majored in physics, but have run my own electronics firm for the past 30 some years....but, most importantly I have operated and installed numerous HF maritime radios on-board many vessels since the early 1970's (a few years before becoming a ham, 35 years ago...)
(as I'm NOT an RF engineer by trade or education, I defer to those of you here that are....but, I DO understand the radios, the various circuitry, and most importantly the real-world problems that poor transmit spectral purity is causing!!)
And still to this day, I regularly operate on both the maritime and ham bands on-board, when at sea and/or tied to the dock...so, in addition to the above facts, I have real world, first-hand experience with the best and the worst of HF transmitters... Smiley }
« Last Edit: May 28, 2014, 02:48:45 PM by KA4WJA » Logged
K2GWK
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« Reply #2 on: May 28, 2014, 03:47:45 PM »

The few receiver tests specs I have, show a wide-spaced IMD3 of 100db, narrow spaced IMD3 of >80db, BDR of 142, and phase noise 134-135dbc/hz....making better than most "ham radios" costing 2 - 3 times as much$$$$....

The $1000 Elecraft KX3's Receiver outperforms the Icom M-802'a Receiver as does the $1600 Kenwood TS-590S.

http://www.sherweng.com/table.html

I will be honest with you. You will never get the manufacturers to change when the products they have designed are within the FCC's spec of 30dBc for 3rd order IMD. Now if you were to get the FCC to change the spec to 40 dBc or better you would see the manufacturers scramble to get something done almost overnight.
« Last Edit: May 28, 2014, 04:18:30 PM by K2GWK » Logged

Guy
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« Reply #3 on: May 28, 2014, 04:16:56 PM »

Guy,
Yes, we can always find some radio that does something better, even for less money....
(and I'm now regretting even mentioning rec specs, as this seems to be clouding the issue... Smiley

My intent is/was not to try to say that this particular radio is so great, etc., nor that anyone should buy/use this particular radio....rather to use this radio as a example of what is currently available as a "12-volt" 150-watt HF radio, that is reasonably "affordable", and that has excellent transmit specs...


BTW, I do like the KX3....but isn't the KX3 a 10-watt radio??
(not that there is anything wrong with QRP, but this is "Amplifiers" forum)  Smiley Smiley





While I'm not naïve, and fully grasp the battle that would be needed, I'm not sure others grasp that the radios are already being made, it's just they'd need to be slightly "redesigned" with different firmware and controls....
Think of the IC-7800 front panel / knobs / display / interfaces....driving the M-802's guts....sell if for 1000's of dollars, make everyone happy???
(yeah, a pipe dream...I know that....just trying to spur some thought about this topic, out in the open, not anonymously...)  Smiley
 


73,
John,  KA4WJA
« Last Edit: May 28, 2014, 04:25:50 PM by KA4WJA » Logged
KI6LZ
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« Reply #4 on: May 28, 2014, 04:21:29 PM »

Perfectly clear to me what John's point is, along with pictures too. Smiley
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« Reply #5 on: May 28, 2014, 04:29:31 PM »

Guy,
Yes, we can always find some radio that does something better, even for less money....
(and I'm now regretting even mentioning rec specs, as this seems to be clouding the issue... Smiley

My intent is/was not to try to say that this particular radio is so great, etc., nor that anyone should buy/use this particular radio....rather to use this radio as a example of what is currently available as a "12-volt" 150-watt HF radio, that is reasonably "affordable", and that has excellent transmit specs...


BTW, I do like the KX3....but isn't the KX3 a 10-watt radio??



73,
John,  KA4WJA


Quote
I will be honest with you. You will never get the manufacturers to change when the products they have designed are within the FCC's spec of 30dBc for 3rd order IMD. Now if you were to get the FCC to change the spec to 40 dBc or better you would see the manufacturers scramble to get something done almost overnight.

Yes it is and I am sure that the 3rd order IMD even at 10 watts is in the 30dBc range. I am not saying Zenki is wrong. I just think he is placing blame on the wrong party. Of course the manufacturers have it within their power to design and build an amplifier that is much better than 30dBc 3rd order IMD. The point I am trying to make is that the Manufacturers (Kenwood, Yaesu, Icom, Elecraft and TenTec) will keep designing their products to meet the 30 dBc FCC spec until the FCC decides to change the spec. There is no incentive for the manufacturers to change until the FCC changes the spec. Maybe instead of Zenki attacking the radio manufacturers he should be holding the FCC responsible for their poor spec limit. Maybe we can get the ARRL to put pressure on the FCC to change the spec if the splatter caused by an amplifier that barely makes 30 dBC 3rd order IMD is becoming a major issue.

« Last Edit: May 28, 2014, 04:41:43 PM by K2GWK » Logged

Guy
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« Reply #6 on: May 28, 2014, 04:38:01 PM »

Perfectly clear to me what John's point is, along with pictures too. Smiley

Me too!! Read my post above.....
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Guy
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« Reply #7 on: May 28, 2014, 04:50:10 PM »

I've stared at too many govt specs. All a manufacturer has to do is comply with the spec and nothing more. Heck, we're now getting radios better than spec.
« Last Edit: May 28, 2014, 04:52:21 PM by KI6LZ » Logged
KA4WJA
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« Reply #8 on: May 28, 2014, 05:37:37 PM »

BTW, in case anyone is wondering, I use an Icom M-802 daily....(I own 2 of them)
But, I still prefer either of my old Drake TR-7's for casual ham operating at home....



But, Icom is NOT the only player here!!!

Here are some other current production and recently discontinued commercial / maritime HF transceivers (all "12 volt" radios)

--- Yaesu / Vertex still has a current production radio that meets these specs/standards....the VX-1700 HF/SSB (which replaced the older, but VERY clean FT-600 / ""system 600")

--- Kenwood still makes their TRC-90 HF-SSB certified for land mobile, etc...(but unfortunately no longer makes their HF marine TKM-707..)

--- Other manufactures, such as Furuno, SEA, Thrane & Thrane / Skantic / Sailor, etc. have all made fully ITU and FCC Part 80 compliant radios , "12 volt" 150 watt output radios ....(as well as 24 volt versions w/ 250-watt, 500-watt, 800-watt, or 1000-watt PA's...)



Just didn't want anyone to think this was an "Icom only" thing....  Smiley



73,
John,  KA4WJA
 
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KH6AQ
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« Reply #9 on: May 28, 2014, 05:46:45 PM »

Very good points on transmitter IMD and the possibilities for amateur service.

Looking at the IC-802M marine transceiver service manual, the 12 volt PA design looks (to me) much like a PA designed for the amateur market. However, the bipolar transistors are SD1487 type, with the datasheet showing operation beyond 150 watts in single-ended service. Comparing the IC718 amateur transceiver PA, it uses the RD70HHF1 MOSFET, with the datasheet showing it running out of steam at 60 watts in single-ended service.

  

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« Reply #10 on: May 28, 2014, 06:01:58 PM »

Guy,
Okay, I think now I understand your comments....
You and I are in agreement that Zenki was placing the blame on the wrong parties (the manufacturers), rather than where I place the blame (on us hams, that accept the status quo)..or where you seem to placing the blame (on the FCC spec Huh)




I think you and I will simply need to politely agree-to-disagree here....
I am not saying Zenki is wrong. I just think he is placing blame on the wrong party. Of course the manufacturers have it within their power to design and build an amplifier that is much better than 30dBc 3rd order IMD. The point I am trying to make is that the Manufacturers (Kenwood, Yaesu, Icom, Elecraft and TenTec) will keep designing their products to meet the 30 dBc FCC spec until the FCC decides to change the spec. There is no incentive for the manufacturers to change until the FCC changes the spec. Maybe instead of Zenki attacking the radio manufacturers he should be holding the FCC responsible for their poor spec limit. Maybe we can get the ARRL to put pressure on the FCC to change the spec if the splatter caused by an amplifier that barely makes 30 dBC 3rd order IMD is becoming a major issue.
In my opinion, the market CAN and DOES enforce changes...and if we try harder, we do NOT need further FCC rules/regs/standards....


If we (hams) actually desire better transmitters (I think this is pretty much a "no-brainer", but others may disagree...), then it is up to us, the amateur radio operators / consumers to "demand" better transmitters (by NOT buying the crappy ones!)....

Again, I'm NOT naïve....I realize this is an extremely difficult goal to achieve...
But...

But, perhaps if the ARRL could be made to publish BIG pictures comparing the transmitter spec / spectral scans of all these radios, especially highlighting the excellent results from other radios made by the SAME manufacturer....then maybe we have a chance!!!
(I joined the ARRL in March of 1974.....and except for a year of lapse, I've been a member for 40 years!!!  Maybe we could get 10's of thousands of ARRL members to "vote" with our dollars / membership dues???)

This, could then be used to have the "vast ham universe" Smiley , force change....by again voting with our $$$$....





73,

John,  KA4WJA
s/v  Annie Laurie,  WDB6927
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KI6LZ
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« Reply #11 on: May 28, 2014, 06:12:03 PM »

It would be nice to see transmitter IMD plots in their ads instead of Ip, DR, BDR, etc. Seems like they are battling it out in the receiver area way past noticeable improvement, somehow we need to steer them toward transmitter improvements and probably the last way is trying to change the specs.
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KM3F
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« Reply #12 on: May 28, 2014, 07:16:17 PM »

It will be a few more years until the mfgers can get the designs worked out but this whole IMD thing is about to change.
It has already been achieved at more than 60 down on the third and brick walled bandwidths.
Look for it in the Flex and ANON radios as soon as the hardware and software is finalized.
I suspect the KW990 may even be capable as soon as it can be implemented with software and supporting hardware.
What you may hear in the future, while on the air, is some op telling you to get a new radio because his built-in spectrum analyzer sees your signal as dirty under it's present design through no fault of yours.
I bet some of you will like to be told that!
Good luck.
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KA4WJA
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« Reply #13 on: May 28, 2014, 08:14:21 PM »

Ken,
I'm afraid I'm not up-to-date with what future developments Flex and ANON might be working on....(thanks for the heads-up, I'll look into it...)

But, the point I'm trying to make is, there ARE currently full-featured, HF transceivers, that provide excellent service on the ham radio bands, that have excellent transmit spectral purity and extremely low IMD products, with the IMD products that actually cause most of the splatter (5th and higher order products), completely non-existent....
And, these radios are now currently on the market (and have been for years), at a reasonably "affordable" price...(< $2000)
The manufacturers are already making these radios and selling them for $1000 - $1800 retail....nobody needs to wait until some software engineer works out kinks in some $10,000 radio...

 

Again, I appreciate the info on what Flex and ANON might be developing...
But...Why should hams "wait 'n see what's coming out next year"?
It will be a few more years until the mfgers can get the designs worked out but this whole IMD thing is about to change.
It has already been achieved at more than 60 down on the third and brick walled bandwidths.
Look for it in the Flex and ANON radios as soon as the hardware and software is finalized.
I suspect the KW990 may even be capable as soon as it can be implemented with software and supporting hardware.
This is a problem that has an easy and currently-available solution....perhaps too many hams are believing marketing hype or "Dayton-speak"?
I'm not sure....

But again, my point is that ARE radios available NOW, at reasonably "affordable" prices,  designed and built by the same guys that are building the ones with poor transmitter specs...
And, I'm asking the questions....

Are hams just too complacent?
Are we all sheep?
Or, are most hams just bowing to "peer pressure"?
(Or, horror of horrors, are many just happily ignorant?  I hope not!!)

So, instead of everyone trying to assess blame, or praise what future radios may be coming....perhaps we can all collectively "demand" better radios now....by simply NOT buying anything (NOTHING at all) from any company that ignores this problem and simply tries to sell crappy transmitters!!!






This would be fine with me!!!
What you may hear in the future, while on the air, is some op telling you to get a new radio because his built-in spectrum analyzer sees your signal as dirty under it's present design through no fault of yours.
I bet some of you will like to be told that!
Good luck.
I always give "honest" signal and audio reports....and while some are insulted, most appreciate it!!!
So, this would be fine with me....

 


73,

John,  KA4WJA
« Last Edit: May 28, 2014, 08:17:36 PM by KA4WJA » Logged
KM3F
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« Reply #14 on: May 28, 2014, 09:22:33 PM »

I occasionally look at the ARRL IMD test results on many radios they test and not impressed.
A lot of the IMD problem is driving amplifiers into distortion or mis adjustment of same.
The RMI line of 12 volt amplifiers are a case in point.
They are not test accepted here in this country operated as they spec them for.
The 300P is mfger rated to 500 + ' horsepower' for 12 volt devices and not good for IMD.
Just recently I monitored the use of one of these 300P amps and see it has some extra 'artifacts' on the outer edges, off frequency so it's not as clean as it should be.
This amplifier really is no worse than the KW480HX that is rated at 200 watts.
The difference is KW limits the drive and output to it's reasonable linear range instead of allowing the final stages to be driven all out and cause a lot of havoc on the bands plus reputation degradation which they don't need.
The coming IMD control involves feeding back an output sample, shifting phase, delaying and some filtering to cancel distortion to a low level..
While not perfect, it is a quantum leap in the IMD cleanup process.
If a new line of devices were to be developed and circuits designed around them, the IMD could become quite low.
I have been monitoring this discussion and applications by very knowledgeable people on the air and done research on the subject, finding is has been worked on as far back as the late 90s.
It's just now filtering into the present day application.
Good luck.
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