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Author Topic: The Longest Journey Starts With A Single Step  (Read 52859 times)
N9AOP
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Posts: 1173




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« Reply #15 on: January 04, 2015, 11:16:55 AM »

I heard somewhere that the big three are considering improving IMD to what you find in the marine radios.  They say this will add $600 to $1000 to each radio but are
not concerned since the amateurs will be glad to pay the upcharge to get better IMD.
Art
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KA4WJA
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Posts: 1098




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« Reply #16 on: January 04, 2015, 05:51:17 PM »

Peter, Scott, et al,

1)  Maritime and other commercial HF transceivers currently do not use any "pre-distortion".... nor, AFAIK, dynamic biasing...
As, Dave, WX7G, mentioned these 12vdc PA's typically just use larger, higher-powered devices and NOT drive the crap out-of-them (like we hams would do)...and in some radios (such as an older SGC) they use multiple discrete-transistor PA modules, each of which would easily produce 200+ watts (400+ watts combined) but the transceiver was type certified at 150 watts....

{and of course then there are the newest higher-power (250, 500, 800, and 1000 watt) maritime transceivers, running on 24vdc...but still not using any "modern" low-distortion techniques....just the ones that have always been known about....not overdriving the devices!}

As I pointed out last year, there is NO "high-cost-redesign", nor "hundreds or thousands of dollars, extra costs involved here"....NONE of that, at all...
It just requires using the proper devices (and usually double the amount of finals), and not driving the crap out-of-'em!!
I'd want to see a good, technical explanation why 12 volt devices work on marine radios, while ham manufacturers are not able to produce the same performance levels?
Perhaps some good articles on improving IMD performance for existing designs that are deficient in this area might be beneficial.

And, while I'd LOVE to see the ARRL publish a whole series of articles on all of this, including the spectral scans of all these transceivers, etc...and ask the tough questions, both in the articles and in editorial pages, "Why won't these same manufacturers charging us 1000's of dollars for TFT or OLED displays, barely useful "bandscopes", and 100's of DSP filter widths, etc., actually spend just a hundred dollars more to manufacture a transmit PA that is CLEAN???"
I'm not holding my breath!




2)  Scott, I understand that "Zenki" rubs many the wrong way....but he DOES make some good points!!!  
And as Pete, K1ZJH, points out, the crap radiated from many VERY expensive, modern transceivers (even operated properly) can seriously effect large parts of our bands...
Guess I fall into line with W8JX.  Much ado about nearly nothing.

I remember a recent post where the King of IMD was seething with rage about some product's NINTH ORDER IMD products.

C'mon.............
Scott, please have a look at the spectral scans of some modern, current production transceivers (and some older and/or maritime/commercial, ones too), rather than trying to just use the 3rd order spec....
The IMD3 spec might be what so many wish to quote/compare, but when you actually look at the scans, you will quickly see why many ARE concerned about this!!

Just look at the K3....would you want to operate within 5khz - 10 kHz of this???  Not to mention, what happens when a whole group of K3's, etc show up on-the-air (contest, etc.)Huh


What if you were trying to work a station that was fairly strong and readable, say a solid 57.....maybe hitting an S-6 to S-7 on your S-meter....and then had a guy suddenly appear just 5-6khz away from your frequency (and he was strong, at 30 - 40db over S-9), running this rig....
Now, guess what, his signal is going to be INSIDE your receiver passband, at levels of S-7 to S-8.....and surprise, surprise, you're not going to be able to easily work (if at all) that guy that was a S-6 to S-7....
And, please understand this in NOT being caused by some yahoo running his mic gain too high, or overdriving his amp....oh no....this is from a guy running a modern multi-thousand dollar transceiver at its designed/specified settings and ratings!!!
Not "splatter" from a lid, or a "CB'er".....no, just the normal, natural garbage coming out of another fellow ham's rig, being operated correctly!!
And, even moving further away....say 10-12khz, doesn't provide you with much in the way of positive results....as this might get you 6db to 10db more of a "cushion" from this guy, and while that would be enough to work this original station (at S-6 or S-7).....but what if the guy is now S-4???
See what I'm getting at???

And, please understand that this has NOTHING at all to do with your receiver, nor its filters, or its "dynamic range", and cannot be solved by typical receiver adjustments such as RF Gain, Attenuators, etc...as this interfering signal is within the passband of your receiver / on the same freq that YOU and the WEAKER GUY are trying to use....
(yes, narrowing your passband, and "shifting" it, may allow you to work the guy....but it will not be fun, and not an armchair rag chew, just a quick exchange of calls, etc...)

And, as I write above, this is NOT being caused by transmitter mis-adjustment / misalignment,  NOT a "all-knob-to-the-right" operator, nor even just some guy who chokes-up a bit or cranks the mic gain up a bit, just to see if he can get thru a pile-up, etc.....
No, these interfering signals are what the radio puts out in completely NORMAL operation.....and that's barefoot, at 100 watts....what do 'ya think his signal would be like after going thru an amp??? (even a good/clean amp, is going to make things worse, both here close-in, and add more/higher-order product issues....)
Or, what happens when he DOES crank up the mic gain??   Oh boy, then you really got problems...

Here's the K3....






AND....lets not forget that it is the lower audio freqs that end up causing even worse distortion products than what we typically use as "tones" in IMD testing (hence why I, and others, crave white noise or dynamic IMD testing....and have no love for the "ESSB" and "hi-fi-SSB" promoters...)



Now, compare that to the scans of a 150-watt, 12vdc, IF-DSP (similar to an IC-756ProII), current production Icom HF Maritime/aviation/land-mobile transceiver, the M-802...






Or, compare it to a FT-1000 running in Class A....(similar to the FTdx-5000 running in Class A)...





Or, compared to the 50-year old Collins 32S-3 transmitter...





You can write about this being "much to do, 'bout nothing", but that doesn't make it so....
Please look at the scans....and read the other referenced discussions, for more info/detail...
Fact is, if you're using a radio with poor transmit spectral purity, poor IMD products, high transmit phase-noise, etc. you are causing interference to your fellow hams!!!
And, once more and more hams end up using these radios.....the bands will become even more full of interfering signals/noise/crap....
 

Please have a look at these recent discussions, and have a look at the wealth of factual info there, not the least of which are the spectral scans of the radios....

"Ham Xcvrs' and Amps', Transmit Spectral Purity, IMD Products, vs. comm/maritime"
http://www.eham.net/ehamforum/smf/index.php/topic,97093.0.html

"Tube vs. SS / Amplifier IMD Tests / Tirode vs. Tetrode vs. Solid-State"
http://www.eham.net/ehamforum/smf/index.php/topic,100600.0.html


I hope this clarifies some things....

73,
John,  KA4WJA
« Last Edit: January 04, 2015, 05:54:47 PM by KA4WJA » Logged
K6AER
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Posts: 5740




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« Reply #17 on: January 04, 2015, 10:04:11 PM »

The real IMD question I how much would you pay to have a transceiver with an IMD number 10 dB better than todays radios?

Typically in order to improve IMD you will need  much higher power supply voltage and devices with higher power ratings. Using switch mode devices to increase the rail voltage on an output power transistor final circuit will probably add 30% to the cost of the radio and reduce the current efficiency.

Now the question of the week.  Most hams are about as cheep as they come. IC-7000 goes for about $1000. Do you think ICOM would have a market if the retail cost of a IC-7000 would be $1700. I doubt it.
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W8JX
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Posts: 13268




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« Reply #18 on: January 05, 2015, 03:40:31 AM »

Given that greater than 30db down means less than .1watts from a 100 watt transmitter or 40db down is 10 mil watts, once again ham radio has far bigger problems. One being excessive power or my favorite over driven amps that splatter and CB mentality "power mics" on modern rigs that causes signal splatter too. We need better funding for more active FCC enforcement far more than a few db less of 3rd, 5th or 9th order harmonics........
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W9FIB
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Posts: 2529




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« Reply #19 on: January 05, 2015, 03:55:51 AM »

Like a bunch of QRP signals along with the main 100W signal. All being radiated from the antenna. That is why it is a problem.
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73, Stan
Wisdom is knowledge you gain after you know it all.
OK4FX
Member

Posts: 57




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« Reply #20 on: January 05, 2015, 04:33:11 AM »

My english, my experiences and knowledge don't have a sufficient level to contribute with something useful here. The more I appreciate the efforts of others.

For those who are trying to trivialize this problem, I can just say this: if you come to report the theft to the police then you should not be surprised when you will get an answer like "let it be, because first we need to solve the bigger problem, murders".
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W9CN
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Posts: 137




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« Reply #21 on: January 05, 2015, 04:59:43 AM »

My english, my experiences and knowledge don't have a sufficient level to contribute with something useful here. The more I appreciate the efforts of others.

For those who are trying to trivialize this problem, I can just say this: if you come to report the theft to the police then you should not be surprised when you will get an answer like "let it be, because first we need to solve the bigger problem, murders".

Which is pretty much how it works with the Police in most major Cities in the USA...  Especially Chicago, New York and LA.

Mike W9CN
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OK4FX
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« Reply #22 on: January 05, 2015, 05:22:12 AM »

Thank you. Now I know who is our idol.  Smiley
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W8JX
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Posts: 13268




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« Reply #23 on: January 05, 2015, 06:49:49 AM »

Like a bunch of QRP signals along with the main 100W signal. All being radiated from the antenna. That is why it is a problem.

No it is not a problem in real world but since you lack real world experience you do not know any better. This is not a slam but rather a comment based on 46 years of experience. Splatter from over driving audio or amp is a much bigger problem and even a clean rig/amp will splatter when over driven. There was a time when FCC monitored and enforced rules but congress cut long ago to fund tax breaks.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W9FIB
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Posts: 2529




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« Reply #24 on: January 05, 2015, 07:02:33 AM »

This is not a slam but rather a comment based on 46 years of experience.

If it is not a slam, why do you say that my 28 years as a ham that I have no real world experience?

Lets face it JX, your just a clown. Attack away! You prove what you are every time!
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73, Stan
Wisdom is knowledge you gain after you know it all.
N3QE
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Posts: 5593




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« Reply #25 on: January 05, 2015, 07:02:55 AM »

I was recently put into a state of awe, when I realized that the AL-1500 biases the tube for 800W quiescent plate dissipation when put in "SSB" mode.
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W8GP
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Posts: 353




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« Reply #26 on: January 05, 2015, 11:49:16 AM »

It's obvious that many people would not recognize IMD if it bit them in the ass,and even less seem to care. It's not uncommon to hear wide signals on a nightly basis, even if you don't know what you're looking for. Sure, much of it is from overdriven amps, but at best an amp will not add to the distortion and it can make it much worse. Realize that the LEVEL of the distortion products is what really matters, a transmitter with distortion products 30 db down driving a perfect KW amplifier will have the same level of transmitted garbage as a 100W transmitter with products only 20 db down, which you will have to admit would be a dismal number. So while this may not be the biggest problem facing ham radio, I think it needs to be addressed and I applaud those that think likewise.
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W8JX
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Posts: 13268




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« Reply #27 on: January 05, 2015, 02:15:10 PM »

This is not a slam but rather a comment based on 46 years of experience.

If it is not a slam, why do you say that my 28 years as a ham that I have no real world experience?

Lets face it JX, your just a clown. Attack away! You prove what you are every time!

The clown troll her is you. Maybe you can find a web link to CYA because it was not on no code extra tests.


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Ham since 1969....  Old School 20wpm REAL Extra Class..
W9FIB
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Posts: 2529




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« Reply #28 on: January 05, 2015, 04:34:47 PM »

The clown troll her is you. Maybe you can find a web link to CYA because it was not on no code extra tests.


LOL What a clown! And I am not a female either. Nice editing skills. And you didn't answer the question...again. I guess trashing me is now your hobby. Better not renew your license, you don't have time to operate. LOL

LOL Typical JX. Keep it coming!
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73, Stan
Wisdom is knowledge you gain after you know it all.
KA4WJA
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Posts: 1098




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« Reply #29 on: January 05, 2015, 05:22:27 PM »

1)  To Peter, DL8OV....
Please accept my apologies on behalf of all my fellow US hams, for the unfortunate juvenile behavior of some...
(and my apologies for posting more info, that may have inadvertently attracted them here...)




2)  To Mike, K6AER...
You've written about the "cost" of this before, and I've written at great length about this being incorrect, as there ARE currently 12vdc radios (w/ 12vdc PA's) that DO meet the stringent Part 80 spec, and have very clean transmitters, and they do NOT cost significantly more than comparable-featured ham rigs...and some may even say they are less expensive!!!

The real IMD question I how much would you pay to have a transceiver with an IMD number 10 dB better than todays radios?

Typically in order to improve IMD you will need  much higher power supply voltage and devices with higher power ratings. Using switch mode devices to increase the rail voltage on an output power transistor final circuit will probably add 30% to the cost of the radio and reduce the current efficiency.

Now the question of the week.  Most hams are about as cheep as they come. IC-7000 goes for about $1000. Do you think ICOM would have a market if the retail cost of a IC-7000 would be $1700. I doubt it.
There is no need to use switch-mode DC-DC converters, nor even a need to use higher-voltage devices at all....
(yes, "higher-voltage-devices" can have better IMD specs, but not necessarily....and as I've pointed out before, they are certainly not needed...)
Please read this thread here again, and you will see again that there are 12vdc rigs that are clean!!

"Ham Xcvrs' and Amps', Transmit Spectral Purity, IMD Products, vs. comm/maritime"

http://www.eham.net/ehamforum/smf/index.php/topic,97093.0.html


Now, I freely admit that "retro-fitting" or "upgrading" existing rigs (especially the small/miniature rigs such as the IC-7000, etc.) would be cost prohibitive for most hams....
But, making/selling an "IC-7600 mkII",or an "IC-718 mk II" etc. with a different PA (such as used in the Icom M-700Pro or M-802) would add no more than $100 - $200 to the cost of the radio....
And, while I do grasp that adding $100 - $200 to the cost of an "entry-level" rig like the IC-718, would effect its price competitiveness....but, how about selling it as the "cleanest, entry-level rig on the market"....

Hey, I could go on and on....and we'll probably never agree on whether or not a manufacturer can actually market "clean transmitters" as a feature....and no worries here Mike...
BUT...
But, please accept that making a clean 12vdc, 100-watt to 150-watt output, HF PA, is not only do-able (it IS being done right now, today), but does NOT cost a lot of money....and would add no more than $100 - $200 max to the cost of our rigs....(see thread referenced above...)

And finally, while I do NOT in any way accept the premise of your comments/question....I do feel it is only polite to answer your question....
Yes, I would pay more for a clean transmitter (and I have done so)...
Would I pay 10% more?  Yes...
Would I pay 20% more?  Yes....
Would I pay 30% more?  Yes....but I might be looking for "a sale"... Smiley






3)  To everyone....
I wonder how many even try to uphold the 5 basic purposes of the Amateur Radio Service??  (whether on-the-air, or here online with other hams???)

And while many might be under the impression that "ham radio" is a hobby....under US and international law it is a SERVICE....we that are licensed under this service, are give unbelievable freedoms that Billions of people around the world only dream of!!!
And then many end up abusing those freedoms, and ignoring these very basic rules/purposes (if they even knew about them to start with???)

Quote
Title 47 – Part 97

Subpart A—General Provisions

§ 97.1 Basis and purpose.

The rules and regulations in this part are designed to provide an amateur radio service having a fundamental purpose as expressed in
the following principles:

(a) Recognition and enhancement of the value of the amateur service to the public as a voluntary noncommercial communication
service, particularly with respect to providing emergency communications.

(b) Continuation and extension of the amateur's proven ability to contribute to the advancement of the radio art.

(c) Encouragement and improvement of the amateur service through rules which provide for advancing skills in both the communication
and technical phases of the art.


(d) Expansion of the existing reservoir within the amateur radio service of trained operators, technicians, and electronics experts.

(e) Continuation and extension of the amateur's unique ability to enhance international goodwill.






4)  To JX and FIB....you guys have already ruined two other recent threads here about amp choices / rigs / IMD....and I, for one, am completely turned off by all of this, and I'm done here!!!
Please read #3 above.....and then please apologize to Peter, DL8OV....





Happy New Year!
(and, I'm outa' here!!)


73,
John,  KA4WJA
« Last Edit: January 05, 2015, 05:26:11 PM by KA4WJA » Logged
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