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Author Topic: The Longest Journey Starts With A Single Step  (Read 52861 times)
DL8OV
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Posts: 1057




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« on: December 28, 2014, 03:08:35 AM »

The following message has just been sent to Icom and Yaesu, any replies received will be posted here.

Peter DL8OV



Dear Sirs

There is at the moment on Eham.net a series of animated technical discussions on the transmit IMD specifications of current amateur radio transceivers. A rough summary of the discussions is as follows:

1) The IMD figures for older tube rigs are good, about 40 dBc for 3rd order products

2) The transmit IMD for current solid-state rigs are poor, varying between -30 dBc and -36 dBc depending on band.

3) The transmit IMD figures for Marine transceivers are much better (yet they are still 12V powered).

So, my suggestion is this. #MANUFACTURER# should use their expertise in Marine transceivers and carry it across to the amateur radio market. Use the power amplifier units from your Marine transceivers in Ham Radio units, alter the settings so that the transmitters are clean and then advertise the fact that #MANUFACTURER# transceivers are now the cleanest on the market. Yes, I know that this will cost money but as the technology is already designed and in use the expense will be minimal. You will however gain respect from radio amateurs world wide for being the first manufacturer to take the big step required to clean up our bands.

73 & All the best for 2015.

DL8OV

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PA1ZP
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« Reply #1 on: December 28, 2014, 05:14:40 AM »

Hi Peter

This was a small step for man, but could be a great leap for HAMkind.

I hope that it will be noticed, and that TX will get cleaner and better.

Best wishes and a lovely healthy 2015
 
73 Jos
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W1QJ
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« Reply #2 on: December 28, 2014, 06:13:20 AM »

ROTSA RUK
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W8JX
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« Reply #3 on: December 28, 2014, 06:16:52 AM »

I think it is a wasted effort. For some reason some are now focused on IMD whose real world effect is somewhat over stated.  What will be next months bitch? 
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Ham since 1969....  Old School 20wpm REAL Extra Class..
K8AXW
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« Reply #4 on: December 28, 2014, 07:12:06 AM »

Peter:  I admire your effort to correct something wrong in the ham manufacturer kingdom.

However, after 79 years of building or using everything from homebrew to Heathkits to Kenwoods, I am very pessimistic about even getting a response.

However, if you do get a response it will be the usual politico BS that we hear from every politician in the world.

I wish you would have asked them why in the world they continue to introduce high-tech features that requires a 150 page manual for the operation of their gear and totally ignore the improvement in their performance.  Sure they have the bells and whistles up the wazzoo but minimize the essential performance parameters.

Anyway, thank you for your efforts and by all means publish their responses.  If you receive any, they should prove interesting reading and fuel for more debate here on eHam.



 
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A Pessimist is Never Disappointed!
VE1IDX
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Posts: 43




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« Reply #5 on: December 28, 2014, 07:28:46 AM »

Peter I also commend you on your efforts however from listening to the bands, IMD is at the bottom of the list of what needs to be done to clean up the bands. Pretty much at the top of that same list is better operator education of how to operate their gear in order to even meet the current manufacturers IMD specs and bandwidth limits.
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KA4WJA
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« Reply #6 on: December 28, 2014, 08:08:57 AM »

Peter,
Thank You!

Danke!

73,
John,  KA4WJA
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KA4WJA
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« Reply #7 on: December 28, 2014, 08:18:04 AM »

I do not personally know anyone here at eham, not face-to-face anyway...
So, I cannot speak for them...

But, I CAN and DO speak for myself, and I do believe that we are all entitled to our opinions (none being any more important than another)...

So, when I read statements like John, W8JX's here, I'm torn....because I assume that this is his honest opinion and I cannot argue what someone holds in their mind or gut....and at the same time, I think "hey, that doesn't describe me....I hope he's not talking about me!" Smiley
I think it is a wasted effort. For some reason some are now focused on IMD whose real world effect is somewhat over stated.  What will be next months bitch? 
You see my conundrum??

So, here goes....(forgive my bluntness, but here are the "facts" that apply to me...)

This subject is not a "new" thing for me...

I was a teenager, in the mid-1970's, studying electronics / morse, and searching for a ham to actually give me novice exam, and found engineering books and QST more enjoyable than Mad Magazine...(I joined the ARRL in March 1974)
And, it was me, this same teen, who taught the supposed "technicians" at the local CB store about RF, how-to neutralize their PA's (both sweep tubes and others), and the hows/whys of Class AB vs. Class C...
(not that they actually cared....'cause they and their customers were more interested in how far the wattmeter needle would move...and while AFAIK, only one of these same guys made the transition to ham radio, he has made a living in ham radio for almost 30 years now, so maybe I did something good? Smiley )

No, I didn't have a spec analyzer back then (and neither did they!), but I did get a chance to actually use one and a few HUGE O'scopes, when a friend took me to BCC (Broward Community College) to audit a class or two, and then spent the afternoon/evening in their electronics lab...and I learned even more (especially more of the practical applications of what I'd been studying in the books)....
But the "coolest" was using their ham station (which at that time was some old Collins gear KWS-1, etc.) and actually seeing what happens to RF...

The reason I mention all of this is to drive the point that "linear" operation, as opposed to "non-linear", has been a hot topic for me for almost 40 years now....and yes, I have railed about this to friends over the years...(trying hard to not let a friend buy an ALS-600....and GIVING another friend my SB-221 years ago, to keep him from ruining his TS-830s' decent transmit purity, etc.), and occasionally discuss this on-the-air as well...
As well as putting my money where my mouth is, by using some older commercial rigs (ITT MacKay, SGC, Icom), and a "decent" HF ham rig (Drake TR-7, at 100 watts vs. it's factory-spec'd 150 watts), and when needed, a pair of 3-500z's or a pair of 8877's....

SO...

So, when I read a comment that this focus on clean signals is a passing fad, or that somehow a on-line discussion is just "the bitch of the month", I wince with incredulation....
And, I wanted to pass on the fact that this is NOT a passing fad to me, and since I've been involved in promoting "linear" operation / reducing IMD products, for almost 40 years now, it should be clear that this is not my "bitch-of-the-month"...

Just reading the first few paragraphs of my thread from 6 months ago, should clue you in that this is not a "new" subject, but rather that things have been getting worse in the ham radio transmit vein...
And, that some have been trying to inform / educate their friend and fellow hams....you know, trying to follow the traditions of ham radio...

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

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

Hello to all....

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...

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.

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

And, if you actually read what I wrote in this more recent thread, you'll see that I was providing information (actual, verified, test results...not advertising hype) and hoping that some may find it useful...not jumping to knee-jerk conclusions, but just trying to help...

"Tube vs. SS / Amplifier IMD Tests / Triode vs. Tetrode vs. Solid-State"

http://www.eham.net/ehamforum/smf/index.php/topic,100600.0.html


The internet (and eham) have both good and bad points...and if we could put away our cynicism for a few minutes, we may just realize that we all share a similar goal....that is our love of radio / radio communications!!

Why not just apply that old advice, "if 'ya can't say something nice, don't say anything", here???
If you choose to disagree that our ham transceivers' spectral purity / transmit IMD are crap, and that some of our amps produce much better IMD results than others....that's your choice...but why throw water on others who are just providing information / attempting to educate their friends and fellow hams??

Again as I wrote, if you choose to disagree with the opinion that our transmit purity and IMD products are crap, that's your choice, and if you wish to voice this opinion, no worries here...we'll just politely disagree...

But, will you PLEASE accept that this subject is NOT a new subject for some of us, and is NOT the "bitch-of-the-month" for many of us???
Is this too much to ask???




Fair winds...
Happy New Year!!

73,
John,  KA4WJA
 
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W8JX
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« Reply #8 on: December 28, 2014, 08:43:35 AM »

So, when I read statements like John, W8JX's here, I'm torn....because I assume that this is his honest opinion and I cannot argue what someone holds in their mind or gut....and at the same time, I think "hey, that doesn't describe me....I hope he's not talking about me!" Smiley
I think it is a wasted effort. For some reason some are now focused on IMD whose real world effect is somewhat over stated.  What will be next months bitch? 
You see my conundrum??

It is not aimed at you. Ham radio has a lot of problems or issue that need attention but IMD concerns is at very bottom of list. Some make a big stink about a minor problem measurable only in a lab are rarely discerned by ear while ignoring far bigger issues in hobby.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W1BR
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Posts: 4194




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« Reply #9 on: December 28, 2014, 09:09:37 AM »

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. Is it a lack of dynamic biasing, and just relying on a diode junction???  I know there were articles on improving the IMD performance of VHF/UHF brick amps, which are pure crap, even when compared to the worst of the RMI HF products.

Unfortunately, this hobby is no longer served by technically inclined publications, nor do hams have the inclination or knowledge to take advantage the information.
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KG9SF
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Posts: 282




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« Reply #10 on: December 29, 2014, 02:29:29 PM »

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................
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KH6AQ
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« Reply #11 on: December 29, 2014, 02:50:32 PM »

Awhile back I looked at the schematic of a marine SSB transceiver - I think it was the Icom - and the PA transistors were bigger (higher power rating) than many amateur transceivers. I could not quickly determine if extra local feedback was used.

The new Palstar transceiver (not yet released or priced) runs MOSFETs in the PA at 50 volts and claims 3rd order IMD of -48 dB PEP.
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ZS6DX
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« Reply #12 on: January 04, 2015, 05:25:21 AM »

Not all ham transceivers are created equal..... If you look at the Transmit 3rd-order IMD, as can be seen in the QST review of the very popular Elecraft K3 it is -29dB, quite dismal, on the other hand in the same test the Yaesu FTdx-5000 is -43dB (FT-2000 -41dB), a LOT better.

In the summery seen in the link below the FTdx-5000 is the best and the Flex-1500 the worst at -22dB.....

http://www.remeeus.eu/hamradio/pa1hr/productreview.htm

Most manufacturers could do better....

73, Rudi de ZS6DX/V51VE
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W1BR
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« Reply #13 on: January 04, 2015, 08:05:58 AM »

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................

In some crap amp designs the odd order IMD products don't fall off and seem to go one forever!  That is a major consideration. Having bad third and fifth order products is bad enough, but when the 9th order garbage is only a few down form the 5th order products you have a large area of spectrum being trashed.

It is silly for ham manufacturers to tote receiver IMD and strong signal handling receiver performance--when those advantages can never be used to full benefit due to interference from equally poor transmitters.

Pete
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DL8OV
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Posts: 1057




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« Reply #14 on: January 04, 2015, 09:04:37 AM »

Granted, it is possible that Yaesu and Icom could be closed for the Christmas and New year break but I have yet to receive a reply to my suggestion from either company.

I can also confirm the IMD figures for the K3 at about -29dB, adding a KPA500 to this rig does not improve matters.

Peter DL8OV
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