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 1 
 on: Today at 04:02:04 AM 
Started by N1CX - Last post by N1UR
Its a complete misunderstanding of how much fuel it takes to get to a place like Bouvet.

The trip is about 4000nm round trip.  There are some 100 - 120 ft ocean going trawlers that can do that with reserve.  How much "hang time" is also important.  About 10,000 gallons of diesel is required.  That's a $30 - $50k budget - not $300k.

The problem becomes when the boat has to be big enough to have helicopters.  Then the boat is 150 - 300 ft.  And the fuel goes up big time to get the beast there.

But the "minimum cost" is WAY out of proportion to the "mega DXpedition" numbers.  We have lost sight of this in recent years.

Sounds like the 3Y0I team may be adding sail to the mix.  That will drop the minimum even more.

Ed  N1UR
(been around the ocean and on boats for a long time)

 2 
 on: Today at 03:02:02 AM 
Started by HAMHOCK75 - Last post by VK6HP
De Maw does refer to referencing to "full power" but Fig.1 in his article appears at odds with that.  It uses (accidentally?) the more widely used convention, referencing to the output tones.  Exactly what that means for the numbers quoted in the text, I'm not sure.  I'm guessing that in fact he was using the more modern convention, rather than the ARRL one, simply because I can't believe anyone would regard -24dB IM3 (-30 dB ref PEP) as satisfactory, even at the time the article was written.

I've seen the QST linear schematic with the 4x6KD6s and the un-tuned input in a few places. If I drove that amplifier with my FTDX-560 (even at 100W), it would lower the bar for on-air IMD rather spectacularly; it might even convince some of the troglodytes in the Amplifier IMD forum that technical progress in transmitters is both allowed and desirable, especially if I set up shack near them.

Thanks for posting the interesting material.

73, Peter.

 3 
 on: Today at 02:56:23 AM 
Started by LADEWILDE - Last post by W1QJ
A keying unit used to provide a low current switch between the rig and amplifier shouldn't be confused with a match unit used between the rig and amplifier in the RF path.
Maybe it's me......??
Bill, AA2UK

No, you are correct.

 4 
 on: Today at 02:27:05 AM 
Started by HAMHOCK75 - Last post by HAMHOCK75
I found the article where the ARRL measured IM3 for the FT101E vs TS820 with 6146's. The measurements do appear to be PEP as the author, Doug DeMaw, refers to dB below full power. The 6146's were better than I recalled. They are at -39 dB ( PEP ).

http://www.thermionic.org/sweep2.html

 5 
 on: Today at 01:39:14 AM 
Started by LADEWILDE - Last post by AA2UK
A keying unit used to provide a low current switch between the rig and amplifier shouldn't be confused with a match unit used between the rig and amplifier in the RF path.
Maybe it's me......??
Bill, AA2UK

 6 
 on: Today at 01:25:02 AM 
Started by AA2UK - Last post by AA2UK
I have an ICOM IC-7410 all functions work but I seem to have an intermittent issue with the main tuning dial. The tuning isn't smooth and even with the tuning speed set to low it appears to skip numbers. I believe it's sensor #4 which is an optical sensor part EX-2500. My question can this component be blown out with canned air? Is there another way to try and clean this circuit? I mainly use CAT control of the rig so this tuning anomaly  hasn't bothered me. It's been doing this or the last 2 years it hasn't gotten any worse than when I noticed it. I'm getting ready to sell the rig so I need to resolve this before doing so. Has anyone else had this problem? Any suggestions?
Bill, AA2UK

 7 
 on: Yesterday at 11:55:05 PM 
Started by N6YFM - Last post by W6RZ
Seems like ADC overload. Assuming N6BV is line of sight, a quick calculation would be:

1500 watts = 62 dBm
10 dBi of TX antenna gain
87 dB of path loss at 14 MHz
10 dBi of RX antenna gain

62 + 10 - 87 + 10 = -5 dBm

 8 
 on: Yesterday at 11:34:09 PM 
Started by N6YFM - Last post by W6UV
I too have the 6400 and running it thru the ringer today on the WW CW contest. Latency is NOT an issue on CW. I have mine on filter level 1 and the skirts are tight with no latency issues noticed with my current operational setup. I am running 28 wpm and mowing them down. The preamps and AGC are fun to play with to get the best S/N ratio.

I too used a Flex in the ARRL DX contest this past weekend (my 6500). Under the crowded contest conditions on 20m it generally worked well, except when some strong locals showed up.

I heard a very strong station that appeared to have a signal that spanned 40 kHz. I could actually hear this station 20 kHz away from his transmit frequency well enough to copy his code. I tried the attenuator and backing down on the gain, but nothing I did completely stopped his signal leaking past the 6500's filters in a big way. It wasn't because he had a dirty signal (it was N6BV, and it's very unlikely his signal is that wide), but because he's only about 25 miles from me. Just to be sure, I looked at his signal on the waterfall of a web SDR receiver located on the opposite side of the country and his signal looked clean.

I'm not sure why I was seeing so much obvious filter blow-by, but suspect it's because I changed the CW filters more towards the low-latency end to reduce the ringing I'm hearing when they're set too far towards the sharp end. Even doing that shouldn't have let me copy a CW signal 20 kHz from where it was being sent. I wish I'd taken a screen shot, but didn't think of it until the contest was over.

This does not happen on my FTdx-5000.


 9 
 on: Yesterday at 10:48:48 PM 
Started by KA4WJA - Last post by KA4WJA
Brian, et al,
Welcome to the discussion! Smiley

As I wrote the other day:
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!
So, I'm glad you've joined in...but why all the talk about filters, and analog vs. digital??

You know, everyone has different experiences in life, and in the amateur radio service (btw, many of us still think of the Amateur Radio Service as a "service" not a "hobby"...but that's a whole 'nother discussion which I won't drift into here. Smiley ), and as such we all have different opinions and points of view...and, nobody's is more or less valid that another's...
So, I'm sincere when I say welcome!
(and, I took no offense to the inference that anyone that wishes to discuss and learn about transmit IMD and spectral purity is somehow in need "medicine"...actually, it made me laugh!!  especially since you included yourself, by contributing here. Smiley )

BTW, if you knew me, I'm darn sure in 30 seconds you'd learn how non-obsessed I am about   IMD...Smiley   (ya' know it's pretty hard to get to know someone by their technical writings...)

And, if you read all of this discussion, you'll see that "too high mic gain" has already been accepted as a major contributor to splatter, and of course the "all knobs to the right"-types causing problems, but what about the remaining 95% of hams on HF SSB, PSK, etc., that adjust / operate their radios correctly, and some (many??) of them are unaware that they are also causing splatter / interference, just by virtue of them using an HF rig with poor transmit IMD specs (and/or the CW ops, with wide signals due to too short rise-time keying, but also poor transmit spectral purity)....what should we do for them?? Ignoring the problem hasn't helped, has it??

Everyone should remember that the issue I started this thread to discuss here, is IMD...and of course this is not controlled by filters, so this discussion is not about filter skirts or roll-offs, 'cuz IMD is not governed by this at all...I know many think it is, but it is not...(now, the "low-end enhanced" ESSB is another issue, but a part of amateur radio that is thankfully fading from our airwaves...and not the focus of this discussion)

Also, please remember that there is no FCC (nor ITU) rule / spec of IMD in the Amateur Radio Service...

Further, I wonder why is it so hard to read the test results of radios and see for yourself that making a clean solid-state HF transmitter (at 100 to 150 watts output) is not expensive...by many accounts it would cost about $25 to $50 more in parts, an extra hour of engineering time to copy already existing circuits that the same manufacturer uses in their other radios, and perhaps an extra 10 to 20 watts of DC power (on transmit)...how in the world is that considered "too expensive" to hams that will drop a quick $1000 (or more) on a rig??  Okay, maybe on a "entry-level" rig that would drive the retail price up from $600 to $700, yep that's a tough nut to advertise...but "too expensive"??  And, who was asking for perfection?? (not me!)

{yes, I know this isn't "global warming" or "election tampering", or even despicable leaders using chemical weapons, nor rogue states threatening nuclear attack, etc...but, I use lots of solar energy on my boat, don't use energy frivolously, I pay attention to political issues, elections, etc. do my homework and vote carefully, and I am horrified by SARIN gas being used openly (and glad my late father didn't live to see this, as he risked his life fighting so nobody would ever suffer this horror again), but poor transmit IMD, etc. is an issue that effects all users of our HF bands, and unfortunately many (most) are actually unaware of what their transmitters are doing...and I don't think that it is beyond the limits of "good engineering" and "good amateur practice" to try to learn more about this and to teach others as well, and truth be told, in MY OPINION, it IS "good engineering" and "good amateur practice" to learn these things and pass on this knowledge to our fellow hams, and not simply repeat false platitudes that sound good 'cuz that's what most are saying!!}

Maybe from the outside it looks weird, but it looked weird to many hams 20 - 25 years ago, when some hams were very frustrated with noisy receiver oscillators, and poor (to non-existent) 1st IF filtering in "modern" rigs, and many of these guys were thought of as "obsessed with receiver IMD", but if it were not for them, we'd all be using receivers like the KWM-380 (anyone ever listen on one, on a busy contest weekend? 'cuz I have, and it was crap!! And, even on a easy weekday, it was crap! BTW, I was considering buying one, way back when, 'til I used it...what a piece of s**t!) or an FT-757 (had a friend that had one connected to a tri-band yagi at 50' and what a crappy rec!), etc...
Maybe if we hams actually take the time to learn and teach each other about transmit IMD and spectral purity, we will see how much better our on-air lives could be, and then we can all vote with our wallets and only buy rigs with good transmitters!!..

BTW, that is what I'm doing....if Apache / ANAN made a rig with knobs (no not a RasberryPi) I'd buy one this spring....
BTW, here is a scan of a printed out (and hand-drawn highlighting of the pre-distortion ON, of the ANAN-8000D)...the test was from  Adam Farson, VA7OJ/AB4OJ..

Sorry about the poor quality image!
The ANAN-8000D's  3rd . 5th / 7th / 9th order IMD
33 / 40 / 54 / 60  (with NO pre-distortion) at 200 watts

67 / 70 / 70 / 70  (with pre-distortion) at 200 watts


And no, Flex is not debuting any pre-distortion rigs this year (and possibly never?)...I'm afraid the IC-7851 is out of my price budget, but the TS-990 is...but even it (or the TS-590SG) isn't clean enough for me....so, I'm stuck with my Icom M-802's (and my old TR-7's)...

What about you?

A quick dozen choices for all of you....Who do you want to operate on SSB, 3 - 6khz away from (or even 10khz to 20khz from) guys with  K3, FT-857D, FT-991, IC-7600, IC-706, TS-590S, etc.,(and what if they're driving an ALS-600??  or a 1.3kFA??)  or a guys with TS-590SG, M-802, 32S-3, TS-830S, IC-765, IC-7851, etc.??  (and maybe these guys are driving a pair of 3cx800's or an 8877??)  Who do you want to operate near??  And, what rig are you using??  





Yep, none of us want to operate next to the guy with the mic gain cranked up...but again what about the other 90% to 95%?? (and, just this past week on-the-air, I helped a guy turn down his mic gain, improve his signal immensely, and he thanked me for it....and I told him about eham.net, and he said he'd check it out...)

{yes, assisting our fellow hams to properly adjust their mic gains and keep from over-driving their amps, are great things....but what about the other 90% to 95% of hams, do we just let them buy crappy rigs and just accept the worsening of our on-air situation?}

And, are you all willing to learn, teach, and vote with your wallet??  

Look at the specs of these "modern" radios....their receivers are great, their transmitters are crap!!...the reason their receivers significantly improved, was due to market pressure and competition...

Has it not dawned on some hams that the same guys asking for better receivers over the past few decades have been saying for the past 10 years that the transmitters are crap!! ??  And, these same guys have been saying now, for the past decade, that the limit of our better HF transceivers' receivers, are the transmitters of others on-the-air!! ??   Is this not clear?? (read what is being written and said, and I think you'll see)
Please read this:
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647


Sorry about the rambling....but I've been asked to write more detail about the real-world and what others are doing/saying, rather than "just the facts"....'cuz many are overloaded with info, and just want some easy way to see where the wind is blowing!!

In addition to many on-air discussions about IMD over the years, I've gotten e-mails regarding these discussions here, thanking me for bringing this subject up!
Now, to be clear, I don't CQ looking for someone to rant to about IMD!!  Smiley  
Not tooting my own horn here, just stating a fact...and showing the difference experiences that I've had...

For explanation...Aside from the obvious that everyone from NC0B and SM5BSZ, to myself, to many HF contesters, etc., have all been saying for the past decade the actual limiting factors in our ham transceivers' receive performance are the other transmitters on-the-air!!  (read just some of the quotes I included this past week)
https://www.eham.net/ehamforum/smf/index.php/topic,97093.msg1053647.html#msg1053647

I myself have been a proponent of clean transmitters and low-IMD for decades now (I was shown and taught about 2-tones IMD tests as a teenager in the 1970's)....but, I'm hesitant to delve too deeply into the "why" I started this discussion here 4 years ago...even though this subject has been important to me for a long time, this particular impetus will drift the discussion a bit, but as long as we don't ramble on about this too much, it's probably okay??
Perhaps I haven't recently made it clear here, but I have actually personally been interfered with on HF (both ham and maritime freqs), by splattering SSB signals many times...

And no, it is not front-end overload!!  (really??) The old TR-7 can take a seriously strong signal before blocking, as can my Icom M-802's....but what I think you might be referring to is RMDR, or maybe 3rd order IM DR?? I know what Reciprocal Mixing is and how it manifests, and I understand the phase-noise limitations of my old TR-7's, but my M-802's do not suffer from these issues...and with some serious 3rd IMDR specs, it takes a band-full of strong signals to cause any  issues....and I do know the difference between what is actually splatter and what are issues caused by receiver's reaction to other signals on-the-air....the main issue that I read on-line and hear on-air, is that most hams do not know these differences, let alone what transmit IMD is!!

In my opinion, If we can all try to learn more, and educate others too, we will all find our on-air lives much happier!

On the ham bands, the splatter I usually hear is from operators that are not well-informed of what transmitter IMD is....and on the maritime freqs, this has been exclusively from others using HF ham rigs on the maritime freqs (and I'm not the only one that experiences this on maritime SSB Voice comms!!)  (in addition to maritime SSB Voice comms, many folks trying to use Sailmail stations, and/or Winlink stations when in various anchorages, find their reception disrupted by other HF users splattering using ham HF rigs)

Here is just one personal example:

Late afternoon, about 5 years ago (a few instances of this, actually spurred my research and was the impetus for me starting this discussion here), I was on 12.359mhz, with two 1Kw SSB stations on 12.362mhz and 12.365mhz (both approx S-5 to S-7), and never heard any artifacts / IMD from them when I was on 12.359mhz, they were only transmitting for about 7 minutes, on a regular schedule top and bottom of the hour, and I use 'em to check propagation....later, after they left the air, a station on 12.353mhz came on, and there was so much splatter on 12.359mhz, that I could no longer copy the weaker stations (mostly vessels sailing across the Atlantic) I was passing traffic for / assisting with weather info, etc., and the offshore weather net closed early that day (and the next day as well, due to the interference from these same folks)...this was a 100-watt station (from another boat, his signal on 12.353mhz was about S-5...found out later he was approx 1000miles from me, running an Yaesu FT-857), he was calling another boat and the other guy was weaker (he was running an IC-706, and was about 700 miles from me).   Understand that maritime channels are 3khz apart, and we were separated by two channels, 6khz....and the splatter from that 100-watt FT-857 was so bad that those running type-certified marine rigs (some of them "down-conversion" rec with excellent 1st IF filters) 6khz away couldn't continue....but, the commercial 1Kw maritime transmissions 3khz and 6khz above us, were not interfering at all!!

Another instance on this same weather net but during a morning sked, found a station on 12.350mhz (a non-standard freq) splattering badly...his signal on 12.350mhz was strong (S-7) but sounded processed and a bit too high mic gain...but his splatter made the morning check-ins 9khz away, difficult...found out later (he told me openly) that he was running an Ameritron ALS-600 amp (he said he was getting 700+ watts out, but I have my doubts as I thought it would soon melt at that power level??), and when I commented that he was flat-topping and severely over-driven, he just said "oh" and changed the subject...

I could go on and on, and highlight experiences on 75m and 40m...and some on 20m (but don't operate there much these days), but I think you see that we have different experiences and the fact that I do openly discuss IMD on-the-air separates us widely, I guess...

{btw, I was asked by some friends to attend the 4th annual TechCon, but don't think I can make it (family issues take priority)...but there is another place that many fellow hams are interested in transmit IMD.}

 
Yep, some splatter on our ham bands is of course mic gain and over-driving amps....and yep, all of this has been well discussed....but again, what about the other 90% to 95% of the hams that are not aware that they may be splattering simply by running their rig as prescribed in the manual??  'Cuz it's these guys that make up a large portion of the splatter that I experience...I would like to say they're the over-whelming majority (which has been my personal experience), but if I write that, all we'll do is argue...so, let's just say that a lot of HF ham SSB transmitters are causing unnecessary splatter / buck-shot / interference to others everyday on-the-air...some might not have this same experience, and I accept that, but please accept that some of us do have these experiences and we do wish to improve things... Smiley


BTW, discussing baseband bandwidth and filter bandwidths/shapes is a big red herring here, as none of those have any effect on IMD levels....of course the wider the baseband bandwidth, the wider the IMD products are spread (but their levels are not effected), and of course when expanding the baseband lower, this also causes opposite sideband leakage, etc. as well as extra stress / loading of power supplies, which can certainly contribute to IMD levels, but again, not really the focus of this discussion...(and thankfully, these ESSB guys are slowly disappearing from the air)...

But, just for clarification:  From the 1930's to the 1950's, telco "SSB" channels were 4kc's wide....the baseband was 300cyl's to 3400cyl's, with "guard bands" taking up the remainder of the channel...then after the 50's (as I explained in detail above) the baseband was narrowed to 300hz to 3000hz, and with good engineering and clean signals, the standard "SSB" channel was narrowed to 3khz...and this has been the commercial / maritime / aviation "standard" for many decades....the more modern (21st Century) "SSB" channel bandwidth is 2.8khz, with baseband from 300hz to 3100hz, and this is the most recent ITU standard...now, of course not all the emissions are contained inside that 2.8khz....but have you seen the emissions mask??  Here's the older one...(will look for the newer one)....



Those hams that haven't been in commercial / maritime / aviation SSB comms, are usually unaware of these requirements and repeat the "myths" that you can't squeeze in every 3khz....now, the ironic part is that this myth is becoming a self-fulfilling prophesy, as the worse our transmitters get, the wider we'll need to space ourselves out...but with more hams on HF, why not find ways to cause less interference, rather than more??

But, the red herring here is that IMD is NOT controlled by filters, IMD levels are not controlled by the baseband bandwidth....this discussion is not about filter skirts or roll-offs, 'cuz IMD is not governed by this...


Yes, of course, help others (as I do) to turn down their mic gains, and assist them in not over-driving their amps....but why not educate them on what rigs have poor transmit IMD and what rigs are better??

Yes, of course, higher voltage SS PA's have devices that can operate longer in the linear range, and hence less time in crossover/transition, and therefore can theoretically be easier to keep linear (produce a cleaner signal) than lower-voltage SS PA's....but, as can be seen by the actual, real-world, scientific tested results, there are 12vdc PA's that provide better IMD results than their higher-voltage cousins...


I mean, it ain't rocket science here...as I wrote to one of best friends this weekend:
Quote
"...in the maritime service, for the past 40-50 years, the cheap and dirty way is to choose devices (bipolar for 12 volt PA's or FET's for higher voltage PA's) for a 300watt PA, BUT...
But design and build a 150 watt PA using those transistors....meaning especially design the output matching section for 150 watts, NOT for the device's 250-300 watt typical design use, and tune/bias the PA properly in Class AB or Class B (run the pre-driver in Class A), making sure whatever load changes that occur at lower than nominal voltages (battery voltages are not "13.8vdc" on a boat) are compensated for....and you've got a clean 150 watt transmitter that will still be clean with 11.5vdc at the back of the rig...(ever heard an IC-706 on a battery??)
Like I said, not rocket science!  Not very expensive, either! (probably would add $50 to the cost of an HF rig!)

Although Kenwood, Yaesu/Vertex, and SGC left the maritime market in late 90's / early 2000's, Icom, JRC, Furuno, Cohban/Thrane&Thrane/Skanti, and SEA are still alive and well making marine HF rigs (but in 2017 Furuno has discontinued their 12vdc rig, designed for the small-boat market...and their newer rigs are all 24vdc, which is the nominal battery voltage on ships..)

With modern 12vdc Icom marine radios, like the M-802 at 150watts out having IMD products of - 47 / -50 / -58 / -60  (and even a little better at 100watts)
And, heck less than 20 years ago, the JRC JST-245 ham rig at 150watts out had IMD products of -39 / -56 / -58 / -60...
And, just 20 - 25 years ago, the Icom IC-765 ham rig had IMD products of -40 / -45 / -48 / -50...

Why do hams now accept 10db to 20db worse IMD for our current radios? (most of them costing many times the cost of the marine radios)"


Okay, enough of my rambling for tonight...

Do hope I helped clarify things??

73,

John,  KA4WJA


 10 
 on: Yesterday at 10:27:47 PM 
Started by AB1ZI - Last post by HAMHOCK75
Those who have designed with dual gate FET's will recognize this immediately. The configuration is called a cascode amplifier which is what dual gate FET's are. One characteristic of the cascode amplifier is high isolation between input/output. Presumably that high isolation prevents the harmonics of the class AB amplifier from getting back to the input.

It is those harmonics that create the problem with solid state exciters. Solid state exciters have wideband SWR bridges but those bridges cannot distinguish between reflected power and harmonic power created by the amplifier which both go back towards the exciter so harmonics can trigger the solid state exciter to shut down just like reflected power. The purpose of input tuned circuits usually in the form of pi networks is similar. Pi networks are low pass filters and passively block harmonics from going back to the exciter.

Below is an image of a solid state exciter driving a grounded grid amplifier with no input tuned circuits. The yellow trace is the solid state exciter output, the blue trace is at the cathodes of the amplifier. Those ripples are the harmonics. As you can see some of the harmonics are starting to appear at the exciter. If they grow in amplitude, those harmonics will trigger the exciter to shut down.



It is a neat idea. AC2RY thanks for sharing.

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