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Author Topic: Is Icom 7610 in trouble?  (Read 33653 times)
K6BRN
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Posts: 450




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« Reply #195 on: September 16, 2017, 12:08:02 AM »

Zenki:

I have to agree with Glen and Neal above... the numbers you are talking about are pretty much irrelevant. 

(My apologies, Glen - you obviously DO know what "too small to make a difference means" - my bad!)

Zenki - how long have you had this obsession with IMD?  Seems like a long time.  And IMD is such an obscure topic.  It might be more useful and productive to obsess about carcinogens in the water supply, lack of good sleep standards for airline pilots, government suppression of UFO sightings... you know... the more conventional ones where you can find a few good friends to sympathize with.

Just a suggestion.
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N0YXB
Member

Posts: 1120




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« Reply #196 on: September 16, 2017, 08:00:22 AM »


Zenki:

You are NOT allowed to buy an Icom radio, because it makes you furious that Icom does not "calibrate" their S-meter to
your requirements, and because, as any puritanical god fearing Christian will tell you, Icom makes "dirty" radios.
In fact, the word Icom makes your skin crawl in much the same way that the word Flex makes Stan's skin crawl.

So, once again, if you are not allowed to buy an Icom radio, WHAT are you still doing in this forum? :-)  :-)

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy
« Last Edit: September 16, 2017, 08:03:10 AM by N0YXB » Logged
GM1FLQ
Member

Posts: 794




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« Reply #197 on: September 16, 2017, 08:49:29 AM »



You are NOT allowed to buy an Icom radio, because it makes you furious that Icom does not "calibrate" their S-meter to
your requirements, and because, as any puritanical god fearing Christian will tell you, Icom makes "dirty" radios.
In fact, the word Icom makes your skin crawl in much the same way that the word Flex makes Stan's skin crawl.

So, once again, if you are not allowed to buy an Icom radio, WHAT are you still doing in this forum? :-)  :-)

As my Boss occasionally says to me;  ...   G O     A W A Y

Seems you don't want some opposing/differing views to be heard, what are YOU doing on an internet forum.  Wink

And don't worry Zenki, *I* will buy the Icom 7610 that you do not, so it won't be wasted.


Absolutely, very predictable pairing.  Grin
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GM1FLQ
Member

Posts: 794




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« Reply #198 on: September 16, 2017, 09:33:43 AM »

Zenki:

I have to agree with Glen and Neal above... the numbers you are talking about are pretty much irrelevant. 

(My apologies, Glen - you obviously DO know what "too small to make a difference means" - my bad!)

Zenki - how long have you had this obsession with IMD?  Seems like a long time........



...........could be as long as some have had the sheeple kaleidoscope/fishfinder obsession.   Smiley
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GM1FLQ
Member

Posts: 794




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« Reply #199 on: September 16, 2017, 09:40:55 AM »


Zenki:

You are NOT allowed to buy an Icom radio, because it makes you furious that Icom does not "calibrate" their S-meter to
your requirements, and because, as any puritanical god fearing Christian will tell you, Icom makes "dirty" radios.
In fact, the word Icom makes your skin crawl in much the same way that the word Flex makes Stan's skin crawl.

So, once again, if you are not allowed to buy an Icom radio, WHAT are you still doing in this forum? :-)  :-)

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy

He claims he's got me on ignore, yet there he goes again, I think he secretly likes me and my GIFs   Grin...........
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KF7DS
Member

Posts: 283




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« Reply #200 on: September 16, 2017, 10:28:01 PM »


Zenki:

You are NOT allowed to buy an Icom radio, because it makes you furious that Icom does not "calibrate" their S-meter to
your requirements, and because, as any puritanical god fearing Christian will tell you, Icom makes "dirty" radios.
In fact, the word Icom makes your skin crawl in much the same way that the word Flex makes Stan's skin crawl.

So, once again, if you are not allowed to buy an Icom radio, WHAT are you still doing in this forum? :-)  :-)

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy

He claims he's got me on ignore, yet there he goes again, I think he secretly likes me and my GIFs   Grin...........

Zenki may be a bit focused on the IMD issue, but you have to appreciate his point of view when you see the spectrum and effects of some Lid with a dirty TX pushing 600w a few clicks from where you are on a band. And, who cares if he doesn't use his call sign, he's Zenki and he knows his stuff.

Time for a gif
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W9IQ
Member

Posts: 1707




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« Reply #201 on: September 17, 2017, 12:57:20 AM »

If you have a 600 watt amplification chain that has a close order IMD of -30 dBc and is feeding into an antenna system with 8 dBi of gain, the spurs are less than 4 watts EIRP. So if you are hearing significant splatter, it is most likely due to operator adjustments and not due to the two tone IMD rating.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
VE3WGO
Member

Posts: 146




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« Reply #202 on: September 17, 2017, 06:27:24 AM »

the CW signal can generate splatter due to 2 possible factors: a non-linear transmitter and an uncontrolled keying pulse.  Most problem cases are due to a combination of these.

If the transmitter has an IMD problem, then the keying pulse, ie the rise and fall times, will be critical since they define the bandwidth of the signal, and the distorting transmitter will create a dirty transmitted spectrum.  If the transmitter is linear, the keying pulse still matters but less so.  In the real world it is the combination of these that causes the worst splatter problems.  In a highly non-linear Class C amplifier, the keying pulse rise/fall times need to be longer in order to keep the CW bandwidth as narrow as possible (and this of course limits the CW speed.  See below). 

Remember the oscilloscope formula?  Bandwidth (3 dB point) = 0.35/Risetime (10 to 90%) ....   it's relevant to what we are talking about and which for our use here can be expressed with units as BW(kHz) = 0.35/RT(msec).  It means that half of the signal power is contained in the bandwidth between DC and the -3 dB point.  It does not apply to all possible waveforms, but it is usefully accurate rule of thumb for sine waves like our CW signal.

So for a 10 msec RT, the BW to the -3 dB point is 35 Hz.  If the keying waveform edges were sped up to say 5 msec, the bandwidth would rise to 70 Hz and so on.  On the other hand, if the key contacts are noisy so that the rising and falling edges of the CW waveform are possibly ragged and having multiple very rapid intermittent makes and breaks per Dit or Dah (with sub-millisecond rise/fall times per intermittent make/break), then the CW signal bandwidth could grow to many hundreds (or even thousands!!!) of Hz. 

So with these "non zero" bandwidths, the IMD matters.

Solution:  keep the transmitter IMD low, AND keep the keying waveform under control with clean make/break and well-controlled rise/fall times, perhaps in the order of 20 milliseonds or so.  This will work up to 40 WPM (total dot duration is only about 60 msec there).  At higher CW speeds the rise/fall times might have to be set even shorter, but the transmitter better be clean in order to avoid clicks - ie no Class C amps for high speed CW!

73, Ed VE3WGO
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KE2TR
Member

Posts: 613




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« Reply #203 on: September 17, 2017, 08:24:49 AM »

Its funny back in the day you could always tell a FT1000D, FT1000MP, FT1000Mk5 and 1000MK5 Field on cw, you could hear them coming 3Khz away and it had nothing to do with what amp you were using. On SSB they were not as bad and with a little bit of processing and keep the ALC in line they sounded good and were not wide at all. The newer radio's from several manufactures do not have any key click issues but many you have to watch your ALC and back it off from its red line point, us a sparring amount (very light) of speech compression and things are not so bad but there no were near the sdr radio's as far as total bandwidth.
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W9IQ
Member

Posts: 1707




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« Reply #204 on: September 17, 2017, 02:16:20 PM »

Quote
Solution:  keep the transmitter IMD low, AND keep the keying waveform under control with clean make/break and well-controlled rise/fall times, perhaps in the order of 20 milliseonds or so. 

The first part is easy - a CW signal that is derived from keying the transmitter carrier on and off has zero IMD. Key shaping and transmitter design is the issue, not IMD. The FT1000 family is well known for its key clicks due to a poor transmitter design - not IMD.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
GM1FLQ
Member

Posts: 794




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« Reply #205 on: September 18, 2017, 12:35:12 AM »

Its funny back in the day you could always tell a FT1000D, FT1000MP, FT1000Mk5 and 1000MK5 Field on cw, you could hear them coming 3Khz away and it had nothing to do with what amp you were using............

..........and the typical Icom "Pro" whatever user, you could hear them coming with their obligatory big boom boom mics and audio racks.  Smiley..........
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W6UV
Member

Posts: 777




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« Reply #206 on: October 30, 2017, 10:10:18 AM »

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy

Why does Zenki insist on hiding behind a pseudonym and not use a call sign on these forums like everyone else does? Makes you wonder what he's got to hide...
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VK3BL
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Posts: 1308


WWW

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« Reply #207 on: November 04, 2017, 06:16:43 AM »

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy

Why does Zenki insist on hiding behind a pseudonym and not use a call sign on these forums like everyone else does? Makes you wonder what he's got to hide...

Probably -30dB or worse iMD Tongue
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J.D. Mitchell - VK3BL / XU7AGA - http://vk3bl.wordpress.com
AB4D
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Posts: 418


WWW

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« Reply #208 on: November 07, 2017, 02:14:14 PM »

In defense of Zenki, at least he likes Anan and he's not continually posting silly GIFs like a certain SDR-hating luddite...   Cheesy

Why does Zenki insist on hiding behind a pseudonym and not use a call sign on these forums like everyone else does? Makes you wonder what he's got to hide...

Maybe, he is one of those famous hams, and doesn't want you slobs begging him for his autograph or QSL card?    Cheesy Cheesy Cheesy :
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VK3BL
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Posts: 1308


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« Reply #209 on: November 08, 2017, 03:10:23 AM »

What Zenki might like in this radio is 'drive adjustment'... from what I can gather it effectively lets you optimize your final stage's operating class... all that should be needed is a cheap 12bit SDR and a dummy load to verify the changes!
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J.D. Mitchell - VK3BL / XU7AGA - http://vk3bl.wordpress.com
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