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#41
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4NEC2?
On Sun, 14 Oct 2018 12:04:52 -0700 (PDT)
Jeefaw K Effkay wrote: On Sunday, October 14, 2018 at 7:33:10 PM UTC+1, Jeff Liebermann wrote: It might help to understand why some bands use LSB while others USB. In the early daze of sideband radio, the common IF frequency was 9MHz. The radios had only one sideband filter. With one filter, it was cheaper and easier to mix and up convert in the transmitter. So, to save the cost of adding a second filter, the bands below 9MHz were designated as LSB and the band above 9MHz became USB. Eventually, radios were built with two sideband filters, and this was no longer important. As usual, the legacy technology remained in place to haunt the survivors to this day. I've seen this explanation before, but it doesn't make sense. A 9MHz USB signal mixed with a 5.0 to 5.5MHz VFO will produce mixing products in the 80m and 20m bands - but both will be upper sideband. crosspost reinstated. |
#42
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4NEC2?
On Sun, 14 Oct 2018 20:25:28 +0100
Brian Howie wrote: In message , Bernie writes On Sun, 14 Oct 2018 05:59:35 -0700 (PDT) Jeefaw K Effkay wrote: On Sunday, October 14, 2018 at 12:57:21 PM UTC+1, Geoff wrote: On Sun, 14 Oct 2018 11:55:13 +0000 Spite sent a message from the other side: On 14/10/2018 11:44, Geoff wrote: On Sun, 14 Oct 2018 11:39:58 +0000 Spite sent a message from the other side: On 14/10/2018 11:04, Geoff wrote: On Sun, 14 Oct 2018 08:50:13 +0000 Spike lied: On 14/10/2018 01:32, Jeff Liebermann wrote: wrote: Gareth once complained about a mobile CB set-up he installed in a 4x4 couldn’t reach further than a quarter mile. That’s all you need to know about Gareth and radio. He probably didn't need any antenna at 1/4 mile (400 meters). snip interesting detection story Stephen Thomas Cole, the PP, just after gaining his UK Full licence by 'acing' all three exams, appeared on a UK Amateur group asking which sideband he should use on 40m. That's all you need to know about him and and his ability with radio. That sounds interesting - can you provide a link to that post? No. For some reason it's been deleted. Then we only have your word that it ever exsisted. I choose not to believe a word of it. 'It's been deleted' means it did exsist. You can't delete was was never posted. You might ask yourself why it was deleted. That's all you need to know about his ego and and his ability with radio. We only have your word for any of that. I choose not to believe a word of it. What STC actually asked was which sideband he should use for RTTY on 40m. Which is, of course, an interesting question as it's not something that was covered in any exam, current or previous. My $0.02 worth is that it doesn't matter, since an RTTY operator will know that he needs to invert the received tones if he sees a string of "46464646" instead of "RYRYRYRY" Here's what was asked, and it wasn't posted no archive, or deleted, or any of the other weak bull**** that Burt has bean spraying around: "Was pottering at my radio last night, heard the scream of data being sent and was triggered to revisit a long parked project; getting going on RTTY! Here's the hardware I'm using: Yaesu FT757-GXii Serial/USB cable interface thing PowerMac G4 running CocoaModem I've got everything hooked up, have CocoaModem configured and displaying a waterfall but when set to RTTY mode it's just decoding gibberish... Other than a couple of short spells at club days, this is my first go at this and I have no idea what I'm doing... Any tips?" https://groups.google.com/forum/#!or...-radio/MjriIIU zuHA/_ityI76x0IMJ Good old Burt. For the record all the data modes including RTTY use upper sideband all the way up from 136KHz . CW A1A is also upper sideband but there can be advantages to be had by swapping to LSB to avoid interference. F1A beacons seem to be a law unto themselves. You can get quite good at reading inverted morse. Amateur RTTY uses inverted tones and a different narrower shift compared with commercial RTTY. I don't know why your getting onto Steve about this as none of it is the radio amateur courses or even online anywhere, unless some smarty pants comes along and tells me it is. Ok it's in here for WSJT It was Burt who was doing the 'getting onto' and when it wasn't going well for him he introduced a new plotline about mysterious disappearing posts and the character defects that could be at the root of the disappearing posts. I joined it to point out that the posts are still there and that Burt is a liar and a ****ing idiot. |
#43
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4NEC2?
On 14/10/2018 20:30, brian wrote:
In message , Gareth's Downstairs Computer writes Whereas such antenna predictors seem to feature in amateur usage, does anyone, anywhere, in the world of amateur radio have an understanding of the underlying principles involved in predicting the performance of antennae, or have we all, regrettably, become indistinguishable from consumerist CBers or beginner licensees? 4NEC2 and EZNEC areÂ* just a fancy front and back ends for NEC2 (and NEC4) Engines. Program description is here :- https://ntrl.ntis.gov/NTRL/dashboard...tail/ADA956129. xhtml. Thanks for the heads up, Brian, but a quick glance suggests that some revision might be necessary of my 3rd year uni textbook, "Fields and Waves in Communications Electronics" by Ramo, Whinnery and Van Duzer. ISTR it to be an excellent book explaining complicated things in words of one syllable, but 46 years down the line, I might have a more romantic memory of it in reality :-) |
#44
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4NEC2?
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#45
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4NEC2?
On Sun, 14 Oct 2018, Roger Hayter wrote:
Geoff wrote: On Sun, 14 Oct 2018 08:50:13 +0000 Spike wrote: On 14/10/2018 01:32, Jeff Liebermann wrote: wrote: Gareth once complained about a mobile CB set-up he installed in a 4x4 couldn't reach further than a quarter mile. That's all you need to know about Gareth and radio. He probably didn't need any antenna at 1/4 mile (400 meters). snip interesting detection story Stephen Thomas Cole, the PP, just after gaining his UK Full licence by 'acing' all three exams, appeared on a UK Amateur group asking which sideband he should use on 40m. That's all you need to know about him and and his ability with radio. That sounds interesting - can you provide a link to that post? I hope I am as open-minded as the next person, but it is really stretching credulity to accept that anyone could actually find that alleged fact remotely interesting. To be fair, it isn't law which sideband is used, but "commaon practice". That actually is about operating, and is a counter example, it doesn't say anything about technical skill. There have to be endless things about "operating practice" that should be on an exam long before "which sideband to use on 40m?" Though I do wonder why someone wouldn't just flip the sideband switch if something isn't working right. Michael |
#46
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4NEC2?
On Sun, 14 Oct 2018, Jeff Liebermann wrote:
On Sun, 14 Oct 2018 08:50:13 +0000, Spike wrote: Stephen Thomas Cole, the PP, just after gaining his UK Full licence by 'acing' all three exams, appeared on a UK Amateur group asking which sideband he should use on 40m. That?s all you need to know about him and and his ability with radio. For what it's worth, I don't know which sideband to use on 40m. That's because I don't operate much on 40m and don't have such details memorized. I use a wall chart with the appropriate modes, frequencies, sub-bands, and dedicated frequencies listed. Oddly, I was able to pass the US extra-class license without knowing or studying any of this. I believe I posted the story previously, but it's interesting enough to repeat again. There was a time when SSB transceiver used mixing schemes so it would always be the "right" sideband when you switched bands. Even rigs that had a lsb/usb switch would sometimes color code so you knew which sideband was "right" for each band. I suspect more recent rigs, with synthesizers and computers, they surely default to the "right" sideband when you switch bands. As I recall, when I was a kid, I knew from reading which sideband got used on which band, SSB was hardly knew then but it was still "new" enough that it got talked about in the magazines. But with an SP-600 and a tuneable BFO, I had to tune the BFO both sides of zerobeat to figure out which worked for which sideband, no convenient crystal controlled BFO marked "lsb/usb". If there was a question on the tests about this sort of thing, it would likely show some frequencies and you'd have to figure out after heterodyning which sideband you were on. Michael |
#47
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4NEC2?
On Sun, 14 Oct 2018, Jeff Liebermann wrote:
On Sun, 14 Oct 2018 18:50:34 +0100, Brian Morrison wrote: On Sun, 14 Oct 2018 10:42:24 -0700 Jeff Liebermann wrote: For what it's worth, I don't know which sideband to use on 40m. For data modes it's just about all USB, and has been for some time. But it's easy to see why people can get confused and wonder what they set up incorrectly. No need to beat anyone up about it, just explain if you're asked. I don't think I'm beating up on anyone, but if an explanation is required, I can do that. It might help to understand why some bands use LSB while others USB. In the early daze of sideband radio, the common IF frequency was 9MHz. The radios had only one sideband filter. With one filter, it was cheaper and easier to mix and up convert in the transmitter. So, to save the cost of adding a second filter, the bands below 9MHz were designated as LSB and the band above 9MHz became USB. Eventually, radios were built with two sideband filters, and this was no longer important. As usual, the legacy technology remained in place to haunt the survivors to this day. Actually with filter rigs, they used only one filter. Military rigs might use two filters, obviously especially if they did ISB, and there must have been some ham rigs, high end, that used two filters, but generally it was one, and the BFO crystal was switched. There's more to this story, but I can't remember at the moment. Michael |
#48
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4NEC2?
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#49
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4NEC2?
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#50
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4NEC2?
On Sun, 14 Oct 2018 08:50:13 +0000
Spike wrote: Stephen Thomas Cole, the PP, just after gaining his UK Full licence by 'acing' all three exams, appeared on a UK Amateur group asking which sideband he should use on 40m. That’s all you need to know about him and and his ability with radio. Burt, I think that could've gone a bit better, Burt. Burt, Thanks, Burt. |
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