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On 11/4/2015 10:53 PM, Jim Henderson wrote:
> On Wed, 04 Nov 2015 22:14:15 +0000, Stephen wrote:
>
>>> Could be - generally a harmonic frequency can cause weirdness as well -
>>> I
>>> was more talking about why it's lines and not just snow. The proximity
>>> of the transmitter to the "receiver" is what causes that.
>>>
>>>
>> From the little I know only having worked, with Comms guys. You are
>> right but then you could tell me anything. It is all magic to me.
>> They even told me that our phone calls were bounced off the sky and the
>> sea. And I believed them.
>
> Well, I do have a radio license. ;)
>
So do I. Albeit the lowest level (RT). I could use a marine radio on a
fishing vessel or stand in for the RO on an Oil Rig.
> But that's the reason that proximity to the transmission point for the EM
> waves matters - and a closer but power power (at transmission point)
> overpower a signal that's farther away but stronger. With a 5W
> transmitter that's not well filtered, an amateur radio operator can
> disrupt commercial radio (AM/FM) and TV (VHF/UHF) transmissions quite
> significantly. Every amateur radio operator has to learn at least a
> little about this in the US, because we're responsible for dealing with
> harmful interference we might cause with our gear.
>
It is quite a fearsome exam. With Morse code and regulations.
> Even with well-filtered equipment, though, if I put the transmission
> source for my radio right next to a computer monitor or CRT display, I
> can cause some interference.
>
Don't forget the cable. Bad connections can cause reflections. ;-)
--
Regards
Stephen
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On Thu, 05 Nov 2015 00:12:17 +0000, Stephen wrote:
> On 11/4/2015 10:53 PM, Jim Henderson wrote:
>> On Wed, 04 Nov 2015 22:14:15 +0000, Stephen wrote:
>>
>>>> Could be - generally a harmonic frequency can cause weirdness as well
>>>> -
>>>> I
>>>> was more talking about why it's lines and not just snow. The
>>>> proximity of the transmitter to the "receiver" is what causes that.
>>>>
>>>>
>>> From the little I know only having worked, with Comms guys. You are
>>> right but then you could tell me anything. It is all magic to me.
>>> They even told me that our phone calls were bounced off the sky and
>>> the sea. And I believed them.
>>
>> Well, I do have a radio license. ;)
>>
>>
> So do I. Albeit the lowest level (RT). I could use a marine radio on a
> fishing vessel or stand in for the RO on an Oil Rig.
I thought you did - so I was a little surprised. :)
>> But that's the reason that proximity to the transmission point for the
>> EM waves matters - and a closer but power power (at transmission point)
>> overpower a signal that's farther away but stronger. With a 5W
>> transmitter that's not well filtered, an amateur radio operator can
>> disrupt commercial radio (AM/FM) and TV (VHF/UHF) transmissions quite
>> significantly. Every amateur radio operator has to learn at least a
>> little about this in the US, because we're responsible for dealing with
>> harmful interference we might cause with our gear.
>>
>>
> It is quite a fearsome exam. With Morse code and regulations.
Code isn't required in the US any more - they dropped it out of (as I
understand it) fear that not enough people would join the hobby to
justify the spectrum use.
>> Even with well-filtered equipment, though, if I put the transmission
>> source for my radio right next to a computer monitor or CRT display, I
>> can cause some interference.
>>
>>
> Don't forget the cable. Bad connections can cause reflections. ;-)
Oh yes, absolutely. I also tend to pick up RF from my PCs on my
headphones (the ones plugged into the PC), even with a proper ground.
Jim
--
"I learned long ago, never to wrestle with a pig. You get dirty, and
besides, the pig likes it." - George Bernard Shaw
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> I left a program running overnight. The next morning, even after booting
> back into Mac OS, the text was still faintly visible.
That should go away after a while, but I'd be careful leaving a static
image for any longer on that screen if that happens already after just a
night.
>>> While we're on the subject, what causes the weird diagonal lines that
>>> all RF-modulated signals have?
>>
>> Non-perfect electronics :-)
>
> Why lines though? Why not random snow or something?
Designing RF stuff is tricky as every part of your circuit will blast
all the other parts with whatever signal is on it. I suspect it's just
some interference or some component creating harmonics, and they just
happen to manifest as diagonal lines.
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On 11/5/2015 1:08 AM, Jim Henderson wrote:
> On Thu, 05 Nov 2015 00:12:17 +0000, Stephen wrote:
>
>>>
>>> Well, I do have a radio license. ;)
>>>
>>>
>> So do I. Albeit the lowest level (RT). I could use a marine radio on a
>> fishing vessel or stand in for the RO on an Oil Rig.
>
> I thought you did - so I was a little surprised. :)
There is a big difference between being able to use a radio and design
and maintenance.
>>>
>>>
>> It is quite a fearsome exam. With Morse code and regulations.
>
> Code isn't required in the US any more - they dropped it out of (as I
> understand it) fear that not enough people would join the hobby to
> justify the spectrum use.
>
It's not? I thought it was an international requirement for a Ham
licence. Even at foundation level (5 wpm).
>>> Even with well-filtered equipment, though, if I put the transmission
>>> source for my radio right next to a computer monitor or CRT display, I
>>> can cause some interference.
>>>
>>>
>> Don't forget the cable. Bad connections can cause reflections. ;-)
>
> Oh yes, absolutely. I also tend to pick up RF from my PCs on my
> headphones (the ones plugged into the PC), even with a proper ground.
>
See, black magic. :-)
--
Regards
Stephen
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On Thu, 05 Nov 2015 08:55:42 +0000, Stephen wrote:
> On 11/5/2015 1:08 AM, Jim Henderson wrote:
>> On Thu, 05 Nov 2015 00:12:17 +0000, Stephen wrote:
>>
>>
>
>>>> Well, I do have a radio license. ;)
>>>>
>>>>
>>> So do I. Albeit the lowest level (RT). I could use a marine radio on a
>>> fishing vessel or stand in for the RO on an Oil Rig.
>>
>> I thought you did - so I was a little surprised. :)
>
> There is a big difference between being able to use a radio and design
> and maintenance.
Well, true - I don't know what the UK tests are like - in the US, there's
a lot of radio theory even in the lowest level exams.
The Extra class license is (or at least "used to be" - I took my exams 20
+ years ago now, and that was only the technician level exam) more
difficult than some of the commercial license exams. At least, that's
what I was told by someone who had both a commercial license and an extra
class license. :)
>>> It is quite a fearsome exam. With Morse code and regulations.
>>
>> Code isn't required in the US any more - they dropped it out of (as I
>> understand it) fear that not enough people would join the hobby to
>> justify the spectrum use.
>>
>>
> It's not? I thought it was an international requirement for a Ham
> licence. Even at foundation level (5 wpm).
Nope, no requirement at all now. The ITU ratified a decision to allow
each country to decide on its own if CW was required or not back in
2003. The FCC dropped the requirement from all license classes in 2006
(effective in 2007).
I got a "technician" class license in the early 90's, just after the
requirement was dropped for that class (but the class was limited to 2m,
70cm, and 6m - nothing in the ranges the ITU required it for - generally
below 30 MHz IIRC). Same exam as the then-new "Technician Plus" (which
was the old "technician" class, confusingly), and my license was
grandfathered back to full Technician when the requierment was dropped
from all classes in 2007.
>>>> Even with well-filtered equipment, though, if I put the transmission
>>>> source for my radio right next to a computer monitor or CRT display,
>>>> I can cause some interference.
>>>>
>>>>
>>> Don't forget the cable. Bad connections can cause reflections. ;-)
>>
>> Oh yes, absolutely. I also tend to pick up RF from my PCs on my
>> headphones (the ones plugged into the PC), even with a proper ground.
>>
>>
> See, black magic. :-)
LOL
--
"I learned long ago, never to wrestle with a pig. You get dirty, and
besides, the pig likes it." - George Bernard Shaw
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On 05/11/2015 08:12 AM, scott wrote:
>> I left a program running overnight. The next morning, even after booting
>> back into Mac OS, the text was still faintly visible.
>
> That should go away after a while,
It did. A few hours later, it was gone.
> but I'd be careful leaving a static
> image for any longer on that screen if that happens already after just a
> night.
Quite. We only have the damned thing for testing purposes...
>> Why lines though? Why not random snow or something?
>
> Designing RF stuff is tricky as every part of your circuit will blast
> all the other parts with whatever signal is on it. I suspect it's just
> some interference or some component creating harmonics, and they just
> happen to manifest as diagonal lines.
OK...
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On 05/11/2015 12:12 AM, Stephen wrote:
> It is quite a fearsome exam. With Morse code and regulations.
But do you have to be able to use a Smith chart?
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On 11/5/2015 4:47 PM, Jim Henderson wrote:
> On Thu, 05 Nov 2015 08:55:42 +0000, Stephen wrote:
>
>
>>
>> There is a big difference between being able to use a radio and design
>> and maintenance.
>
> Well, true - I don't know what the UK tests are like - in the US, there's
> a lot of radio theory even in the lowest level exams.
>
What I meant was the difference between theory and practice.
> The Extra class license is (or at least "used to be" - I took my exams 20
> + years ago now, and that was only the technician level exam) more
> difficult than some of the commercial license exams. At least, that's
> what I was told by someone who had both a commercial license and an extra
> class license. :)
>
I should hope so. Was it military training? I've worked with a couple of
exRN "Sparkers" and "bunting tossers". There would be a lot of drink
involved, I would guess.
>>>> It is quite a fearsome exam. With Morse code and regulations.
>>>
>>> Code isn't required in the US any more - they dropped it out of (as I
>>> understand it) fear that not enough people would join the hobby to
>>> justify the spectrum use.
>>>
>>>
>> It's not? I thought it was an international requirement for a Ham
>> licence. Even at foundation level (5 wpm).
>
> Nope, no requirement at all now. The ITU ratified a decision to allow
> each country to decide on its own if CW was required or not back in
> 2003. The FCC dropped the requirement from all license classes in 2006
> (effective in 2007).
>
Obviously I'm not up to date. I imagine "Attics, cardigans and a tuned
loop antenna".
> I got a "technician" class license in the early 90's, just after the
> requirement was dropped for that class (but the class was limited to 2m,
> 70cm, and 6m - nothing in the ranges the ITU required it for - generally
> below 30 MHz IIRC). Same exam as the then-new "Technician Plus" (which
> was the old "technician" class, confusingly), and my license was
> grandfathered back to full Technician when the requierment was dropped
> from all classes in 2007.
>
All done by Magic. :-)
>>>
>>>
>> See, black magic. :-)
>
> LOL
>
>
>
--
Regards
Stephen
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On 11/5/2015 6:28 PM, Orchid Win7 v1 wrote:
> On 05/11/2015 12:12 AM, Stephen wrote:
>> It is quite a fearsome exam. With Morse code and regulations.
>
> But do you have to be able to use a Smith chart?
Not for an operator's ticket.
--
Regards
Stephen
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FYI
Humphrey Lyttelton. That reminds me.
http://www.bbc.co.uk/programmes/b007jndb
--
Regards
Stephen
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