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Old October 14th 18, 06:03 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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On Sun, 14 Oct 2018 10:26:55 +0100, Jeff wrote:


I inspected the electrical system and found that fuse on the negative
lead had blown. Why manufacturers persist in providing a negative
wire fuse will remain a mystery as there are very few positive ground
vehicles still in service and even marine radios with floating grounds
are scarce. I have no idea where the radio was getting its ground
return for reasons that will soon be obvious. I replaced the fuse and
continued looking for problems.


The negative fuse is nothing to do with positive ground vehicles (and a
radio with the case connected to negative would not work in a positive
ground vehicle anyway without additional isolation).

The negative fuse is there to stop high currents, such as the starter
motor, being drawn through the radio wiring and coax should the battery
to chassis connection be high resistance or open circuit, and prevent a
possible fire.

This is at greatest risk if the radio negative is wired directly to the
battery.

Jeff


That seems reasonable. However, I've never seen that happen.

More common was blowing or removing the negative power cable fuse to
the radio. That makes the DC ground return for the radio go through
either the car frame, which will produce alternator noise on the
transmit signal, or through the coax cable, which will produce a
smoking coax cable in transmit. I've seen both about 5 times each in
the last 50 years. I would consider these faults to be a greater risk
than a disconnected battery to chassis (or engine) ground cable.

"Wiring and Grounding"
http://www.k0bg.com/wiring.html
And as shown, the negative lead fuse should not be removed.
The reason is, if the grounding point should lose its integrity,
excessive current could flow through the transceiver's
negative lead. It also prevents a minor ground loop between
the leads.

Most vehicles have a ground strap between the engine block and frame
and another ground cable between the frame and negative battery
terminal. I sometimes see a third cable from battery to engine block.
In this arrangement, any one of the three wires could be disconnected
and one would still have a tolerable grounding system. Fiberglass
body automobiles have duplicate ground wiring since there is no frame
ground.

"How To Properly Ground An Automotive Electrical System"
https://www.hotrodwires.com/how-to-ground-automotive-electrical-system.html

"Is it necessary to have two ground wires (1 to engine and 1 to"
car-frame)?
https://mechanics.stackexchange.com/questions/5903/is-it-necessary-to-have-two-ground-wires-1-to-engine-and-1-to-car-frame

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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Old October 14th 18, 06:39 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 4NEC2?

In article ,
says...

The negative fuse is nothing to do with positive ground vehicles (and a
radio with the case connected to negative would not work in a positive
ground vehicle anyway without additional isolation).

The negative fuse is there to stop high currents, such as the starter
motor, being drawn through the radio wiring and coax should the battery
to chassis connection be high resistance or open circuit, and prevent a
possible fire.

This is at greatest risk if the radio negative is wired directly to the
battery.

Jeff


That seems reasonable. However, I've never seen that happen.

More common was blowing or removing the negative power cable fuse to
the radio. That makes the DC ground return for the radio go through
either the car frame, which will produce alternator noise on the
transmit signal, or through the coax cable, which will produce a
smoking coax cable in transmit. I've seen both about 5 times each in
the last 50 years. I would consider these faults to be a greater risk
than a disconnected battery to chassis (or engine) ground cable.



I don't know anything about the tractor trailer wiring, but around 1972
I picked up extra money repairing the CB radios. Several truckers
brought in rigs that were blown up when switching from the car to the
truck. None of them had a fuse in the negative power lead. By blown
up, most had a diode across the poer wires inside the transceiver and
that diode had shorted and blew the fuse. I seem to remember then they
talked about the tractor haveing a positive ground. Probably ran on 24
volts also.

I have only ran FM ham rigs in a car. I used to ground the rig to the
frame and run the positive to a relay that comes on when the car is
started. Never had any alternator whine or problems. For about the
last 10 or more years I just plug into the lighter or accessory socket
in the car. My Toyota power on those sockets only come on when the car
is started.
  #33   Report Post  
Old October 14th 18, 06:39 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 4NEC2?

In article ,
says...
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...A/_ityI76x0IMJ


Good old Burt.





If the wrong sideband or inversion of the tones is the problem, it will
not be a string of 4646 instead of RYRY. They are both the same except
the printer is shifted for the 4646. What will hapen is that instead of
RYRY it will be YRYR but all the other characters will be scrambled.

It does not matter what sideband is used for RTTY if the tones are
inverted. However in most normal ham RTTY lower side band is used for
receiving and if audio tones are fed into the audio for transmitting.
This makes the tones come out the same when used on AM or FM on VHF.

For HF it does not even matter what the frequency of the audio tones are
if they are the usual 170 Hz difference as long as they pass through the
audio of the transmitter and receiver. Usually 2125 and 2295 are used
as this is about as high as will pass the audio and if running a ssb
transmitter the 2 nd and higher harmonics are filtered out to some
extent if need be by the transmitter filter.
  #34   Report Post  
Old October 14th 18, 06:42 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 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. Thats 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.

I don't recall what year, but at the time, the FCC decided to drop the
US Morse Code requirements. Since the technician class license
consisted of the exact same technical questions as the general class
license (element 3), it was decided that one could upgrade from
technician to general without taking any additional tests and by
simply paying a nominal processing fee.

I arrived at the scheduled VEC exam session and presented my
collection of expired licenses and forms as proof that I passed the
technician class exam. Since I didn't need to pass an exam, I hadn't
studied. I was then informed that I could take the extra class exam
(element 4). If I failed, I would still get the general class
license. Seemed like a reasonable thing to do. So, I took the extra
class exam, totally and completely unprepared. I didn't even bring a
calculator.

Except for some creative wording in many of the questions, the
technical parts were quite familiar and easy. However, element 4 also
included some questions that required operating experience, such as
band edges for the extra class only sub-bands, and similar questions.
I did my best by guessing and was certain that I had failed the exam.
Amazingly, I passed.

So, if anyone asks if it is possible to pass the US extra class exam
without knowing much about HF operating standards, I would answer that
it might be possible.

From my warped perspective, the ham license is NOT a demonstration of
competence. It's simply the minimum one is expected to know so that
they can operate a ham transmitter without breaking any rules,
becoming a nuisance, or otherwise making a mess of the frequencies.
One learns ham radio AFTER obtaining a license, not before.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #35   Report Post  
Old October 14th 18, 07:12 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 4NEC2?

On Sun, 14 Oct 2018 08:49:51 +0000, Spike
wrote:

On 13/10/2018 20:43, Jeff Liebermann wrote:

I understand how antenna work and how to predict performance. I can
even do it without 4NEC2 or other antenna modeling program. For
example, the uglier the antenna, the better it works. Antennas that
are more expensive, bigger, and in violation of local building
ordinances, work the best. Experimental prototype antennas always
work while the production versions never seem to work as well. If
there are two ways to assemble an antenna, the wrong way will have
higher gain, lower VSWR, or both. High gain, small size, or wide
bandwidth; pick any two. Using these rules of thumb and others,
anyone can predict how well an antenna will perform by inspection and
without using computer models, Smith charts, or tedious calculations.


WHS


Thou shalt not abrev. What does WHS mean?

There has been much talk on UKRA in the recent past about the merits or
otherwise of various makes and models of VNAs. It's my view that the
point of having an Amateur licence is to be able to transmit signals
intended to be received by another station. One of the alleged virtues
of a VNA is to be able to set up one's aerial system. However, I
maintain that using cheap torch bulbs is an equally valid indicator of
the state of tune of one's station, and that a distant station cannot
tell the difference between a system set up with the aid of a VNA and
one set up with the aid of a torch bulb or two.


In a past life (1970's), I used to design marine radios and antennas.
At the time, my weapon of choice was the HP4815A vector impedance
meter:
https://www.google.com/search?q=hp4815a&tbm=isch
No fancy display, no pretty graphs, no Smith chart display. Just
accurate numbers for the HF bands. I used it for everything that
needed impedance matching, including antennas. If you're thinking of
buying one, make sure that it includes the probe kit. It's useless
without the probe kit.
http://electropuces.pagesperso-orange.fr/Photos/HP4193.jpg

One of my ace technicians had a different way of doing RF. During the
day, he would use the best test equipment that the company could
afford. After hours, he would work on his own radios. However,
instead of using proper test equipment, he would literally tune for
maximum into a light bulb. I was disgusted, tried to help, but
failed. He insisted that a light bulb was "good enough". It took me
a while to decode what was happening.

Anyone can produce a workable antenna using primitive techniques. By
workable, I mean minimally functional and generally usable. For at
time, I was building matching networks for using an aluminum step
ladder as a VHF directional antenna. It worked, but improvements
beyond minimally functional were difficult.

So, why bother with all the fancy test equipment (VNA) if a light bulb
will do as well? Because with the fancy test equipment will squeeze
the last few decibels of performance out the antenna while the light
bulb is unlikely to do the same. If minimally acceptable is your
standard of excellence, then please continue using a light bulb for
tuning antennas. However, if you want to get all the performance
possible, then you'll need some fancy test equipment.

What was happening with my tech was that he did not want to expend the
time learning how to properly operate, understand, and analyze the
output from the fancy test equipment. While I consider this close to
sacrilege in a production environment, to someone just trying to get
his radio or antenna on the air, it's sufficient. If I light bulb got
him close enough to a working system, and didn't require any time to
study, it was "good enough".

Some of the local hams are very much into DX, contesting, and EME. To
be successful, one has to have a very efficient radio system with
everything optimized to the best possible performance. Everything has
to be optimized for the best possible performance. One can't do that
with a light bulb.

Since your view of ham radio is "to be able to transmit signals
intended to be received by another station", you don't need a VNA to
do that. An antenna tuner and a random length of wire will suffice.
However, if you plan to do more than that, some test equipment might
be useful.



--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


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Old October 14th 18, 07:33 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Posts: 1,333
Default 4NEC2?

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.

The problem repeated itself with the rise of the digital modes. People
wanted mult-band radios, but didn't want two filters in the radio.
So, someone flipped a coin and decided that everything should be USB
when using digital modes. For example, with JT65A, it's USB on all
bands:
http://hflink.com/jt65/
I'm not quite sure if that's also the case with other digital modes.
For example, PSK31 (BPSK) doesn't care if you use USB or LSB, but by
convention, USB is preferred.

For marine radio HF communications, it's all USB.




--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #37   Report Post  
Old October 14th 18, 07:49 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Posts: 1,333
Default 4NEC2?

On Sun, 14 Oct 2018 13:39:38 -0400, Ralph Mowery
wrote:

I don't know anything about the tractor trailer wiring, but around 1972
I picked up extra money repairing the CB radios. Several truckers
brought in rigs that were blown up when switching from the car to the
truck. None of them had a fuse in the negative power lead. By blown
up, most had a diode across the poer wires inside the transceiver and
that diode had shorted and blew the fuse. I seem to remember then they
talked about the tractor haveing a positive ground. Probably ran on 24
volts also.


I installed a few radios in White Freightliner tractors in the 1960's.
They were all positive ground 12V. I think they switch to negative
ground in about 1975. Many other older tractors were positive ground
but switched to negative ground in about 1954-56. I vaguely recall
conversion kits being sold at the time.

I've seen a few 24V electrical systems, but those were all in military
vehicles.

I have only ran FM ham rigs in a car. I used to ground the rig to the
frame and run the positive to a relay that comes on when the car is
started. Never had any alternator whine or problems. For about the
last 10 or more years I just plug into the lighter or accessory socket
in the car. My Toyota power on those sockets only come on when the car
is started.


You might want to put a voltmeter across the power connector going to
your radio and across the battery, and compare voltages in transmit.
Methinks you'll find a rather substantial voltage drop through the
cigarette igniter jack. Also, that connector was never designed to
handle a plug and jack connector arrangement. It's the only connector
that I know of that has a spring which pushed the plug OUT of the jack
and lacks a retention system.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #38   Report Post  
Old October 14th 18, 08:06 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 4NEC2?

In article ,
says...

So, if anyone asks if it is possible to pass the US extra class exam
without knowing much about HF operating standards, I would answer that
it might be possible.

From my warped perspective, the ham license is NOT a demonstration of
competence. It's simply the minimum one is expected to know so that
they can operate a ham transmitter without breaking any rules,
becoming a nuisance, or otherwise making a mess of the frequencies.
One learns ham radio AFTER obtaining a license, not before.




Now with the questions and answers being published,anyone with a good
memory can get an Extra class license without actually knowing anything.
My wife got her Technician class just so she could talk to me on the
repeaters . She hardly knew which end of the mic to talk into.

Even back around 1972 when I was 22 I passed the First Class Phone and
had never seen a TV transmitter or really how it worked. Knew very
little about the broadcast radio either. I did know enough to do well
on the 2nd class which I really wanted,but it was only a dollar more to
take the First Class.

I almost don't see what any of the test for anything are worth now days.
I know licensed electricians that I would not let change a battey in a
one cell flashlight. Plumbers that I hate to even see hook up the
garden hose.

I do agree that it is best to get a ham license and much of the learning
comes after.

With all the digital modes and menues and computer problems now it is
almost a wonder many hams can even get that to work.
  #39   Report Post  
Old October 14th 18, 08:25 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Default 4NEC2?

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

https://physics.princeton.edu/pulsar/k1jt/doc/wsjt/

"Turn on your radio, select USB (or USB Data) mode, and tune to a clear
frequency so that only background noise is sent to the sound card"

Brian



--
Brian Howie
  #40   Report Post  
Old October 14th 18, 08:30 PM posted to uk.radio.amateur,rec.radio.amateur.antenna
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Posts: 7
Default 4NEC2?

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 are 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.

"Part I of the document includes the equations on which the code is
based and a discussion of the approximations and numerical methods used
in the numerical solution. Some comparisons to demonstrate the range of
accuracy of approximations are also included. Details of the coding and
a User's Guide are provided as parts 11 and 111, respectively."

It's pretty straight forward stuff for someone good (1st year uni) at
maths*. The rest of us just have to take their word for it. The code is
written in good old FORTRAN, so I can at least follow the code.


*It's USAnian maths. Which is a different dialect to British maths.

Brian

--
Brian Howie


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