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Gareth's Downstairs Computer October 13th 18 09:33 AM

4NEC2?
 
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?


Jim GM4DHJ ...[_3_] October 13th 18 09:40 AM

4NEC2?
 

"Gareth's Downstairs Computer"
wrote in message
...
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?


you will only need a cellphone antenna to enjoy amateur radio in the future
.....



Stephen Thomas Cole[_3_] October 13th 18 05:51 PM

4NEC2?
 
Rambo wrote:
Gareth's Downstairs Computer headstone255.but.n
Wrote in message:
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?



G is for Gentleman


R is for rimjob.

--
STC / M0TEY /
http://twitter.com/ukradioamateur

Stephen Thomas Cole[_3_] October 13th 18 05:51 PM

4NEC2?
 
Gareth's Downstairs Computer
wrote:
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?


G is for genital warts.

--
STC / M0TEY /
http://twitter.com/ukradioamateur

Stephen Thomas Cole[_3_] October 13th 18 05:54 PM

4NEC2?
 
Brian Morrison wrote:
On Sat, 13 Oct 2018 09:33:55 +0100
Gareth's Downstairs Computer
wrote:

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?


I currently have a build of openEMS going on my Fedora system, once it's
built and installed I shall have a play and see what I can glean from
it.

Yes, I understand the underlying principles of antennas,


Burt thought he did, too.

--
STC / M0TEY /
http://twitter.com/ukradioamateur

Rambo October 13th 18 06:13 PM

4NEC2?
 
Gareth's Downstairs Computer headstone255.but.n
Wrote in message:
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?



G is for Gentleman
--

Jeff Liebermann[_2_] October 13th 18 09:43 PM

4NEC2?
 
On Sat, 13 Oct 2018 09:33:55 +0100, Gareth's Downstairs Computer
wrote:

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?


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.

As for your inability to distinguish yourself from consumerist CBers
and beginning licensees, it might be because you have most of the
characteristics of both.

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

Stephen Thomas Cole[_3_] October 13th 18 09:53 PM

4NEC2?
 
Jeff Liebermann wrote:
On Sat, 13 Oct 2018 09:33:55 +0100, Gareth's Downstairs Computer
wrote:

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?


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.

As for your inability to distinguish yourself from consumerist CBers
and beginning licensees, it might be because you have most of the
characteristics of both.


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.

--
STC / M0TEY /
http://twitter.com/ukradioamateur

Jeff Liebermann[_2_] October 14th 18 02:32 AM

4NEC2?
 
On 13 Oct 2018 20:53:13 GMT, Stephen Thomas Cole
wrote:

Gareth once complained about a mobile CB set-up he installed in a 4x4
couldnt reach further than a quarter mile. Thats all you need to know
about Gareth and radio.


He probably didn't need any antenna at 1/4 mile (400 meters).

About two months ago, one of my friends was complaining that the range
of his VHF/UHF mobile was severely limited. He decided that he must
have blown up his radio. I did a bench test of the radio and it was
fine. That left the vehicle power system, power cord, coax cable, and
antenna as the remaining potential suspects.

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.

Next came the coax and antenna system. I have a nifty little gadget I
built that has been very handy for troubleshooting mobile installs.
It's an NMO antenna "connector" to UHF adapter.
https://www.americanradiosupply.com/opek-nmo-8-nmo-antenna-connector-to-uhf-female-so-239-adapter/
I remove the NMO antenna, screw this adapter onto the NMO mount, and
check for RF power. In this case, no RF as in zero, zilch, none, no
RF. However, at the radio end, there was 45 watts of VHF RF. So, the
coax must be the problem.

Fast forward an hour of fruitless testing and I'm still not seeing any
RF. Eventually, I run a simple ohmmeter continuity test between the
ends of the coax cable and find that it's open circuit. Huh? Unless
something has cut the cable (we have a local mouse problem), even a
defective coax cable will show end to end continuity.

I trace out the coax cable only to find two identical cables running
in parallel. That wasted another hour because all the multiple radio
cables were behind a workbench and a pile of junk in the van. One
coax cable had the RF connector at the radio end and nothing at the
other end. The other cable had the NMO connector on one end, and
nothing on the other end. I should have guessed but I had assumed
that the owner had done a VSWR test during the initial coax cable
installation. Apparently, it had been like that for several weeks
before the owner noticed that his VHF/UHF coverage was lacking. Since
he lives just below the local repeaters, that's somewhat
understandable.

So, if anyone asks if they really need an antenna, tell them no.



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

Stephen Thomas Cole[_3_] October 14th 18 05:48 AM

4NEC2?
 
Jeff Liebermann wrote:
On 13 Oct 2018 20:53:13 GMT, Stephen Thomas Cole
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).

About two months ago, one of my friends was complaining that the range
of his VHF/UHF mobile was severely limited. He decided that he must
have blown up his radio. I did a bench test of the radio and it was
fine. That left the vehicle power system, power cord, coax cable, and
antenna as the remaining potential suspects.

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.

Next came the coax and antenna system. I have a nifty little gadget I
built that has been very handy for troubleshooting mobile installs.
It's an NMO antenna "connector" to UHF adapter.
https://www.americanradiosupply.com/opek-nmo-8-nmo-antenna-connector-to-uhf-female-so-239-adapter/
I remove the NMO antenna, screw this adapter onto the NMO mount, and
check for RF power. In this case, no RF as in zero, zilch, none, no
RF. However, at the radio end, there was 45 watts of VHF RF. So, the
coax must be the problem.

Fast forward an hour of fruitless testing and I'm still not seeing any
RF. Eventually, I run a simple ohmmeter continuity test between the
ends of the coax cable and find that it's open circuit. Huh? Unless
something has cut the cable (we have a local mouse problem), even a
defective coax cable will show end to end continuity.

I trace out the coax cable only to find two identical cables running
in parallel. That wasted another hour because all the multiple radio
cables were behind a workbench and a pile of junk in the van. One
coax cable had the RF connector at the radio end and nothing at the
other end. The other cable had the NMO connector on one end, and
nothing on the other end. I should have guessed but I had assumed
that the owner had done a VSWR test during the initial coax cable
installation. Apparently, it had been like that for several weeks
before the owner noticed that his VHF/UHF coverage was lacking. Since
he lives just below the local repeaters, that's somewhat
understandable.

So, if anyone asks if they really need an antenna, tell them no.


LOL! That’s a great story, cheers! :-D

--
STC / M0TEY /
http://twitter.com/ukradioamateur


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