"Jeff Liebermann" wrote in message
...
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.



no idea why but that reminds me of a car I had that lost the engine earth
and it earthed through the accelerator cable which overheated and caused a
lot of smoke...just thought I would throw that in ....no idea why

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

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.


--
Spike

"Nearly all men can stand adversity,
but if you want to test a man's character,
give him an internet group to manage"

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.



--
Spike

"Nearly all men can stand adversity,
but if you want to test a man's character,
give him an internet group to manage"

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?

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.

--

Roger Hayter

"Spike" wrote in message
...
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.



even I know that one .....

"Jeff" wrote in message news

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).

I wired up a neg ground rev counter to my pos earth 1963 mini in 1969 by
insulating the live case of the rev counter and earthing the live
terminal...worked well .....

On 14/10/2018 11:04, 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?

No. For some reason it's been deleted.


--
Spike

"Nearly all men can stand adversity,
but if you want to test a man's character,
give him an internet group to manage"

On 14/10/2018 11:18, 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.

It's only interesting as in its showing how any stick can be useful to a
person of a particular mind-set to beat a dog, as it were, even if the
beater can be then be beaten in turn with a similar stick, raising the
question of why the mind-set of the original beater impels him to do
this self-destructive act repeatedly.


--
Spike

"Nearly all men can stand adversity,
but if you want to test a man's character,
give him an internet group to manage"

On Sun, 14 Oct 2018 11:39:58 +0000
Spike wrote:

On 14/10/2018 11:04, 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?

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.