On Mon, 6 Oct 2008 17:23:03 +1300, "PeeCee" wrote:

wrote in message
...
Hi Guys,

I need to get a VGA signal from the Nav Station in my boat to the
monitor in the bridge. I could just run a VGA cable (about 4m worth)
but I need to pass the cable through some small holes for the looming
(sp?) and the DB15 connectors wont fit unless I make the hole bigger.

I am thinking about running the VGA singal over CAT5e, which a Google
search seems to suggest is possible. I was wondering if anyone had any
better ideas, keeping costs fairly low.

Has anyone here had any success cutting the end off a VGA cable and
wiring on a new DB15 for example?

Thanks in advance,

-Al



Al

Well I was going to say different cable for different uses, but then I found
this site:
http://www.geocities.com/dougburbidge/vgaovercat5.html
The author says they've achieved 15 metres.
For the cost of the cable and solder time, worth trying.

I used to make up VGA cables for control room applications. 15M using
individual screened conductors was about the recommended limit


If that doesn't work you can get gadgets that convert from VGA to RJ45 and
back again:
http://www.svideo.com/vgacat5.html

Best
Paul.

"philo" wrote in message
...

wrote in message
...
Hi Guys,

I need to get a VGA signal from the Nav Station in my boat to the
monitor in the bridge. I could just run a VGA cable (about 4m worth)
but I need to pass the cable through some small holes for the looming
(sp?) and the DB15 connectors wont fit unless I make the hole bigger.

I am thinking about running the VGA singal over CAT5e, which a Google
search seems to suggest is possible. I was wondering if anyone had any
better ideas, keeping costs fairly low.

Has anyone here had any success cutting the end off a VGA cable and
wiring on a new DB15 for example?

Thanks in advance,

-Al


VGA cable is shielded
and CAT5 is not, so you would get some horrible ghosting.

BTW, there may still be some ghosting even with VGA cable


STP CAT5e or CAT 6 would do the trick, and at these lengths the cost
difference isn't an issue.

-John O

Alfred wrote:
On Sun, 5 Oct 2008 21:05:00 -0700 (PDT), wrote:

Hi Guys,

I need to get a VGA signal from the Nav Station in my boat to the
monitor in the bridge. I could just run a VGA cable (about 4m worth)
but I need to pass the cable through some small holes for the looming
(sp?) and the DB15 connectors wont fit unless I make the hole bigger.

I am thinking about running the VGA singal over CAT5e, which a Google
search seems to suggest is possible. I was wondering if anyone had any
better ideas, keeping costs fairly low.

Has anyone here had any success cutting the end off a VGA cable and
wiring on a new DB15 for example?




If you are handy with a soldering iron there is no problem. You may
have to buy a new plug/socket though as the one you cut off may be
potted.


Unfortunately, unless you do this for a living, one is unlikely to have
a nice temperature controlled iron with a micro-chisel tip, like a MetCal.

I've spent most of my adult life doing this and fine soldering without
ballsing things up is both an art and a skill, takes practise, a good
eye and a steady hand.

Buy an adaptor and use the Cat5 or 6 route, probably be a lot less headache.

Cheers
Marty

It might be worthwhile to think-out a bit beyond the size of the hole
though which you want to pass this signal. Stuff like "what will
hold-up best when I'm at the bridge, in a storm, near a rocky shore
and I really need to know where I am?" I say that only half in jest.

rick jones
--
oxymoron n, commuter in a gas-guzzling luxury SUV with an American flag
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

In article ,
glen herrmannsfeldt wrote:

JohnO wrote:

"philo" wrote in message
(snip)

VGA cable is shielded
and CAT5 is not, so you would get some horrible ghosting.

BTW, there may still be some ghosting even with VGA cable

STP CAT5e or CAT 6 would do the trick, and at these
lengths the cost difference isn't an issue.

There might be a minimum amount that they will sell, but the
real problem isn't shielding but impedance and
balanced/unbalanced line.

If you transition from a balanced line (UTP) to an unbalanced
line (coax), unless exactly impedance matched, it won't
work right. UTP cable depends on the voltage and currents
on the two wires being exactly opposite to cancel out and
not radiate the signal. Coax depends on the voltage on the
shield being zero. To couple between them you either need
a transformer (if there is no DC component), or active
circuitry such as differential amplifiers. VGA has a
DC component so you can't use transformers.

-- glen

You can use a transformer, but wired as a *balun* (coils in series with
the lines instead of across them); this provides the required impedance
transformation while still passing DC.


--
Rich Seifert Networks and Communications Consulting
21885 Bear Creek Way
(408) 395-5700 Los Gatos, CA 95033
(408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

JohnO wrote:

"philo" wrote in message
(snip)

VGA cable is shielded
and CAT5 is not, so you would get some horrible ghosting.

BTW, there may still be some ghosting even with VGA cable

STP CAT5e or CAT 6 would do the trick, and at these
lengths the cost difference isn't an issue.

There might be a minimum amount that they will sell, but the
real problem isn't shielding but impedance and
balanced/unbalanced line.

If you transition from a balanced line (UTP) to an unbalanced
line (coax), unless exactly impedance matched, it won't
work right. UTP cable depends on the voltage and currents
on the two wires being exactly opposite to cancel out and
not radiate the signal. Coax depends on the voltage on the
shield being zero. To couple between them you either need
a transformer (if there is no DC component), or active
circuitry such as differential amplifiers. VGA has a
DC component so you can't use transformers.

-- glen

Rich Seifert wrote:
(snip)

You can use a transformer, but wired as a *balun* (coils in series with
the lines instead of across them); this provides the required impedance
transformation while still passing DC.

So that is how they do it.

TV baluns, from 300 ohm balanced to 75 ohm coax, don't do that.

http://en.wikipedia.org/wiki/Balun

Does that restrict which impedance transformation you can make?

-- glen

On 6 Oct, 18:30, Rick Jones wrote:
It might be worthwhile to think-out a bit beyond the size of the hole
though which you want to pass this signal. *Stuff like "what will
hold-up best when I'm at the bridge, in a storm, near a rocky shore
and I really need to know where I am?" *I say that only half in jest.


I have worked with commercial solutions using this technology.
Was about 5 or 6 years ago.

I forget the name of the product.

One serious problem was that by *design* (as I understand it)
the various different pairs in the cat5 cable have different
twist rates. This results in different cable lengths and
produces different delays for each of the
RGB and Sync. The solution overcame this by having
user adjustable delays controlled by DIP switches
at the remote end.

(or is sync on one of the RGB?) doesn't matter - is still broken.

NIGHTMARE - in the event of any moves or changes.

Not sure of your proposed length would run into this or not.
I suspect it would since the frequency required to drive
a display is rather high.

In the case I observed the differential delay issue
was *very* significant over two floors of
a narrow buillding.

There of course may be commercial solutions available now that
avoid the problems entirely. Perhaps by combining the
signals into one pair.

Composite Video?

On Mon, 6 Oct 2008 16:27:41 -0700 (PDT), wrote:

There of course may be commercial solutions available now that
avoid the problems entirely. Perhaps by combining the
signals into one pair.

The most common solution now is to use an ethernet KVM (keyboard,
video and mouse) switch. All signals get packetized.

On Oct 7, 3:55*am, Martin Baxter wrote:
Alfred wrote:
On Sun, 5 Oct 2008 21:05:00 -0700 (PDT), wrote:

Hi Guys,

I need to get a VGA signal from the Nav Station in my boat to the
monitor in the bridge. I could just run a VGA cable (about 4m worth)
but I need to pass the cable through some small holes for the looming
(sp?) and the DB15 connectors wont fit unless I make the hole bigger.

I am thinking about running the VGA singal over CAT5e, which a Google
search seems to suggest is possible. I was wondering if anyone had any
better ideas, keeping costs fairly low.

Has anyone here had any success cutting the end off a VGA cable and
wiring on a new DB15 for example?

If you are handy with a soldering iron there is no problem. You may
have to buy a new plug/socket though as the one you cut off may be
potted.

Unfortunately, unless you do this for a living, one is unlikely to have
a nice temperature controlled iron with a micro-chisel tip, like a MetCal..

I've spent most of my adult life doing this and fine soldering without
ballsing things up is both an art and a skill, takes practise, a good
eye and a steady hand.

Buy an adaptor and use the Cat5 or 6 route, probably be a lot less headache.

Cheers
Marty

Haha. Actually I am lucky - I have a Hakko 936 Temp Controlled Iron,
but have found a place I can buy a HD15 connector I can use with crimp
pins - this might be easier than trying to solder it?