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.

Length in this case 4m absolute MAX!

-Al

wrote:

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?

Oh absolutely, most connectors that I assemble these day, (high density
military AMPHENOLs) are done with a crimping tool. Big drawback is the
initial cost of the requisite crimper, $400 plus.

Cheers
Marty

"philo" writes:

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.

Thethe wrong cable impedance and lack of shileding between
RGB signals will not cause ghosting. Most ghosting will
be caused by the impedance mismatches.

The lack of shield in cable will cause that that cable
will pick up more easily external interference
and will radiate out more RF interference and properly
shielded VGA cable.


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

True. The VGA cables vary in quality. The good ones are good
but there are also bad ones. One thing to keep in mind
in VGA connections is that it is a good idea to keep the
number of VGA connectors along the link minimum (ideally
only at source and destination), because the VGA connector
impedance is not exactly 75 ohms as the system is designed
for, and having many such wrong impedance connectors on
the way will cause impedanc mismatches that cause
reflections. For VGA cables is best to use a correct
length cable in the beginning, and avoid using
orignal cable + extension cable combinations.


--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/

In article ,
glen herrmannsfeldt wrote:

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?


The impedance transformation is determined by the winding ratio,
regardless of whether the coils are in series or parallel with the
lines.

Putting the balun in series provides better low-frequency response (down
to DC), but of course this configuration does not provide any electrical
isolation. It functions very much like a common-mode choke, with an
impedance change.


--
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

"Alfred" wrote in message
...
On Mon, 6 Oct 2008 17:23:03 +1300, "PeeCee" wrote:
snip

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



mmm wouldn't surprise me.
I've seen VGA extension cables as short as 2M exhibit ghosting.

P.

"PeeCee" writes:

"Alfred" wrote in message
...
On Mon, 6 Oct 2008 17:23:03 +1300, "PeeCee" wrote:
snip

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



mmm wouldn't surprise me.
I've seen VGA extension cables as short as 2M exhibit ghosting.

There are well built VGA extension cables (use 75 ohm mini coax cables
at least for RGB signals). Those work generally well.
Also there are those crappy cables built just from general purpose
computer cable with lots of wires inside one outer shield. Those
cheap cables have typically wrong impedance and considerable
crosstalk between signals - ghosting problems

Then the used resolution + refresh combination has effect.
Almost any crapphy cable works for 640x480 60 Hz resolution
but for 1280x12o4 and higher resolutions the quality of the cable
starts really slow up.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/