amdx wrote:
On 3/16/2014 12:50 PM, Michael A. Terrell wrote:
amdx wrote:
On 3/16/2014 3:02 AM, Michael A. Terrell wrote:
VGA monitor cable?
I'm not aware of what is inside,
does this super VGA type look right?
http://www.ebay.com/itm/6FT-10FT-30F...-/350979305532
They have three miniature 75 ohm coax cables and an outer shield, along
with several other single conductors. This is for your homemade Boonton
RF probe, so I've seen the cable they use. Don't you have a spare
monitor cable laying around, or a recycler that will let you swipe a
cable off a bad monitor?
I opened up the cable I have and it is aluminum shield, won't work
for my purpose.
An aluminum foil shield can be quieter than braided, tinned copper
when the cable is flexed. The drain wire allows you to connect it to the
connector, and probe body as needed. Not all VGA cable is foil
shielded, but the more flexible is likely to be made that way since you
need multiple layers of braid to achieve the same level of shielding.
Some cable has enough free space that you could pull out the unwanted
conductors. S-video cable might work, if you could find it with an outer
shield, but VGA cable is the closest, off the shelf wire available.
Plus too many wires.
All you have to do is tie any unused wires to ground at the connector
end.
Belden 1277P or 1277R is just three 75 ohm miniature coax cables with a
bonded foil shield, but it's about $1.06 or $1.58 per foot when you buy
1000 feet at a time.
I'm looking at this audio cable with XLR connectors.
http://www.amazon.com/XLR-Male-Femal...pr_product_top
I suspect this is a twisted pair inside a shield, pins 1, 2, and 3 and
then a shield around everything that connects to the housing of the
connector.
It says, "These cables... because of their combination of heavy duty
construction as well as their inner and outer protective RF shielding of
heavy duty copper conductors.
So it has two shields, but is each conductor shielded?
Why would each conductor be shielded, for low impedance, balanced
audio?
The use is the Boonton RF meter the cable carries DC voltage at low
voltages, as low as 1mV.
I'm still trying to find the right cable. I'd like to find something
commercial and cut a 25ft cable into 5 pieces and put ends on them.
Mikek
http://www.uniqueelectronics.com/ could make what you want, but you
better have your chair bolted to the floor and a seatbelt on when you
ask for a quote. I haven't dealt with them for years, but I did show
them how to prove that some customer supplied microwave cable was
garbage. The customer claimed it was their test equipment, but the semi
rigid cables I had proved it was in spec. One of their engineers was in
my computer club at the time.
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.