Very low capacitance coax

[skyboltone]

Greetings Lads:
Let's go find some of this stuff and split the cost somehow. Measuring with this:
http://www.aade.com/lcmeter.htm

I get 16.5pf per foot!!
Commscope 73501P type 735 Plenum 9300851 125C 26AWG made in USA

I got 15 feet someplace. I've never seen any other Commscope product.

Dan H

[stoo]

That's cable tv coax. It's high grade stuff like they might use in the "Head End" (like central office in Telco).
Stew

[paulster]

I've been using the Sommer Onyx 2025 for a while, which is pretty easy to get, and nice and thin. It's figure 8 so you can use it for a send/return pair, or separate it out into two cores.

Manufacturer's spec is 60pF/m, which would equate to 18pF/foot.

http://www.sommercable.com/2__produkte/ ... _0101.html

[odourboy]

Lava MINI ELC is 15 pF per foot. Mark would probably cut and sell you any length you want. Thicker than RG174 I think, but pretty flexible.

http://www.lavacable.com/Lava%20Cable.htm

[skyboltone]

Lava MINI ELC is 15 pF per foot. Mark would probably cut and sell you any length you want. Thicker than RG174 I think, but pretty flexible.

http://www.lavacable.com/Lava%20Cable.htm

Wow, thanks for that. I had often thought through the years of setting up a store for stuff like that. The cable guy indeed. I would love to read a shootout between his instrument cable and the Klotz that Weber sells over at Kendrick.

The Commscope is sure nice for what we do because it's so tiny. Barely bigger than an RG 174/178.

Dan

[Funkalicousgroove]

I get 11pf/ft from my gepco digital audio cable, it's foil shield.

[skyboltone]

I get 11pf/ft from my gepco digital audio cable, it's foil shield.

And the winner is!!!! Wow, that's pretty low.

I'm still digging through my stack of stuff and I found some cable that I stripped out of a Gates BC-1J 1KW broadcast transmitter. It appears to be just a woven basket shield around a single plastic insulated wire. I thought it should have been quite low because it had no outer sheath. Alas it measured terrible. 75pf/foot.

[Allynmey]

I get 11pf/ft from my gepco digital audio cable, it's foil shield.

Funk, how much and where to buy?

[theundeadelvis]

Would this wire work? http://store.haveinc.com/Ebus30/Parts/P ... PVDM230BLA

[skyboltone]

Would this wire work? http://store.haveinc.com/Ebus30/Parts/P ... PVDM230BLA

I don't know why not. At 50' minimum order you'll have a lifetime supply.

[jaysg]

please delete post

[JammyDodger]

To All,

The capacitance of a cable is related to it's rated impedance.

I've attached the math involved in this... but, in general the higher the impedance, the lower the capacitance.

The highest normally available cable is RG63 which is 125 Ohms. Belden makes this as do others. This cable will run <10pF per ft.

Cheers, Mike

[Funkalicousgroove]

allyn, I have 1000 ft of this stuff, if you want some.

I buy it direct from gepco.

[Allynmey]

Funk, I'll grab a little when you ship the stuff.

[skyboltone]

To All,

The capacitance of a cable is related to it's rated impedance.

I've attached the math involved in this... but, in general the higher the impedance, the lower the capacitance.

The highest normally available cable is RG63 which is 125 Ohms. Belden makes this as do others. This cable will run <10pF per ft.

Cheers, Mike

Hi Mike: Sounds good on paper. I can show you perhaps 5 different 50 ohm cables (that's just the ones I have the most of) and they will all measure differently. RG-58 for instance at about 45pf per foot. RG-174 at around 30pf per foot. I'll measure some high quality foam core RG-8 when next I'm at the shop.