Author Topic: Help find a low capacitance miniature coax cable?  (Read 2599 times)

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Offline cvancTopic starter

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Help find a low capacitance miniature coax cable?
« on: March 14, 2020, 04:24:19 pm »
Currently using RG174 which is tiny and flexible and 31pF/foot.  I've looked for other small coax with less capacitance but came up empty.

I can use something larger if needed, but all I've found that has significantly lower C was almost a half inch in diameter; that's too big.

Am I missing a good candidate somewhere, or is RG174 about as good as it gets?

Impedance does not matter - it will carry analog audio.  Thanks...
« Last Edit: March 14, 2020, 04:30:42 pm by cvanc »
 

Offline Mechatrommer

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Re: Help find a low capacitance miniature coax cable?
« Reply #1 on: March 14, 2020, 04:58:15 pm »
why do you care at capacitance if its only for audio? there are much smaller 1.13mm dia coax in ebay, but about the same capacitance as stated. i think a pair of audio or twisted wires is much lower capacitance.
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Offline cvancTopic starter

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Re: Help find a low capacitance miniature coax cable?
« Reply #2 on: March 14, 2020, 05:08:21 pm »
why do you care at capacitance if its only for audio?

Fairly long runs; they're about 30ft/10m
 

Offline daqq

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Re: Help find a low capacitance miniature coax cable?
« Reply #3 on: March 14, 2020, 06:27:24 pm »
Try the higher Z0 ones, such as https://www.mouser.sk/datasheet/2/46/89269-84006.pdf , with 12.8pF/ft.
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Online Someone

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Re: Help find a low capacitance miniature coax cable?
« Reply #4 on: March 15, 2020, 07:47:55 am »
why do you care at capacitance if its only for audio?
Fairly long runs; they're about 30ft/10m
Audio bandwidth into 1nF still isn't hard and would be typical of normal balanced+shielded audio cable for those lengths.
 
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Offline Conrad Hoffman

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Re: Help find a low capacitance miniature coax cable?
« Reply #5 on: March 15, 2020, 01:51:38 pm »
Look at Belden 8421 and similar. It's larger, but quite flexible.
 
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Offline jonpaul

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Re: Help find a low capacitance miniature coax cable?
« Reply #6 on: March 15, 2020, 02:21:03 pm »
Audio bandwidth or digital audio eg AES/EBU, AES3id, SP/DIF?

There is a trade off between cable diameter and capacitance.

Impossible to make a practical cable of very small OD and very low C.

Jean-Paul



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Offline TimFox

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Re: Help find a low capacitance miniature coax cable?
« Reply #7 on: March 15, 2020, 02:31:58 pm »
RG-174 has a solid polyethylene dielectric, which has the highest dielectric constant of the common coax insulators.
For lower capacitance, you can use foam polyethylene, teflon, or foam teflon to get lower dielectric constants and smaller capacitance for a given diameter.
 
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