Montrose coax - Revision history

Thomas: some more stats

2018-10-24T19:41:27Z

some more stats

← Older revision		Revision as of 19:41, 24 October 2018
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	</gallery>		</gallery>

	== ~~to be added~~ ==		== Further measurements ==

	~~There's a plan to characterize the coax with a spectrum analyzer and a noise source~~.		Attenuation/100 meters:
			@26MHz=1.33dB,
			@50MHz=1.81dB,
			@70MHz=1.99dB,
			@145MHz=3.35dB.

Thomastheo at 20:31, 30 September 2017

2017-09-30T20:31:46Z

← Older revision		Revision as of 20:31, 30 September 2017
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	}}		}}

	One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on this very same coax, but so far nothing is out there to be found. In an effort to remedy that, here's what we managed to figure out for ourselves.		One of our participants (thanks gert!) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on this very same coax, but so far nothing is out there to be found. In an effort to remedy that, here's what we managed to figure out for ourselves.

	The cable is marked as follows:		The cable is marked as follows:

Thomastheo at 19:19, 30 September 2017

2017-09-30T19:19:28Z

← Older revision		Revision as of 19:19, 30 September 2017
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	MONTROSE / CDT 16 AWG (UL) CL2P SHIELDED COAXIAL 125C CSA CXC 60C FT4 & FT6		MONTROSE / CDT 16 AWG (UL) CL2P SHIELDED COAXIAL 125C CSA CXC 60C FT4 & FT6

	It's 50 ohm coax, ~~and~~ has a braid ~~and~~ foil shielding. The velocity factor is 0.85, suggesting a foam polyethylene dielectric. The exterior is supposedly UV resistant.		It's 50 ohm coax, it has a braid/foil shielding, and a stranded center conductor. The velocity factor is 0.85, suggesting a foam polyethylene dielectric. The exterior is supposedly UV resistant.

Thomastheo at 19:18, 30 September 2017

2017-09-30T19:18:14Z

← Older revision		Revision as of 19:18, 30 September 2017
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	}}		}}

	One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on ~~the~~ very same ~~cable~~, but so far nothing is out there ~~on this stuff~~. In an effort to remedy that, here's what we managed to figure out		One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on this very same coax, but so far nothing is out there to be found. In an effort to remedy that, here's what we managed to figure out for ourselves.

	The cable is marked as follows:		The cable is marked as follows:
Line 29:		Line 29:

	</gallery>		</gallery>

			== to be added ==

			There's a plan to characterize the coax with a spectrum analyzer and a noise source.

Thomastheo at 17:46, 30 September 2017

2017-09-30T17:46:51Z

← Older revision		Revision as of 17:46, 30 September 2017
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	\|Contact=thomas		\|Contact=thomas
	}}		}}


	One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on the very same cable, but so far nothing is out there on this stuff. In an effort to remedy that, here's what we managed to figure out		One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on the very same cable, but so far nothing is out there on this stuff. In an effort to remedy that, here's what we managed to figure out

Thomastheo at 17:46, 30 September 2017

2017-09-30T17:46:34Z

← Older revision		Revision as of 17:46, 30 September 2017
Line 7:		Line 7:
	}}		}}

	~~== The coax itself ==~~

	One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on the very same cable, but so far nothing is out there on this stuff. In an effort to remedy that, here's what we managed to figure out		One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on the very same cable, but so far nothing is out there on this stuff. In an effort to remedy that, here's what we managed to figure out

Thomastheo: Created page with " {{Project |Name=Montrose coax |Picture=Montrosecoax.jpg |Omschrijving=Mystery coax specifications. |Status=Completed |Contact=thomas }} == The coax itself =..."

2017-09-30T17:46:14Z

Created page with " {{Project |Name=Montrose coax |Picture=Montrosecoax.jpg |Omschrijving=Mystery coax specifications. |Status=Completed |Contact=thomas }} == The coax itself =..."

New page

{{Project
|Name=Montrose coax
|Picture=Montrosecoax.jpg
|Omschrijving=Mystery coax specifications.
|Status=Completed
|Contact=thomas
}}

== The coax itself ==

One of our participants (gert) showed up with a load of old (but seemingly high quality) coaxial cable from a data center. There are other people online looking for info on the very same cable, but so far nothing is out there on this stuff. In an effort to remedy that, here's what we managed to figure out

The cable is marked as follows:

MONTROSE / CDT 16 AWG (UL) CL2P SHIELDED COAXIAL 125C CSA CXC 60C FT4 & FT6

It's 50 ohm coax, and has a braid and foil shielding. The velocity factor is 0.85, suggesting a foam polyethylene dielectric. The exterior is supposedly UV resistant.

== Measurement ==

The velocity factor was measured with time domain reflectometry. I built a cheap and easy fast-rising-edge pulse generator after a design by Alan Wolke (W2AEW). [https://www.youtube.com/watch?v=9cP6w2odGUc See his video for details].

My version is a dip 74AC14 with all necessary components, connections and even an SMA connector soldered directly onto the chip. The 74AC14 offers six inverting schmitt triggers. The first one is used to invert an incoming signal, driving the remaining five schmitt triggers, which are ganged together and connected to the coax under test via the SMA. I'm just using a signal generator to provide the first schmitt trigger with a square wave, but you can implement Alan's solution of using the first Schmitt trigger in an oscillator with the addition of just a single resistor and capacitor.

<gallery>
File:Tdr.png|The complete circuit, all soldered onto the dip chip.
File:Tdr_risetime.png|The rising edge, on the order of a few nanoseconds.
File:Coaxreflection.png|The actual measurement, showing a round trip of 136.4ns. The actual length of the cable is 17.3m, which works out to a velocity factor of 0.85 or so.

</gallery>