10BASE5 Transceivers

[HoJoPo]

I have an entire spool (700 feet?) of yellow thicknet cable. I was considering using it for amateur radio, as the propagation characteristics are similar to RG-8. And the spool I have is underground conduit rated (not direct bury, though).

 

[lowen]

...
It's not your classic "frozen yellow garden hose" and it's not entirely to the spec but with the longest piece being only 30' long I doubt I'll be running into signal loss issues due to the length.

Straight RG-8 and even RG-214 aren't as tightly controlled for overall outside diameter as Belden 9880 is; if you use N connectors and N connector pass-throughs for the MAU's this will work fine. Vampire taps may or may not work, since they rely on the cable OD tolerance being tight.

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I have an entire spool (700 feet?) of yellow thicknet cable. I was considering using it for amateur radio, as the propagation characteristics are similar to RG-8. And the spool I have is underground conduit rated (not direct bury, though).

I would think that how well it will work would depend on the frequency and power level. RG-214 or Belden 9914 would likely be a much better choice. 9880 might handle 1,500W PEP on 40 meters and it might not. When in doubt, go larger; although you probably wouldn't want something like the recently-discontinued Andrew LDF12-50 (2-1/4" corrugated foam dielectric semi-flexible cable; the hole in the center conductor is large enough to thread 9880 through it, and it can handle 250KW PEP). (I have a short cutoff piece if anybody wants to see what such a thing looks like....)

But if you have 9880 and it works for you.... it certainly would be a talking point when somebody visits you and asks about the banded yellow cable! Tell them you have a tiger in your rig!

 

[hornbetw]

NeXT,

That "free" coax from the cable company should be 75 Ohm not 50 Ohm. 10BASE2 & 5 are 50 Ohm. I would expect that coax to work poorly if at all.

Tom

 

[NeXT]

Again, not close to spec but it doesn't hurt to try anyways.

 

[HoJoPo]

I would think that how well it will work would depend on the frequency and power level. RG-214 or Belden 9914 would likely be a much better choice. 9880 might handle 1,500W PEP on 40 meters and it might not. When in doubt, go larger; although you probably wouldn't want something like the recently-discontinued Andrew LDF12-50 (2-1/4" corrugated foam dielectric semi-flexible cable; the hole in the center conductor is large enough to thread 9880 through it, and it can handle 250KW PEP). (I have a short cutoff piece if anybody wants to see what such a thing looks like....)

But if you have 9880 and it works for you.... it certainly would be a talking point when somebody visits you and asks about the banded yellow cable! Tell them you have a tiger in your rig!

With a solid copper center conductor and four layer shield (foil, braid, foil, braid) on the thicknet cable, I think it'll hold up to the 100W power I run on my rig just fine.

 

[lowen]

Again, not close to spec but it doesn't hurt to try anyways.

For a 30' run 75 ohm RG-11 (which is what yours looks like) you might be ok; just use 75 ohm terminators with it. Even though the MAU's are rated 50 ohms, there will be less of a problem using 50 ohm MAU's with a properly terminated 75 ohm backbone than with a 75 ohm backbone terminated with 50 ohms. That is, a MAU can probably better deal with the standing-wave ratio (SWR) of 1.5 once (MAU tap to 75 ohm backbone) better than twice (1.5 at tap and 1.5 at terminators). The incidence of collisions will go up.

It will be interesting to see if there really is a problem.

Now, the vampire tap may or may not work with the smaller center conductor of RG-11; but it's worth a try.