My first 10BASE5 network segment

Ian McLaughlin ian at
Fri Aug 26 10:00:35 CDT 2016

> On Aug 26, 2016, at 7:56 AM, Paul Koning <paulkoning at> wrote:
> That reminds me of an amusing error in a 1980s trade rag for DEC users ("The DEC Professional").  It discussed how you could mix 10Base5 and 10Base2 hosts by coupling the two size coax cables through an N to BNC adapter.  That's fine so long as you use the 10Base2 limits.  But instead of a barrel adapter, the article had a photo showing a T connector at the transition, with a "terminator" attached to it.  So that network had three terminators: one at each end and one in the middle.  I suspect it didn't work, or at least quite poorly.

Are you sure about that? I’m by no means an RF expert, but, for example, the cable TV plant is a huge tree of cables and splitters. They advise that all open sockets should have a 75 ohm terminator attached to them. Even this whole mess with 75 ohm terminators everywhere, and the characteristic impedance of the network is still 75 ohm. Remember this is AC impedance, not DC resistance.


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