[time-nuts] 50 vs 75 ohm cables

Poul-Henning Kamp phk at phk.freebsd.dk
Thu May 10 16:52:50 EDT 2007


In message <E1HmBTB-0006jt-SN at febo.com>, John Day writes:

>So 75 ohms as we 
>know it now is a compromise between the low attenuation 77 ohms and 
>the 73 ohm dipole feed-point.

I can confirm that the choice of 75 Ohm for telecom use indeed
is because of the low attenuation.  The first use of coax was
for "Carrier Frequency" systems, where a number of telephone
conversations were AM modulated on individual carriers, usually
4 kHz apart.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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