[W2CRA] Ohms Opinion Exercise

[William Powell]

All,

Measured control to transmitter phone line and thought it would be
neat to drop it here as a practical exercise:
At the control site there is a ~12V power supply that connects to the
phone line via relay contacts.  When the transmit site interface sees
voltage on the phone line it activated the transmitter.
We need to replace the transmit site interface as it is not documented
and made from "unobtanium" (Google it if you must).
At the TRANSMITTER end I measure the following:
Voltage across the phone with everything connected as normal:
	12.25V
Voltage across the phone with everything DISconnected: 
	12.39V
Voltage across the phone with it terminated with a 100.5 Ohm resistor:
	5.66V
Voltage across 100.5 Ohm resistor when placed in SERIES with the
normal setup:
	0.20V

What is the nominal resistance of the phone line?
What are the parameters required of the replacement interface relay:
 - Coil resistance?
 - Coil voltage?

To make things interesting find me a relay that:]
 - Meets the needs above,
 - Plugs into a socket,
 - Has at least 5000 V isolation between coil and contacts,
 - Reliable to 1,000,000+ operations,
and
 - Where we can get such a beastie.

GL es 73,
Bill - WB1GOT