[Boatanchors] Re: Dow Key Relay Identification

[Garey Barrell]

Roger -

You can't see it because it is the inner conductor of the connector on 
the receive side.   On the standard relay this is just a solid pin with 
the relay contact on one end and the female coax connector center 
conductor on the other.  On the high isolation type there is a break in 
the center "inside" the threaded connector body.

The isolation type has a much longer connector body on the receive 
side.   The isolation is spec'd at 40 dB at 50 MHz for the standard 
type, and 85 dB for the high isolation "G" type.    So 40 dB down from 
100W is 0.01 Watt or 10 mW.  A healthy signal, but most receivers should 
be able to stand that.  Plus the isolation would be higher still at 30 
MHz and below.

If you measure the resistance of the high isolation contact from relay 
end to the female coax connector socket, it will measure open with the 
relay coil energized, i.e., in "transmit".   If you de-energize the 
relay, you will measure very near 0 ohms from the "arm" coax connector 
socket to the "receive" socket.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://hr99.home.mindspring.com/R-4C_Servicez/>



RKofler at aol.com wrote:

>I must have the unisolated relay because I can't see where either connector 
>has any moving parts. What should the contact spacing be when the relay is in 
>receive or unenergized position? How important is the difference between the 
>isolated and unisolated models? I probably will never run more than 100W through 
>it.
>Thanks
>Roger K7DDG
>
>  
>