[Boatanchors] Re: Dow Key Relay Identification

[Gary Schafer]

Hi Roger,

If you have the isolated type the coax connector on the receive side 
will be longer by I think 3/4" than the transmit one.

You can easily check by removing the little press in cap on the end of 
the relay between the connectors. When you move the contact that 
normally gets moved by the coil, it looks like a long flat spring, you 
will see the fixed contact on the receive connector move out about a 
1/16" or less. The fixed contact on the transmit connector does not move.

The little moving contact end on the receive connector opens inside the 
barrel of the connector and also shorts to ground on transmit.

I have found that most of those are more problems than they are worth 
though. What usually happens is the contact inside the barrel does not 
always make well in receive mode. There is no way to fix them as you 
can't get at it to clean the contact.
I take out the whole barrel and put in one the same as is used on the 
transmit side so it has solid contact. You don't get as much receive 
isolation but it works. Somewhere around an 1/8" contact clearance will 
be ok.

73
Gary  K4FMX

If it is not the isolated type then there will be no moving contact on 
the receive side.

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
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