[Elecraft] Antenna question

[Mike K2MK]

Hi George,

I'm not 100% sure but I don't think your SUB RX has to be ON to be damaged.
I believe that just connecting an antenna to the AUX RF input will allow RF
into the SUB RX. 

There is an internal protective device on the input to the SUB RX called a
carrier operated relay (COR). You can see it in the manual in some of the
block diagrams. When you get your vertical you can try transmitting with the
yagi at low power and gradually increase your power. If you hear a clicking
sound you are tripping the COR. That's your positive indication that you
should either decrease power or add external protection. 

There are devices available to put in your SUB RX antenna line for overload
protection but you can also use the KEY OUT signal to energize a relay to
disconnect your SUB RX antenna. There is also a lower current KEY OUT signal
on pin 10 of the accessory connector. You can use that to trip a low current
device that in turn activates a relay.

73,
Mike K2MK



George A. Thornton-2 wrote
> This might be a stupid question, but here goes.
> 
> I have a small lot.  I currently am using a 3 element Yagi that barely
> fits on the property.  I was thinking about getting a vertical as a second
> HF antenna.  If I put it up it is going to have to be pretty close to the
> Yagi.
> 
> I have a dual receive K3.  If I have both receivers going, one on each
> channel, and I broadcast on one of these antennas, am I in any danger of
> overloading and frying the other receiver?





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