[Elecraft] K3 Sub Receiver Antenna

[Ian White GM3SEK]

Bill N3KKM wrote:
>The K3 manual indicates that the Sub Receiver's AUX antenna must be 
>well-isolated from the transmit antenna to avoid activating the sub's 
>carrier carrier-operated relay. From a practical, real world 
>standpoint, what is "well isolated?"
>

The easiest way to make sure is to check the RF power level from the aux 
antenna using a simple "expendable" diode detector, before connecting 
the antenna to the K3.

The detector can be made in a couple of minutes from a 47 ohm resistor, 
a 1N4148 or similar diode and a 0.01uF ceramic capacitor. The rectified 
DC output is connected to a DMM,

Any DC reading below about 1.0V will be fine.

N4ZR has also published a passive protection circuit at:

http://wiki.contesting.com/index.php/Basic_Receiver_Protection


Next time I have the covers off the K3, I plan to install at least one 
+12V DC output with TX/RX switching, for use with preamps and protection 
relays.


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek