[Elecraft] K3 Receiver Protection

[Win Kriegl DK9IP/KH7CD]

Hi Jeff,

I have done that by comparing BAND DATA signals from both K3s using a 
74HC688 8-Bit Comparator. When both BAND DATA signals are equal the P=Q 
output from the HC688 disables transmitting on both K3s (TXinh). I used 
the HC688 because I have decimal BAND DATA signals from my band filter.
If you want 12V logic or only need 4 Bit (BCD BAND DATA) you can use 
CMOS 4063 (4-Bit Comparator) as well.

This circuit saved K3 frontend several times  :-)

73, Win DK9IP


Am 01.06.2014 06:04, schrieb Jeff via Elecraft:
>
> My station consists of two K-3's, each with a dedicated legal limit amplifier and SteppIr antenna. To minimize interference between bands I am using Array Solutions Bandpass filters. However, if both rigs accidentally wind up on the same band I run the risk of overloading the front end of the opposite rig and damaging the receiver (which I've done once...). Does anyone have a way of taking the band data information and disabling transmit capability on both rigs if they are on the same band? How are others using SO2R avoiding same band transmission and subsequent receiver damage? Anyone have any experience with the Array Solutions AS-RXFEP front end protector?
>
> Thanks,
> Jeff Larimore
> K0RG
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