[Elecraft] K3 Receiver Protection

[Joe Subich, W4TV]

A simple interlock can be built with a single quad XOR gate package,
half a dual 4 input NOR package and a few transistors/resistors if one
is driving the inhibit input.  Add half of a quad NOR gate package if
you want to disable PTT.

73,

    ... Joe, W4TV


On 2014-06-01 10:54 AM, Joe Subich, W4TV wrote:
>
>> How are others using SO2R avoiding same band transmission and
>> subsequent receiver damage?
>
> SO2R controllers like the microHAM MK2R+ have built-in "same band"
> interlocks that prevent PTT if both rigs are on the same band or
> if one rig stops responding to control polling.  Some of the "contest"
> software also prevents selecting the same band on both rigs.
>
> I have not seen any dedicated hardware that compares "band data" from
> the K3 or Yaesu rigs and opens the PTT lines or asserts the inhibit
> lines if both rigs are on the same band but it would not be difficult
> to do so with a PIC or even a programmable gate array.
>
> 73,
>
>     ... Joe, W4TV
>
>
> On 2014-06-01 12:04 AM, Jeff via Elecraft wrote:
>>
>> 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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