[Elecraft] K3 Sub Receiver and protecting the Sub RX input

[dmb at lightstream.net]

I've been using the Array Solutions device (AS-RXFEP) for over a year on
my K3. I have a homebrew magnetic loop connected to the K3 sub rx, with
the loop located about 15 feet from the transmitting ground plane (about
6' above ground). Prior to installing the AS-RXFEP, the sub rx COR would
be triggered with anything over about 25 watts. With the AS-RXFEP in
place, I can run the KPA-500 at 600W without the COR ever tripping.

The S-RXFEP has no relays, requires no supply voltage, and is simply
installed in between the rx antenna and the sub rx antenna input via a
pair of SO-239 connectors.

73, Dale
WA8SRA




> There are a couple of things to think about. How much power are you
> running?
> How close is the receive antenna to your transmitting antenna? Does your
> receive only antenna possibly have an interface that can connect to the
> key
> out of the K3? (My Pixel Loop antenna has such a device)
>
> You can also try it out and listen for a clicking noise from the carrier
> operated relay inside the K3. It is a protective relay that will energize
> if
> it sees too much power coming in on the RX antenna input. If you hear it
> clicking then it is a good idea to consider additional protection.
>
> There are external protective devices available that you can purchase. DX
> Engineering and Array Solutions have them I think there are others out
> there.
>
> http://www.dxengineering.com/search/department/antennas/section/receive-antennas-and-arrays/product-line/dx-engineering-receiver-guard-5000-electronic-rf-limiters?autoview=SKU&N=4294953330%2B4294951218&sortby=Default&sortorder=Ascending
>
> http://www.arraysolutions.com/Products/as_rxfep.htm
>
> 73,
> Mike K2MK
>
>
> Elecraft mailing list wrote
>> I ordered the sub receiver and in the conversation with Elecraft I was
>> informed that it is good idea to build a device that would short the
>> dedicated RX antenna to ground to protect it during transmit.
>> The simple way would be a relay but I'd rather not hear a relay click
>> with
>> each transmission.
>> I was wondering what others are using to accomplish this.
>>
>> Thank you
>
>