[Elecraft] K3 Ant2 Issue With KPA500

[James Bennett]

Did a lot of head scratching and perusing not only the Elecraft K3 manual but also the KE7X book on the K3. No question about it - I need a device like that one from Array Solutions. The price is good and probably will work. 

My concern is that if I put it in the line between my vertical and ANT2, I can then never use the vertical for transmitting, something I rarely do, but all it would take would be one time and bye-bye $55+ dollars. I thought I could place a high quality coax switch in the line, with the common running to the vertical, and then one side direct to ANT2 and the other switch position through the Front End Protector (FEP) to the Aux BNC antenna connector. That brings up some ugliness in that I’d have to re-wire my Sub Receiver to have it go to the Aux BNC connector rather than the KAT3 ATU as it does now. Ughhh…

I diagrammed it on paper and came up with another idea. What “should” work is to have a coax switch that completely takes the FEP out of the circuit, basically a “ganged” coax switch, for lack of a better term. When set to one position, the FEP is in the circuit between the vertical and ANT2, and when in the other position, the vertical would be connected directly to ANT2. This action could be done with two individual switches, but would make things easier if I could locate an SO-239-based coax switch that switches two ports at the same time. Anyone know if such a device exists, and it so, where it might be sold?

Thanks, Jim / W6JHB


> On   Tuesday, May 5, 2015, at  Tuesday, 5:30 AM, Harry Yingst <hlyingst at yahoo.com> wrote:
> 
> Here is something I did out of curiosity...
> 
> 
> I hooked my RX antenna to the input of a wattmeter and the output of the wattmeter into a dummy load.
> 
> I then then observed how much power was being sent back to me through the RX antenna.
> 
> 
> It may not be accurate, but it was enough for me to install a front end protector. (I got an AS_RXFEP from Array Solutions)
> 
> 
> 
> From: James Bennett <w6jhb at me.com>
> To: Elecraft Reflector Reflector <elecraft at mailman.qth.net> 
> Sent: Monday, May 4, 2015 11:57 PM
> Subject: [Elecraft] K3 Ant2 Issue With KPA500
> 
> The situation: I've got an 88 foot long doublet at 45 feet, fed with 110 feet of ladder line, a 4:1 balun, and six feet of RG8-X connected to ANT1. Also got a Hustler 6BTV mounted on the ground in the back yard with 75 feet of RG8 running to the ANT2 connector. 
> 
> When running the K3 on low power I have no problem using diversity mode. However, when the power is increased, the internal relays start chattering in the K3. I understand that this the K3's way of protecting itself from too much RF on ANT2 - it temporarily disconnects ANT2. The amount of K3 output needed to cause the relay chatter depends on the band I'm on. Sometimes 20 watts will do it, other times I'm good at 100 watts - depends on the band. When I turn on the KPA500 it'll chatter on EVERY band. Obviously it's because the vertical (ANT2) is less than 50 feet from the doublet - I get that.
> 
> My question(s) - can I assume that this relay chatter is not good, that it will cause problems if I continue running QRO in diversity mode? 
> 
> If this in fact is a bad thing, how do others run QRO and diversity? Are there devices on the market that can be put in the ANT2 line that can handle the RF? I could do it with a manual coax switch but that kinda puts a crimp in QSK operating.
> 
> Jim / W6JHB
> Folsom, CA
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