[Elecraft] Re: K3 KRX3 - BNC or KAT3?

[David Ferrington, M0XDF]

Wayne (and anyone else who has installed the KRX3), there are some  
questions buried in here, marked with 2 ** to help spot them.

Hmmmm, from original reading of the Owners manual and discussions on  
here last year, I thought selection of either the KAT3 non-Tx ANT1/2  
or the Aux BNC Jack (AUX.RF) would be via software.

** I assume that this has proven to be a problem and so now it's a  
'choose at installation time' option (as per KRX3 installation manual)?

Even now, reading the Owners Manual, the diagrams on pg 41 and 42 (of  
rev D1) suggest the AUX.RF is connected to SA4, along with the KAT3  
connection.

** Should the horizontal line from SA4 to KAT3 be dotted as well, with  
a note saying installation option (choose one of two)?


I wish to use 2 antennas and may transmit on either and I had planned  
to be able to listen on both and then transmit on one of them. So for  
me, using the KAT3 method appears to be best. Issue with COR and delay  
etc. won't come into it (I think).

However, the work to install the AUX.RF connector is  
'significant' (well, ok, it’s a bit more, involving removing side  
panels etc.) so I'd like to do this while I'm installing the KRX3,  
just so it's done.

But then, not connect the TMP lead to the KRX3, but sleeve the  
connector and 'tuck' it out of the way somewhere.

** Is it possible/acceptable to install the AUX.RF BNC jack, but not  
connect it to anything?
** Would there be any implications of stray RF on the lead to worry  
about?

And, if at some point in the future, I choose to use AUX.RF, switch  
the lead to the KAT3 with the AUX.RF lead, again sleeving the KAT3 TMP  
to avoid any shorts.

** Again, is there any issue with leaving the KAT3 lead connected to  
the KAT3, but not connected to the KRX3?

** Perhaps it would be advisable to install an additional TMP socket  
with both pin and shield grounded and to connect the unused TMP lead  
to it?

** Might that be a future mod for you, providing an unused TMP socket  
just to terminate the unused lead?

-- 
There is no pillow so soft as a clear conscience. -French proverb

On 14 Aug 2008, at 00:19, wayne burdick wrote:

> Tony, N2TK wrote:
>
> > Is it recommended to hook up the BNC connector on the back to
> > the KRX3 or to use the second SO-239 on the K3 or does it make any
> > difference?
>
> Hi Tony,
>
> If you have a KAT3, you can optionally use the non-transmit KAT3  
> antenna (which might be ANT1 or ANT2 at any given time) as the sub  
> receiver's secondary antenna source. If not, you'll need to use the  
> BNC jack.
>
> The BNC jack is recommended anyway, and an appropriate cable is  
> supplied with the KRX3 module. It's the way we set up factory-built  
> K3s. It's more flexible, because you can connect a receive-only  
> antenna for use with the sub receiver that is well-isolated from  
> your transmit antennas. (Physical and electrical isolation for a  
> receive antenna is good practice in general.)
>
> If you don't have a special RX antenna for use with the sub  
> receiver, but you do have two antennas connected (to ANT1 and ANT2),  
> the KAT3 non-transmit antenna might be a better choice.
>
> This selection has no impact on *shared* use of the main antenna by  
> the sub receiver. You can do that in any case.
>
>
> > Most of the time I will be using the same antenna for both
> > receivers.
>
> That's the "shared" case.
>
>
> > When the K3 has the capability of having the two
> > receivers on two different bands I would like to monitor another
> > band with a second antenna. An example would
> > be to monitor 6M. Figured I could use the second SO-239 for this.
>
> Either the KAT3 non-transmit antenna or the BNC jack would work. If  
> you use the KAT3 non-transmit antenna, be sure to keep the antennas  
> on ANT1 and ANT2 very well isolated so the sub receiver's carrier- 
> operated relay doesn't get triggered when you transmit.
>
>
> > I assume that when I am listening to both receivers on the same band
> > that if I am using the receive antenna input the receive antenna
> > will go to both receivers. Is this correct?
>
> Yes.