[Elecraft] Question about KRX3 install

[Cady, Fred]

Hi Tom,
Here is how I have it figured out:

When you install your Sub receiver you must chose an antenna configuration and then physically connect a TMP cable inside the K3 from the Sub receiver's J92 antenna input to one of two places.  First, you can connect the receiver to the K3's ATU, which allows the Sub receiver to either share the same antenna the Main receiver is using (ANT1, ANT 2, or RX ANT IN if a KXV3A is installed).  You may also choose to have the Sub receiver use whichever antenna the Main receiver is NOT using (ANT 2 if Main is using ANT1, or vice versa).  You must set CONFIG:KRX3 Ant=Atu for this option.  This may be your best choice for all around operating with a variety of antennas.  Section 5.10.3 shows antenna selections when you make this choice.

The second choice is to connect the receiver to a separate auxiliary RF BNC antenna connector.  In this case, the Sub receiver can share an antenna with the Main or it can use a different antenna connected to the AUX RF BNC.  Set CONFIG:KRX3 Ant=bnc if you choose this option.  This may be your best choice for diversity receiver operation with specialized receive antennas.  Section 5.10.4 gives diagrams showing antenna choices for this configuration.
Note: You cannot transmit on the AUX RF BNC.

I think some of the confusion comes from what the K3 displays when you switch the Sub's antenna.  When sharing the main antenna, it shows MAIN;  when switched to the other choice, it shows AUX but that doesn't necessarily mean the AUX BNC.  In this case it depends how you have your Sub receiver connected -- Ant=Atu or Ant=bnc.

Cheers,
Fred KE7X

Author of:
"The Elecraft K3: Design, Configuration and Operation 2nd ed"
"The Elecraft KX3 - Going for the summit"
"The Elecraft KPA500 and KAT500 - the K-Line Dream Station"
Printed, coil bound copies of these are all available at www.elecraft.com
KPA500 and KAT500 Quick Set Up Guide
http://www.ke7x.com/home/k-line-introduction-and-set-up-guide
KAT500 and KXPA500 Tuner Operation
http://www.ke7x.com/home/kat500-and-kxpa100-tuners

"The Elecraft KXPA100, PX3 and 2M/4M Transverters - Assembling the KX3-Line Station" available at www.lulu.com.

("The Elecraft K3S and P3" in preparation)

> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of
> Thomas Schaefer
> Sent: Saturday, June 13, 2015 8:30 AM
> To: Elecraft at mailman.qth.net
> Subject: [Elecraft] Question about KRX3 install
> 
> Hello,
> 
> I have a question about the sub receiver I installed this weekend.
> 
> The procedure for the aux antenna states you have two options for an
> AUX antenna, either put the BNC in the back of the radio OR connect
> though the KAT3 so the non used antenna port is the AUX.
> 
> From reading the book, I presumed this is an optional step. In other
> words, I can do the BNC jack, connect the KRX3 to the KAT3 or NEITHER.
> 
> I choose neither. I hope I got that right.
> 
> My question is that when I tell the radio that I am using the KRX3, I
> select from Not Installed, AUX-BNC or AUX-KAT (paraphrasing). Well,
> since I did not do either of what I consider optional steps, neither
> one of those makes sense to select. I selected the KAT option but if
> the steps are really optional, I would thing the CONFIG options should
> be ON-NoAUX, AUX-BNC or AUX-KAT.
> 
> Can someone clarify if the AUX steps are indeed optional and if so,
> which KRX3 option should I select in CONFIG.
> 
> Thanks,
> 
> Tom NY4I
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Tom Schaefer
> 727-437-2771
> 
> P.S. Drowning in email? I use SaneBox to instantly clean up my Inbox:
> http://sanebox.com/t/gdaz7
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> 
> 
> 
> 
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