Rerouting the KRX3 AUX Input from the Rear BNC to the KAT3

[Sverre Holm (LA3ZA)]

When I built my K3 some years ago I routed the second receiver's AUX antenna input to the rear panel BNC connector. But now I have changed my mind and want to route it through the KAT3 instead, in order to try diversity reception.

How complex is this to accomplish? I know I need to plug in another 30 cm tmp cable to the KRX3 board than the one I am using now. But how many panels do I need to remove from the K3? The top I'm sure I need to remove, but is that enough?

[Arie Kleingeld PA3A-2]

Sverre,

just curious, why would you like to route the 2nd RX through the KAT3?
What is it that you trying to accomplish?

Arie PA3A

Op 1-4-2016 om 19:56 schreef Sverre Holm (LA3ZA):

> When I built my K3 some years ago I routed the second receiver's AUX antenna
> input to the rear panel BNC connector. But now I have changed my mind and
> want to route it through the KAT3 instead, in order to try diversity
> reception.
>
> How complex is this to accomplish? I know I need to plug in another 30 cm
> tmp cable to the KRX3 board than the one I am using now. But how many panels
> do I need to remove from the K3? The top I'm sure I need to remove, but is
> that enough?
>
>
>
>
>
> -----
> Sverre, LA3ZA
>

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[Nr4c]

I put both cables in at build time. Unused one is routed into the shielded area and secured to the shield.

Easy to re-configure. Take off top and change cables. A pair of surgical clamps may be useful.

Sent from my iPhone
...nr4c. bill

> On Apr 1, 2016, at 1:56 PM, Sverre Holm (LA3ZA) <[hidden email]> wrote:
>
> When I built my K3 some years ago I routed the second receiver's AUX antenna
> input to the rear panel BNC connector. But now I have changed my mind and
> want to route it through the KAT3 instead, in order to try diversity
> reception.
>
> How complex is this to accomplish? I know I need to plug in another 30 cm
> tmp cable to the KRX3 board than the one I am using now. But how many panels
> do I need to remove from the K3? The top I'm sure I need to remove, but is
> that enough?
>
>
>
>
>
> -----
> Sverre, LA3ZA
>
> K2 #2198, K3 #3391,
> LA3ZA Blog: http://la3za.blogspot.com,
> LA3ZA Unofficial Guide to K2 modifications: http://la3za.blogspot.com/p/la3za-unofficial-guide-to-elecraft-k2.html
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Rerouting-the-KRX3-AUX-Input-from-the-Rear-BNC-to-the-KAT3-tp7615802.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Don Wilhelm-4]

Sverre,

That task can be accomplished by removing only the top cover.

The angled TMP connector on the subRX is a little difficult to reach
without tilting the back of the subRX up a bit, but it can be done.

73,
Don W3FPR

On 4/1/2016 1:56 PM, Sverre Holm (LA3ZA) wrote:
> When I built my K3 some years ago I routed the second receiver's AUX antenna
> input to the rear panel BNC connector. But now I have changed my mind and
> want to route it through the KAT3 instead, in order to try diversity
> reception.
>
> How complex is this to accomplish? I know I need to plug in another 30 cm
> tmp cable to the KRX3 board than the one I am using now.

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[Sverre Holm (LA3ZA)]

Thanks for very quick responses to my question - I'm overwhelmed! I'll remove the top cover and start right away!

I have two antennas, and no special receive antenna, and the two antennas are connected to ANT1 and ANT2 all the time. If I reroute the KRX3 AUX input to the KAT3, I will be able to check out diversity - provided that the antennas in practice are well enough isolated. It's a horizontal loop and a vertical so I hope it should be fine, although the vertical is in one of the corners of the loop.


73 and thanks

[Rose]

Some models of UHF under-dash Motorola mobiles have a short (+/- 6") TMP
M/M jumper cable connecting two boards.  A female circuit board connector
can be salvaged from the the radio for use as a end connector on the short
cable, making a M/F extension for the input to the 2nd receiver.  I have
the ends of this extension cable and the cable from the rear BNC rear
connector laid atop the 2nd receiver, making it an easy task to lift the
top cover and choose the antenna being fed to the 2nd receiver's input.

I'm not been able to find a source for cable-end female TMP connectors, or
even a part number to order them from Motorola ... and I'm a retired
two-way tech. (;-)

Perhaps Elecraft parts may have them.  I "scrounged" several cables and
boards from a friend who owns a two-way radio shop when I made mine and a
couple for friends.

73

Ken - K0PP
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[Elecraft mailing list]

Don,
I have my sub receiver connected to the AUX input, and it still works just fine with diversity receive.  The way you do is connect your receive only antenna to the RX in BNC on the back of the K3,  then run a short piece of coax with male BNC connectors on each in between the RX OUT and the AUX input.  Not sure why this method has not been mentioned in the manual. I have being doing this since I purchased my original K3.  I use either Beverages, or the Hi Z 8 now; but am in the process of erecting a SAL 30 fro Array Solutions.   That will give me three different choices for receive antennas.
Dick, K8ZTT 

      From: Don Wilhelm <[hidden email]>
 To: Sverre Holm (LA3ZA) <[hidden email]>; [hidden email]
 Sent: Friday, April 1, 2016 12:23 PM
 Subject: Re: [Elecraft] Rerouting the KRX3 AUX Input from the Rear BNC to the KAT3
   
Sverre,

That task can be accomplished by removing only the top cover.

The angled TMP connector on the subRX is a little difficult to reach
without tilting the back of the subRX up a bit, but it can be done.

73,
Don W3FPR

On 4/1/2016 1:56 PM, Sverre Holm (LA3ZA) wrote:
> When I built my K3 some years ago I routed the second receiver's AUX antenna
> input to the rear panel BNC connector. But now I have changed my mind and
> want to route it through the KAT3 instead, in order to try diversity
> reception.
>
> How complex is this to accomplish? I know I need to plug in another 30 cm
> tmp cable to the KRX3 board than the one I am using now.

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[Elecraft mailing list]

Interesting thread and one that I have a question on. I have three antennas coming in to the KAT3 and one jumper running from the KAT3 XMTR connector to my K3 Ant1. When I installed the KRX3, I made the choice to have the main and sub receiver share the antenna output of the KAT3. Since I had two choices at the time it seems like the most practical and because all my antennas were routed through the KAT500. So my question given the presence of the KAT,  is there still a practical way to switch back and forth between my present setup and using the KRX3 for diversity receive? Hope question is not too confusing.
73 Paulkc2nyu
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[Don Wilhelm-4]

Paul,

You don't have to do anything to share the mainRX with the subRX - the
K3 will split the receive (through the 3dB splitter) to the main antenna
for both receivers.  That is good for SPLIT operation, but will not
produce diversity receive.

For diversity, you do need two antennas which are separated either by
space or by orientation ( for example, 1 horizontal and the other
vertical) or by using a separate receive only antenna.  That cannot be
accomplished by a single coax to the K3 ANT1 jack.

Since you currently have the cable from the KAT3 to the subRX AUX ANT
input, you could put the RX antenna for the subRX on the non-transmit
(presumably ANT2) connector for diversity - but that is 'dangerous'
because if you accidentally select ANT2 for transmit, you will transmit
into your receive antenna - if it contains a preamp, that preamp may be
destroyed by transmitting into its output.

The safer way (in your case) is to change the K3 cable to the subRX AUX
ANT input to use the BNC jack.  You can then connect the RX ANT to the
BNC jack and using BSET, tell the subRX to use the auxiliary antenna input.

The inclusion of the KAT500 does complicate the situation.  If you look
at the KAT500 as providing the antenna for transmit as well as the
mainRX antenna (and also for the subRX when sharing the antenna with the
mainRX), then you will be OK, but that will not do diversity receive
since both receivers will be listening to the same antenna.

For diversity receive, select the AUX antenna input for the subRX and
connect the receive antenna to the BNC jack.

73,
Don W3FPR


On 4/3/2016 12:58 PM, paul ecker via Elecraft wrote:
> Interesting thread and one that I have a question on. I have three antennas coming in to the KAT3 and one jumper running from the KAT3 XMTR connector to my K3 Ant1. When I installed the KRX3, I made the choice to have the main and sub receiver share the antenna output of the KAT3. Since I had two choices at the time it seems like the most practical and because all my antennas were routed through the KAT500. So my question given the presence of the KAT,  is there still a practical way to switch back and forth between my present setup and using the KRX3 for diversity receive? Hope question is not too confusing.
>

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