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KRX3 insatall

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Mike Reublin

KRX3 insatall

In anticipation of my KRX3 arriving tomorrow, I've been reading the install manual. I plan to have the KRX3 share the same antenna as the main RX. I don't think I can do diversity RX.

I have a second antenna (R8) but I'm not sure it's well enough isolated (40' from the tower) and it doesn't hear as well as the 4L SteppIR. 160/80M are 1/4 wave slopers on the tower.

I assume(DANGER WIll Robinson!) that I skip from "Auxiliary KRX3 Antenna Input (Optional)" on p.25 to "Assembling the KRX3 Subreceiver Module" on p. 30.

Any "gotchas" I need to watch out for?

73, Mike NF4L

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Edward R Cole

Re: KRX3 insatall

Mike,

I have the KRX3 installed in my K3 with antenna connected to Aux
antenna jack. I have not connected another HF antenna while
operating on HF so do not know if there is danger to the
sub-receiver. I thought the KRX3 also had some diodes protecting the
input from extreme RF levels.

You need two antennas to operated diversity reception. With both
receivers sharing a single antenna all you accomplish is being able
to receive split (which may be nice in some circumstances).

I use my KRX3 to receive a horizontal polarity 2m signals when the
main receiver is receiving vertical polarity. Special sw takes both
signals and is able to strip out the actual polarization angle and
optimize the signal to that polarization. It called dual-polarity
adaptive reception. One could accomplish the same for HF by using
two dipoles strung at right angles to each other and adding one
quarter wavelength of coax to one dipole. The two dipoles then are
quadrature phased and one can detect circular polarized signals. In
fact nearly all HF is CP after passing thru the ionosphere.

15m thru 6m is easy to set up with such an antenna (due to smaller size).

73, Ed - KL7UW

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Cady, Fred

Re: KRX3 insatall

In reply to this post by Mike Reublin

Hi Mike,
You are going to like using the sub receiver. It makes finding the right
place in the pileup to call SOOO much easier.
If you are not that much interested in diversity reception just go ahead
and connect the sub receiver ant to the ATU. That will give you the most
flexible installation where you can use the R8 on the sub RX and do
diversity plus use the R8 connected to the main for transmitting also.
If you connect the sub RX to the Aux BNC, you are limited to only
sharing the main antenna or listening to a receiver antenna on the Aux
BNC. Some people find that useful if they have, say, a receive vertical
antenna on 6 meters to listen for band openings. In any case, do install
the Aux ant BNC in case you ever want to switch.
73 and have fun,
Fred, KE7X

"The Elecraft K3: Design, Configuration and Operation"
www.ke7x.com

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike Reublin
Sent: Monday, October 29, 2012 4:33 PM
To: Elecraft Reflector
Subject: [Elecraft] KRX3 insatall

In anticipation of my KRX3 arriving tomorrow, I've been reading the
install manual. I plan to have the KRX3 share the same antenna as the
main RX. I don't think I can do diversity RX.

I have a second antenna (R8) but I'm not sure it's well enough isolated
(40' from the tower) and it doesn't hear as well as the 4L SteppIR.
160/80M are 1/4 wave slopers on the tower.

I assume(DANGER WIll Robinson!) that I skip from "Auxiliary KRX3 Antenna
Input (Optional)" on p.25 to "Assembling the KRX3 Subreceiver Module" on
p. 30.

Any "gotchas" I need to watch out for?

73, Mike NF4L

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Mike Reublin

Re: KRX3 insatall

In reply to this post by Mike Reublin

The KRX3 is installed and working! Time was 5 1/2 hours including configuration. Usual outstanding fit and instructions.

I installed it to use the ATU for aux, and I put the BNC in if I ever want to change.

I have it set to use the SUB AF control as balance.

FIrst impression listening to one station working up 1 on 30M:
The KRX3 has a noticeably lower volume.

And I found out my speakers and headphones are opposite (left/right) to each other...😥

Mike, NF4L

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wayne burdick

Re: KRX3 insatall

Administrator

Mike,

The KRX3 should have the same overall gain as the K3's main receiver.

Try going into BSET Mode to see if the preamp is turned on on the sub
receiver. You can also adjust other sub-RX settings in BSET mode,
including NB, NR, and filter bandwidth, all of which can affect gain.

73,
Wayne
N6KR

On Oct 30, 2012, at 5:48 PM, Mike Reublin wrote:

> The KRX3 is installed and working! Time was 5 1/2 hours including
> configuration. Usual outstanding fit and instructions.
>
> I installed it to use the ATU for aux, and I put the BNC in if I
> ever want to change.
>
> I have it set to use the SUB AF control as balance.
>
> FIrst impression listening to one station working up 1 on 30M:
> The KRX3 has a noticeably lower volume.
>
> And I found out my speakers and headphones are opposite (left/right)
> to each other...😥
>
> Mike, NF4L
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Cady, Fred

Re: KRX3 insatall

What Wayne said Mike plus you can double tap A>B to set the sub to the main settings as the main. You can fix you left/right challenged speakers with the L-MIX-R menu too.
Cheers,
Fred

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Wayne Burdick
Sent: Tuesday, October 30, 2012 7:28 PM
To: Mike Reublin
Cc: Elecraft Reflector
Subject: Re: [Elecraft] KRX3 insatall

Mike,

The KRX3 should have the same overall gain as the K3's main receiver.

Try going into BSET Mode to see if the preamp is turned on on the sub receiver. You can also adjust other sub-RX settings in BSET mode, including NB, NR, and filter bandwidth, all of which can affect gain.

73,
Wayne
N6KR

On Oct 30, 2012, at 5:48 PM, Mike Reublin wrote:

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Mike Reublin

Re: KRX3 insatall

In reply to this post by wayne burdick

Thanks Wayne. All the settings look good. With the balance knob fully clockwise, the sub is in the right ear. Turning CCW, the main starts to be heard at 3:30.

73, Mike NF4L

On Oct 30, 2012, at 9:28 PM, Wayne Burdick <[hidden email]> wrote:

> Mike,
>
> The KRX3 should have the same overall gain as the K3's main receiver.
>
> Try going into BSET Mode to see if the preamp is turned on on the sub receiver. You can also adjust other sub-RX settings in BSET mode, including NB, NR, and filter bandwidth, all of which can affect gain.
>
> 73,
> Wayne
> N6KR
>
> On Oct 30, 2012, at 5:48 PM, Mike Reublin wrote:
>
>> The KRX3 is installed and working! Time was 5 1/2 hours including configuration. Usual outstanding fit and instructions.
>>
>> I installed it to use the ATU for aux, and I put the BNC in if I ever want to change.
>>
>> I have it set to use the SUB AF control as balance.
>>
>> FIrst impression listening to one station working up 1 on 30M:
>> The KRX3 has a noticeably lower volume.
>>
>> And I found out my speakers and headphones are opposite (left/right) to each other...😥
>>
>> Mike, NF4L
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
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>

Edward R Cole

Re: KRX3 insatall

In reply to this post by Mike Reublin

I built my K3/10 and installed the KRX3 with no issues of different
audio levels.

BTW running both Rx with dual LP-Pan on MAP65v2.3 sw shows the audio
level on a bar graph for each (when in diversity mode).

Two things were recently done to improve use of the
LP-Pan: 1) Enabling an open filter position in the K3 and KRX3
eliminates gain "suck out" by roofing filter which is connected in
parallel with the IF output jack. It shows as a dip in gain on a
panadaptor spectrum display at center freq. 2) Installed 32.860 MHz
xtal in LP-Pan which is 4x the IF freg of 8.215 MHz which eliminates
the previous +6 KHz freq. off set in the display sw (thanks to Larry, N8LP).

My 2m-eme dual-polarity adaptive receive system will get a work-out
in this weekend's eme contest. It extensively uses the dual-Rx
diversity reception mode of the K3.

73, Ed - KL7UW

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ab2tc

Re: KRX3 insatall

Hi,

I have absolutely no dip in the center of my LP-Pan display and I have never heard anybody else having this problem either. The IF out port and the crystal filter bank are driven in parallel by a buffer amplifier that appears to be capable of driving both without gain loss due to the crystal filter load.

AB2TC - Knut

Edward R Cole wrote

I built my K3/10 and installed the KRX3 with no issues of different
audio levels.

BTW running both Rx with dual LP-Pan on MAP65v2.3 sw shows the audio
level on a bar graph for each (when in diversity mode).

Two things were recently done to improve use of the
LP-Pan: 1) Enabling an open filter position in the K3 and KRX3
eliminates gain "suck out" by roofing filter which is connected in
parallel with the IF output jack. It shows as a dip in gain on a
panadaptor spectrum display at center freq. 2) Installed 32.860 MHz
xtal in LP-Pan which is 4x the IF freg of 8.215 MHz which eliminates
the previous +6 KHz freq. off set in the display sw (thanks to Larry, N8LP).

My 2m-eme dual-polarity adaptive receive system will get a work-out
in this weekend's eme contest. It extensively uses the dual-Rx
diversity reception mode of the K3.

73, Ed - KL7UW

alsopb

Re: KRX3 insatall

If one looks at the schematic there is a JFET buffer between the IF and
the IF out in the main RX. Isolation and impedance matching is its
function. There is no stock IF out for the subrx and hence no JFET.

JFETs have really high input impedances.

A one resistor "gain mod" is on the K3 site reduces the signal loss in
this JFET stage for those using the IF output jack.

73 de Brian/K3KO

On 10/31/2012 21:10, ab2tc wrote:

> Hi,
>
> I have absolutely no dip in the center of my LP-Pan display and I have never
> heard anybody else having this problem either. The IF out port and the
> crystal filter bank are driven in parallel by a buffer amplifier that
> appears to be capable of driving both without gain loss due to the crystal
> filter load.
>
> AB2TC - Knut
>
>
> Edward R Cole wrote
>> I built my K3/10 and installed the KRX3 with no issues of different
>> audio levels.
>>
>> BTW running both Rx with dual LP-Pan on MAP65v2.3 sw shows the audio
>> level on a bar graph for each (when in diversity mode).
>>
>> Two things were recently done to improve use of the
>> LP-Pan: 1) Enabling an open filter position in the K3 and KRX3
>> eliminates gain "suck out" by roofing filter which is connected in
>> parallel with the IF output jack. It shows as a dip in gain on a
>> panadaptor spectrum display at center freq. 2) Installed 32.860 MHz
>> xtal in LP-Pan which is 4x the IF freg of 8.215 MHz which eliminates
>> the previous +6 KHz freq. off set in the display sw (thanks to Larry,
>> N8LP).
>>
>> My 2m-eme dual-polarity adaptive receive system will get a work-out
>> in this weekend's eme contest. It extensively uses the dual-Rx
>> diversity reception mode of the K3.
>>
>> 73, Ed - KL7UW
>
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/KRX3-insatall-tp7564774p7564863.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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> Checked by AVG - www.avg.com
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>
>

-----
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Checked by AVG - www.avg.com
Version: 2012.0.2221 / Virus Database: 2441/5365 - Release Date: 10/31/12

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Mike Reublin

Re: KRX3 insatall

In reply to this post by ab2tc

I don't have an L-P Pan.

Mike NF4L

On Oct 31, 2012, at 5:10 PM, ab2tc <[hidden email]> wrote:

Mike Reublin

Re: KRX3 insatall

In reply to this post by alsopb

Is that the addition across R91 if R91 is greater that 22 ohms? IF out would affect the P3, not audio volume, right?

Mike NF4L

On Oct 31, 2012, at 5:55 PM, Brian Alsop <[hidden email]> wrote:

> If one looks at the schematic there is a JFET buffer between the IF and
> the IF out in the main RX. Isolation and impedance matching is its
> function. There is no stock IF out for the subrx and hence no JFET.
>
> JFETs have really high input impedances.
>
> A one resistor "gain mod" is on the K3 site reduces the signal loss in
> this JFET stage for those using the IF output jack.
>
> 73 de Brian/K3KO
>
> On 10/31/2012 21:10, ab2tc wrote:
>> Hi,
>>
>> I have absolutely no dip in the center of my LP-Pan display and I have never
>> heard anybody else having this problem either. The IF out port and the
>> crystal filter bank are driven in parallel by a buffer amplifier that
>> appears to be capable of driving both without gain loss due to the crystal
>> filter load.
>>
>> AB2TC - Knut
>>
>>
>> Edward R Cole wrote
>>> I built my K3/10 and installed the KRX3 with no issues of different
>>> audio levels.
>>>
>>> BTW running both Rx with dual LP-Pan on MAP65v2.3 sw shows the audio
>>> level on a bar graph for each (when in diversity mode).
>>>
>>> Two things were recently done to improve use of the
>>> LP-Pan: 1) Enabling an open filter position in the K3 and KRX3
>>> eliminates gain "suck out" by roofing filter which is connected in
>>> parallel with the IF output jack. It shows as a dip in gain on a
>>> panadaptor spectrum display at center freq. 2) Installed 32.860 MHz
>>> xtal in LP-Pan which is 4x the IF freg of 8.215 MHz which eliminates
>>> the previous +6 KHz freq. off set in the display sw (thanks to Larry,
>>> N8LP).
>>>
>>> My 2m-eme dual-polarity adaptive receive system will get a work-out
>>> in this weekend's eme contest. It extensively uses the dual-Rx
>>> diversity reception mode of the K3.
>>>
>>> 73, Ed - KL7UW
>>
>>
>>
>>
>>
>> --
>> View this message in context: http://elecraft.365791.n2.nabble.com/KRX3-insatall-tp7564774p7564863.html
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> Elecraft mailing list
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>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2012.0.2221 / Virus Database: 2441/5365 - Release Date: 10/31/12
>>
>>
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.2221 / Virus Database: 2441/5365 - Release Date: 10/31/12
>
> ______________________________________________________________
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k6dgw

Re: KRX3 insatall

On 10/31/2012 4:34 PM, Mike Reublin wrote:
> Is that the addition across R91 if R91 is greater that 22 ohms? IF
> out would affect the P3, not audio volume, right?

Long thread, getting confused.

1. The IF output [to a P3 or anything else listening to 8215 KHz on the
IF OUT BNC connector] comes from the main receiver in the K3.

2. So far as I know, there is *no* IF output from the sub-receiver
unless you home brew it.

3. "Earlier" K3 S/N's had a somewhat low IF output for a P3, which
probably didn't exist then. Elecraft offers a mod [you're surprised?
:-)]. It involves removing one SM resistor and replacing it with
another. They supply both an SMD and a leaded-resistor, with
instructions for both. I used the leaded one, works fine.

4. I don't know what "earlier" means, but my K3 is S/N 642 and I did
the mod. Second biggest problem was disconnecting the nest of wires
from my "wireless" to get it out to work on. Biggest problem was
reconnecting all of them.

5. Somewhere in the delivery of "later" S/N's, the mod has been
incorporated.

6. With the mod completed [really easy], and all the wires reconnected,
I calibrated my S-meter to S9=50uV from my service monitor. The P3 then
calibrated nicely so S9=-73dBm on the ordinate.

That's my story and I'm sticking to it.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2013 Cal QSO Party 5-6 Oct 2013
- www.cqp.org

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Mike Reublin

Re: KRX3 insatall

In reply to this post by Mike Reublin

Thanks to all who offered suggestions. I just got off the phone with Howard in Elecraft support. He got it sorted in very short order.

As is so often the case, it was pilot error. RF gain was turned down. DOH! 😡

73, Mike NF4L
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