K3 Sub Receiver Deaf


Chuck ke9uw
 

I recently sold a K3 with a sub recvr, new synth, and KIO3B.
The sub recvr is not hearing the signal in the right speaker earphone from the single antenna when it's set to the same vfo signal as the A vfo.
It does hear a nearby radio in the right earphone when the other radio is in xmit on a dummy load.
So it seems that the sub is working, just not connected to the antenna or the audio is not being heard.
And it does hear hiss in the right earphone when the sub recvr is turned on.
The right earphone does hear audio when the sub is turned off and the config is set to 2 speakers.
The coax is all plugged in as far as we can see, except we cannot see under the 100 watt amp to see it plugged into the ATU 1 socket. But we're pretty positive it is. That was not touched when the KIO3B and new synths were installed.
What I am asking for is ideas due to Config, settings, etc. as to what might not allow the sub to be heard signal wise. All else is working after installing the IO3B and new synths. 


Mel Marcus
 

This may not  apply, but do you have two new synthesizers. One new on the main, and one old one the sub, will not work properly

Mel
NE9A

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> on behalf of Chuck ke9uw via groups.io <c-hawley@...>
Sent: Tuesday, September 27, 2022 7:22 PM
To: Elecraft-K3@groups.io <Elecraft-K3@groups.io>
Subject: [Elecraft-K3] K3 Sub Receiver Deaf
 
I recently sold a K3 with a sub recvr, new synth, and KIO3B.
The sub recvr is not hearing the signal in the right speaker earphone from the single antenna when it's set to the same vfo signal as the A vfo.
It does hear a nearby radio in the right earphone when the other radio is in xmit on a dummy load.
So it seems that the sub is working, just not connected to the antenna or the audio is not being heard.
And it does hear hiss in the right earphone when the sub recvr is turned on.
The right earphone does hear audio when the sub is turned off and the config is set to 2 speakers.
The coax is all plugged in as far as we can see, except we cannot see under the 100 watt amp to see it plugged into the ATU 1 socket. But we're pretty positive it is. That was not touched when the KIO3B and new synths were installed.
What I am asking for is ideas due to Config, settings, etc. as to what might not allow the sub to be heard signal wise. All else is working after installing the IO3B and new synths. 


Chuck ke9uw
 

Both are the new ones. Thanks though. Any idea is welcome.


Mike Flowers
 

I ran into a situation like that and some setting linked or unlinked the RF or AF gain of the two receivers.   Or some squelch setting.  

Traveling and away from the shack. 

-- 73 de Mike Flowers, K6MKF, NCDXC - "It's about DX!" 

On Sep 28, 2022, at 10:39 AM, Chuck ke9uw <c-hawley@...> wrote:

Both are the new ones. Thanks though. Any idea is welcome.


Geert Jan de Groot
 

The subreceiver may receive antenna signals in a number of ways. Check "Sub Receiver Antenna Selection" on page 50 of the KRX3A subreceiver manual and "Main and Sub Receiver Antenna Routing" in the K3 manual.

You did not document your K3 configuration, depending on the hardware the sub RX may listen on the aux RF port (if your K3 has it) or even on the other antenna socket. Check the manual.

73, Geert Jan PE1HZG


Colin Smithers
 

I had this problem once. After going through the manual very carefully a number of times and changing the antenna configurations around a lot, I realsed there was a large loss in one of the signal paths. It turned out to be a blown PIN diode, almost certainly my fault, although I don't know how I did it. Too much RF into one of the ports probably. If you can access another similar K3 this will be very helpful, so you can compare good against possibly faulty.

But working systematically through the settings is the first task, and isn't super easy.

Good luck,

73, Colin G4CWH


Randy Farmer W8FN
 

First thing to do is to check all the small TMP RF cables. It's quite possible one isn't making good contact. It's a bit of a pain to get to the ones associated with the Sub, but you need to get in and use a pair of small needle nose pliers to CAREFULLY pull out and reseat each connector.

73...
Randy, W8FN

On 9/27/2022 8:22 PM, Chuck ke9uw wrote:

I recently sold a K3 with a sub recvr, new synth, and KIO3B.
The sub recvr is not hearing the signal in the right speaker earphone from the single antenna when it's set to the same vfo signal as the A vfo.
It does hear a nearby radio in the right earphone when the other radio is in xmit on a dummy load.
So it seems that the sub is working, just not connected to the antenna or the audio is not being heard.
And it does hear hiss in the right earphone when the sub recvr is turned on.
The right earphone does hear audio when the sub is turned off and the config is set to 2 speakers.
The coax is all plugged in as far as we can see, except we cannot see under the 100 watt amp to see it plugged into the ATU 1 socket. But we're pretty positive it is. That was not touched when the KIO3B and new synths were installed.
What I am asking for is ideas due to Config, settings, etc. as to what might not allow the sub to be heard signal wise. All else is working after installing the IO3B and new synths.


Chuck ke9uw
 

We're thinking the issue is not realizing the BNC is the input for the Sub. I didn't remember what I decided back in 2010. The buyer has not connected the BNC to a tuned antenna yet though. The buyer, however, wants to connect it to the ATU instead. So I have sent him a TMP cable and we'll go from there.
Thank you very much for the interest and replies.


Jim Brown
 

There are multiple ways in which the input of the sub-RX can be wired. It's been 13-14 years since I did mine, so don't remember the details. Check the manual for the sub-RX. Probably in the build-install instructions. Everything is on the Elecraft website.

73, Jim K9YC

On 9/29/2022 6:46 AM, Chuck ke9uw wrote:
We're thinking the issue is not realizing the BNC is the input for the Sub. I didn't remember what I decided back in 2010. The buyer has not connected the BNC to a tuned antenna yet though. The buyer, however, wants to connect it to the ATU instead. So I have sent him a TMP cable and we'll go from there.


Chuck ke9uw
 

The confusion on wiring of the Sub. I did some study of the Cady manual (for the K3s) and it shows a diagram of the wiring and it's options. It also shows why the K3 will sometimes says USE AUX. That is because the switching to the MAIN is before the band pass filters...and that the Sub is set to a band above the MAIN. I have to say that Elecraft's coverage of the Sub is not easy to decode.
One confusing issue is that the Sub has a coax input on the back of it's chassis, but that's not the input to the Sub. It is only the input to the AUX decision by the relay which is on the input to the Sub. The other relay decision is the MAIN. The actual input to the Sub is internal to the Sub chassis and connected to the K3 by the two multi pin connectors on the bottom of the Sub.
The simple answer is that you can always switch to the MAIN or to the AUX by press hold RX ANT and toggling when the Sub is turned on. And the AUX is wired by the builder either to the rear so239s if you have the ATU, thru the ATU, (the K3 uses the input you're not transmitting on), OR to the BNC. You can also use B SET and ANT to switch to MAIN or AUX.
In any case, you can always share the MAIN. Or use the AUX. And the AUX you get is whichever one you wired the coax from the Sub to.
 


Steve Masticola
 

Maybe this has already been covered, but it could be that you've got a different antenna jack selected for the sub. Try B SET, then ANT.

The other possibility is that you're in diversity mode.

73, -Steve WX2S


Chuck ke9uw
 

Yes something like that. Not hardware. He told me yesterday that it all works now. Some switch pressing was the solution. Yea!


Steve Masticola
 

Glad you found it, Chuck! And glad it was just a bumped setting, not hardware.

73, -Steve WX2S