Topics

K3 reduced or no TX output on low and high bands

Jarmo Blomster
 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.
 
Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:
 
Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG
  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

mikerodgerske5gbc
 

Not sure with those two bands if it could be the dreaded lpa board failure. 

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 8:59 AM, Jarmo Blomster <jarmoblo@...> wrote:

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.
 
Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:
 
Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG
  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

Ray Maxfield
 

I had a similar problem.

Locate the 3 Driver Fets that use the bottom cover as a Heat Sink (see Assembly Manual).

I would do this test on 80 Meters. In the SSB or AM mode Key the PTT or TX and FEEL

The bottom cover to see if the Driver  FETS Gets HOT.   If Hot they are most likely shorted.

I think I found this test on U-TUBE.  If none of the Driver Fets gets Hot, then I would look

At the Output FETS.  If you are Comfortable Working on the Radio, you can take the bottom

Cover off and remove the FETs from the board and test them with a Multi-meter.

Hope that helps…….. Ray WA6VAB.         

 

From: Jarmo Blomster
Sent: Thursday, April 16, 2020 6:59 AM
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 reduced or no TX output on low and high bands

 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.

 

Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:

 

Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG

  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

 

mikerodgerske5gbc
 

If they are cold they are dead.  It's usually 1.  You do the test in ssb with power at zero.  I can dig up the information. 
The fet's are field serviceable or if elecraft has extra complete boards.  

Been there done that. 
Note: I believe my problem was on 15 meters so be careful there?

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:26 AM, Ray Maxfield <wa6vab@...> wrote:

I had a similar problem.

Locate the 3 Driver Fets that use the bottom cover as a Heat Sink (see Assembly Manual).

I would do this test on 80 Meters. In the SSB or AM mode Key the PTT or TX and FEEL

The bottom cover to see if the Driver  FETS Gets HOT.   If Hot they are most likely shorted.

I think I found this test on U-TUBE.  If none of the Driver Fets gets Hot, then I would look

At the Output FETS.  If you are Comfortable Working on the Radio, you can take the bottom

Cover off and remove the FETs from the board and test them with a Multi-meter.

Hope that helps…….. Ray WA6VAB.         

 

From: Jarmo Blomster
Sent: Thursday, April 16, 2020 6:59 AM
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 reduced or no TX output on low and high bands

 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.

 

Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:

 

Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG

  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

 

mikerodgerske5gbc
 

I'd be glad to take a look at any utube videos and see if it's the elecraft recommended test. 

There used to be no swr protection for this board. 

Still the case?  Don't know. 

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:35 AM, mikerodgerske5gbc via groups.io <mikerodgerske5gbc@...> wrote:

If they are cold they are dead.  It's usually 1.  You do the test in ssb with power at zero.  I can dig up the information. 
The fet's are field serviceable or if elecraft has extra complete boards.  

Been there done that. 
Note: I believe my problem was on 15 meters so be careful there?

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:26 AM, Ray Maxfield <wa6vab@...> wrote:

I had a similar problem.

Locate the 3 Driver Fets that use the bottom cover as a Heat Sink (see Assembly Manual).

I would do this test on 80 Meters. In the SSB or AM mode Key the PTT or TX and FEEL

The bottom cover to see if the Driver  FETS Gets HOT.   If Hot they are most likely shorted.

I think I found this test on U-TUBE.  If none of the Driver Fets gets Hot, then I would look

At the Output FETS.  If you are Comfortable Working on the Radio, you can take the bottom

Cover off and remove the FETs from the board and test them with a Multi-meter.

Hope that helps…….. Ray WA6VAB.         

 

From: Jarmo Blomster
Sent: Thursday, April 16, 2020 6:59 AM
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 reduced or no TX output on low and high bands

 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.

 

Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:

 

Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG

  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

 

Jarmo Blomster
 

Mike, please send the info if you can find it. 
Could that cause the bandwidth reduction, as other bands seems to be ok.

-- OH8KVA

to 16. huhtik. 2020 klo 18.39 mikerodgerske5gbc via groups.io (mikerodgerske5gbc=yahoo.com@groups.io) kirjoitti:

I'd be glad to take a look at any utube videos and see if it's the elecraft recommended test. 

There used to be no swr protection for this board. 

Still the case?  Don't know. 

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:35 AM, mikerodgerske5gbc via groups.io <mikerodgerske5gbc@...> wrote:

If they are cold they are dead.  It's usually 1.  You do the test in ssb with power at zero.  I can dig up the information. 
The fet's are field serviceable or if elecraft has extra complete boards.  

Been there done that. 
Note: I believe my problem was on 15 meters so be careful there?

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:26 AM, Ray Maxfield <wa6vab@...> wrote:

I had a similar problem.

Locate the 3 Driver Fets that use the bottom cover as a Heat Sink (see Assembly Manual).

I would do this test on 80 Meters. In the SSB or AM mode Key the PTT or TX and FEEL

The bottom cover to see if the Driver  FETS Gets HOT.   If Hot they are most likely shorted.

I think I found this test on U-TUBE.  If none of the Driver Fets gets Hot, then I would look

At the Output FETS.  If you are Comfortable Working on the Radio, you can take the bottom

Cover off and remove the FETs from the board and test them with a Multi-meter.

Hope that helps…….. Ray WA6VAB.         

 

From: Jarmo Blomster
Sent: Thursday, April 16, 2020 6:59 AM
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 reduced or no TX output on low and high bands

 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.

 

Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:

 

Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG

  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

 

Jarmo Blomster
 

I did the suggested SSB zero Power (Bias) test and: yes the Q1, Q2, Q4 and Q5 get hot, so I guess they are healthy.
So did the the Q7 and R31 get hot.

-- Jarmo OH8KVA

to 16. huhtik. 2020 klo 18.57 Jarmo Blomster via groups.io (jarmoblo=gmail.com@groups.io) kirjoitti:

Mike, please send the info if you can find it. 
Could that cause the bandwidth reduction, as other bands seems to be ok.

-- OH8KVA

to 16. huhtik. 2020 klo 18.39 mikerodgerske5gbc via groups.io (mikerodgerske5gbc=yahoo.com@groups.io) kirjoitti:
I'd be glad to take a look at any utube videos and see if it's the elecraft recommended test. 

There used to be no swr protection for this board. 

Still the case?  Don't know. 

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:35 AM, mikerodgerske5gbc via groups.io <mikerodgerske5gbc@...> wrote:

If they are cold they are dead.  It's usually 1.  You do the test in ssb with power at zero.  I can dig up the information. 
The fet's are field serviceable or if elecraft has extra complete boards.  

Been there done that. 
Note: I believe my problem was on 15 meters so be careful there?

73
Mike R

7!
Absolutely Awesome 

On Apr 16, 2020, at 10:26 AM, Ray Maxfield <wa6vab@...> wrote:

I had a similar problem.

Locate the 3 Driver Fets that use the bottom cover as a Heat Sink (see Assembly Manual).

I would do this test on 80 Meters. In the SSB or AM mode Key the PTT or TX and FEEL

The bottom cover to see if the Driver  FETS Gets HOT.   If Hot they are most likely shorted.

I think I found this test on U-TUBE.  If none of the Driver Fets gets Hot, then I would look

At the Output FETS.  If you are Comfortable Working on the Radio, you can take the bottom

Cover off and remove the FETs from the board and test them with a Multi-meter.

Hope that helps…….. Ray WA6VAB.         

 

From: Jarmo Blomster
Sent: Thursday, April 16, 2020 6:59 AM
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 reduced or no TX output on low and high bands

 

I sent this to K3 support, while waiting their answer I ask here also.

Serial is 0691.

 

Last week I noticed that my K3 has no TX output on 6m band.
I run Transmitter gain adjustment procedure on all bands.
I noticed that 160m and 10-6m has problems and can not finish properly the adjustment procedure.
Here are my results using a dummy load:

 

Transmitter Gain adjustment
Measures RX: 14.9V, 1.19A, PA 24C, FP 20C
Band, Reaching Power, SWR,   Voltage, Current, Error
160m,             2W, 1.2-1, 14.7V,    2.78A, ERR TXG
 80m,             5W, 1.0-1, 14.6V,    3.27A
 60m,             5W, 1.0-1, 14.6V,    3.33A
 40m,             5W, 1.1-1, 14.6V,    3.30A
 30m,             5W, 1.0-1, 14.6V,    3.38A
 20m,             5W, 1.0-1, 14.6V,    3.19A
 17m,             5W, 1.0-1, 14.6V,    3.19A
 15m,             5W, 1.0-1, 14.6V,    3.25A
 12m,             5W, 1.0-1, 14.6V,    3.24A
 10m,             5W, 1.0-1, 14.6V,    3.35A, ERR TXG

  6m,           0.1W, --,    14.8V,    2.19A.

For the measurements I replaced the KAT with the antenna interface card, so the problem is not in KAT.
I guess that possible components that can cause such problems are LPA and maybe the SWR Bridge.
What components in the LPA or in SWR bridge can cause such?
Has anybody had similar problems?

73 de Jarmo, OH8KVA

 

Keith_WE6R
 

Hi Jarmo;
Check that your filter for CW TX is correctly set (either a 2.7 or 2.8), and if you have a 2.7, it should have an offset like -.89   If a 2.8, then zero offset.

Set PWR SET to nor, then set power to 11.9 Watts (7.9 on 6m).
Then long press XMIT to do a TUNE and see if it will make good power on all bands  (I assume 6m is dead).

If KXV3 equipped, put a dummy load on the XVTR BNC and runt he MW tx gain cal, that can show problems.

If the MW passes with good numbers (please send), and the LPA does not make good power, the LPA has an issue.
6m problems can be one (or more) of the 4 little blue coils on the mixer board L1-L4. The should be about 4 ohms and can easily be damaged and open.
Keith WE6R
Elecraft K3 Tech.

Jarmo Blomster
 

Thanks Keith,
The problem was faulty mixer, I swapped the 2nd RX mixer in place of 1st mixed and now I can do the tx gain calibration in all bands.
Now I just need to fix the mixer.

-- Jarmo, OH8KVA



pe 17. huhtik. 2020 klo 0.11 Keith_WE6R (keithtrinity@...) kirjoitti:

Hi Jarmo;
Check that your filter for CW TX is correctly set (either a 2.7 or 2.8), and if you have a 2.7, it should have an offset like -.89   If a 2.8, then zero offset.

Set PWR SET to nor, then set power to 11.9 Watts (7.9 on 6m).
Then long press XMIT to do a TUNE and see if it will make good power on all bands  (I assume 6m is dead).

If KXV3 equipped, put a dummy load on the XVTR BNC and runt he MW tx gain cal, that can show problems.

If the MW passes with good numbers (please send), and the LPA does not make good power, the LPA has an issue.
6m problems can be one (or more) of the 4 little blue coils on the mixer board L1-L4. The should be about 4 ohms and can easily be damaged and open.
Keith WE6R
Elecraft K3 Tech.

Keith_WE6R
 

Hi Jarmo;
Ohm the 4 little blue coils, L1-L4. This is easiest done on the adjacent capacitor pads.
One or more is probably open.
We have the parts, but may have to pull them from the Tech area.
E690143
Keith WE6R
Elecraft K3 Tech

Jarmo Blomster
 

Ok Keith, I'll check them out.

Thanks 73 Jarmo, OH8KVA

la 18. huhtik. 2020 klo 17.46 Keith_WE6R (keithtrinity@...) kirjoitti:

Hi Jarmo;
Ohm the 4 little blue coils, L1-L4. This is easiest done on the adjacent capacitor pads.
One or more is probably open.
We have the parts, but may have to pull them from the Tech area.
E690143
Keith WE6R
Elecraft K3 Tech