Date   

Re: KPA3 output erratic

Keith_WE6R
 

What does the internal K3 show when you do a TUNE and the radio IS drawing normal current at 100 watts? (approx 18amps, depends on band etc). 
If it shows around expected power, and your external meter says zero, then the problem is somewhere between where the KAT3 or KANT3 board plugs into the RF board and your external meter. 
Check for loose center-socket on the SO-239 Ant 1 socket. Try Ant 2.

Inspect T4 on the RF board next to the KAT3 or KANT3 board, it is in the SWR/PWR sense circuit and can get burnt from DC being applied to the antenna.

But if the power drops exactly when the KPA3 kicks in, and the internal meter says 0, it is probably not the above.
I have seen one of those big blue caps, C43 & C44, right at the output of the KPA3 go bad and the radio will draw current but no RF makes it out of the amp (but they usually work or not, IE not intermittent).
Pull the KPA3 and inspect for burnt parts. Look at the big blue/black diode D10, replace if it does not look right.
You did the right thing replacing the corresponding Riser-Board connector when replacing the burnt pins. (they have always been gold-plated inside and only need to be changed if the pins get burnt).

Your slow rise of power is a puzzler. Voltage sag would result in a HI CUR message as the radio would increase gain to try to make power.
However, it could just be that you have not done a successful TX gain calibration.
**Can you get it to pass manual TX gain cal? IE set TUN PWR to nor, set to exactly 50watts, then do a TUNE for several seconds.
You should see the TXGN HP number change if successful, or get an ERR TXG if not.

You have something else beside DC voltage sag because you have issues right at 13W when the KPA3 kicks in.
But FYI;
On my Tech bench, I have about 2 feet of beefy Motorola DC cable (from their 100W trunk-mount units).
I have a digital meter remotely connected right at the Anderson cable end at the back of the radio.
I see 13.8 only drop to 13.7 at ~20 amps.
The internal K3 Display volt-meter drops from 13.8 to 13.5.  It is measured after a few things, so it is just rough accuracy.
Don't forget to set the config-menu item ADC REF. That will make the K3's internal measurements more accurate.
Keith WE6R Elecraft K3 Tech.


Re: K3 Receive Function Attenuated Immediately After Transmission

K9MA
 

Sounds like a bad connection or contact between the antenna and radio. Relays are notorious for this. A little oxide builds up and blocks low-level currents. The high voltage on transmit breaks through the oxide, but it can build up again between transmissions.

I would clean every connector, relay, and switch in the signal path.

73,
Scott K9MA

----------

Scott Ellington

--- via iPad

On Aug 11, 2020, at 9:40 AM, N6KR <n6kr@elecraft.com> wrote:

All T/R switching in the K3 is via PIN diodes, not relays. But there are relays in the band-pass filters. These are only switched on band change, normally. Please contact support for troubleshooting suggestions.

Wayne
N6KR


On Aug 11, 2020, at 7:37 AM, KE1F Lou <lmecseri@cfl.rr.com> wrote:

I am under that impression also.
73, Lou KE1F

On 8/11/2020 7:59 AM, David M wrote:
Elecraft radios have solid state T/R switching.

On Tue, Aug 11, 2020, 6:48 AM David Cutter via groups.io <d.cutter=ntlworld.com@groups.io> wrote:
I've known it happening on other transceivers and it has turned out to be a relay

David G3UNA

On 11 August 2020 at 10:51 KE1F Lou <lmecseri@cfl.rr.com> wrote:

I don't know if it happens after transmission, but I will look for it.
I experienced similar problem. My P3 clearly shows the "atennuation of the RF signal" and a "dit" restores the RF gain.
I am also using microHam II interface.
73 Lou KE1F.



Sent from my Galaxy Tab® A

-------- Original message --------
From: "Harry Rudolph via groups.io" <hgrudolphs=yahoo.com@groups.io>
Date: 8/10/20 7:38 PM (GMT-05:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 Receive Function Attenuated Immediately After Transmission

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function. I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition. The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on. Usually if I added a quick "dit" it would return to the normal receive level. I fooled around with the AGC which had no effect. I changed from Ant 1 input to Ant 2 input with no effect. If I switched to the RX antenna input, it seemed normal. I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved. But after a few more hours of operation, I noticed that I did actually have the problem with the replacement but just at a much lower frequency.

Anyone experience anything like this or have any suggestions? I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C





Re: KPA500, Win4K3, and DDU

w3qt_mike
 

Bill,
Thanks for the reply.  You understanding is exactly correct. 

73, Mike, W3QT


Re: K3 Receive Function Attenuated Immediately After Transmission

 

All T/R switching in the K3 is via PIN diodes, not relays. But there are relays in the band-pass filters. These are only switched on band change, normally. Please contact support for troubleshooting suggestions.

Wayne
N6KR

On Aug 11, 2020, at 7:37 AM, KE1F Lou <lmecseri@cfl.rr.com> wrote:

I am under that impression also.
73, Lou KE1F

On 8/11/2020 7:59 AM, David M wrote:
Elecraft radios have solid state T/R switching.

On Tue, Aug 11, 2020, 6:48 AM David Cutter via groups.io <d.cutter=ntlworld.com@groups.io> wrote:
I've known it happening on other transceivers and it has turned out to be a relay

David G3UNA

On 11 August 2020 at 10:51 KE1F Lou <lmecseri@cfl.rr.com> wrote:

I don't know if it happens after transmission, but I will look for it.
I experienced similar problem. My P3 clearly shows the "atennuation of the RF signal" and a "dit" restores the RF gain.
I am also using microHam II interface.
73 Lou KE1F.



Sent from my Galaxy Tab® A

-------- Original message --------
From: "Harry Rudolph via groups.io" <hgrudolphs=yahoo.com@groups.io>
Date: 8/10/20 7:38 PM (GMT-05:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 Receive Function Attenuated Immediately After Transmission

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function. I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition. The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on. Usually if I added a quick "dit" it would return to the normal receive level. I fooled around with the AGC which had no effect. I changed from Ant 1 input to Ant 2 input with no effect. If I switched to the RX antenna input, it seemed normal. I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved. But after a few more hours of operation, I noticed that I did actually have the problem with the replacement but just at a much lower frequency.

Anyone experience anything like this or have any suggestions? I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C



Re: K3 Receive Function Attenuated Immediately After Transmission

KE1F Lou
 

I am under that impression also.
73, Lou KE1F

On 8/11/2020 7:59 AM, David M wrote:
Elecraft radios have solid state T/R switching.

On Tue, Aug 11, 2020, 6:48 AM David Cutter via groups.io <d.cutter=ntlworld.com@groups.io> wrote:
I've known it happening on other transceivers and it has turned out to be a relay

David G3UNA

On 11 August 2020 at 10:51 KE1F Lou <lmecseri@...> wrote:

I don't know if it happens after transmission, but I will look for it.
I experienced similar problem. My P3 clearly shows the "atennuation of the RF signal" and a "dit" restores the RF gain.
I am also using microHam II interface.
73 Lou KE1F. 



Sent from my Galaxy Tab® A

-------- Original message --------
From: "Harry Rudolph via groups.io" <hgrudolphs=yahoo.com@groups.io>
Date: 8/10/20 7:38 PM (GMT-05:00)
Subject: [Elecraft-K3] K3 Receive Function Attenuated Immediately After Transmission

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.

Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C

 

 


Re: K3 Receive Function Attenuated Immediately After Transmission

Stewart G3RXQ
 

By any chance are you using a SPE 1k-FA amplifier ?

73 Stewart G3RXQ / G3Q


Re: K3 Receive Function Attenuated Immediately After Transmission

Michael Kopec
 

Hello Harry, I experienced the same problem here a couple a times. It also showed on the P3. Turned out both times to be a dirty PL259 connection at the antenna. I inspected the pl259, it is soldered and sealed, and then cleaned everything with Deoxit. Problem solved for 2 yrs and then reoccurred. Same fix took care of it. de Mike K8NS

On Tuesday, August 11, 2020, 12:13:03 AM EDT, Harry Rudolph via groups.io <hgrudolphs@...> wrote:


Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.

Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C


Re: K3 Receive Function Attenuated Immediately After Transmission

Joe Subich, W4TV
 

Start by removing any amplifier from the signal path. Then check
all feedline connectors and antenna switches for loose connections
and/or water ingress.

I plan to do some more A/B comparisons and take the MK II and amp out
of the equation but wanted to see if anyone else has run into this.
MK II (or any other microHAM interface) does not impact the RF path.
It can not possibly cause attenuation of the receive signal.

73,

... Joe, W4TV


On 2020-08-10 7:38 PM, Harry Rudolph via groups.io wrote:
Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.
Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.
Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.
Thanks.
Harry
WX8C


Re: KPA3 output erratic

James Kvochick
 

Chuck;

If you’d like, and we can get our schedules to align, I would be happy to chat with you via phone and or zoom.
For my money, I’m still betting on an issue with the final module, assuming low power TX gain calibration works.

Jim
k8jk@...


Re: K3 Receive Function Attenuated Immediately After Transmission

David Cutter
 

I've known it happening on other transceivers and it has turned out to be a relay

David G3UNA

On 11 August 2020 at 10:51 KE1F Lou <lmecseri@...> wrote:

I don't know if it happens after transmission, but I will look for it.
I experienced similar problem. My P3 clearly shows the "atennuation of the RF signal" and a "dit" restores the RF gain.
I am also using microHam II interface.
73 Lou KE1F. 



Sent from my Galaxy Tab® A

-------- Original message --------
From: "Harry Rudolph via groups.io" <hgrudolphs@...>
Date: 8/10/20 7:38 PM (GMT-05:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 Receive Function Attenuated Immediately After Transmission

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.

Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C

 

 


Re: K3 Receive Function Attenuated Immediately After Transmission

KE1F Lou
 

I don't know if it happens after transmission, but I will look for it.
I experienced similar problem. My P3 clearly shows the "atennuation of the RF signal" and a "dit" restores the RF gain.
I am also using microHam II interface.
73 Lou KE1F. 



Sent from my Galaxy Tab® A

-------- Original message --------
From: "Harry Rudolph via groups.io" <hgrudolphs@...>
Date: 8/10/20 7:38 PM (GMT-05:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] K3 Receive Function Attenuated Immediately After Transmission

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.

Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C


Re: K3 Receive Function Attenuated Immediately After Transmission

 

The times I encountered this, the problem was in the linear T/R relay.

Solution: check/replace relay   or    Do some CW with QSK at normal power. Sometimes long strings of dots will have a sort of cleaning effect on the relay contacts.

73,

Arie PA3A

Op 11-8-2020 om 01:38 schreef Harry Rudolph via groups.io:



Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C


K3 Receive Function Attenuated Immediately After Transmission

Harry WX8C
 

Was playing around in the WAE CW contest this past weekend and began to experience some problems with the receive function.  I believe I ran into this on several bands but I was mostly on 20 meters so this is where I mostly experienced the condition.  The performance issue was that immediately following a transmission, perhaps in about 10% of the instances, the receive function would come back sounding as if the attenuator was on.  Usually if I added a quick "dit" it would return to the normal receive level.  I fooled around with the AGC which had no effect.  I changed from Ant 1 input to Ant 2 input with no effect.  If I switched to the RX antenna input, it seemed normal.  I was running with a Microham MK II interface and with an amp but did not see any indication that the problem was related to the overall setup, including the antenna.

Curiously, I switched to a different K3 and initially the problem seemed to be resolved.  But after a few more hours of operation, I noticed that I did actually have the problem with the replacement  but just at a much lower frequency.

Anyone experience anything like this or have any suggestions?  I plan to do some more A/B comparisons and take the MK II and amp out of the equation but wanted to see if anyone else has run into this.

Thanks.

Harry
WX8C


Re: WSJT-X audio problems

Bob McGraw - K4TAX
 

Reduce power to 10 - 20 watts and see if it happens. If not, it most likely is a RF problem that appears at higher power. Add 2 or 3 clamp-on ferrite chokes to the cables between the radio and computer.

Bob, K4TAX


Re: KPA3 output erratic

Bob McGraw - K4TAX
 

Power distribution strips will always add series resistance of some value. Likewise, it is strongly suggested one connect the radio power leads directly to the power supply terminals.

In-line fuses will always add series resistance and likewise for any in-line switch. Remember E = I x R? Therefore, any value of series R will cause a voltage drop, E, with the TX current of the radio.

Bob, K4TAX


Re: KPA3 output erratic

mikerodgerske5gbc
 

Lou, I thought it was where did it read the voltage?  

Maybe not. 

Mike R

7!
Absolutely Awesome 


Re: KPA500, Win4K3, and DDU

Bill Mader
 

Apparently, the DDU design requires it to querry the KPA500, according to your description.  That design doesn't consider how many, if not most, KPA500's and KAT500's are connected to logging or other programs and what a second RS-232 transmitter will do to that communications.  I am glad to know this is how these work and sorry for your predicament Mike.

73, Bill, K8TE


Re: KPA3 output erratic

Ed Pflueger
 

Push the DISP button and turn the VFO B knob until you see the voltage.

 

Ed.. AB4IQ

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of KE1F Lou
Sent: Monday, August 10, 2020 8:41 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA3 output erratic

 

I have similar issues.

Where is the internal K3 Volt meter measures the voltage?

Lou KE1F 

 

 

 

Sent from my Galaxy Tab® A

 

-------- Original message --------

From: Brian K0DTJ <huntinhmb@...>

Date: 8/10/20 12:12 AM (GMT-05:00)

Subject: Re: [Elecraft-K3] KPA3 output erratic

 

Hi Chuck,
I would say that 1.2v is excessive.  I started out with the 60 inch or so #12 Elecraft standard power lead and had a slow power hunting problem.  It varied by band but each time I changed the power setting or bands it go to max and then drop down and slowly come to set power.  The power calibration ran OK but didn't solve the problem.

I changed to about 3 ft of #10 stranded automotive wire in a twisted pair setup.  I set the RS-35A Astron supply to about 14.2v.  With that I get 14v at the K3 on receive and 13.3v on transmit at 100w (80m).  Measuring the voltage at the PS under load I get less than 0.1v sag in the Astron regulator.  Then ran the K3 Utility TX gain calibration _twice_ and all is OK now.

Note, in all cases the high current K3 power lead was connected directly to the Astron terminals, not though the RigRunner I use for low current 12v distribution in the shack.

Hope this helps.  Good luck.

73,
Brian, K0DTJ

On 8/9/2020 16:23, Chuck Miller wrote:

What amount of sag is useable? I removed the inline fuse from the power cable, and cranked the 35 amp Astron up to 14.2 volt according to the K3. It drops to 13 volts at 100w watts. The power cable is about 6 feet long as the Astron is a rack mount, and sits on the floor. The power is slow to rise mostly on 160 and 80, and to a less amount on 60 meters. 30 meters and up don't have that lagging power. Still got to check all my coax jumpers
.
73, Chuck
N0NC

 


Re: KPA3 output erratic

KE1F Lou
 

I have similar issues.
Where is the internal K3 Volt meter measures the voltage?
Lou KE1F 



Sent from my Galaxy Tab® A

-------- Original message --------
From: Brian K0DTJ <huntinhmb@...>
Date: 8/10/20 12:12 AM (GMT-05:00)
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA3 output erratic

Hi Chuck,
I would say that 1.2v is excessive.  I started out with the 60 inch or so #12 Elecraft standard power lead and had a slow power hunting problem.  It varied by band but each time I changed the power setting or bands it go to max and then drop down and slowly come to set power.  The power calibration ran OK but didn't solve the problem.

I changed to about 3 ft of #10 stranded automotive wire in a twisted pair setup.  I set the RS-35A Astron supply to about 14.2v.  With that I get 14v at the K3 on receive and 13.3v on transmit at 100w (80m).  Measuring the voltage at the PS under load I get less than 0.1v sag in the Astron regulator.  Then ran the K3 Utility TX gain calibration _twice_ and all is OK now.

Note, in all cases the high current K3 power lead was connected directly to the Astron terminals, not though the RigRunner I use for low current 12v distribution in the shack.

Hope this helps.  Good luck.

73,
Brian, K0DTJ

On 8/9/2020 16:23, Chuck Miller wrote:
What amount of sag is useable? I removed the inline fuse from the power cable, and cranked the 35 amp Astron up to 14.2 volt according to the K3. It drops to 13 volts at 100w watts. The power cable is about 6 feet long as the Astron is a rack mount, and sits on the floor. The power is slow to rise mostly on 160 and 80, and to a less amount on 60 meters. 30 meters and up don't have that lagging power. Still got to check all my coax jumpers
.
73, Chuck
N0NC


Re: KPA3 output erratic

Brian K0DTJ
 

Hi Chuck,
I would say that 1.2v is excessive.  I started out with the 60 inch or so #12 Elecraft standard power lead and had a slow power hunting problem.  It varied by band but each time I changed the power setting or bands it go to max and then drop down and slowly come to set power.  The power calibration ran OK but didn't solve the problem.

I changed to about 3 ft of #10 stranded automotive wire in a twisted pair setup.  I set the RS-35A Astron supply to about 14.2v.  With that I get 14v at the K3 on receive and 13.3v on transmit at 100w (80m).  Measuring the voltage at the PS under load I get less than 0.1v sag in the Astron regulator.  Then ran the K3 Utility TX gain calibration _twice_ and all is OK now.

Note, in all cases the high current K3 power lead was connected directly to the Astron terminals, not though the RigRunner I use for low current 12v distribution in the shack.

Hope this helps.  Good luck.

73,
Brian, K0DTJ

On 8/9/2020 16:23, Chuck Miller wrote:
What amount of sag is useable? I removed the inline fuse from the power cable, and cranked the 35 amp Astron up to 14.2 volt according to the K3. It drops to 13 volts at 100w watts. The power cable is about 6 feet long as the Astron is a rack mount, and sits on the floor. The power is slow to rise mostly on 160 and 80, and to a less amount on 60 meters. 30 meters and up don't have that lagging power. Still got to check all my coax jumpers
.
73, Chuck
N0NC

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