Topics

PA temp reading problem [K3]


Keith_WE6R
 

Try pulling and re-seating the KPA3 and KPAIO3 riser board. If those get oxidized or there is any corrosion (something spilled into radio) it can affect the voltage. 
Here are my notes; 

KPA3 temperature swings, not correct, PA temp
The line runs all the way from Q1/R12 on the KPA3 to U6 on the RF board (by FP connector). (Different Q# on the KPA3"A" revisions, Q10 on KPA3A rev A&C, Q5 on rev E boards).
Any opens ("core samples") or corrosion to ground affecting the delicate approx 4.2 volts will mess it up;
OR: if U6 is damaged, bolt for Q1 loose or anodized bolt not making ground, fragile cut trace on the edge of the KPA3.
I measured pin 13/14 at the top the KPA3, VTPA, (4th ones in from the far left of the far left connector P68A that comes from R12 and Q1) to ground.
I calibrated the PA temp, then used coolit spray on Q1;
I got;
4.320 volts at 20C
4.199 at 30C
4.143 at 34C
("core sample" means the bottom right rear foot bolt hit the RF board and cut the trace when the radio was dropped or heavy weight on that foot).
You can see any corrosion or ? that can take this voltage down will easily affect the readings.
Keith WE6R Elecraft K3 Tech.


Robert W5AJ
 

Excellent

 

Keith – I’m not seeing temperature swings like KK9H,  I’m chasing that one of the K3s runs hotter (fans never go to stage 4 – full blast – quit test at 50C)

 

Just a KPA3 and pins all looked good.

took heat sink off and added heat paste

 

IMPORTANT for those doing this:  Don’t remove the heat conductive but electrically insulated paper – used on two discrete devices.   I applied small amount of heat conductive paste there too.

 

73 W5AJ

 

PS:  Now reloading firmware

 

Robert

Midland, Texas

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Keith_WE6R
Sent: Wednesday, July 22, 2020 11:45 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Try pulling and re-seating the KPA3 and KPAIO3 riser board. If those get oxidized or there is any corrosion (something spilled into radio) it can affect the voltage. 
Here are my notes; 

KPA3 temperature swings, not correct, PA temp
The line runs all the way from Q1/R12 on the KPA3 to U6 on the RF board (by FP connector). (Different Q# on the KPA3"A" revisions, Q10 on KPA3A rev A&C, Q5 on rev E boards).
Any opens ("core samples") or corrosion to ground affecting the delicate approx 4.2 volts will mess it up;
OR: if U6 is damaged, bolt for Q1 loose or anodized bolt not making ground, fragile cut trace on the edge of the KPA3.
I measured pin 13/14 at the top the KPA3, VTPA, (4th ones in from the far left of the far left connector P68A that comes from R12 and Q1) to ground.
I calibrated the PA temp, then used coolit spray on Q1;
I got;
4.320 volts at 20C
4.199 at 30C
4.143 at 34C
("core sample" means the bottom right rear foot bolt hit the RF board and cut the trace when the radio was dropped or heavy weight on that foot).
You can see any corrosion or ? that can take this voltage down will easily affect the readings.
Keith WE6R Elecraft K3 Tech.


Keith_WE6R
 

Robert; Does it go full speed when set to FN4? If not, look at the 2 big flat resistors on the riser board just below the Fan connector pins. I have seen a poor solder joint there that prevented all of the speeds from working.
You don't have to cook your KPA3 to test, just set the config PA TEMP to a higher number and see if it goes to full speed. 
Keith WE6R Elecraft K3 Tech.


Robert W5AJ
 

Hi Keith,

great test

 

Yes, goes Full Speed when KPA3 set on FN4

 

on varying PA TEMP

 

Fan ON temperatures (Close):

37C – 1

42C – 2

50C – 3

55C – 4

 

so it is getting to fan speed four!  

 

THANKS!!

 

73 W5AJ

Robert

Midland, Texas

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Keith_WE6R
Sent: Thursday, July 23, 2020 10:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Robert; Does it go full speed when set to FN4? If not, look at the 2 big flat resistors on the riser board just below the Fan connector pins. I have seen a poor solder joint there that prevented all of the speeds from working.
You don't have to cook your KPA3 to test, just set the config PA TEMP to a higher number and see if it goes to full speed. 
Keith WE6R Elecraft K3 Tech.


Ray Maxfield
 

Robert………… So is it Fixed ?

Or are you going to Run it Hard ?   ray  

 

From: Robert W5AJ
Sent: Thursday, July 23, 2020 1:06 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Hi Keith,

great test

 

Yes, goes Full Speed when KPA3 set on FN4

 

on varying PA TEMP

 

Fan ON temperatures (Close):

37C – 1

42C – 2

50C – 3

55C – 4

 

so it is getting to fan speed four!  

 

THANKS!!

 

73 W5AJ

Robert

Midland, Texas

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Keith_WE6R
Sent: Thursday, July 23, 2020 10:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Robert; Does it go full speed when set to FN4? If not, look at the 2 big flat resistors on the riser board just below the Fan connector pins. I have seen a poor solder joint there that prevented all of the speeds from working.
You don't have to cook your KPA3 to test, just set the config PA TEMP to a higher number and see if it goes to full speed. 
Keith WE6R Elecraft K3 Tech.

 


Robert W5AJ
 

I'm calling it OK for now....   ran FT8/FT4 yesterday at 80 to 100 watts.   K3 seems to be doing OK
Good news the rig's PA never gets to 55C so fan level 4 isn't kicking in.  ah, never saw 50C so fan speed level 3 never came on

Thanks again,  on to repairing other things!!    73 W5AJ

On Thu, Jul 23, 2020 at 9:01 PM Ray Maxfield <wa6vab@...> wrote:

Robert………… So is it Fixed ?

Or are you going to Run it Hard ?   ray  

 

From: Robert W5AJ
Sent: Thursday, July 23, 2020 1:06 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Hi Keith,

great test

 

Yes, goes Full Speed when KPA3 set on FN4

 

on varying PA TEMP

 

Fan ON temperatures (Close):

37C – 1

42C – 2

50C – 3

55C – 4

 

so it is getting to fan speed four!  

 

THANKS!!

 

73 W5AJ

Robert

Midland, Texas

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Keith_WE6R
Sent: Thursday, July 23, 2020 10:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Robert; Does it go full speed when set to FN4? If not, look at the 2 big flat resistors on the riser board just below the Fan connector pins. I have seen a poor solder joint there that prevented all of the speeds from working.
You don't have to cook your KPA3 to test, just set the config PA TEMP to a higher number and see if it goes to full speed. 
Keith WE6R Elecraft K3 Tech.

 


Ray Maxfield
 

Your Welcome, Keeep your Fingers Clear……….   ray

 

Sent from Mail for Windows 10

 

From: Robert W5AJ
Sent: Friday, July 24, 2020 3:54 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

I'm calling it OK for now....   ran FT8/FT4 yesterday at 80 to 100 watts.   K3 seems to be doing OK

Good news the rig's PA never gets to 55C so fan level 4 isn't kicking in.  ah, never saw 50C so fan speed level 3 never came on

 

Thanks again,  on to repairing other things!!    73 W5AJ

 

On Thu, Jul 23, 2020 at 9:01 PM Ray Maxfield <wa6vab@...> wrote:

Robert………… So is it Fixed ?

Or are you going to Run it Hard ?   ray  

 

From: Robert W5AJ
Sent: Thursday, July 23, 2020 1:06 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Hi Keith,

great test

 

Yes, goes Full Speed when KPA3 set on FN4

 

on varying PA TEMP

 

Fan ON temperatures (Close):

37C – 1

42C – 2

50C – 3

55C – 4

 

so it is getting to fan speed four!  

 

THANKS!!

 

73 W5AJ

Robert

Midland, Texas

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Keith_WE6R
Sent: Thursday, July 23, 2020 10:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] PA temp reading problem [K3]

 

Robert; Does it go full speed when set to FN4? If not, look at the 2 big flat resistors on the riser board just below the Fan connector pins. I have seen a poor solder joint there that prevented all of the speeds from working.
You don't have to cook your KPA3 to test, just set the config PA TEMP to a higher number and see if it goes to full speed. 
Keith WE6R Elecraft K3 Tech.