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KPA 1500 Fan Speed Transition Issue

wb6bee
 

According to the notes to the firmware, the Fans are supposed to transition up from Level 0 to level 1 at 50C, returning to Level 0 at 40C.    Transition from Level 1 to Level 2 at 70C and returning to level 1 at 55C.  Transition from level 2 to level 3 at 80C and returning to level 2 at 75C.   Once the temperature reaches the "increase" threshold, the fans are to lock in at the higher fan speed until the unit cools to the "decrease" threshold.

The unit I have doesn't not do that.   For example, if you hold key down until it reaches 50C and release the key, it immediately drops back to 49C and the fan reverts back to level 0.   Release the key at 70C, it immediately drops back to 69C and the fan reverts to level 1.   Release the key at 80C, it immediately drops back to 79C and the fan reverts to level 2.

The effect when keying CW is the fan jumps back and forth multiple times between transition speeds at the transition points.   It is particularly annoying at 80C when the fan is cycling from a very loud level 3 to an acceptable level 2.   Four, five or six cycles between fan speed before the temperature gets above the threshold and it locks in (usually plus 2C or 3C over the threshold.

This has occurred through multiple firmware upgrades

So far, Elecraft has tried reset and/or replace configuration files.   That did not work.     They are sending two capacitors and a sensor for replacement.   Effectiveness of this change is unknown (parts not here).

I have a video of this event, but not sure how to attach a file to this email.

Any observations or recommendations?

Don
WB6BEE

Drew Vonada-Smith K3PA
 

Don,

The two capacitors are part of a field mod to keep noise out of the temp sensor so that transmitting does not indicate a false decrease in temperature.  It does not eliminate the effect, but it helps quite a bit.  This does normally help the TX fan cycling problem. 

I don't quite understand the sensor replacement if the temperatures you see seem to make sense.  I can't say why the intended hysteresis would not work, since it is all done in software.

73,
Drew K3PA

wb6bee
 

Once QRZ comes back up and I can get your email, Drew, I will send you the short video I took of the event.   The temperatures seem to be right.   Not like they are jumping around erratically.   It's a smooth movement going up and down.   The 80C cycling from level 2 to 3 is really annoying.   Of course, the Elecraft tech I was working with left,  now have a new one and the new one is off all next week

Don
WB6BEE

Roger N1RJ
 

Don...

What is the serial number of your amp?

73, Roger

On 8/31/2019 8:44 AM, wb6bee wrote:
According to the notes to the firmware, the Fans are supposed to transition up from Level 0 to level 1 at 50C, returning to Level 0 at 40C.    Transition from Level 1 to Level 2 at 70C and returning to level 1 at 55C.  Transition from level 2 to level 3 at 80C and returning to level 2 at 75C.   Once the temperature reaches the "increase" threshold, the fans are to lock in at the higher fan speed until the unit cools to the "decrease" threshold.
The unit I have doesn't not do that.   For example, if you hold key down until it reaches 50C and release the key, it immediately drops back to 49C and the fan reverts back to level 0.   Release the key at 70C, it immediately drops back to 69C and the fan reverts to level 1.   Release the key at 80C, it immediately drops back to 79C and the fan reverts to level 2.
The effect when keying CW is the fan jumps back and forth multiple times between transition speeds at the transition points.   It is particularly annoying at 80C when the fan is cycling from a very loud level 3 to an acceptable level 2.  Four, five or six cycles between fan speed before the temperature gets above the threshold and it locks in (usually plus 2C or 3C over the threshold.
This has occurred through multiple firmware upgrades
So far, Elecraft has tried reset and/or replace configuration files.   That did not work.     They are sending two capacitors and a sensor for replacement.  Effectiveness of this change is unknown (parts not here).
I have a video of this event, but not sure how to attach a file to this email.
Any observations or recommendations?
Don
WB6BEE

wb6bee
 

Have to check   Bought it November 2018

Don
WB6BEE

wb6bee
 

In installed the new temp sensor and the cap modification kit from Elecraft last night.   So far, it seems to have resolved the issue.   Transitions now appear to be normal.

Don
WB6BEE

Jeff AC0C
 

I will have to as E about this again.  I used the single cap solution which was the first fix and it calmed down the wild swings on 40m enough to let me use the fan utility but the reported temp still bounces around like crazy on 40m.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 9/1/19 10:51 AM, wb6bee wrote:

In installed the new temp sensor and the cap modification kit from Elecraft last night.   So far, it seems to have resolved the issue.   Transitions now appear to be normal.

Don
WB6BEE

Drew Vonada-Smith K3PA
 

Me too Jeff...

wb6bee
 

I changed both the sensor and added the single blue cap to the leads of the sensor.   I do not see swings in temp and I am on 40 most of the time.

Drew had a recording of my issue before I made the change.   At transition points, the amp would upshift and downshift a few times before locking it

Don