Re: [Elecraft] KPA500 faults

[Bill Frantz]

I will add that 240 volt wiring frequently uses what we 120v people would think 
of as wimpy wire sizes. If you do the math, they give the same wattage as we 
get with our #12 or #14 wore at 120v.  Or at least that’s what I’ve seen when 
I’ve looked at the house wiring in 240v land.

73 Bill AE6JV


> On Mar 3, 2022, at 21:19, j...@kk9a.com wrote:
> 
> I believe St Lucia's power is 50Hz if that makes any difference to the
> KPA500.
> 
> John KK9A
> 
> Mike Fatchett w0mu wrote:
> 
> St. Lucia is 240v.  I don't know why he would run it on 120v or 110v.


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Re: [Elecraft] KPA500 faults

[Andy Durbin]

"Yep.   I think it’s the connections.   The resistor network seems to be fine
and the right values."


Then I'd be looking at U18 and U14B.

Following signals through KPA500 schematics would be a lot easier if they 
didn't change the signal names multiple times.

Andy, k3wyc





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[Elecraft] KPA500 faults

[Andy Durbin]

Ref PA Module schematic.  J4 pin 13 seems to be 60V/32 and it appears to be fed 
by divider R12/R13.

Andy, k3wyc
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Re: [Elecraft] KPA500 faults

[Rick Bates, NK7I]

As I recall, when I got one of the first KPA500 kits available, it was 
also important to note the HV under load... I'd have to dig through 
ancient notes to see what the allowed window should be... or it may be 
in the manual.


That points to the usable power of the house supply circuit; more so in 
old wiring that might not be adequate for such a load (you don't share 
that circuit with a microwave oven).


Mine was borderline, sagged to the low end of that range, on the middle 
post (in a newish home).  When moved to another tap to increase the 
voltage; was still in the 'ok' range for unloaded voltage (it CAN be too 
high).


A little testing and experimentation is needed in setup of the amp; and 
at any new location.


Mine didn't fault in the sag, my goal was a cleaner output with the 
higher voltage while keeping in that window.


73,
Rick NK7I



On 3/2/2022 10:39 PM, Jim Brown wrote:

On 3/2/2022 9:38 PM, Dr. William J. Schmidt wrote:

I have a KPA500 that faults on low (60 VDC) voltage.


Hi Bill,

It MIGHT be faulting because the HV is too low. It's an un-regulated 
supply, so if line voltage is low, HV will be low. There's a jumper to 
re-tap the power transformer, accessible with the top off, details in 
the manual. We used to run into that when running two K3/KPA500 
stations on the same 2kVA Honda on county expeditions for 7QP and CQP.


73, Jim K9YC

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Re: [Elecraft] KPA500 faults

[Jim Brown]

On 3/2/2022 9:38 PM, Dr. William J. Schmidt wrote:

I have a KPA500 that faults on low (60 VDC) voltage.


Hi Bill,

It MIGHT be faulting because the HV is too low. It's an un-regulated 
supply, so if line voltage is low, HV will be low. There's a jumper to 
re-tap the power transformer, accessible with the top off, details in 
the manual. We used to run into that when running two K3/KPA500 stations 
on the same 2kVA Honda on county expeditions for 7QP and CQP.


73, Jim K9YC
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[Elecraft] KPA500 faults

[Dr. William J. Schmidt]

I have a KPA500 that faults on low (60 VDC) voltage.  After measuring the
power supply voltage at the PA module is perfectly fine.  The voltage read
by the processor on the front panel via pin 10 of P1 is lower than it should
be and hence the fault condition.  I suspect there is a voltage divider on
the LPF board that drops the 60 VDC to something that the processor can read
and digitize (in the 0 to 3-5 volt range).  The set of schematics I have do
not show the voltage divider anywhere. does anyone have this part of the
schematics for the KPA500 so that I can adequately troubleshoot this amp and
get it on the air for the contest this weekend?   Multiple notes to Elecraft
have gone unanswered.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
VP2EHZ

 

 

email:    b...@wjschmidt.com

 

 

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[Elecraft] KPA500 faults on first dit at times

[Bill Hammond]

Seasons Greetings Ellecrafters,

KPA500 faults on first dit at times

It doesn't happen all the time and I can't pin down the sequence of events when 
it happens, the last time was after a band QSY after clicking on a spot in my 
logging software. I am wondering if others have had issue or have solved the 
problem.  The fault on the KPA500 is too much drive.  I have the drive adjusted 
per band and none above 32 watts.  It resets quickly and all is well after the 
initial fault.  It usually happens once or twice a day. 

After bringing the amplifier back on line, all is well.  It just scares me when 
it happens :)

73,
Bill
AK5X
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Re: [Elecraft] KPA500 faults on first dit at times

[Ken Wagner K3IU]

I suggest you run the TX Gain 
Calibration procedure on the K3. That 
worked for me.

73, Ken K3IU

On 12/27/2012 8:24 PM, Bill Hammond wrote:

Seasons Greetings Ellecrafters,

KPA500 faults on first dit at times

It doesn't happen all the time and I can't pin down the sequence of events when 
it happens, the last time was after a band QSY after clicking on a spot in my 
logging software. I am wondering if others have had issue or have solved the 
problem.  The fault on the KPA500 is too much drive.  I have the drive adjusted 
per band and none above 32 watts.  It resets quickly and all is well after the 
initial fault.  It usually happens once or twice a day.

After bringing the amplifier back on line, all is well.  It just scares me when 
it happens :)

73,
Bill
AK5X
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[Elecraft] KPA500 Faults, ATTEN REL

[Forest Summers]

I have KPA sn 666 on the air! I purchased the kit. Assembly took 6 hrs. I had
some initial FAULT conditions that showed a HIGH SWR. I am running the amp
through a Palstar AT1500DT, into an HF9V Butternut vertical, ground mounted.
I also have a TH3MK3 beam. I suspected a ground loop, so, I improved my
ground system and have only had very few FAULT conditions since. The KPA500
SWR bar graph is what I use to tune with, SWR being 1.1:1, with one SWR
segment lit. I also started having POUT HI Faults, (yesterday, after using
the amp for a two days.) I drive it with 15W, (I want to go easy on it
breaking it in)  These FAULTs were occuring when the amp was switched from
BAND to BAND, using either the K3, or KPA500. Also, these FAULTs would occur
when switching from OPER to STBY and STBY to OPER, but not every time. What
could be causing this to occur? I did adjust the ATTEN REL setting to 2
(DEFAULT is 3), and this seemed to cure the FAULTs. Is this common?
 I love the little amp, I enjoyed building it and it is a great addition to
the K3! I do have the AUXBUS between the two.  Any thoughts would be
appreciated.  Thanks  Forest  (Gene) 

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