Hi Jim,
thanks for your KPA500 issue update and returning the thread to its original
point there.
Let us know the results once you gets there.
Ahoj,
Petr
-
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe: https://bit.ly/2FmwvDt
--
-boun...@mailman.qth.net on
behalf of K9MA
Sent: 11 February 2020 17:11
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
That's very high efficiency for a solid-state amplifier. Are they
operating in class C? Are there any IMD specs at those output levels?
73,
Scott
That's very high efficiency for a solid-state amplifier. Are they
operating in class C? Are there any IMD specs at those output levels?
73,
Scott K9MA
On 2/11/2020 03:18, Edward R Cole wrote:
I checked the operating specs on two of my QRO amps. Not a KPA500.
2m-1500w PA using a MRF1K50 in
I checked the operating specs on two of my QRO amps. Not a KPA500.
2m-1500w PA using a MRF1K50 in class AB:
945w 1398w dc 67% eff 453w disp
1511w 1888w dc 80% eff 377w disp
2m-1200w PA using a MRFE6VP61K25H in class AB:
566w 1200w dc 47% eff 634w disp
1133w 1542w dc 73% eff 409w disp
UPDATE:
Jack/W6FB contacted me directly shortly after posting. I sent him my fault
log to analyze and a detailed description of my equipment setup. Best guess
is a cable or antenna failure causing high SWR sometime in the recent past
that stressed the finals. They gave up the ghost when I was
: elecraft-boun...@mailman.qth.net On
Behalf Of Bob McGraw K4TAX
Sent: Monday 10 February 2020 18:47
To: Andy Durbin
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
Unless one is concerned about power consumption, the efficiency factor should
be really of no concern. Total
Sent: Monday 10 February 2020 18:47
To: Andy Durbin
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
Unless one is concerned about power consumption, the efficiency factor should
be really of no concern. Total heat output will always be greater at maximum
output
Yes, I was wondering why this was so interesting.
Chuck Jack Hawley
KE9UW
Sent from my iPhone, cjack
> On Feb 10, 2020, at 12:47 PM, Bob McGraw K4TAX wrote:
>
> Unless one is concerned about power consumption, the efficiency factor should
> be really of no concern. Total heat output will
Unless one is concerned about power consumption, the efficiency factor should
be really of no concern. Total heat output will always be greater at maximum
output and less at lower power. Nice for warming the shack on a Winter day.
Bob, K4TAX
Sent from my iPhone
> On Feb 10, 2020, at
"This is probably what folks are thinking of when they assume maximum
dissipation occurs at less than full output."
A possible source of error in my data is that the dummy load is cool at the
start of the power ramp and hot by the time peak power is reached. I recorded
LP-100A data during
: [Elecraft] QRO - KPA500 Failure
"I understand that efficiency decreases as one derates from
the maximum of 1500W output.It surprises me that the power dissipated would
peak at half power output or 750
Watts."
I have no test data for the KPA1500 and will not speculate on
to 600W for RTTY.
73 Doug EI2CNSent from my Samsung Galaxy smartphone.
Original message From: K9MA Date:
10/02/2020 16:29 (GMT+00:00) To: elecraft@mailman.qth.net Subject: Re:
[Elecraft] QRO - KPA500 Failure Several others have posted test data for the
KPA500 here
"I understand that efficiency decreases as one derates from the maximum of
1500W output.It surprises me that the power dissipated would peak at half power
output or 750 Watts."
I have no test data for the KPA1500 and will not speculate on the shape of the
PA dissipation curves. All I have is
of this but maybe some guidance from Elecraft itself would be
helpful for both KPA 500 and 1500.
73 Doug EI2CN
From: Andy Durbin
Sent: Monday 10 February 2020 14:04
To: Doug Turnbull ; elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
Doug
nce from Elecraft itself would be
> helpful for both KPA 500 and 1500.
>
> 73 Doug EI2CN
>
>
>
> From: Andy Durbin
> Sent: Monday 10 February 2020 14:04
> To: Doug Turnbull ; elecraft@mailman.qth.net
> Subject: Re: [Elecraft] QRO - KPA5
To: Doug Turnbull ; elecraft@mailman.qth.net
Subject: Re: [Elecraft] QRO - KPA500 Failure
Doug,
"I would like to know if running 2/3, 1/2 or even 1/4 maximum power output
increases reliability and MTBF."
I have no experience of amplifier design but I would expect reliability of
Doug,
"I would like to know if running 2/3, 1/2 or even 1/4 maximum power output
increases reliability and MTBF."
I have no experience of amplifier design but I would expect reliability of the
finals to depend on temperature. Finals temperature will depend on the power
dissipated in the
Sent: Monday 10 February 2020 01:45
To: elecraft@mailman.qth.net
Subject: [Elecraft] QRO - KPA500 Failure
"I am seeing a lot of confusion and erroneous conclusions based on the terms
'efficiency', 'dissipation' coupled with 'power output'."
Yes, very true. Only a few have actually c
"I am seeing a lot of confusion and erroneous conclusions based on the terms
'efficiency', 'dissipation' coupled with 'power output'."
Yes, very true. Only a few have actually contributed test data. All the rest
is assumption and speculation.
Andy, k3wyc
John,
You are correct. I am seeing a lot of confusion and erroneous
conclusions based on the terms 'efficiency', 'dissipation' coupled with
'power output'.
As an example, consider that a PA running at 50% efficient at 500 watts
will dissipate 500 watts of heat and 500 watts of power out.
Jim,
maybe it is not your case but check this first:
http://ok1rp.blogspot.com/2017/02/elecraft-kpa500-lpf-tr-switch-rework.html?_sm_au_=iQWn28RMHPpHWSZ6cLpsvK618Vf61
-
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe:
There may be reasons for running at less than the amplifier max such
as the US 200 watt 30m band limitation. I have no RF engineering
knowledge but after looking at your data I see less heat with lower
output wattage which seems to me like it would be less stress on finals.
John KK9A
I run my KPA500 output just below the level I feel I can get away
with...without lighting up the neighborhood. About 350 watts :)
John K7FD
> On Feb 6, 2020, at 2:06 PM, Bob McGraw K4TAX wrote:
>
> I've never seen much if any advantage in running a linear below its rated
> output. I know
"Basically, based on Bob's measurements, the power dissipated is fairly
independent of drive level. So, running at reduced power really isn't stressing
anything any more that full output."
I have done quite extensive testing of my KPA500 and provided links to my
results. My KPA500 PA
Basically, based on Bob's measurements, the power dissipated is fairly
independent of drive level. So, running at reduced power really isn't
stressing anything any more that full output. (Unlike an "ideal" class B
amplifier.)
73,
Scott K9MA
On 2/6/2020 16:06, Bob McGraw K4TAX wrote:
I've
The advantage I have is that it doesn't set off my fire alarm.
On Thu, 6 Feb 2020, Bob McGraw K4TAX wrote:
I've never seen much if any advantage in running a linear below its
rated output. I know the regulation state never run more power than
needed for adequate communications or terms like
When I blew the final on my KPA500 Elecraft diagnosed the problem. I had to
make a few meter readings and they figured out the problem. They gave me
the option of removing the transformer for shipping (most of the amp
weight). They gave me instructions to remove and reassemble when it
returned.
As a follow up to my previous message I measured PA voltage and current for
OPER mode not keyed and OPER mode keyed with no RF drive input.
PAI not keyed .0, keyed .2
PAV not keyed 80.9, keyed 77.8
Hi reflected power fault can't happen with no drive so won't influence the
results.
I've never seen much if any advantage in running a linear below its
rated output. I know the regulation state never run more power than
needed for adequate communications or terms like that. The difference
between 500 watts and 100 watts is 6.9 dB or about 1 S unit.
In fact, most all of
"On key down (input of 15W) the asterisk briefly displays, then display changes
to 18.1, back to HV display on key up."
Are you saying the "HV" text in the display goes away or that it reads HV 18.1?
Normally the HV display continues to read the PA supply voltage regardless of
whether the
Elecraft self-insures on outbound shipments (i.e., shipments from Elecraft
to customer). That means they accept the responsibility of carrier loss or
damage because their history of loss/damage has been low.
The fact that they self-insure doesn't cover shipments to them unless the
company is
They self-insure OUTbound from Elecraft; it falls on the shipper to
insure, not the recipient.
I had to send in the RF deck (only) of the KPA1500 for factory upgrades
and I asked for Elecraft to cover shipping. I waited a few days.
An hour after I got back from shipping it UPS from Idaho
I'm not sure who asked the question first, but check your email from
Elecraft support about shipping. I was told Elecraft self-insures, so my
shipping of my KPA1500 amp from Portland, OR to the mothership was
around $20.
On Thu, 6 Feb 2020, Rick Bates, NK7I wrote:
While also not cheap in
Hi Rick,
I like your call sign! :)
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources
On 2/6/20 1:07 PM, Rick Bates, NK7I wrote:
Since the SWR is still nominal into the amp (as shown on your
Since the SWR is still nominal into the amp (as shown on your radio),
it's not likely the tuned input circuits (which is confirmed from no
output on all bands).
This points to the high power module. Running low output power from it,
is far less efficient than pushing it hard (compare
Amps making noises like that usually mean you have to take the covers off.
They are easy enough to repair if you are so inclined. If not, then you
will need to contact Elecraft support and odds are you will have to send it
home for a Spa day.
Mike va3mw
On Thu, Feb 6, 2020 at 3:35 PM Jim
On 2/6/2020 12:15 PM, Jim Mullen wrote:
Any pointers of where to start looking?
1) What SWR does the rig see with the amp off?
2) Make notes of any error messages given by the KPA500 display.
3) Call Elecraft Support
73, Jim K9YC
__
Was running about 150W on 18 MHz this afternoon. My KPA 500 made a loud
pop. No more output. Any pointers of where to start looking?
*Details:*
KPA500 (use with KAT500 and Icom 7610)
Antenna on this band is a SteppIR
Amp has been running FB
KPA Utility 1.13.7.16
240V supply
A single loud pop was
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