Re: [Elecraft] KPA500 distorts transmit signal in Bypass

[Jim Brown]

On 6/11/2024 12:40 PM, qat ken brookner wrote:

  Any ideas?


Is everything in your shack well bonded? See
http://k9yc.com/GroundingAndAudio.pdf

What modes? CW or SSB? Both?

Are any audio accessories running from the same 12V supply as the 
transceiver? See this link.


http://k9yc.com/PowerSupplyBondingAndAudioDistortion.pdf

What specifically do you see/hear in the spectrum?  If you can do a 
screen grab of a waterfall that's 10-20 kHz wide, it might yield clues. 
This reflector will reject it, but you could send it to me directly.


73, Jim K9YC
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[Elecraft] KPA500 distorts transmit signal in Bypass

[qat ken brookner]

Hi Everyone,

I have a KPA500 SN 4414 that I use with a Flex 6600 and an upgraded K3. I’ve 
started getting reports of dirty signals when I use the KPA500 at >200 watts 
with either rig.  The problem is there at lower power it turns out, but I guess 
it’s not bad enough to get complaints.  I did some testing, swapping, checking 
cables…

If the KPA500 is switched OFF, the signals pass through and look good to me on 
a separate SDR. I’m using a dummy load for testing and use various power 
settings.  As soon as I switch the amp ON, even in bypass I see tons of spurs 
when transmitting at various power levels (even down to just a few watts).  
Doesn’t matter if I’m using the Flex or the K3.  Turn the amp to operate and 
the same thing, just bigger signal.  Turn the KPA500 off and the signal from 
the Flex or K3 looks good again.

So…  I’m hoping someone has seen this before and that it’s something I can fix 
without shipping this back to Elecraft.  Any ideas?

Thanks & 73
de Ken NS7V
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[Elecraft] KPA500 + KAT500 new price

[Rajiv Dewan]

For sale KPA500 and KAT500 Combo in perfect condition for $2,150 including free 
shipping in CONUS.
Reason for sale: I am replacing them with a RF2K-S.

KPA500 Ser # 0887
Currently wired for 220v.  I will include the cable.  The 220V operation 
requires two 6A fuses that are currently installed in the radio.
I will also include cable and 12A fuses that are needed or 110V operation. Very 
easy switchover.  No need to open the unit.  I have operated the amp at 110V 
and it produces a steady 500W output.
Also included is the AUX cable to go from rig to amp.

KAT500 Ser # 0309
Includes the AUX cable to go from KAT500 to KPA500.
Also, included is the optional KXUSB for connecting to a PC (allows software 
updates and remote operation)

Glad to answer your questions.

73
Raj, N2RD

--
Raj Dewan, N2RD
FN13ua
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[Elecraft] KPA500 & KAT500 Combo for sale

[Rajiv Dewan]

For sale KPA500 and KAT500 Combo in perfect condition for $2,750 including free 
shipping in CONUS.
Reason for sale: I am replacing them with a RF2K-S.

KPA500 Ser # 0887
Currently wired for 220v.  I will include the cable.  The 220V operation 
requires two 6A fuses that are currently installed in the radio.
I will also include cable and 12A fuses that are needed or 110V operation. Very 
easy switchover.  No need to open the unit.  I have operated the amp at 110V 
and it produces a steady 500W output.
Also included is the AUX cable to go from rig to amp.

KAT500 Ser # 0309
Includes the AUX cable to go from KAT500 to KPA500.
Also, included is the optional KXUSB for connecting to a PC (allows software 
updates and remote operation)

Glad to answer your questions.

73
Raj, N2RD

--
Raj Dewan, N2RD
FN13ua
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Re: [Elecraft] KPA500 Failure

[Mark Musick]

Dick,
Here is a link to information on many Elecraft products.

https://www.qsl.net/wb4kdi/Elecraft/index.html

Scroll down and you will see the KPA500.
You will see the schematic links.
Select the Low Pass Filter. It is REV D2 dated 12/5/13. I believe that is the 
latest.
The schematic I have is from 1/30/11.

73,
Mark, WB9CIF

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Dick Bingham
Sent: Thursday, May 2, 2024 02:16
To: elecraft@mailman.qth.net
Subject: [Elecraft] KPA500 Failure

-- An update on my KPA500 failure --

I extracted the amplifier/LPF assembly from the case and examined the two units:

- Power FETs and all components *appear* to be OK
- *LPF Module Rev D* bd appears to be what failed. The
  SM component positioned between C97, C110 and
  C111 *MAY* be C96 - hard to identify after cleaning the
  white vapor-deposited 'stuff' from the PCA using
  acetone solvent. There was what appeared to be a
  "tombstone-positioned" '*something*' sitting on a pad
  in the damaged area that I can not identify.

I have not been able to locate a schematic or PCA picture for this LPF assembly 
to identify the missing component. If someone could provide a link to the Rev D 
LPF assy, I would appreciate it very much.

73 and TU to all who have, so-far, provided helpful suggestions. I am now 
waiting to hear what Elecraft's Service Department has to say about the failure 
info and picture I sent to them today.

Dick/w7wkr
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[Elecraft] KPA500 Failure

[Dick Bingham]

-- An update on my KPA500 failure --

I extracted the amplifier/LPF assembly from the case
and examined the two units:

- Power FETs and all components *appear* to be OK
- *LPF Module Rev D* bd appears to be what failed. The
  SM component positioned between C97, C110 and
  C111 *MAY* be C96 - hard to identify after cleaning the
  white vapor-deposited 'stuff' from the PCA using
  acetone solvent. There was what appeared to be a
  "tombstone-positioned" '*something*' sitting on a pad
  in the damaged area that I can not identify.

I have not been able to locate a schematic or PCA
picture for this LPF assembly to identify the missing
component. If someone could provide a link to the
Rev D LPF assy, I would appreciate it very much.

73 and TU to all who have, so-far, provided helpful
suggestions. I am now waiting to hear what Elecraft's
Service Department has to say about the failure info
and picture I sent to them today.

Dick/w7wkr
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[Elecraft] KPA500 and KA500 for sale

[Richard Gilley]

Selling my KPA500 #3792 and KAT500 #2879.  Both units clean and in top 
condition, casual CW, no DATA or SSB, not used much due to antenna 
restrictions.  Includes interconnect cables for K3/K3S, power cables, KUSB 
interface, KPA500 power ca for 240 Vac. Prefer to sell as a unit, but open for 
discussion.
Asking $2900. Including shipping and insurance CONUS.  Payment via PayPal or 
certified check.

Contact via richgilley...@gmail.com 

Thank you
R Gilley
AD1G
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Re: [Elecraft] KPA500 metering

[W3FPR]

A 1.5 KW external wattmeter is much less expensive than a major KPA500 
repair - I would not risk it.


73,
Don W3FPR

On 4/3/2024 6:15 PM, Mike Murray wrote:

If a KPA500 is in standby, can it be used to determine power output from
another amp by feeding the signal thru the KPA?  I don't currently have an
external power meter I can utilize to check output of an SB200, but I also
don't want to risk damaging the KPA.

73,
Mike - W0AG
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Re: [Elecraft] KPA500 metering

[Ken Winterling]

Check the KPA500 manual. From memory, the max throughput in standby is
200W. As I say, check my memory against the manual.

*Ken*
*WA2LBI*




On Wed, Apr 3, 2024 at 6:36 PM Mike Murray  wrote:

> If a KPA500 is in standby, can it be used to determine power output from
> another amp by feeding the signal thru the KPA?  I don't currently have an
> external power meter I can utilize to check output of an SB200, but I also
> don't want to risk damaging the KPA.
>
> 73,
> Mike - W0AG
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[Elecraft] KPA500 metering

[Mike Murray]

If a KPA500 is in standby, can it be used to determine power output from
another amp by feeding the signal thru the KPA?  I don't currently have an
external power meter I can utilize to check output of an SB200, but I also
don't want to risk damaging the KPA.

73,
Mike - W0AG
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[Elecraft] Wanted: Elecraft KPA500 and KAT500

[Randy via Elecraft]

I am looking for an Elecraft KPA500 amplifier and KAT500 antenna tuner.
   73 Randy
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Re: [Elecraft] KPA500

[AL7CR]

Check eBay.  One was just listed.

On Mon, Mar 18, 2024, at 10:26 AM, Josep via Elecraft wrote:
> Looking for a KPA500 for my Remote station, does anyone have any that 
> don´t need/use anymore..?
> Thanks,
>
>
> 73, 
> JosepEA6BF
> BUG #256  -  CWOps #3072  -  FOC #2182 (ex 1724)  -  CTDXCC - HSC #2016
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[Elecraft] KPA500

[Josep via Elecraft]

Looking for a KPA500 for my Remote station, does anyone have any that don´t 
need/use anymore..?
Thanks,


73, 
JosepEA6BF
BUG #256  -  CWOps #3072  -  FOC #2182 (ex 1724)  -  CTDXCC - HSC #2016
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Re: [Elecraft] KPA500 Receives Keying Signal but does not XMT

[G4GNX]

OK so are you sure that the cables have been connected exactly according to the 
KAT500 manual (page 5)?

When you power up the KPA500 (with the K3 already on) do you see the KPA500 
announce itself in the VFO-B area of the K3? 

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700




> On 5 Dec 2023, at 02:41, Peter M Iverson  wrote:
> 
> Yes, both cables are Elecraft 15-pin cables.
> 
> Sent from my iPhone//Pete
> 
>> On Dec 4, 2023, at 15:30, G4GNX  wrote:
>> 
>> Can we have a little more info please.
>> 
>> Do you have two 15pin cables, one from the K3 to the KAT500 and one from the 
>> KAT500 to the KPA500?
>> 
>> Are the cables genuine Elecraft E850463 Aux Interface Cables or are they VGA 
>> style cables (which won’t work)?
>> 
>> You should not need any other cables connected to the setup apart from power 
>> and RF.
>> 
>> Page 5 of the KAT500 user manual shows the correct cabling.
>> 
>> 73,
>> Alan - G4GNX
>> South Coast UK
>> Elecraft K4D / KPA500 / KAT500 / IC-9700
>> 
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Re: [Elecraft] KPA500 Receives Keying Signal but does not XMT

[Masadaman via Elecraft]

Can anybody tell me how to unsubscribe from this?

Sent from Yahoo Mail on Android 
 
  On Mon, Dec 4, 2023 at 6:34 PM, G4GNX wrote:   Can we have a 
little more info please.

Do you have two 15pin cables, one from the K3 to the KAT500 and one from the 
KAT500 to the KPA500?

Are the cables genuine Elecraft E850463 Aux Interface Cables or are they VGA 
style cables (which won’t work)?

You should not need any other cables connected to the setup apart from power 
and RF.

Page 5 of the KAT500 user manual shows the correct cabling.

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700



> On 4 Dec 2023, at 23:18, Peter Iverson  wrote:
> 
> Here’s the problem: I’ve been successfully running a K3/KPA500/LDG 
> AT-600ProII with no problems, usually USB and digital modes at about 400W 
> out. I recently obtained a KAT500 and replaced the LDG tuner. I used the 
> Elecraft 15-pin cables for full integration. The KPA500 follows the K3 when I 
> switch bands, but when I go from STBY to OPER, the KPA500 shows no output. 
> Neither SWR nor POWER led’s light up. I tried my original configuration with 
> the LDG tuner but same problem occurs—KPA500 no output. I know the K3 is 
> producing output because on STBY the LDG shows POWER and I’m making contacts 
> barefoot. I’ve even tried the basic hookup with RCA cables but no joy. The 
> KPA500 does show an asterisk in the left corner of the display when I key the 
> K3 so it is receiving a keying signal. I’ve checked to make sure I have the 
> latest firmware version and I’ve doubled checked to make sure that INHIB IN 
> is DISABLED in the menu. I’m running the KPA500 on 240V mains. I’m hoping 
> someone can help me solve this dilemma.
> 
> Pete
> KH6GK


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Re: [Elecraft] KPA500 Receives Keying Signal but does not XMT

[G4GNX]

Can we have a little more info please.

Do you have two 15pin cables, one from the K3 to the KAT500 and one from the 
KAT500 to the KPA500?

Are the cables genuine Elecraft E850463 Aux Interface Cables or are they VGA 
style cables (which won’t work)?

You should not need any other cables connected to the setup apart from power 
and RF.

Page 5 of the KAT500 user manual shows the correct cabling.

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700



> On 4 Dec 2023, at 23:18, Peter Iverson  wrote:
> 
> Here’s the problem: I’ve been successfully running a K3/KPA500/LDG 
> AT-600ProII with no problems, usually USB and digital modes at about 400W 
> out. I recently obtained a KAT500 and replaced the LDG tuner. I used the 
> Elecraft 15-pin cables for full integration. The KPA500 follows the K3 when I 
> switch bands, but when I go from STBY to OPER, the KPA500 shows no output. 
> Neither SWR nor POWER led’s light up. I tried my original configuration with 
> the LDG tuner but same problem occurs—KPA500 no output. I know the K3 is 
> producing output because on STBY the LDG shows POWER and I’m making contacts 
> barefoot. I’ve even tried the basic hookup with RCA cables but no joy. The 
> KPA500 does show an asterisk in the left corner of the display when I key the 
> K3 so it is receiving a keying signal. I’ve checked to make sure I have the 
> latest firmware version and I’ve doubled checked to make sure that INHIB IN 
> is DISABLED in the menu. I’m running the KPA500 on 240V mains. I’m hoping 
> someone can help me solve this dilemma.
> 
> Pete
> KH6GK


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[Elecraft] KPA500 Receives Keying Signal but does not XMT

[Peter Iverson]

Here’s the problem: I’ve been successfully running a K3/KPA500/LDG AT-600ProII 
with no problems, usually USB and digital modes at about 400W out. I recently 
obtained a KAT500 and replaced the LDG tuner. I used the Elecraft 15-pin cables 
for full integration. The KPA500 follows the K3 when I switch bands, but when I 
go from STBY to OPER, the KPA500 shows no output. Neither SWR nor POWER led’s 
light up. I tried my original configuration with the LDG tuner but same problem 
occurs—KPA500 no output. I know the K3 is producing output because on STBY the 
LDG shows POWER and I’m making contacts barefoot. I’ve even tried the basic 
hookup with RCA cables but no joy. The KPA500 does show an asterisk in the left 
corner of the display when I key the K3 so it is receiving a keying signal. 
I’ve checked to make sure I have the latest firmware version and I’ve doubled 
checked to make sure that INHIB IN is DISABLED in the menu. I’m running the 
KPA500 on 240V mains. I’m hoping someone can help me solve this dilemma.

Pete
KH6GK
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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Jack Brindle via Elecraft]

If you use the key-line interrupter, then you must use the phono-plug cables to 
connect the K3, KPA and KAT. Otherwise PTT will not get to the amplifier.
Of course using both without the key line interrupter is very redundant. You 
just don’t want to use both if an external device is included.

73,
Jack, W6FB


> On Oct 12, 2023, at 11:35 AM, Andy Durbin  wrote:
> 
> SteppIR will accept up to 200 W without damage and opening the amplifier key 
> line is the standard way protect SteppIR antennas.
> 
> It has been asserted that "NO key line interrupter is needed".  However, 
> Elecraft recognizes that they may be such a need and sells an adapter to 
> disable keying by AUX cable.  The description even mentions including the W2 
> is the protection system.
> 
> https://ftp.elecraft.com/KPA/Manuals%20Downloads/E740160%20-%20KPAK3AUX%20Cable%20Set%20Instructions%20Rev%201E.pdf
> 
> Andy, k3wyc
> 
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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Andy Durbin]

SteppIR will accept up to 200 W without damage and opening the amplifier key 
line is the standard way protect SteppIR antennas.

It has been asserted that "NO key line interrupter is needed".  However, 
Elecraft recognizes that they may be such a need and sells an adapter to 
disable keying by AUX cable.  The description even mentions including the W2 is 
the protection system.

https://ftp.elecraft.com/KPA/Manuals%20Downloads/E740160%20-%20KPAK3AUX%20Cable%20Set%20Instructions%20Rev%201E.pdf

Andy, k3wyc

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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Jack Brindle via Elecraft]

Key line interrupt would probably not be a good way since the transceiver is 
still transmitting, but at a lower level. All key line interrupt does is to 
disable the amplifier.
I would think a better way would be to use the K3’s inhibit input signal if you 
really need no tx power coming out.

Note that this has been handled in many, many stations to this point with few 
(or no) issues.

73,
Jack, W6FB


> On Oct 12, 2023, at 10:32 AM, Andy Durbin  wrote:
> 
> "In the KAT500 manual, page 5, Figure 1 Cabling Diagram, is the better and 
> safer way to configure the system.  NO key line interrupter is needed.
> 
> How does an Elecraft station that controls KPA500 and KAT500 using AUX cables 
> inhibit keying when a SteppIR antenna is moving the tapes?  This protection 
> must be provided or element tapes and brushes can be damaged.
> 
> Andy, k3wyc
> 
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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Andy Durbin]

"In the KAT500 manual, page 5, Figure 1 Cabling Diagram, is the better and 
safer way to configure the system.  NO key line interrupter is needed.

How does an Elecraft station that controls KPA500 and KAT500 using AUX cables 
inhibit keying when a SteppIR antenna is moving the tapes?  This protection 
must be provided or element tapes and brushes can be damaged.

Andy, k3wyc

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[Elecraft] KPA500 / KAT500 and W2 watt meter question

[Bob McGraw]

Andy:

With my K3S station I use the AUX cable system between the K3S connected 
to the KAT500 and then connected from the KAT500 to the KPA500.   No 
interrupter is needed.   The AUX lines handles the proper control for 
the tuner and the amp.  I do NOT use the Key Line cables, sometimes 
called PTT, to handle T/R switching. Correctly configured, the K3S is 
set for 20 watts TUNE power and Power Per Band, as required.   I find no 
need for multiple methods.  My general philosophy is; "more connectors, 
more cables equal more problems".   KISS


In the KAT500 manual, page 5, Figure 1 Cabling Diagram, is the better 
and safer way to configure the system.  NO key line interrupter is needed.


As to the Kenwood, I have no knowledge of the system.

73

Bob, K4TAX


On 10/12/2023 7:33 AM, elecraft-requ...@mailman.qth.net wrote:
Message: 15 Date: Wed, 11 Oct 2023 23:02:09 + From: Andy Durbin 
 To: "elecraft@mailman.qth.net" 
 Subject: [Elecraft] KPA500 / KAT500 and W2 
watt meter question Message-ID: 
 
Content-Type: text/plain; charset="iso-8859-1" "I just ordered the 
KPA500/KAT500 combo and W2 watt meter for my K3S. Should I use the key 
line interrupt connected to the W2 watt meter or should I connect the 
key line interrupt to the KAT500? Do I even need to use key line 
interrupt with the K line set up?" Why would it hurt to have multiple 
ways to inhibit KPA500 keying? I run a Kenwood rig so no AUXBus 
control but my KPA500 key line passes through my LP-100A and through a 
SteppIR inhibit circuit. Both can open the key line. In addition my 
station controller can assert KAT500 key inhibit by serial command. 
KAT500 key line inhibited is my default condition. I only allow the 
key line to be enabled if several critical checks have passed. (e.g. 
KAT500 frequency, KPA500 band selection, Kenwood drive power setting.) 
I'll do anything I can to avoid being on the list of people who fried 
their KPA500. I can fix stuff but I'd prefer to chase DX. 73, Andy, k3wyc

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[Elecraft] KPA500 / KAT500 and W2 watt meter question

[Andy Durbin]

"I just ordered the KPA500/KAT500 combo and W2 watt meter for my K3S. Should I 
use the key line interrupt connected to the W2 watt meter or should I connect 
the key line interrupt to the KAT500? Do I even need to use key line interrupt 
with the K line set up?"

Why would it hurt to have multiple ways to inhibit KPA500 keying?  I run a 
Kenwood rig so no AUXBus control but my KPA500 key line passes through my 
LP-100A and through a SteppIR inhibit circuit.  Both can open the key line. In 
addition my station controller can assert KAT500 key inhibit by serial command.

KAT500 key line inhibited is my default condition.  I only allow the key line 
to be enabled if several critical checks have passed. (e.g. KAT500 frequency, 
KPA500 band selection, Kenwood drive power setting.)

I'll do anything I can to avoid being on the list of people who fried their 
KPA500.  I can fix stuff but I'd prefer to chase DX.

73,
Andy, k3wyc
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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Tom N4LSJ]

The KAT500 will interrupt the amp properly.  Radio key line goes to KAT, 
then KAT key line goes to KPA.  Coax is opposite: Rig to Amp, then Amp 
to Tuner, then Tuner to Antenna.


On 10/10/23 08:17, Glenn Maclean wrote:

I just ordered the KPA500/KAT500 combo and W2 watt meter for my K3S. Should I 
use the key line interrupt connected to the W2 watt meter or should I connect 
the key line interrupt to the KAT500? Do I even need to use key line interrupt 
with the K line set up?
Thanks in advance
Glenn WA7SPY

Sent from my iPhone
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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Jack Brindle via Elecraft]

Glenn;

You will want the two Aux cables to connect the K3S to the KAT500, then the 
KAT500 to the KPA500. The cables are described in the equipment manuals.
When the KAT500 is in a tune or finds some error situation, it will negate the 
key line to the KPA500 until the KAT is able to correct the situation.

With this setup, you don’t need the key line interrupter that the W2 provides 
since the KAT500 is doing it for you.

If you need any help, just ask. We hope you really enjoy your KPA500/KAT500 
combination!

73,
Jack, W6FB


> On Oct 10, 2023, at 7:17 AM, Glenn Maclean  wrote:
> 
> I just ordered the KPA500/KAT500 combo and W2 watt meter for my K3S. Should I 
> use the key line interrupt connected to the W2 watt meter or should I connect 
> the key line interrupt to the KAT500? Do I even need to use key line 
> interrupt with the K line set up?
> Thanks in advance
> Glenn WA7SPY
> 
> Sent from my iPhone
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Re: [Elecraft] Elecraft] KPA500 / KAT500 and W2 watt meter question

[john]

The original post is in the archives so I am sure that was distributed:
https://mailman.qth.net/pipermail/elecraft/2023-October/293543.html

John KK9A

Dean, K2WW wrote;

I don't see the original thread only Bob's reply?
I've noticed these broken thread quite frequently...Has anyone else see
this?

73
Dean K2WW

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Re: [Elecraft] KPA500 / KAT500 and W2 watt meter question

[Dean L/ K2WW]

I don't see the original thread only Bob's reply?
I've noticed these broken thread quite frequently...Has anyone else see
this?

73
Dean K2WW

On Tue, Oct 10, 2023, 11:09 AM Bob McGraw  wrote:

> Glenn:
>
> In the KAT500 manual, page 5. Figure 1 Cabling Diagram is the better way
> to connect the items.  It does not use the key line interrupt. That is
> the configuration which I have used, very successfully, for years.
>
> In the K3S, set the MENU for 20 watts TUNE power, and from the CONFIG
> menu PWR SET to Per Band.
>
> 73
>
> Bob, K4TAX
>
>
>
> On 10/10/2023 7:18 AM, elecraft-requ...@mailman.qth.net wrote:
> > Message: 23 Date: Tue, 10 Oct 2023 05:17:26 -0700 From: Glenn Maclean
> >  To: elecraft@mailman.qth.net Subject: [Elecraft]
> > KPA500 / KAT500 and W2 watt meter question Message-ID:
> > <3a0e28e4-8411-4394-a880-0fec58bf3...@att.net> Content-Type:
> > text/plain; charset=us-ascii I just ordered the KPA500/KAT500 combo
> > and W2 watt meter for my K3S. Should I use the key line interrupt
> > connected to the W2 watt meter or should I connect the key line
> > interrupt to the KAT500? Do I even need to use key line interrupt with
> > the K line set up? Thanks in advance Glenn WA7SPY
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[Elecraft] KPA500 / KAT500 and W2 watt meter question

[Bob McGraw]

Glenn:

In the KAT500 manual, page 5. Figure 1 Cabling Diagram is the better way 
to connect the items.  It does not use the key line interrupt. That is 
the configuration which I have used, very successfully, for years.


In the K3S, set the MENU for 20 watts TUNE power, and from the CONFIG 
menu PWR SET to Per Band.


73

Bob, K4TAX



On 10/10/2023 7:18 AM, elecraft-requ...@mailman.qth.net wrote:
Message: 23 Date: Tue, 10 Oct 2023 05:17:26 -0700 From: Glenn Maclean 
 To: elecraft@mailman.qth.net Subject: [Elecraft] 
KPA500 / KAT500 and W2 watt meter question Message-ID: 
<3a0e28e4-8411-4394-a880-0fec58bf3...@att.net> Content-Type: 
text/plain; charset=us-ascii I just ordered the KPA500/KAT500 combo 
and W2 watt meter for my K3S. Should I use the key line interrupt 
connected to the W2 watt meter or should I connect the key line 
interrupt to the KAT500? Do I even need to use key line interrupt with 
the K line set up? Thanks in advance Glenn WA7SPY

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[Elecraft] KPA500 / KAT500 and W2 watt meter question

[Glenn Maclean]

I just ordered the KPA500/KAT500 combo and W2 watt meter for my K3S. Should I 
use the key line interrupt connected to the W2 watt meter or should I connect 
the key line interrupt to the KAT500? Do I even need to use key line interrupt 
with the K line set up?
Thanks in advance
Glenn WA7SPY

Sent from my iPhone
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[Elecraft] FS: Elecraft KPA500 and KAT500

[Bill Phillips]

I'm selling my KAT500 and KPA500. I've hardly used the KPA500, 
preferring to operate at 100 watts. It's currently wired for 240 Volts.  
Power cords included, but no interconnects.  $2000.  Buyer pays 
shipping.  Thanks for looking.


Bill  AD6JV

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Re: [Elecraft] KPA500 / KAT500 Combo

[James Bennett via Elecraft]

The amp and tuner have been sold. Thanks for your interest.


> On Oct 4, 2023, at 4:27 PM, James Bennett via Elecraft 
>  wrote:
> 
> Time to clean house of items that are rarely used. I’m selling my KPA500 
> (serial # 3645) and KAT500 (serial #2726). Both were built by me a few years 
> ago and work perfectly. I started out using them with a K3, then a K4D, and 
> most recently a Kenwood TS-890. Both the tuner and the amp work perfectly. 
> Neither has any scratches, dings, or dents and have been used in 100 percent 
> non-smoking environments. The amp is set for 117 volt operation and includes 
> the correct power cable.
> 
> Included will be the following manuals: KPA500 Kit Assembly Instructions, 
> KPA500 Owner’s Manual, KAT500 Owner’s Manual, and the Fred Cady (KE7X, SK) 
> book on the KPA500 and KAT500, 2nd edition.
> 
> In addition you’ll get the interconnecting cables. I currently have the pair 
> connecting my TS-890. You’ll get the corresponding cable(s) for that 
> arrangement along with the cables to connect to a K3 or K4 if that’s what you 
> have.
> 
> The amp and tuner have been in use here at my Idaho QTH for 2-1/2 years, 
> connected to a Zerofive Flagpole Vertical. With 110 feet of RG213, the tuner 
> has been able to get a match on 160 - 6 meters, no small feat indeed! Sadly, 
> I simply don’t use the amp and tuner all that often, I need the dollars, so 
> they’ve gotta go.
> 
> The KPA500 will be shipped in an Elecraft factory double boxed carton. I’ll 
> have UPS professionally package up the KAT500.
> 
> I much prefer to sell the amp and tuner as one package, price: $2,900, FREE 
> SHIPPING, NO SALES TAX. Check the price for a brand new pair and add tax - my 
> price will save you some serious dollars!
> 
> I prefer PayPal friends and family, but will accept cash or personal check 
> (10 days to clear a check, sorry).
> 
> Please contact me off-list. K7TXA at ARRL DOT NET
> 
> Jim / K7TXA (ex-W6JHB)
> Eagle, ID
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Re: [Elecraft] KPA500 17M missing

[Jim Brown]

On 8/31/2023 2:45 PM, Henry Pfizenmayer via Elecraft wrote:

I have a friend across town who has a KPA500  built from a kit  Aug 2017 SN 
33XX who has never used his K3S or KPA500  on17 m and just got an antenna for 
17 and lo and behold NOTHING he does will allow operation on 17.


Hank,

Will the K3S transmit on 17M with the antenna connected directly to it?

73, Jim K9YC
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[Elecraft] KPA500 17M missing

[Henry Pfizenmayer via Elecraft]

I have a friend across town who has a KPA500  built from a kit  Aug 2017 SN 
33XX who has never used his K3S or KPA500  on17 m and just got an antenna for 
17 and lo and behold NOTHING he does will allow operation on 17.


 He normally always used the Utility to change bands etc  .So he took that 
RS232 cable off off and used the KPAK3AUX cable between the K3S and its 
switching between ALL bands following the K3S band but on17M the KPA500 SWR is 
OK in bypass but is high SWR  in OPR and the K3S detects itand will just show 
high SWR. The K3S will put out power in STBY but of course not in KPA500 OPER 
because of the SWR. 



He has checked with his  VNA and in fact  the path thru the KPA is  is 
essentially open on17 and in OPR and OK in STBY (50 ohm dummy load) . He tried 
cycling the bands many times thinking maybe the 17 M LPF relays were not making 
good contact since he had never tried 17M .No joy. 



He installed the latest firmware today and no change. 



So has anyone seen this ??   Archive search so far shows people have had 17 M 
issues but for other reasons. He plans to open it up and look at the LPF filter 
test port later if no ideas. 



Thanks 



Hank K7HP
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Re: [Elecraft] KPA500 gain variation with serial number

[Tom N4LSJ]

Mine was bought new in the Summer of 2022 and on most bands it needs 
watts to be in the mid to upper 30s to get the 500 out.


On 7/20/23 13:04, Andy Durbin wrote:

I have been told that the gain of the KPA500 has increased over the years it has been produced.   
"Early" KPA500 are reported to need 35-39 W to produce 500 W out. "Later" 
KPA500 are reported to need only 20-25 W for full output.  The difference in gain has been 
attributed to difference in the PA transistors as well as component changes in the LPF.

I'm interested in knowing where my KPA500 serial number falls in the spread of 
required drive power.  I would like to receive data from KPA500 owners so I can 
get an idea of what gain can be associated with a serial number range.   To 
minimize the spread of data I'd like to specify 20 m band,  non reactive 50 ohm 
load,  key down CW mode.  It would be preferable for drive power and output 
power to be measured with the same instrument but I'll take what I can get.  If 
a KAT500 or other tuner is in circuit it should be in Bypass mode.

Requested data:

Serial number;  frequency; drive power; output power (target 500 W); PA voltage 
(front panel HV); PA current (front panel CUR); power measurement instrument(s).

Only one data point for 20 m band is requested but additional data won't be 
discarded.   I'll collate any data and share it if here is any interest.

Thanks and 73,
Andy, k3wyc




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Re: [Elecraft] KPA500 gain variation with serial number

[Dave (NK7Z)]

Andy,

Pitch out the highest, and lowest, and it looks fairly flat...

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 7/26/23 11:00, Andy Durbin wrote:

I now have data for nine KPA500 with serial numbers ranging from 11x to 478x 
(exact serial number intentionally obscured).  Thanks to everyone who 
contributed.

The data show no significant increase in gain from the earliest to the latest 
serial numbers.  However, the data do seem to suggest that serial numbers near 
2,000  have gain well above average.

Perhaps the most interesting data came from one owner of two KPA500.  Serial 
209x had a gain of 14.4 dB but serial 478x had a gain of 12.0.  These numbers 
are from the same person using the same power measurement device and same 
measurement technique.

Lowest reported gain was 11.5 dB (2 samples) and one of those is mine.  There 
are three others at 11.8 dB.  All except 3 fall in the range 11.5 to 12.0.

Plot can be found here - 
https://www.dropbox.com/s/jk1t9j2417lh9gz/KPA500%2020%20m%20gain.png?dl=0

I also have some information on two other KPA500 that have high gain but I 
don't have serial numbers for them.  I'll update my plot if I receive any 
additional data.

73,
Andy, k3wyc


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Re: [Elecraft] KPA500 gain variation with serial number

[Andy Durbin]

I now have data for nine KPA500 with serial numbers ranging from 11x to 478x 
(exact serial number intentionally obscured).  Thanks to everyone who 
contributed.

The data show no significant increase in gain from the earliest to the latest 
serial numbers.  However, the data do seem to suggest that serial numbers near 
2,000  have gain well above average.

Perhaps the most interesting data came from one owner of two KPA500.  Serial 
209x had a gain of 14.4 dB but serial 478x had a gain of 12.0.  These numbers 
are from the same person using the same power measurement device and same 
measurement technique.

Lowest reported gain was 11.5 dB (2 samples) and one of those is mine.  There 
are three others at 11.8 dB.  All except 3 fall in the range 11.5 to 12.0.

Plot can be found here - 
https://www.dropbox.com/s/jk1t9j2417lh9gz/KPA500%2020%20m%20gain.png?dl=0

I also have some information on two other KPA500 that have high gain but I 
don't have serial numbers for them.  I'll update my plot if I receive any 
additional data.

73,
Andy, k3wyc


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Re: [Elecraft] KPA500 gain variation with serial number

[Andy Durbin]

Thanks to all those who have submitted test data.  I shall need more to have 
any hope of seeing a correlation so please keep it coming.

Requested data:

Serial number;  frequency; drive power; output power (target 500 W); PA voltage 
(front panel HV); PA current (front panel CUR); power measurement instrument(s).

Only one data point for 20 m band is requested but additional data won't be 
discarded.

Thanks and 73,
Andy, k3wyc


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[Elecraft] KPA500 gain variation with serial number

[Andy Durbin]

I have been told that the gain of the KPA500 has increased over the years it 
has been produced.   "Early" KPA500 are reported to need 35-39 W to produce 500 
W out. "Later" KPA500 are reported to need only 20-25 W for full output.  The 
difference in gain has been attributed to difference in the PA transistors as 
well as component changes in the LPF.

I'm interested in knowing where my KPA500 serial number falls in the spread of 
required drive power.  I would like to receive data from KPA500 owners so I can 
get an idea of what gain can be associated with a serial number range.   To 
minimize the spread of data I'd like to specify 20 m band,  non reactive 50 ohm 
load,  key down CW mode.  It would be preferable for drive power and output 
power to be measured with the same instrument but I'll take what I can get.  If 
a KAT500 or other tuner is in circuit it should be in Bypass mode.

Requested data:

Serial number;  frequency; drive power; output power (target 500 W); PA voltage 
(front panel HV); PA current (front panel CUR); power measurement instrument(s).

Only one data point for 20 m band is requested but additional data won't be 
discarded.   I'll collate any data and share it if here is any interest.

Thanks and 73,
Andy, k3wyc




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Re: [Elecraft] KPA500 PA DISS fault

[Jim Brown]

On 7/16/2023 6:43 AM, Rajiv Dewan wrote:

What do you think I should check or do?


Call Elecraft support. Their service techs will likely have seen it before.

73, Jim K9YC
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Re: [Elecraft] KPA500 PA DISS fault

[Glenn Anderson]

I had the same problem about a year ago.  It's a problem with the output PIN 
diode switch. There will be a burned toroid in the output switch circuit. I 
sent mine back for repair. It's been working fine since.Good luck,Glenn WB5TUF 
 Original message From: Rajiv Dewan  Date: 
7/16/23  08:45  (GMT-06:00) To: elecraft@mailman.qth.net Subject: [Elecraft] 
KPA500 PA DISS fault Hello,   My KPA500 developed a PA DISS fault right the 
start of the VHF contest operating FT8 on 6m.  It is:* showing this message on 
all bands.   The antenna is fine.  (1.2 SWR)* same fault even when feeding a 
good dummy load* I smelt acrid smoke :(What do you think I should check or 
do?Thanks for any tips,Best,Raj N2RD-- --Rajiv Dewan, 
N2RD__Elecraft 
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[Elecraft] KPA500 PA DISS fault

[Rajiv Dewan]

Hello,

  My KPA500 developed a PA DISS fault right the start of the VHF 
contest operating FT8 on 6m.  It is:


* showing this message on all bands.   The antenna is fine.  (1.2 SWR)

* same fault even when feeding a good dummy load

* I smelt acrid smoke :(

What do you think I should check or do?

Thanks for any tips,

Best,

Raj N2RD

--
--
Rajiv Dewan, N2RD

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Re: [Elecraft] KPA500

[EA6BF, Josep via Elecraft]

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Re: [Elecraft] KPA500

[Ian Kahn]

There are also taps inside the KPA500 that need to be set correctly, for
the voltage you wish to use. The assembly manual fully describes setting
the taps appropriately, for your desired voltage.

73 de,

Ian, NV4C

On Mon, Jun 5, 2023, 10:58 AM Irwin KD3TB  wrote:

> Joe,
> On the back of the KPA 500 you will find a fuse plug. You will switch this
> between voltages using different fusses. Be careful to use the correct
> fusses for the specific voltage. You can find the directions in the manual.
>
> Irwin KD3TB
>
> On Mon, Jun 5, 2023 at 7:03 AM Josep via Elecraft <
> elecraft@mailman.qth.net>
> wrote:
>
> > Hi guys,
> > just a question.I have recently bought a KPA500 (#0762) in the US.I
> > have another one at home that a friend of mine built for me in the US.I
> > know the amplifier works 100-120VAC and 200-240VAC so the question is if
> I
> > need to switch some kinda interruptor inside the amplifier.I need to know
> > that so when it comes here I can check wether its set, to 110VAC or
> 240VAC,
> > and correct it if needed.
> > Thanks for help.
> >
> >
> > 73,
> > JosepEA6BFMyWebsiteBUG #256  -  CWOps #3072  -  FOC #2182 (ex 1724)
> > __
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>
> --
> Irwin KD3TB
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Re: [Elecraft] KPA500

[Irwin KD3TB]

Joe,
On the back of the KPA 500 you will find a fuse plug. You will switch this
between voltages using different fusses. Be careful to use the correct
fusses for the specific voltage. You can find the directions in the manual.

Irwin KD3TB

On Mon, Jun 5, 2023 at 7:03 AM Josep via Elecraft 
wrote:

> Hi guys,
> just a question.I have recently bought a KPA500 (#0762) in the US.I
> have another one at home that a friend of mine built for me in the US.I
> know the amplifier works 100-120VAC and 200-240VAC so the question is if I
> need to switch some kinda interruptor inside the amplifier.I need to know
> that so when it comes here I can check wether its set, to 110VAC or 240VAC,
> and correct it if needed.
> Thanks for help.
>
>
> 73,
> JosepEA6BFMyWebsiteBUG #256  -  CWOps #3072  -  FOC #2182 (ex 1724)
> __
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-- 
Irwin KD3TB
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[Elecraft] KPA500

[Josep via Elecraft]

Hi guys,
just a question.I have recently bought a KPA500 (#0762) in the US.I have 
another one at home that a friend of mine built for me in the US.I know the 
amplifier works 100-120VAC and 200-240VAC so the question is if I need to 
switch some kinda interruptor inside the amplifier.I need to know that so when 
it comes here I can check wether its set, to 110VAC or 240VAC, and correct it 
if needed.
Thanks for help.


73, 
JosepEA6BFMyWebsiteBUG #256  -  CWOps #3072  -  FOC #2182 (ex 1724)
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[Elecraft] KPA500 for sale; delivery at HamVention

[Rus Healy]

I am the second owner of a very nice KPA500. I have recently replaced the
finals. The amplifier puts out full power on all bands. I am selling it to
fund some microwave EME purchases.

The amp is wired for 240 V ac but it is easily changed to 120 V without
opening the covers. (New ceramic fuses of the correct rating would be
required.)

Includes power cord and factory packaging. I would prefer to deliver in
person this week at HamVention (Thursday evening through early Sunday), but
I could ship it next week as well.

Price is $2400 firm for in-person delivery, or $2400 plus actual shipping
and insurance costs (domestic US only) for shipping.

PayPal (F) or cash. Message me directly at [k2ua at arrl dot net], not to
the list. Thanks.

--73, Rus, K2UA
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[Elecraft] KPA500 Fan Question

[Andy Durbin]

"The issue: The fan comes on in a very short time - less than 20 seconds - and 
the temp display runs up to 50+ degrees. If I start calling CQ or get into a 
QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is 
running at max."

Max fan speed of a KPA500 is setting 6.  With a PA temperature between 60 and 
65 deg C the fan should be running at level 3.  Transition to level 4 is at 
about 65 deg C on my KPA500.   It has to get quite a bit hotter that 60 deg C 
for the fan to be running "at max".

What is making the fan come on in a very short time before you start calling 
CQ?  Are you saying the fan runs after you power the KPA500 but before you 
transmit?  If so, check that KPA500 is not being continuously keyed.  That will 
cause enough PA dissipation to run the fans even with no RF output.

Andy, k3wyc


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Re: [Elecraft] KPA500 Fan Question

[Jack Brindle via Elecraft]

Hi Jim!
Hope you are enjoying Idaho. I hear it is a great place to be!

The fan in the KPA500 goes to level 3 at 60 degrees. It goes to full-on at 80 
degrees. 
The levels are:
level 1 - 50C degrees
level 2 - 55C degrees
level 3 - 60C degrees
level 4 - 65C degrees
level 5 - 70C degrees
level 6 - 80C degrees
The amplifier will fault at a temperature is 90C.

What mode are you operating? And, for those using TS-890s, why would the KPA 
behave any differently than it does with a K3? Has anyone checked for spurs or 
harmonics coming out of the transmitter? (NOT suggesting there are any, mind 
you). I’m looking for reasons the KPA would heat up any faster than with a K3. 
Are you seeing anything else, like strange band changes?

But, rest assured that the KPA will run just fine at 60 or 65 degrees. The fan 
sound is just telling you the KPA is doing its normal great job at protecting 
itself.

73,
Jack, W6FB
p.s. I didn’t want the snow, so I went the other way, going home to Louisiana…


> On May 14, 2023, at 12:23 PM, James Bennett via Elecraft 
>  wrote:
> 
> Got a question (problem?) regarding the fan in my KPA500. I'm driving the amp 
> at 29 watts from a Kenwood TS-890S. The amp is connected to a KAT500, which 
> in turn is hooked to a 30 foot tall Zerofive flagpole vertical. The tuner has 
> provided me with a nice 1.2:1 SWR, as displayed on the amp. The resting temp 
> of the amp shows 42C. At 29 watts input to the amp, I’m seeing about 480 
> watts of power from the amp. The amp has nothing sitting on top of it, and 
> the wall behind it is over 12” away. There is about 2” clearance on either 
> side of the amp, and it is sitting on top of the KAT500.
> 
> The issue: The fan comes on in a very short time - less than 20 seconds - and 
> the temp display runs up to 50+ degrees. If I start calling CQ or get into a 
> QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is 
> running at max.
> 
> When I had a K3 and more recently, a K4D - this did NOT happen. The fan would 
> come on but NEVER at the max, loud level. Interestingly, many moons ago I 
> also had a KX3 and had it connected to the KPA500. I noticed that the fan 
> would also come on fairly quickly with that rig driving the amp, but I never 
> thought too much about it. Until now...
> 
> But now, I think there is some sort of problem. It seems to me that the temp 
> shouldn’t get that high that fast nor should the fan start roaring in that 
> short amount of time. I could understand it if the SWR was really bad, but at 
> 1.2:1
> 
> Any ideas why the amp fan should be acting this way with a non-K3 or non-K4 
> driving it?
> 
> Jim / K7TXA
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Re: [Elecraft] KPA500 Fan Question

[Peter Lascell]

My K3 into the KPA500 for over ten years . . . .   The FAN REV is 1.54
(this might be software)The resting temp is 27C.  When on RTTY I set
the FAN to 4.  Otherwise 2 for most of the time.  Knowing temperature is
the killer of electronics (short of lightning) I try to keep things cool.
For 10 years I have had a 24 V muffin fan running at 12 V sitting on top of
the amp (and another one on the K3).

To rule out VSWR issues, how about connecting the KPA500 directly into a
dummy load.

Pete W4WWQ

On Sun, May 14, 2023 at 1:24 PM James Bennett via Elecraft <
elecraft@mailman.qth.net> wrote:

> Got a question (problem?) regarding the fan in my KPA500. I'm driving the
> amp at 29 watts from a Kenwood TS-890S. The amp is connected to a KAT500,
> which in turn is hooked to a 30 foot tall Zerofive flagpole vertical. The
> tuner has provided me with a nice 1.2:1 SWR, as displayed on the amp. The
> resting temp of the amp shows 42C. At 29 watts input to the amp, I’m seeing
> about 480 watts of power from the amp. The amp has nothing sitting on top
> of it, and the wall behind it is over 12” away. There is about 2” clearance
> on either side of the amp, and it is sitting on top of the KAT500.
>
> The issue: The fan comes on in a very short time - less than 20 seconds -
> and the temp display runs up to 50+ degrees. If I start calling CQ or get
> into a QSO, it doesn’t take long for the temp to show over 60 degrees and
> the fan is running at max.
>
> When I had a K3 and more recently, a K4D - this did NOT happen. The fan
> would come on but NEVER at the max, loud level. Interestingly, many moons
> ago I also had a KX3 and had it connected to the KPA500. I noticed that the
> fan would also come on fairly quickly with that rig driving the amp, but I
> never thought too much about it. Until now...
>
> But now, I think there is some sort of problem. It seems to me that the
> temp shouldn’t get that high that fast nor should the fan start roaring in
> that short amount of time. I could understand it if the SWR was really bad,
> but at 1.2:1
>
> Any ideas why the amp fan should be acting this way with a non-K3 or
> non-K4 driving it?
>
> Jim / K7TXA
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-- 
Pete Lascell
Forest, VA
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Re: [Elecraft] KPA500 Fan Question

[AL7CR]

My setup is like yours and the response is exactly the same.   Starting use on 
fan speed 4 delays the temp rise for a short time. Mine has run many many  
hours at temps up to 70 with no problems.   Hottest on 20m and  requires the 
most drive on that band also. 

On Sun, May 14, 2023, at 10:23 AM, James Bennett via Elecraft wrote:
> Got a question (problem?) regarding the fan in my KPA500. I'm driving 
> the amp at 29 watts from a Kenwood TS-890S. The amp is connected to a 
> KAT500, which in turn is hooked to a 30 foot tall Zerofive flagpole 
> vertical. The tuner has provided me with a nice 1.2:1 SWR, as displayed 
> on the amp. The resting temp of the amp shows 42C. At 29 watts input to 
> the amp, I’m seeing about 480 watts of power from the amp. The amp has 
> nothing sitting on top of it, and the wall behind it is over 12” away. 
> There is about 2” clearance on either side of the amp, and it is 
> sitting on top of the KAT500.
>
> The issue: The fan comes on in a very short time - less than 20 seconds 
> - and the temp display runs up to 50+ degrees. If I start calling CQ or 
> get into a QSO, it doesn’t take long for the temp to show over 60 
> degrees and the fan is running at max.
>
> When I had a K3 and more recently, a K4D - this did NOT happen. The fan 
> would come on but NEVER at the max, loud level. Interestingly, many 
> moons ago I also had a KX3 and had it connected to the KPA500. I 
> noticed that the fan would also come on fairly quickly with that rig 
> driving the amp, but I never thought too much about it. Until now...
>
> But now, I think there is some sort of problem. It seems to me that the 
> temp shouldn’t get that high that fast nor should the fan start roaring 
> in that short amount of time. I could understand it if the SWR was 
> really bad, but at 1.2:1
>
> Any ideas why the amp fan should be acting this way with a non-K3 or 
> non-K4 driving it?
>
> Jim / K7TXA
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Re: [Elecraft] KPA500 Fan Question

[Mike Maloney]

 Your resting temperature at 42C seems TOO warm to me?   My KPA resting temp 
runs about the same as ambient temperature of shack, 25-30C.   With 25-30W 
drive from TS-890,my KPA seldom reaches 3rd stage 60 degrees.   Have you 
checked SWR or cable between 890 and KPA?  
73, Mike AC5P
On Sunday, May 14, 2023 at 12:38:56 PM CDT, James Bennett via Elecraft 
 wrote:  
 
 Yes, but the amp is not seeing the mis-match, correct? The tuner is taking 
care of that mis-match and I would have thought that the amp should be 
perfectly happy… Yes?

> On May 14, 2023, at 11:35 AM, Dr. William J. Schmidt  
> wrote:
> 
> You are trying to transform a mis-match and that burns energy.  That’s why 
> the fan is running.
> 
> 
> 
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On 
> Behalf Of James Bennett via Elecraft
> Sent: Sunday, May 14, 2023 12:24 PM
> To: Elecraft Reflector Reflector 
> Subject: [Elecraft] KPA500 Fan Question
> 
> Got a question (problem?) regarding the fan in my KPA500. I'm driving the amp 
> at 29 watts from a Kenwood TS-890S. The amp is connected to a KAT500, which 
> in turn is hooked to a 30 foot tall Zerofive flagpole vertical. The tuner has 
> provided me with a nice 1.2:1 SWR, as displayed on the amp. The resting temp 
> of the amp shows 42C. At 29 watts input to the amp, I’m seeing about 480 
> watts of power from the amp. The amp has nothing sitting on top of it, and 
> the wall behind it is over 12” away. There is about 2” clearance on either 
> side of the amp, and it is sitting on top of the KAT500.
> 
> The issue: The fan comes on in a very short time - less than 20 seconds - and 
> the temp display runs up to 50+ degrees. If I start calling CQ or get into a 
> QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is 
> running at max.
> 
> When I had a K3 and more recently, a K4D - this did NOT happen. The fan would 
> come on but NEVER at the max, loud level. Interestingly, many moons ago I 
> also had a KX3 and had it connected to the KPA500. I noticed that the fan 
> would also come on fairly quickly with that rig driving the amp, but I never 
> thought too much about it. Until now...
> 
> But now, I think there is some sort of problem. It seems to me that the temp 
> shouldn’t get that high that fast nor should the fan start roaring in that 
> short amount of time. I could understand it if the SWR was really bad, but at 
> 1.2:1
> 
> Any ideas why the amp fan should be acting this way with a non-K3 or non-K4 
> driving it?
> 
> Jim / K7TXA
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Re: [Elecraft] KPA500 Fan Question

[James Bennett via Elecraft]

Yes, but the amp is not seeing the mis-match, correct? The tuner is taking care 
of that mis-match and I would have thought that the amp should be perfectly 
happy… Yes?

> On May 14, 2023, at 11:35 AM, Dr. William J. Schmidt  
> wrote:
> 
> You are trying to transform a mis-match and that burns energy.  That’s why 
> the fan is running.
> 
> 
> 
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On 
> Behalf Of James Bennett via Elecraft
> Sent: Sunday, May 14, 2023 12:24 PM
> To: Elecraft Reflector Reflector 
> Subject: [Elecraft] KPA500 Fan Question
> 
> Got a question (problem?) regarding the fan in my KPA500. I'm driving the amp 
> at 29 watts from a Kenwood TS-890S. The amp is connected to a KAT500, which 
> in turn is hooked to a 30 foot tall Zerofive flagpole vertical. The tuner has 
> provided me with a nice 1.2:1 SWR, as displayed on the amp. The resting temp 
> of the amp shows 42C. At 29 watts input to the amp, I’m seeing about 480 
> watts of power from the amp. The amp has nothing sitting on top of it, and 
> the wall behind it is over 12” away. There is about 2” clearance on either 
> side of the amp, and it is sitting on top of the KAT500.
> 
> The issue: The fan comes on in a very short time - less than 20 seconds - and 
> the temp display runs up to 50+ degrees. If I start calling CQ or get into a 
> QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is 
> running at max.
> 
> When I had a K3 and more recently, a K4D - this did NOT happen. The fan would 
> come on but NEVER at the max, loud level. Interestingly, many moons ago I 
> also had a KX3 and had it connected to the KPA500. I noticed that the fan 
> would also come on fairly quickly with that rig driving the amp, but I never 
> thought too much about it. Until now...
> 
> But now, I think there is some sort of problem. It seems to me that the temp 
> shouldn’t get that high that fast nor should the fan start roaring in that 
> short amount of time. I could understand it if the SWR was really bad, but at 
> 1.2:1
> 
> Any ideas why the amp fan should be acting this way with a non-K3 or non-K4 
> driving it?
> 
> Jim / K7TXA
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[Elecraft] KPA500 Fan Question

[James Bennett via Elecraft]

Got a question (problem?) regarding the fan in my KPA500. I'm driving the amp 
at 29 watts from a Kenwood TS-890S. The amp is connected to a KAT500, which in 
turn is hooked to a 30 foot tall Zerofive flagpole vertical. The tuner has 
provided me with a nice 1.2:1 SWR, as displayed on the amp. The resting temp of 
the amp shows 42C. At 29 watts input to the amp, I’m seeing about 480 watts of 
power from the amp. The amp has nothing sitting on top of it, and the wall 
behind it is over 12” away. There is about 2” clearance on either side of the 
amp, and it is sitting on top of the KAT500.

The issue: The fan comes on in a very short time - less than 20 seconds - and 
the temp display runs up to 50+ degrees. If I start calling CQ or get into a 
QSO, it doesn’t take long for the temp to show over 60 degrees and the fan is 
running at max.

When I had a K3 and more recently, a K4D - this did NOT happen. The fan would 
come on but NEVER at the max, loud level. Interestingly, many moons ago I also 
had a KX3 and had it connected to the KPA500. I noticed that the fan would also 
come on fairly quickly with that rig driving the amp, but I never thought too 
much about it. Until now...

But now, I think there is some sort of problem. It seems to me that the temp 
shouldn’t get that high that fast nor should the fan start roaring in that 
short amount of time. I could understand it if the SWR was really bad, but at 
1.2:1

Any ideas why the amp fan should be acting this way with a non-K3 or non-K4 
driving it?

Jim / K7TXA
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Re: [Elecraft] KPA500/KAT500 with Yaesu FT-710 Transciever

[john]

You could just connect the RF cables and the relay cable and let the KPA/KAT
detect and automatically change bands. It will work very well this way.

John KK9A


William Santos KN6UDK wrote:

Hello gang,

I'm considering purchase of a KPA500/KAT500 combo to use with my FT-710
Transciever.

Under the "Cables for non-Elecraft Transceivers" section of the KPA500
Elecraft web page, the FT-710 is not listed.

1. What cables do I need for a KPA500/KAT500 combo interfaced with a Yaesu
FT-710 Transciever?

2. Does anyone out there use this configuration? How do you like it? Any
quirks, problems, workarounds?

Thanks and 73,

Bill
KN6UDK

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[Elecraft] KPA500/KAT500 with Yaesu FT-710 Transciever

[William Santos via Elecraft]

Hello gang,

I'm considering purchase of a KPA500/KAT500 combo to use with my FT-710 
Transciever.

Under the "Cables for non-Elecraft Transceivers" section of the KPA500 Elecraft 
web page, the FT-710 is not listed.

1. What cables do I need for a KPA500/KAT500 combo interfaced with a Yaesu 
FT-710 Transciever?

2. Does anyone out there use this configuration? How do you like it? Any 
quirks, problems, workarounds?

Thanks and 73,

Bill
KN6UDK

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Re: [Elecraft] KPA500-KAT500 Combo For Sale.

[Mike Dodd]

On 3/2/2023 12:14 PM, Ramon Batista wrote:

Prefer Local Pick-Up Or Meet Up To 100 Miles


QTH?


My QRZ Information Is
Up To Date


And your call sign is??

--- Mike N4CF

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[Elecraft] KPA500-KAT500 Combo For Sale.

[Ramon Batista]

*For Sale An Elecraft KPA500-F HF-6M Amplifier & KAT500-F HF-6M ATU. Both
Units Are Factory Built In Like New And Excellent Cosmetic And Operational
Conditions With No Dents, Dings Or Scratches. The Sale Include Original
Boxes With Inserts Power Cables And Accessory Cables To Interconnect Both
Units And Radio. Prefer Local Pick-Up Or Meet Up To 100 Miles And Welcome
To Come And Do A Test Drive. Asking Price Is $2850.00 Shipped And Insured
And Payment Through Zelle, USPS Money Order Or Check. My QRZ Information Is
Up To Date And Phone Number 239-227-9414. Pictures and Videos Upon Request.*

*Package Details:*

*KPA500-F*
*KAT500-F*
*KPAK3AUX Cable*
*KXUSBA USB To 3.5mm*
*PWR-USA 120V Power Cable*
*E85046 Aux Cable K4-K3S-K3 To KPA500*
*Spare Fuses for 240v-120v*
*E980262 KAT500 Power Cable*
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Re: [Elecraft] KPA500 failure

[davidg3una]

Lyn

Just a thought: the rig has a remote on/off facility and you may be getting
extraneous signals into that port.  I know nothing more, but it may give you
a clue where to start looking.  

73 David G3UNA

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Lyn Norstad
Sent: 09 February 2023 15:57
To: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 failure

Here's another twist that makes me thing it could be a PS issue.

Early this morning, I was hunting down 3Y0J on 10m FT8 (very strong signal
here).  WSJT-X was in F/H and S/P mode.  I stepped out of the shack for a
few minutes, and when I came back the KAP500 was powered ON, in Standby mode
with the Fault LED lit up.  It had been powered Off with the front panel
switch since yesterday (the rear panel switch was ON as usual).

How is that possible?

Thx,
Lyn

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Lyn Norstad
Sent: Wednesday, February 08, 2023 4:00 PM
To: Elecraft@mailman.qth.net
Subject: [Elecraft] KPA500 failure

A couple days ago, I stepped out of the shack for a few minutes and upon
returning found the KPA500 had shut down.  I didn’t note any brief power
outage, and I’m quite sure it was “ON” when I stepped away.

 

It has been a little quirky in keying since that time.  Yesterday it gave
off a funny smell and the Power and SWR LEDs were jumping up and down for no
apparent reason. The  display screen jumps to frequency readout when I key
the exciter, no matter what it is set for.

 

The KAT500 seems to be working normally with the amp either OFF or in
Standby.

 

I did a total power reset and reloaded the current firmware (v01.54), but no
change.

 

I have not pulled it apart yet, but I seem to remember these being the
symptoms discussed some time ago that required an LPF rebuild.  Somewhere
along the line, Elecraft switched to a SM board and that’s when the trouble
started.

 

So my question … besides asking for general advice … is if anyone knows the
serial number when Elecraft made that change.  My KPA500 is s/n 03835.

 

Thanks!

 

73

Lyn, WØLEN

 

 

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delivered to davidg3...@gmail.com 

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Re: [Elecraft] KPA500 failure

[Lyn Norstad]

Here's another twist that makes me thing it could be a PS issue.

Early this morning, I was hunting down 3Y0J on 10m FT8 (very strong signal
here).  WSJT-X was in F/H and S/P mode.  I stepped out of the shack for a
few minutes, and when I came back the KAP500 was powered ON, in Standby mode
with the Fault LED lit up.  It had been powered Off with the front panel
switch since yesterday (the rear panel switch was ON as usual).

How is that possible?

Thx,
Lyn

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Lyn Norstad
Sent: Wednesday, February 08, 2023 4:00 PM
To: Elecraft@mailman.qth.net
Subject: [Elecraft] KPA500 failure

A couple days ago, I stepped out of the shack for a few minutes and upon
returning found the KPA500 had shut down.  I didn’t note any brief power
outage, and I’m quite sure it was “ON” when I stepped away.

 

It has been a little quirky in keying since that time.  Yesterday it gave
off a funny smell and the Power and SWR LEDs were jumping up and down for no
apparent reason. The  display screen jumps to frequency readout when I key
the exciter, no matter what it is set for.

 

The KAT500 seems to be working normally with the amp either OFF or in
Standby.

 

I did a total power reset and reloaded the current firmware (v01.54), but no
change.

 

I have not pulled it apart yet, but I seem to remember these being the
symptoms discussed some time ago that required an LPF rebuild.  Somewhere
along the line, Elecraft switched to a SM board and that’s when the trouble
started.

 

So my question … besides asking for general advice … is if anyone knows the
serial number when Elecraft made that change.  My KPA500 is s/n 03835.

 

Thanks!

 

73

Lyn, WØLEN

 

 

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[Elecraft] KPA500 failure

[Lyn Norstad]

A couple days ago, I stepped out of the shack for a few minutes and upon
returning found the KPA500 had shut down.  I didn’t note any brief power
outage, and I’m quite sure it was “ON” when I stepped away.

 

It has been a little quirky in keying since that time.  Yesterday it gave
off a funny smell and the Power and SWR LEDs were jumping up and down for no
apparent reason. The  display screen jumps to frequency readout when I key
the exciter, no matter what it is set for.

 

The KAT500 seems to be working normally with the amp either OFF or in
Standby.

 

I did a total power reset and reloaded the current firmware (v01.54), but no
change.

 

I have not pulled it apart yet, but I seem to remember these being the
symptoms discussed some time ago that required an LPF rebuild.  Somewhere
along the line, Elecraft switched to a SM board and that’s when the trouble
started.

 

So my question … besides asking for general advice … is if anyone knows the
serial number when Elecraft made that change.  My KPA500 is s/n 03835.

 

Thanks!

 

73

Lyn, WØLEN

 

 

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[Elecraft] KPA500 repair

[Andy Durbin]

Well that's an interesting failure report.  I don't see any obvious single 
factor except for overheating of the entire PA module.

Was the fan functioning normally, air vents clear, and external airflow 
unobstructed?

"Capton tape on the "S" bracket is interesting.  Did they mean "Kapton tape on 
the Z bracket"?  Sounds like the fix I was going to attempt but the clicking 
went away as my KPA500 aged.

Andy, k3wyc
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[Elecraft] KPA500 repair

[n1ix]

My KPA500 is on the way back from Watsonville. Just in time for the Bouvet 
DXpedition 

I am trying to understand what might have caused the problem. Here are the 
details. 

 

Problem(s) found:

T/R circuit failure due thermal damaged diode D10 causing damage to traces and 
pads on LPF module.  Thermal damaged relays K3,K5,K7 on LPF module. (diodes 
physically near D10)   Amp clicking when getting hot. 

 

Repair(s) performed:

Repaired damaged traces and pads on LPF module.  Replaced diode D10 and 
K3,K5,K7 on LPF module. Replaced diodes D7, D8, D9 on LPF module as preventive 
measure.Added capton tape to “S” bracket to avoid amp clicking. 

 

Dave N1IX

 

 

 

 

 

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[Elecraft] KPA500 Won’t Tune

[Jim Ruff via Elecraft]

I’m running a K3,KPA500,KAT500 into a 10-80 meter OCFD at ~ 50 ft.  It will 
tune 40M great but fault on all other bands.  This is not a new problem, but 
has been going on for a few years. Any ideas what could be causing this?  I’m 
following the instructions in the tuner manual. 
Thanks,Jim W7JHR


Sent from Yahoo Mail for iPad
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[Elecraft] KPA500 Faulting

[marv marvrossphoto . com]

Thanks to Jack for suggesting I take a look at the output cable to see if it 
had any issues.  Sure enough, when I got the top cover off, the end of the 
black wire that comes from the Gnd Output connector on the PA board and goes to 
the solder lug on the SO-239 Power Out connector, was staring at me.  This now 
made complete sense that the SWR issue was more pronounced at higher 
frequencies.  This was a "ground loop".  The ground loop was a bigger 
percentage of a wavelength on the higher frequencies and therefore a bigger 
discontinuity.

The amp is happy now and I am glad to have this in the rear-view mirror.

Cheers,

Marv
W0PSY
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Re: [Elecraft] KPA500 Also faulting for High SWR inappropriately

[Fred Jensen]

1. "The Problem" is almost never caused by "the worst thing that could 
happen."


2.  Humans will nearly always assume it's "the worst thing that could 
happen."


While learning to fly an airplane many years ago, IP told me, "By far, 
the reason for landing with the gear up is because you abandoned the 
checklist and forgot to put the wheels down.  It's almost never the 
airplane's fault."


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

Tom N4LSJ wrote on 1/4/2023 6:31 AM:
I got a KPA500 this summer and it was doing a lot of faulting.  I had 
to "correct" a few things that were just fine at 100 watts.


1: I discovered that a solder joint in the UNUN had gone bad, and 
fixed that.  That solved most of the faults.
2: With still the occasional fault, I looked again and discovered 
there was a spot on one of the windings in my UNUN that had been 
scraped free of enamel.  I applied insulation.
3: After several months of great operation, my receiver had started to 
"cut out" after transmitting.  At first, I thought my rig was going 
kaput, but it was an inline SO-239 barrell that had gotten heated up 
because of no longer being a tight fit. Replacing that cured it.


Moral: It's almost always the antenna system, somewhere.



On 12/30/22 15:20, Jack Brindle via Elecraft wrote:

Amazingly, it is probably not the KPA500.

We have been seeing quite a few inquiries about this. Analysis almost 
always shows an issue in the antenna system caused by high power.


There are a few things at play. When measuring SWR (or better, 
antenna S parameters) at low power, you will get the results of the 
low power measurements. These are usually quite good for determine 
antenna characteristics and generally tell you almost everything 
going on with the antenna. They do not tell you how the antenna 
handles high power.


Antenna system components, including the feed line , connectors, wire 
and so forth, are designed to handle some level of power before they 
will fail in some way.
As an example, spacing of the windings in loading coils matters. Too 
small, and the coil will arc at high power. The same is true with 
connectors, center insulators and the like. Many antennas have 
matching boxes at their feed point to properly match the feed line to 
the antenna. These have a rating, and many are amazingly low.
One popular (and very good) commercial dipole antenna is rated for 
1000 watts ICAS. The specifications later state that the antenna 
should not exceed 500 watts on CW. This is especially important when 
running digital modes such as FT8 which keep power applied to the 
antenna for long periods of time. As power is applied, the components 
will heat and will eventually fail. When they fail, probably not 
catastrophically, they will change the matching characteristics, and 
the amplifier will see a very high reflected power that will cause it 
to protect itself. When the user inspects the components (with power 
off), they will probably not see a problem - unless the component 
failed catastrophically, it will have cooled by then. The problem 
will repeat itself, of course. No measurement taken with an antenna 
analyzer or VNA will show the problem, because they work at very low 
power levels.


When you select an antenna, the ratings must be taken into 
consideration. Manufacturers like to hide the power ratings 
(especially those with built-in matching systems) in order to get 
more sales. If you want to run high power, don’t use a miniature beam 
- they need lots of matching and are almost always designed to run at 
low power. The same is true for compromise wire antennas and those 
that require matching networks at their feed point. Also watch for 
compromise connectors and adapters. Right-angle UHF adapters are 
notorious for arcing. You can’t see it because it is inside the 
connector, but that arcing is probably the cause of a PA Dissipation 
fault in the amplifier. Make sure connections are tight - hand tight 
is not good enough. Use the best connectors you can get. The industry 
standard is Amphenol - they have very high quality standards.


In short, make sure the antenna system you are using is designed to 
handle high power for doing periods of time. If not, it will fail, 
and when you inspect it you will wonder why.


73,
Jack, W6FB

On Dec 30, 2022, at 12:46 PM, marv marvrossphoto.com 
 wrote:


I have pretty much the same symptoms reported by the KPA1500 users 
here.  The higher the frequency the more likely to see a fault.  10M 
is the worst one.  The amp shows a 2:1 SWR and that is running it 
into a tuned KAT500, which shows 1.2:1 and a Daiwa bridge showing 
1.1:1 into the antenna.  It's the same on a dummy load.


I don't understand Bob McGraw's logic as if it does require power, 
my Daiwa is gonna see it.  If I measure the feedline, lightning 
protection and antenna with a network analyzer I will be doing it 
with mili Watts.


Cheers,

Marv
W0PSY




--
This email has been checked for 

Re: [Elecraft] KPA500 Also faulting for High SWR inappropriately

[Tom N4LSJ]

I got a KPA500 this summer and it was doing a lot of faulting.  I had to 
"correct" a few things that were just fine at 100 watts.


1: I discovered that a solder joint in the UNUN had gone bad, and fixed 
that.  That solved most of the faults.
2: With still the occasional fault, I looked again and discovered there 
was a spot on one of the windings in my UNUN that had been scraped free 
of enamel.  I applied insulation.
3: After several months of great operation, my receiver had started to 
"cut out" after transmitting.  At first, I thought my rig was going 
kaput, but it was an inline SO-239 barrell that had gotten heated up 
because of no longer being a tight fit. Replacing that cured it.


Moral: It's almost always the antenna system, somewhere.



On 12/30/22 15:20, Jack Brindle via Elecraft wrote:

Amazingly, it is probably not the KPA500.

We have been seeing quite a few inquiries about this. Analysis almost always 
shows an issue in the antenna system caused by high power.

There are a few things at play. When measuring SWR (or better, antenna S 
parameters) at low power, you will get the results of the low power 
measurements. These are usually quite good for determine antenna 
characteristics and generally tell you almost everything going on with the 
antenna. They do not tell you how the antenna handles high power.

Antenna system components, including the feed line , connectors, wire and so 
forth, are designed to handle some level of power before they will fail in some 
way.
As an example, spacing of the windings in loading coils matters. Too small, and 
the coil will arc at high power. The same is true with connectors, center 
insulators and the like. Many antennas have matching boxes at their feed point 
to properly match the feed line to the antenna. These have a rating, and many 
are amazingly low.
One popular (and very good) commercial dipole antenna is rated for 1000 watts 
ICAS. The specifications later state that the antenna should not exceed 500 
watts on CW. This is especially important when running digital modes such as 
FT8 which keep power applied to the antenna for long periods of time. As power 
is applied, the components will heat and will eventually fail. When they fail, 
probably not catastrophically, they will change the matching characteristics, 
and the amplifier will see a very high reflected power that will cause it to 
protect itself. When the user inspects the components (with power off), they 
will probably not see a problem - unless the component failed catastrophically, 
it will have cooled by then. The problem will repeat itself, of course. No 
measurement taken with an antenna analyzer or VNA will show the problem, 
because they work at very low power levels.

When you select an antenna, the ratings must be taken into consideration. 
Manufacturers like to hide the power ratings (especially those with built-in 
matching systems) in order to get more sales. If you want to run high power, 
don’t use a miniature beam - they need lots of matching and are almost always 
designed to run at low power. The same is true for compromise wire antennas and 
those that require matching networks at their feed point. Also watch for 
compromise connectors and adapters. Right-angle UHF adapters are notorious for 
arcing. You can’t see it because it is inside the connector, but that arcing is 
probably the cause of a PA Dissipation fault in the amplifier. Make sure 
connections are tight - hand tight is not good enough. Use the best connectors 
you can get. The industry standard is Amphenol - they have very high quality 
standards.

In short, make sure the antenna system you are using is designed to handle high 
power for doing periods of time. If not, it will fail, and when you inspect it 
you will wonder why.

73,
Jack, W6FB



On Dec 30, 2022, at 12:46 PM, marv marvrossphoto.com  
wrote:

I have pretty much the same symptoms reported by the KPA1500 users here.  The 
higher the frequency the more likely to see a fault.  10M is the worst one.  
The amp shows a 2:1 SWR and that is running it into a tuned KAT500, which shows 
1.2:1 and a Daiwa bridge showing 1.1:1 into the antenna.  It's the same on a 
dummy load.

I don't understand Bob McGraw's logic as if it does require power, my Daiwa is 
gonna see it.  If I measure the feedline, lightning protection and antenna with 
a network analyzer I will be doing it with mili Watts.

Cheers,

Marv
W0PSY
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Re: [Elecraft] KPA500 Also faulting for High SWR inappropriately

[Jack Brindle via Elecraft]

Amazingly, it is probably not the KPA500. 

We have been seeing quite a few inquiries about this. Analysis almost always 
shows an issue in the antenna system caused by high power.

There are a few things at play. When measuring SWR (or better, antenna S 
parameters) at low power, you will get the results of the low power 
measurements. These are usually quite good for determine antenna 
characteristics and generally tell you almost everything going on with the 
antenna. They do not tell you how the antenna handles high power. 

Antenna system components, including the feed line , connectors, wire and so 
forth, are designed to handle some level of power before they will fail in some 
way.
As an example, spacing of the windings in loading coils matters. Too small, and 
the coil will arc at high power. The same is true with connectors, center 
insulators and the like. Many antennas have matching boxes at their feed point 
to properly match the feed line to the antenna. These have a rating, and many 
are amazingly low. 
One popular (and very good) commercial dipole antenna is rated for 1000 watts 
ICAS. The specifications later state that the antenna should not exceed 500 
watts on CW. This is especially important when running digital modes such as 
FT8 which keep power applied to the antenna for long periods of time. As power 
is applied, the components will heat and will eventually fail. When they fail, 
probably not catastrophically, they will change the matching characteristics, 
and the amplifier will see a very high reflected power that will cause it to 
protect itself. When the user inspects the components (with power off), they 
will probably not see a problem - unless the component failed catastrophically, 
it will have cooled by then. The problem will repeat itself, of course. No 
measurement taken with an antenna analyzer or VNA will show the problem, 
because they work at very low power levels.

When you select an antenna, the ratings must be taken into consideration. 
Manufacturers like to hide the power ratings (especially those with built-in 
matching systems) in order to get more sales. If you want to run high power, 
don’t use a miniature beam - they need lots of matching and are almost always 
designed to run at low power. The same is true for compromise wire antennas and 
those that require matching networks at their feed point. Also watch for 
compromise connectors and adapters. Right-angle UHF adapters are notorious for 
arcing. You can’t see it because it is inside the connector, but that arcing is 
probably the cause of a PA Dissipation fault in the amplifier. Make sure 
connections are tight - hand tight is not good enough. Use the best connectors 
you can get. The industry standard is Amphenol - they have very high quality 
standards.

In short, make sure the antenna system you are using is designed to handle high 
power for doing periods of time. If not, it will fail, and when you inspect it 
you will wonder why.

73,
Jack, W6FB


> On Dec 30, 2022, at 12:46 PM, marv marvrossphoto.com  
> wrote:
> 
> I have pretty much the same symptoms reported by the KPA1500 users here.  The 
> higher the frequency the more likely to see a fault.  10M is the worst one.  
> The amp shows a 2:1 SWR and that is running it into a tuned KAT500, which 
> shows 1.2:1 and a Daiwa bridge showing 1.1:1 into the antenna.  It's the same 
> on a dummy load.
> 
> I don't understand Bob McGraw's logic as if it does require power, my Daiwa 
> is gonna see it.  If I measure the feedline, lightning protection and antenna 
> with a network analyzer I will be doing it with mili Watts.
> 
> Cheers,
> 
> Marv
> W0PSY
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[Elecraft] KPA500 Also faulting for High SWR inappropriately

[marv marvrossphoto . com]

I have pretty much the same symptoms reported by the KPA1500 users here.  The 
higher the frequency the more likely to see a fault.  10M is the worst one.  
The amp shows a 2:1 SWR and that is running it into a tuned KAT500, which shows 
1.2:1 and a Daiwa bridge showing 1.1:1 into the antenna.  It's the same on a 
dummy load.

I don't understand Bob McGraw's logic as if it does require power, my Daiwa is 
gonna see it.  If I measure the feedline, lightning protection and antenna with 
a network analyzer I will be doing it with mili Watts.

Cheers,

Marv
W0PSY
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Re: [Elecraft] KPA500 App

[Joel Black]

Thanks, Jack. Yeah, I realized what I did after Walter sent the link. I went 
here (https://elecraft.com/pages/kpa1500-kpa500-kat500-remote-software) the 
first time and only saw the Windows files. I thought I had seen them for macOS 
previously but, for the life of me, I couldn’t find them again.

Thanks again.

Joel - W4JBB

> On Dec 14, 2022, at 6:20 PM, Jack Brindle  wrote:
> 
> Joel;
> 
> It’s worth the look. We have most apps for both Windows and Mac. 
> By the way, the KPA500 firmware was developed and is still maintained using a 
> Mac mini, which is a good
> indication as to how important both Windows and macOS are to us.
> 
> Welcome to the Elecraft world; we hope you will enjoy your KPA500/KAT500 pair!
> 
> 73,
> Jack, W6FB
> 
> 
>> On Dec 14, 2022, at 5:06 PM, Joel Black  wrote:
>> 
>> Before I go looking too hard, is there a macOS app for the KPA500 or *just* 
>> the Windows app on the Elecraft site.
>> 
>> If it matters, I’m looking to interface the KPA500/KAT500 combo to a Flex 
>> 6400… Maybe. I’ve not bought the amp or tuner… Yet.
>> 
>> My preferred OS is macOS but I do use Win11 in a VM for Winlink using my 
>> Flex.
>> 
>> Thanks,
>> Joel - W4JBB
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Re: [Elecraft] KPA500 App

[Jack Brindle via Elecraft]

Joel;

It’s worth the look. We have most apps for both Windows and Mac. 
By the way, the KPA500 firmware was developed and is still maintained using a 
Mac mini, which is a good
indication as to how important both Windows and macOS are to us.

Welcome to the Elecraft world; we hope you will enjoy your KPA500/KAT500 pair!

73,
Jack, W6FB


> On Dec 14, 2022, at 5:06 PM, Joel Black  wrote:
> 
> Before I go looking too hard, is there a macOS app for the KPA500 or *just* 
> the Windows app on the Elecraft site.
> 
> If it matters, I’m looking to interface the KPA500/KAT500 combo to a Flex 
> 6400… Maybe. I’ve not bought the amp or tuner… Yet.
> 
> My preferred OS is macOS but I do use Win11 in a VM for Winlink using my Flex.
> 
> Thanks,
> Joel - W4JBB
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Re: [Elecraft] KPA500 App

[Walter Underwood]

It is right here, under “Macintosh”.

https://elecraft.com/pages/kpa500-500-watt-linear-amplifier-firmware-and-utility

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Dec 14, 2022, at 3:06 PM, Joel Black  wrote:
> 
> Before I go looking too hard, is there a macOS app for the KPA500 or *just* 
> the Windows app on the Elecraft site.
> 
> If it matters, I’m looking to interface the KPA500/KAT500 combo to a Flex 
> 6400… Maybe. I’ve not bought the amp or tuner… Yet.
> 
> My preferred OS is macOS but I do use Win11 in a VM for Winlink using my Flex.
> 
> Thanks,
> Joel - W4JBB
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[Elecraft] KPA500 App

[Joel Black]

Before I go looking too hard, is there a macOS app for the KPA500 or *just* the 
Windows app on the Elecraft site.

If it matters, I’m looking to interface the KPA500/KAT500 combo to a Flex 6400… 
Maybe. I’ve not bought the amp or tuner… Yet.

My preferred OS is macOS but I do use Win11 in a VM for Winlink using my Flex.

Thanks,
Joel - W4JBB
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[Elecraft] KPA500 Low 40m Output

[Mike Cizek W0VTT]

Greetings,

 

Working on a KPA 500, #2441.  All bands except 40m work properly; 40m output
is about 125w.  Testing into a dummy load:

Drive level: ~20w for all bands.  

Voltage and current levels all seem normal; lower PA current and slightly
less voltage drop on 40m.

SWR back to exciter (K3s) is 1:1 on all bands

Output SWR on the internal meter reads 1:1, even on 40m

No fault messages on any band, no smoke, no funny noises.

 

The most obvious (to me) culprit is the 40m low pass filter.  I was hoping
to find an obviously fried cap or coil, but everything looks  OK.  A web
search shows some folks reporting similar single-band faults, but they all
have obviously fried components (usually a cap) on the RF or LPF boards.  Is
there anything else that could be at fault, other than the LPF circuit?  It
appears everything else is common to all bands.  I'm not sure my test gear
is sufficient to check the components in circuit.

 

Thank you.

 



73,

Mike Cizek W0VTT

 

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Re: [Elecraft] KPA500 transformer removal

[Mike Maloney]

 Am guessing that toroid transformer is 70% or more of total KPA mass?
Has anyone put it on a scale and remembed its weight? 
Be sure to seat and torque bolt properly when putting it back in.  
Mike AC5P
On Tuesday, November 22, 2022 at 07:50:22 AM CST, Michael Walker 
 wrote:  
 
 Not really.

Just label the wires so you know were to put them when it comes back.

Undo the bolt and pull the big torroid out.  You'll notice the KPA500 is a
lot lighter now.  :)

73, mike va3mw

On Tue, Nov 22, 2022 at 6:42 AM  wrote:

> I am sending my KPA500 to Watsonville for service. The shipping
> instructions
> say to "remove the transformer unless otherwise instructed."
>
> Are there any instructions for transformer removal? I've looked at the
> assembly instructions and it seems straightforward.
>
> Are there any potential pitfalls that I should be aware of?
>
>
>
> Dave N1IX
>
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Re: [Elecraft] KPA500 transformer removal

[Michael Walker]

Not really.

Just label the wires so you know were to put them when it comes back.

Undo the bolt and pull the big torroid out.  You'll notice the KPA500 is a
lot lighter now.  :)

73, mike va3mw

On Tue, Nov 22, 2022 at 6:42 AM  wrote:

> I am sending my KPA500 to Watsonville for service. The shipping
> instructions
> say to "remove the transformer unless otherwise instructed."
>
> Are there any instructions for transformer removal? I've looked at the
> assembly instructions and it seems straightforward.
>
> Are there any potential pitfalls that I should be aware of?
>
>
>
> Dave N1IX
>
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[Elecraft] KPA500 transformer removal

[n1ix]

I am sending my KPA500 to Watsonville for service. The shipping instructions
say to "remove the transformer unless otherwise instructed."

Are there any instructions for transformer removal? I've looked at the
assembly instructions and it seems straightforward. 

Are there any potential pitfalls that I should be aware of?

 

Dave N1IX

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Re: [Elecraft] KPA500 Voltage?

[Ed Cole]

PS:  Only the mains line is aluminum and connections treated with 
antioxidant paste.  All new wiring in the new hamshack is copper (12-2 
for 120vac and 10-3 for 240vac).


The 3000w Meanwell 50v PS is served with a short 10-3 line to a 30A 
twist-lock receptacle in a floor mounted utility box with three foot 8-3 
jumper to the PS (All copper).  Max load is 12.5A; fused at 15A. 
Meanwell has internal overload and overtemp auto shutdown.


Main thermostat (3000w) is programmable, so heat load will only be 
highest when the area is occupied.  The workshop has manual thermostat 
which can be turned off when shop not in use (dividing wall is insulated 
between hamshack and workshop).


The building will have a monitored (24/7) security system with smoke 
monitors.  Monitor service calls police/fire dept if no one answers the 
phone.  Two FD stations within five miles.


I guess I could add thermistors to the mains contacts to alert overtemp. 
 I use such a system on my QRO amp heatsinks to protect the amps 
(auto-overtemp shutdown of B+).


I will monitor initial application of 240vac power to look for problems.
In my college years I was a Electrician assistant for one summer job and 
got a good practical education installing ckts (even 440 industrial).


Thanks for all the comments!

Ed - KL7UW
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[Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

[Andy Durbin]

"It can't be solved. The SSB and/or Data at that AF MARS frequency  is just
slightly below the band pass filter change over to the 5.3 bandpass filter
on the KPA500. That means that when you are on SSB, part of your rf envelope
crosses over to the 5.3 band filter which causes the amp to switch to the
higher bandpass (5.3) and when the rf at the frequency stops, the amp
switches back to the 3.5 bandpass.""

A similar problem was solved in the KAT500 by allowing the user to decide how 
much "importance" to assign the the RF detected frequency.  This was a welcome 
change from the Elecraft philosophy that "RF knows best and will be obeyed".

KPA500 doesn't have any published command that will prevent RF detected 
frequency from taking priority over a band or frequency command and it's not a 
problem when operating in the amateur bands the KPA500 was designed for.   

I see no reason the problem could not be solved for MARS users by a hardware 
mod that disables RF frequency detection.  There is obviously some risk that 
the amplifier could be damaged if normal band switching fails and RF detection 
has been defeated.  

There are several undocumented KPA500 serial commands that I became aware of as 
I developed my station controller software.  You could ask support if there is 
a command that allows the RF power required for band change to be user 
specified.

73,
Andy, k3wyc
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Re: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

[w1ie]

GM Joe,

It can't be solved. The SSB and/or Data at that AF MARS frequency  is just
slightly below the band pass filter change over to the 5.3 bandpass filter
on the KPA500. That means that when you are on SSB, part of your rf envelope
crosses over to the 5.3 band filter which causes the amp to switch to the
higher bandpass (5.3) and when the rf at the frequency stops, the amp
switches back to the 3.5 bandpass. It is not that noticeable at SSB
operations because most men's vocal range does not stay or reach up high
enough to trigger the switch. On data, however it's a different story. Since
the M101 waveform has a bandwidth of 2.8 KHz, your signal is almost always
going to cross over that "flash point" causing the amp to go from OPER to
STBY and vice-a-versa. There is a slight delay in the switching because of
what I believe, are the high and low thresh holds of the filter frequency
change point. There is also some delay in the changeover since again, what I
believe is a hardware/software operation which says "I know you have change
to a higher/or lower frequency, but I am not going to change to the correct
band pass filter until - say 100 milliseconds later, because you might not
have meant to do this". That's just a rhetorical guess on my part.

I brought this problem up with Elecraft some time ago so they know about the
MARS Radio. Elecraft said there could be a software solution to move the
trip points up a little bit. There were not, however, going to do it
because the demand for the change is too low, there would be a lot of effort
to test the modification and finally, it would be a another parallel version
of the product to maintain.

Hope this helps

With best regards,

Jerry, W1IE, AFA3GK 

-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Joe Rogers
Sent: Monday, November 14, 2022 21:00 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

I am operating the KPA500 KAT500 power combo with the K3.  The combination
works great and normally makes frequency and antenna changes really simple.
I operate on MARS frequencies and normally all works just fine outside of
all the amateur bands with the KPA500/KAT500/K3 there is, however, one
frequency where there is an issue.
When transmitting at about 4.5 MHz using SSB or digital modes, using the
KPA500/KAT500/K3 combination, the band indication shoes the KPA500
spuriously shifting back and forth between 3.5 and 5.3 MHz bands.  This also
affects the amplifier output power. I can also hear what sounds like
contact/relay cycling.   This makes the combo unusable on this frequency.
How can I resolve this problem so that the KPA500 is usable on this
frequency?
73
Joe AJ1Y
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-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of Joe Rogers
Sent: Monday, November 14, 2022 21:00 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

I am operating the KPA500 KAT500 power combo with the K3.  The combination
works great and normally makes frequency and antenna changes really simple.
I operate on MARS frequencies and normally all works just fine outside of
all the amateur bands with the KPA500/KAT500/K3 there is, however, one
frequency where there is an issue.
When transmitting at about 4.5 MHz using SSB or digital modes, using the
KPA500/KAT500/K3 combination, the band indication shoes the KPA500
spuriously shifting back and forth between 3.5 and 5.3 MHz bands.  This also
affects the amplifier output power. I can also hear what sounds like
contact/relay cycling.   This makes the combo unusable on this frequency.
How can I resolve this problem so that the KPA500 is usable on this
frequency?
73
Joe AJ1Y
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Re: [Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

[Rick NK7I]

Have you tried putting the KAT500 into MAN mode (not bypass or AUTO)?  
Once trained for bands (memory loaded), MAN is the best way to use the 
tuner.  It'll recall the tuning combination but won't go into auto-retune.


73,
Rick nk7i


On 11/14/2022 6:00 PM, Joe Rogers wrote:

I am operating the KPA500 KAT500 power combo with the K3.  The combination 
works great and normally makes frequency and antenna changes really simple.  I 
operate on MARS frequencies and normally all works just fine outside of all the 
amateur bands with the KPA500/KAT500/K3 there is, however, one frequency where 
there is an issue.
When transmitting at about 4.5 MHz using SSB or digital modes, using the 
KPA500/KAT500/K3 combination, the band indication shoes the KPA500 spuriously 
shifting back and forth between 3.5 and 5.3 MHz bands.  This also affects the 
amplifier output power. I can also hear what sounds like contact/relay cycling. 
  This makes the combo unusable on this frequency.
How can I resolve this problem so that the KPA500 is usable on this frequency?
73
Joe AJ1Y
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[Elecraft] KPA500 Shifting Bands without any change in K3 Frequency

[Joe Rogers]

I am operating the KPA500 KAT500 power combo with the K3.  The combination 
works great and normally makes frequency and antenna changes really simple.  I 
operate on MARS frequencies and normally all works just fine outside of all the 
amateur bands with the KPA500/KAT500/K3 there is, however, one frequency where 
there is an issue.
When transmitting at about 4.5 MHz using SSB or digital modes, using the 
KPA500/KAT500/K3 combination, the band indication shoes the KPA500 spuriously 
shifting back and forth between 3.5 and 5.3 MHz bands.  This also affects the 
amplifier output power. I can also hear what sounds like contact/relay cycling. 
  This makes the combo unusable on this frequency.
How can I resolve this problem so that the KPA500 is usable on this frequency?
73
Joe AJ1Y
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Re: [Elecraft] KPA500 Voltage?

[Lyn Norstad]

It's all Cu now.  They just replaced all the underground cables in our
subdivision.  Big stuff.  200A service is the residential standard these
days (we had 400A at the office).

The more expensive it is, the better they like it since the utility rates
guarantee them a fixed percentage of return on their capital investments.

73
Lyn, WØLEN


-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Brown
Sent: Monday, November 14, 2022 5:20 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

On 11/14/2022 2:08 PM, Lyn Norstad wrote:
> Aluminum does not meet any current (pun by chance ...) building codes
around
> here.

I don't know what Chicago Codes are like now, but Comm Ed pulled Al 
conductors to my meter when I requested 100A service, and they refused 
to pull Cu. This would have been around 1987-90.

73, Jim K9YC


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Re: [Elecraft] KPA500 Voltage?

[Jim Brown]

On 11/14/2022 2:08 PM, Lyn Norstad wrote:

Aluminum does not meet any current (pun by chance ...) building codes around
here.


I don't know what Chicago Codes are like now, but Comm Ed pulled Al 
conductors to my meter when I requested 100A service, and they refused 
to pull Cu. This would have been around 1987-90.


73, Jim K9YC


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Re: [Elecraft] KPA500 Voltage?

[David Gilbert]

Yes ... both.  Go look for yourself.

Flexible cords like line cords are almost never aluminum ... I assume 
because line cords use fine stranded wires and if I'm not mistaken 
copper is more ductile than aluminum.


Dave   AB7E



On 11/14/2022 3:42 PM, Lou Mecseri wrote:

BUT NOT BOTH.

How about line cords?"

Lou KE1F

On 11/14/2022 22:32, David Gilbert wrote:



There is absolutely nothing inherently wrong with aluminum wire, and 
it is typically what is used for very large gauge wire ... even for 
the utility entrance in my location.  I would bet that if you look 
closely at your breaker box you will see the same for the main feed 
coming in unless you have a very lowly rated box for current.  I 
don't think you can even find , for example, 4/0 wire in copper at 
places like Home Depot or Lowes.


The historical problem associated with aluminum wire was the material 
used for connections at the sockets and other places. That has all 
been changed long ago and if you look closely at many electrical 
fixtures and buss bars you will see that the contacts are stamped to 
be rated for either copper or aluminum.


Dave   AB7E



On 11/14/2022 3:08 PM, Lyn Norstad wrote:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently 
about half
the price of copper, but a townhouse I lived in from 1979-1982 in 
Chicago

caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building 
codes around

here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to 
liberally apply

antioxidant where needed.

73
Lyn, WØLEN




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Re: [Elecraft] KPA500 Voltage?

[Rick NK7I]

Aluminum was legal at one point, as I recall it was the 80's (copper 
prices were obscene).  It was an expensive mistake to allow aluminum wiring.


I attended some fires as a result of aluminum wire (career firefighter, 
eventually Captain).  My suspicion was that as switches and plugs were 
used, aluminum tolerated the small flexing less than copper (which 
basically self heals, molds to the connection being softer) and as it is 
exposed to air, a layer of aluminum oxide is produced (wrapping the 
internal content ) creating higher resistance.


Over time the resistance and small flexes caused arcing, that gets to a 
point that it heats; causing the excitement.


I don't have the chemistry or metallurigc background to confirm this; 
but this was the result of the cause investigation..


Adding a copper pigtail is a practical solution (cheaper than replacing 
all the wire).  Aluminum wire is not used by me, anywhere, just like the 
backstab plugs and switches (if you can't bind them down; don't use 
them).  I have seen the harm that can result and don't want to lose my 
house and possessions as I've seen others lose.


In the cost of a house or shack, copper; the small increase in cost 
reaps major benefits (and aluminum is no longer legal for new 
construction, at least when I retired).


73,
Rick nk7i


On 11/14/2022 2:25 PM, Fred Jensen wrote:
When my younger brother was finally out of the house for good, Mom and 
Dad bought a double-wide, sold the house in So. Central LAX, and moved 
south into a "Mobile Estates Park" in Costa Mesa.  The wiring was Al.  
About 3 years later, they had a problem in one of the outlets that 
involved a small amount of smoke.  That wasn't a serious incident, but 
Dad had to go around to each of the switches and outlets and put Cu 
pigtails on the Al wires to connect to the devices.  I never got a 
clear story about what caused the original problem or why this would 
fix it.  But, I'm really wary of Al wiring in house in which we sleep.


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

Lyn Norstad wrote on 11/14/2022 2:08 PM:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently 
about half
the price of copper, but a townhouse I lived in from 1979-1982 in 
Chicago

caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes 
around

here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to 
liberally apply

antioxidant where needed.

73
Lyn, WØLEN






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Re: [Elecraft] KPA500 Voltage?

[Lou Mecseri]

BUT NOT BOTH.

How about line cords?"

Lou KE1F

On 11/14/2022 22:32, David Gilbert wrote:



There is absolutely nothing inherently wrong with aluminum wire, and 
it is typically what is used for very large gauge wire ... even for 
the utility entrance in my location.  I would bet that if you look 
closely at your breaker box you will see the same for the main feed 
coming in unless you have a very lowly rated box for current.  I don't 
think you can even find , for example, 4/0 wire in copper at places 
like Home Depot or Lowes.


The historical problem associated with aluminum wire was the material 
used for connections at the sockets and other places. That has all 
been changed long ago and if you look closely at many electrical 
fixtures and buss bars you will see that the contacts are stamped to 
be rated for either copper or aluminum.


Dave   AB7E



On 11/14/2022 3:08 PM, Lyn Norstad wrote:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently 
about half
the price of copper, but a townhouse I lived in from 1979-1982 in 
Chicago

caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes 
around

here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to 
liberally apply

antioxidant where needed.

73
Lyn, WØLEN




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Re: [Elecraft] KPA500 Voltage?

[Lou Mecseri]

Aluminum wiring is "penny wise and pound foolish".
Coming from a retired Fire Investigator.
Good Luck and 73, Lou KE1F


On 11/14/2022 22:08, Lyn Norstad wrote:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently about half
the price of copper, but a townhouse I lived in from 1979-1982 in Chicago
caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes around
here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to liberally apply
antioxidant where needed.

73
Lyn, WØLEN


-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ed Cole
Sent: Monday, November 14, 2022 3:43 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

On the general subject of house wiring, loads, and resulting voltage:

I am wiring my new hamshack with 240vac mains extension from the house.
I selected three No. 2 awg aluminum lines (copper not commonly used
these days).  These are approx 1/4-inch diameter.

That is rated for 90A (in general).  Resistance is 0.318 ohms/1000-feet
so my 120-foot run has 0.0382 ohms.  At 50A this results in a voltage
drop of 1.9v.  My service voltage is 243VAC.

Estimation of max load at the new hamshack/workshop calculates as 36.5A.
   Maximum will likely never exist as not everything will be activated
simultaneously, but good design is for max load.

Largest load is electric baseboard heat (4000w); 50v PS is next (3000w).
All my QRO amps are LDMOS and run about 2500w dc-input.  I use three of
these switching PS, but only one at a time.

Info on my website: www.kl7uw.com

73, Ed - KL7UW

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Re: [Elecraft] KPA500 Voltage?

[David Gilbert]

There is absolutely nothing inherently wrong with aluminum wire, and it 
is typically what is used for very large gauge wire ... even for the 
utility entrance in my location.  I would bet that if you look closely 
at your breaker box you will see the same for the main feed coming in 
unless you have a very lowly rated box for current.  I don't think you 
can even find , for example, 4/0 wire in copper at places like Home 
Depot or Lowes.


The historical problem associated with aluminum wire was the material 
used for connections at the sockets and other places.  That has all been 
changed long ago and if you look closely at many electrical fixtures and 
buss bars you will see that the contacts are stamped to be rated for 
either copper or aluminum.


Dave   AB7E



On 11/14/2022 3:08 PM, Lyn Norstad wrote:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently about half
the price of copper, but a townhouse I lived in from 1979-1982 in Chicago
caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes around
here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to liberally apply
antioxidant where needed.

73
Lyn, WØLEN




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Re: [Elecraft] KPA500 Voltage?

[Fred Jensen]

When my younger brother was finally out of the house for good, Mom and 
Dad bought a double-wide, sold the house in So. Central LAX, and moved 
south into a "Mobile Estates Park" in Costa Mesa.  The wiring was Al.  
About 3 years later, they had a problem in one of the outlets that 
involved a small amount of smoke.  That wasn't a serious incident, but 
Dad had to go around to each of the switches and outlets and put Cu 
pigtails on the Al wires to connect to the devices.  I never got a clear 
story about what caused the original problem or why this would fix it.  
But, I'm really wary of Al wiring in house in which we sleep.


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

Lyn Norstad wrote on 11/14/2022 2:08 PM:

Ed -

I cringe when I think of aluminum wiring.  I know it's currently about half
the price of copper, but a townhouse I lived in from 1979-1982 in Chicago
caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes around
here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to liberally apply
antioxidant where needed.

73
Lyn, WØLEN





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Re: [Elecraft] KPA500 Voltage?

[Jim Brown]

On 11/14/2022 1:43 PM, Ed Cole wrote:
That is rated for 90A (in general).  Resistance is 0.318 ohms/1000-feet 
so my 120-foot run has 0.0382 ohms.  At 50A this results in a voltage 
drop of 1.9v.  My service voltage is 243VAC.


It's important to realize that current on AC mains is FAR from being a 
sine wave. This has been true for at least 30 years, as loads have been 
strongly dominated by switch-mode power supplies in almost every piece 
of equipment wiring into or plugged into, the system, and square-wave 
modulated controllers for nearly all large loads, like motors and 
heating devices. Current flows in pulses, usually short ones, that 
recharge the input capacitors of associated power supplies.


The result of this is that both IR drop and the resulting heating are at 
least one-third greater than predicted by Ohm's Law applied to a sine 
wave. It is, therefore, very good engineering practice to oversize 
conductors, as you have done! Before we moved into the home we bought in 
NorCal, I had the outbuilding housing my shack rewired, and even though 
the runs from the panelboard are pretty short, had #10 pulled in for the 
20A-240V circuit. Since I will never have more than one amp on at a 
time, I felt that 20A was sufficient. All of the 120V circuits are 20A, 
wired with #12, not oversized, since the only heavy load, 1 12A space 
heater, has its own circuit.


73, Jim K9YC

73, Jim K9YC
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Re: [Elecraft] KPA500 Voltage?

[Lyn Norstad]

Ed -

I cringe when I think of aluminum wiring.  I know it's currently about half
the price of copper, but a townhouse I lived in from 1979-1982 in Chicago
caught fire because of aluminum wiring and copper outlets.  In fact,
statistics show that 50% of home fires are due to aluminum wiring.

Aluminum does not meet any current (pun by chance ...) building codes around
here.  It's all copper. Has been for at least 40 years.

If you're stuck with aluminum (and it's legal??), be sure to liberally apply
antioxidant where needed.

73
Lyn, WØLEN


-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ed Cole
Sent: Monday, November 14, 2022 3:43 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

On the general subject of house wiring, loads, and resulting voltage:

I am wiring my new hamshack with 240vac mains extension from the house.
I selected three No. 2 awg aluminum lines (copper not commonly used 
these days).  These are approx 1/4-inch diameter.

That is rated for 90A (in general).  Resistance is 0.318 ohms/1000-feet 
so my 120-foot run has 0.0382 ohms.  At 50A this results in a voltage 
drop of 1.9v.  My service voltage is 243VAC.

Estimation of max load at the new hamshack/workshop calculates as 36.5A. 
  Maximum will likely never exist as not everything will be activated 
simultaneously, but good design is for max load.

Largest load is electric baseboard heat (4000w); 50v PS is next (3000w).
All my QRO amps are LDMOS and run about 2500w dc-input.  I use three of 
these switching PS, but only one at a time.

Info on my website: www.kl7uw.com

73, Ed - KL7UW

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Re: [Elecraft] KPA500 Voltage?

[Ed Cole]

On the general subject of house wiring, loads, and resulting voltage:

I am wiring my new hamshack with 240vac mains extension from the house.
I selected three No. 2 awg aluminum lines (copper not commonly used 
these days).  These are approx 1/4-inch diameter.


That is rated for 90A (in general).  Resistance is 0.318 ohms/1000-feet 
so my 120-foot run has 0.0382 ohms.  At 50A this results in a voltage 
drop of 1.9v.  My service voltage is 243VAC.


Estimation of max load at the new hamshack/workshop calculates as 36.5A. 
 Maximum will likely never exist as not everything will be activated 
simultaneously, but good design is for max load.


Largest load is electric baseboard heat (4000w); 50v PS is next (3000w).
All my QRO amps are LDMOS and run about 2500w dc-input.  I use three of 
these switching PS, but only one at a time.


Info on my website: www.kl7uw.com

73, Ed - KL7UW

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Re: [Elecraft] KPA500 Voltage?

[Lyn Norstad]

Jim -

Of course, that's what the various taps are for.  But at the higher setting,
although the voltage was within the published "acceptable" range, 2
components in the power supply failed.

This was the second time it had been back for service - the first time they
discovered missing components (it was factory built).

I'm not going to argue with the Mothership.  It has been flawless since the
second service trip.  If I'm down a couple watts (not at all sure that's the
case), it's better than being down a couple Franklins.

73
Lyn, WØLEN

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Brown
Sent: Monday, November 14, 2022 12:37 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

On 11/14/2022 6:38 AM, Lyn Norstad wrote:
> I had mine set up, as Rick suggests - but when it was in for service, they
dropped it back a notch saying it was too high.

That's the difference between their mains wiring and yours. I'd stick 
with what is highest, within range, at your QTH.

73, Jim K9YC
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Re: [Elecraft] KPA500 Voltage?

[Jim Brown]

On 11/14/2022 9:36 AM, Jon Poland wrote:

My 12 year old house has 200 amp service.  I don't know why.  But since
building it, we have shifted to 90+% LED lighting, high efficiency
dishwasher, fridge, and clothes washer.  My entire lighting load at any
given time is less than 120W.  A smart thermostat reduces AC and furnace
loads.  The 2 largest electrical loads are the clothes dryer and gas
furnace blower.  This house is also better insulated than any home I have
ever owned - also reducing the furnace load (gas and electricity).


What you're missing, Jon, is that IR drop to that outlet that feeds the 
KPA500 is NOT the total load to the home, but primarily the IR drop FROM 
THE PANEL of the circuit that feeds the amp. The feed from the street to 
that panel is usually a small fraction of that.


73, Jim K9YC
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Re: [Elecraft] KPA500 Voltage?

[Jim Brown]

On 11/14/2022 6:38 AM, Lyn Norstad wrote:

I had mine set up, as Rick suggests - but when it was in for service, they 
dropped it back a notch saying it was too high.


That's the difference between their mains wiring and yours. I'd stick 
with what is highest, within range, at your QTH.


73, Jim K9YC
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Re: [Elecraft] KPA500 Voltage?

[Rick NK7I]

:
> Gordon -
>
> I had mine set up, as Rick suggests - but when it was in for
service, they dropped it back a notch saying it was too high.
>
> My readings now agree with yours.
>
> 73
> Lyn, WØLEN
>
>
> -Original Message-
> From:elecraft-boun...@mailman.qth.net
<mailto:from%3aelecraft-boun...@mailman.qth.net>
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Rick NK7I
> Sent: Saturday, November 12, 2022 1:03 PM
> To:elecraft@mailman.qth.net <mailto:to%3aelecr...@mailman.qth.net>
> Subject: Re: [Elecraft] KPA500 Voltage?
>
> I'd move it up one tap as long as it does NOT EXCEED 85V at receive.
>
> Higher voltage not only gives you better output but also
cleaner.  That
> matters too.
>
> 73,
> Rick nk7i
>
>
> On 11/12/2022 10:25 AM, Gordon LaPoint wrote:
>> My KPA500 is showing 57-58 VDC at 450-500 watts out, and 71-72
VDC on rx.
>>
>> Is this normal or should I move up one tap?
>>
>> Thanks,
>>
>> Gordon - N1MGO
>>
>>
>> __
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Re: [Elecraft] KPA500 Voltage?

[Jon Poland]

I disagree with Rick.  It is true that modern houses have more electric
capacity.  But as homeowners shift to more efficient appliances and
lighting, electric loads (and bills) are consistently dropping.  The one
trend that counters that though is that modern homes (at least in the US)
are consistently larger than their older counterparts and require more
energy to keep comfortable.  That trend does not explain voltage drops
though.

My 12 year old house has 200 amp service.  I don't know why.  But since
building it, we have shifted to 90+% LED lighting, high efficiency
dishwasher, fridge, and clothes washer.  My entire lighting load at any
given time is less than 120W.  A smart thermostat reduces AC and furnace
loads.  The 2 largest electrical loads are the clothes dryer and gas
furnace blower.  This house is also better insulated than any home I have
ever owned - also reducing the furnace load (gas and electricity).

Curiously, the next largest load in many homes are the TV's turned on in
every bedroom... (But their heat reduces the amount of time the furnace
needs to run.)

Of course, if you have an electric car charger the picture changes
drastically...  But that is still a small percentage of US homes today.

jon  N0WL

On Mon, Nov 14, 2022 at 11:10 AM Rick Bates, NK7I 
wrote:

> Too high at THEIR location.
>
> Power company feeds, vary (not a lot but their load changes, they adjust).
>
> House wiring varies and other devices on that circuit can cause other
> variations too.  Older homes (1950's and older) often have less capacity
> than newer homes (didn't need it then).  Today we use a LOT more energy
> than then; some house circuits are no longer 'adequate' (causing fires
> in some cases because folks abuse the wiring in ignorance).
>
> Part of station set up and operations, is knowing what the circuit(s) of
> the house wiring, is connected to besides the station.  Fridge, washer,
> HVAC, electric oven shared with the station?
>
> If you need one more tap to get within the right voltage window, use one
> more tap to achieve that.  If you change circuits, remeasure.  And if on
> the same circuit, maybe don't run the washing machine or oven at the
> same time as the amp. ;-)
>
> 73,
> Rick nk7i
>
>
> On 11/14/2022 6:38 AM, Lyn Norstad wrote:
> > Gordon -
> >
> > I had mine set up, as Rick suggests - but when it was in for service,
> they dropped it back a notch saying it was too high.
> >
> > My readings now agree with yours.
> >
> > 73
> > Lyn, WØLEN
> >
> >
> > -Original Message-
> > From:elecraft-boun...@mailman.qth.net  [mailto:
> elecraft-boun...@mailman.qth.net] On Behalf Of Rick NK7I
> > Sent: Saturday, November 12, 2022 1:03 PM
> > To:elecraft@mailman.qth.net
> > Subject: Re: [Elecraft] KPA500 Voltage?
> >
> > I'd move it up one tap as long as it does NOT EXCEED 85V at receive.
> >
> > Higher voltage not only gives you better output but also cleaner.  That
> > matters too.
> >
> > 73,
> > Rick nk7i
> >
> >
> > On 11/12/2022 10:25 AM, Gordon LaPoint wrote:
> >> My KPA500 is showing 57-58 VDC at 450-500 watts out, and 71-72 VDC on
> rx.
> >>
> >> Is this normal or should I move up one tap?
> >>
> >> Thanks,
> >>
> >> Gordon - N1MGO
> >>
> >>
> >> __
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Re: [Elecraft] KPA500 Voltage?

[Rick Bates, NK7I]

Too high at THEIR location.

Power company feeds, vary (not a lot but their load changes, they adjust).

House wiring varies and other devices on that circuit can cause other 
variations too.  Older homes (1950's and older) often have less capacity 
than newer homes (didn't need it then).  Today we use a LOT more energy 
than then; some house circuits are no longer 'adequate' (causing fires 
in some cases because folks abuse the wiring in ignorance).


Part of station set up and operations, is knowing what the circuit(s) of 
the house wiring, is connected to besides the station.  Fridge, washer, 
HVAC, electric oven shared with the station?


If you need one more tap to get within the right voltage window, use one 
more tap to achieve that.  If you change circuits, remeasure.  And if on 
the same circuit, maybe don't run the washing machine or oven at the 
same time as the amp. ;-)


73,
Rick nk7i


On 11/14/2022 6:38 AM, Lyn Norstad wrote:

Gordon -

I had mine set up, as Rick suggests - but when it was in for service, they 
dropped it back a notch saying it was too high.

My readings now agree with yours.

73
Lyn, WØLEN


-Original Message-
From:elecraft-boun...@mailman.qth.net  
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Rick NK7I
Sent: Saturday, November 12, 2022 1:03 PM
To:elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

I'd move it up one tap as long as it does NOT EXCEED 85V at receive.

Higher voltage not only gives you better output but also cleaner.  That
matters too.

73,
Rick nk7i


On 11/12/2022 10:25 AM, Gordon LaPoint wrote:

My KPA500 is showing 57-58 VDC at 450-500 watts out, and 71-72 VDC on rx.

Is this normal or should I move up one tap?

Thanks,

Gordon - N1MGO


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Re: [Elecraft] KPA500 Voltage?

[Lyn Norstad]

Gordon -

I had mine set up, as Rick suggests - but when it was in for service, they 
dropped it back a notch saying it was too high.

My readings now agree with yours.

73
Lyn, WØLEN


-Original Message-
From: elecraft-boun...@mailman.qth.net 
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Rick NK7I
Sent: Saturday, November 12, 2022 1:03 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA500 Voltage?

I'd move it up one tap as long as it does NOT EXCEED 85V at receive.

Higher voltage not only gives you better output but also cleaner.  That 
matters too.

73,
Rick nk7i


On 11/12/2022 10:25 AM, Gordon LaPoint wrote:
> My KPA500 is showing 57-58 VDC at 450-500 watts out, and 71-72 VDC on rx.
>
> Is this normal or should I move up one tap?
>
> Thanks,
>
> Gordon - N1MGO
>
>
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Re: [Elecraft] KPA500 Voltage?

[Jim Brown]

On 11/13/2022 10:52 AM, Andy Durbin wrote:

Note that the drop is not related only to power output but is a function of 
total PA input power


It's also a function of IR drop in ALL of the AC wiring between the 
distribution panel and the amp. In North America, building codes call 
for at least #14 for circuits fused at 15A, and #12 for 20A. Copper is 
expensive, so larger sizes are rarely installed.


73, Jim K9YC
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