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KPA500 Coax size requirements

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N3AO

KPA500 Coax size requirements

Hello friends,

I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
from my Elecraft K2/100 rig. I hope I would be able to do that!

From what I have read on eHam Reviews, it appears that I can run the
amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
as well?

I cannot find any mention of the coax requirements, from the radio/combo
out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
able to use 8X coax.

Will I still be able to use that coax cable with up to 500 Watts output?

What other considerations do I need to make?

Thanks in advance,

Carter Craigie, N3AO
Blacksburg, VA

--
Carter, N3AO
Blacksburg, VA
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David Bunte

Re: KPA500 Coax size requirements

Carter -

I run my KPA500 from the 120v outlet in my shack. I have done so for years
with no problems. I use LMR400 coax, but I know several folks who use RG8-X
with the KPA500, even on very long runs and some with amps putting out 1000
to 1500 watts. The better your antenna the less of a problem with that. If,
however, your antenna has a very high SWR without the use of the KAT500
tuner, then the tuner will make the rig happy, but there will still be SWR
loss on the coax, and it will be greater with RG8-X than with a larger and
lower loss coax.

Best of luck.

73 de Dave - K9FN

On Tue, Aug 20, 2019 at 3:20 PM Carter Craigie <[hidden email]>
wrote:

> Hello friends,
>
> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
> from my Elecraft K2/100 rig. I hope I would be able to do that!
>
> From what I have read on eHam Reviews, it appears that I can run the
> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
> as well?
>
> I cannot find any mention of the coax requirements, from the radio/combo
> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
> able to use 8X coax.
>
> Will I still be able to use that coax cable with up to 500 Watts output?
>
> What other considerations do I need to make?
>
> Thanks in advance,
>
> Carter Craigie, N3AO
> Blacksburg, VA
>
>
> --
> Carter, N3AO
> Blacksburg, VA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Bob McGraw - K4TAX

Re: KPA500 Coax size requirements

In reply to this post by N3AO

Carter:

The KAT500 can be {should be} powered from the radio 12V supply. I
don't suggest a separate wall wart.

The KPA500 can be powered from either 120VAC or 240VAC, your choice. It
should drive on all bands with 20 to 30 watts output from the K2 to
reach full 500 watts output from the amp.

As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low. The
Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz.   These
power ratings are matched conditions.

What is the SWR on your wire loop on the feed line for all bands?   Per
Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50 ohms,
i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms, i.e. 10:1
SWR, is 500 volts. So to answer your question, YES and NO, depending on
SWR on the coax between the tuner output and the loop antenna feed point.

In general, R-8X is OK at 500 watts below 30 MHz.   From experience, it
will get "warm" to the touch. "Warm" is created by loss which is then
heat generated from RF. And that is RF which is not getting to the
antenna.

Personally I'd opt for a balanced open wire feed to the loop and a very
good 1:1 balun rated for legal limit or more at the KAT500 tuner output.

73

Bob, K4TAX

On 8/20/2019 2:11 PM, Carter Craigie wrote:

k6mrmagnet

Re: KPA500 Coax size requirements

“The KAT500 can be {should be} powered from the radio 12V supply.”

Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.

I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.

Ken K6MR

________________________________
From: [hidden email] <[hidden email]> on behalf of Bob McGraw K4TAX <[hidden email]>
Sent: Tuesday, August 20, 2019 12:59:11 PM
To: [hidden email] <[hidden email]>
Subject: Re: [Elecraft] KPA500 Coax size requirements

Carter:

The KAT500 can be {should be} powered from the radio 12V supply. I
don't suggest a separate wall wart.

The KPA500 can be powered from either 120VAC or 240VAC, your choice. It
should drive on all bands with 20 to 30 watts output from the K2 to
reach full 500 watts output from the amp.

As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low. The
Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
power ratings are matched conditions.

What is the SWR on your wire loop on the feed line for all bands? Per
Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50 ohms,
i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms, i.e. 10:1
SWR, is 500 volts. So to answer your question, YES and NO, depending on
SWR on the coax between the tuner output and the loop antenna feed point.

In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
will get "warm" to the touch. "Warm" is created by loss which is then
heat generated from RF. And that is RF which is not getting to the
antenna.

Personally I'd opt for a balanced open wire feed to the loop and a very
good 1:1 balun rated for legal limit or more at the KAT500 tuner output.

73

Bob, K4TAX

On 8/20/2019 2:11 PM, Carter Craigie wrote:

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ke9uw

Re: KPA500 Coax size requirements

I think the issue is to be sure the tuner powers up with or after the K3.
But, mine turns on first and then the K3 later with no issues. I have pretuned it and run it on manual if that makes any difference.

Chuck Jack Hawley
KE9UW

Sent from my iPhone, cjack

> On Aug 20, 2019, at 3:27 PM, Ken K6MR <[hidden email]> wrote:
>
> “The KAT500 can be {should be} powered from the radio 12V supply.”
>
>
>
> Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.
>
>
>
> I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.
>
>
>
> Ken K6MR
>
>
>
>
>
> ________________________________
> From: [hidden email] <[hidden email]> on behalf of Bob McGraw K4TAX <[hidden email]>
> Sent: Tuesday, August 20, 2019 12:59:11 PM
> To: [hidden email] <[hidden email]>
> Subject: Re: [Elecraft] KPA500 Coax size requirements
>
> Carter:
>
> The KAT500 can be {should be} powered from the radio 12V supply. I
> don't suggest a separate wall wart.
>
> The KPA500 can be powered from either 120VAC or 240VAC, your choice. It
> should drive on all bands with 20 to 30 watts output from the K2 to
> reach full 500 watts output from the amp.
>
> As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low. The
> Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
> Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
> power ratings are matched conditions.
>
> What is the SWR on your wire loop on the feed line for all bands? Per
> Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50 ohms,
> i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms, i.e. 10:1
> SWR, is 500 volts. So to answer your question, YES and NO, depending on
> SWR on the coax between the tuner output and the loop antenna feed point.
>
> In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
> will get "warm" to the touch. "Warm" is created by loss which is then
> heat generated from RF. And that is RF which is not getting to the
> antenna.
>
> Personally I'd opt for a balanced open wire feed to the loop and a very
> good 1:1 balun rated for legal limit or more at the KAT500 tuner output.
>
> 73
>
> Bob, K4TAX
>
>
>> On 8/20/2019 2:11 PM, Carter Craigie wrote:
>> Hello friends,
>>
>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
>> from my Elecraft K2/100 rig. I hope I would be able to do that!
>>
>> From what I have read on eHam Reviews, it appears that I can run the
>> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
>> as well?
>>
>> I cannot find any mention of the coax requirements, from the radio/combo
>> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
>> able to use 8X coax.
>>
>> Will I still be able to use that coax cable with up to 500 Watts output?
>>
>> What other considerations do I need to make?
>>
>> Thanks in advance,
>>
>> Carter Craigie, N3AO
>> Blacksburg, VA
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Chuck, KE9UW

Mark Musick

Re: KPA500 Coax size requirements

I am pretty sure this dates back (literally years) to when the KAT500 first came out.
There was an issue if the KAT500 was not powered up before the K3, the K3 had problems during power on.
If the KAT500 was on a separate power supply many powered on the KAT500 before powering on the K3.
It was later discovered that the KAT500 only needed power to the coax power connector on the rear of the KAT500. The KAT500 did not actually need to be powered on. To this end it was advised that the K3 and KAT500 be powered from the same power supply.
All this went away in a K3 firmware update (version 4.9x. I don't remember which one) and has not been a problem since.
Since then the K3 and KAT500 can be powered from separate power supplies and the power supply connected to the KAT500 does not need to be on prior to powering on the K3.

73,
Mark, WB9CIF

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of hawley, charles j jr
Sent: Tuesday, August 20, 2019 20:45
To: Ken K6MR <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] KPA500 Coax size requirements

I think the issue is to be sure the tuner powers up with or after the K3.
But, mine turns on first and then the K3 later with no issues. I have pretuned it and run it on manual if that makes any difference.

Chuck Jack Hawley
KE9UW

Sent from my iPhone, cjack

> On Aug 20, 2019, at 3:27 PM, Ken K6MR <[hidden email]> wrote:
>
> “The KAT500 can be {should be} powered from the radio 12V supply.”
>
>
>
> Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.
>
>
>
> I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.
>
>
>
> Ken K6MR
>
>
>
>
>
> ________________________________
> From: [hidden email]
> <[hidden email]> on behalf of Bob McGraw K4TAX
> <[hidden email]>
> Sent: Tuesday, August 20, 2019 12:59:11 PM
> To: [hidden email] <[hidden email]>
> Subject: Re: [Elecraft] KPA500 Coax size requirements
>
> Carter:
>
> The KAT500 can be {should be} powered from the radio 12V supply. I
> don't suggest a separate wall wart.
>
> The KPA500 can be powered from either 120VAC or 240VAC, your choice.
> It should drive on all bands with 20 to 30 watts output from the K2 to
> reach full 500 watts output from the amp.
>
> As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low.
> The Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
> Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
> power ratings are matched conditions.
>
> What is the SWR on your wire loop on the feed line for all bands? Per
> Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50
> ohms, i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms,
> i.e. 10:1 SWR, is 500 volts. So to answer your question, YES and NO,
> depending on SWR on the coax between the tuner output and the loop antenna feed point.
>
> In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
> will get "warm" to the touch. "Warm" is created by loss which is then
> heat generated from RF. And that is RF which is not getting to the
> antenna.
>
> Personally I'd opt for a balanced open wire feed to the loop and a
> very good 1:1 balun rated for legal limit or more at the KAT500 tuner output.
>
> 73
>
> Bob, K4TAX
>
>
>> On 8/20/2019 2:11 PM, Carter Craigie wrote:
>> Hello friends,
>>
>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving
>> it from my Elecraft K2/100 rig. I hope I would be able to do that!
>>
>> From what I have read on eHam Reviews, it appears that I can run the
>> amp/tuner combo on 117v. from the convenient wall socket. Is that
>> correct, as well?
>>
>> I cannot find any mention of the coax requirements, from the
>> radio/combo out to our 80-meter wire loop antenna. Right now, using
>> only my K2/100 I am able to use 8X coax.
>>
>> Will I still be able to use that coax cable with up to 500 Watts output?
>>
>> What other considerations do I need to make?
>>
>> Thanks in advance,
>>
>> Carter Craigie, N3AO
>> Blacksburg, VA
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]

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Bob McGraw - K4TAX

Re: KPA500 Coax size requirements

In reply to this post by k6mrmagnet

Because in the manual, page 4, item 2 states "Connect to the station 11
to 15 VDC power supply with the white striped lead to the positive
terminal."

I view it best to always follow the manufactures instructions and not
re-engineer the product or rewrite the manual.

73

Bob, K4TAX

On 8/20/2019 3:27 PM, Ken K6MR wrote:

> “The KAT500 can be {should be} powered from the radio 12V supply.”
>
>
>
> Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.
>
>
>
> I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.
>
>
>
> Ken K6MR
>
>
>
>
>
> ________________________________
> From: [hidden email] <[hidden email]> on behalf of Bob McGraw K4TAX <[hidden email]>
> Sent: Tuesday, August 20, 2019 12:59:11 PM
> To: [hidden email] <[hidden email]>
> Subject: Re: [Elecraft] KPA500 Coax size requirements
>
> Carter:
>
> The KAT500 can be {should be} powered from the radio 12V supply. I
> don't suggest a separate wall wart.
>
> The KPA500 can be powered from either 120VAC or 240VAC, your choice. It
> should drive on all bands with 20 to 30 watts output from the K2 to
> reach full 500 watts output from the amp.
>
> As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low. The
> Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
> Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
> power ratings are matched conditions.
>
> What is the SWR on your wire loop on the feed line for all bands? Per
> Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50 ohms,
> i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms, i.e. 10:1
> SWR, is 500 volts. So to answer your question, YES and NO, depending on
> SWR on the coax between the tuner output and the loop antenna feed point.
>
> In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
> will get "warm" to the touch. "Warm" is created by loss which is then
> heat generated from RF. And that is RF which is not getting to the
> antenna.
>
> Personally I'd opt for a balanced open wire feed to the loop and a very
> good 1:1 balun rated for legal limit or more at the KAT500 tuner output.
>
> 73
>
> Bob, K4TAX
>
>
> On 8/20/2019 2:11 PM, Carter Craigie wrote:
>> Hello friends,
>>
>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
>> from my Elecraft K2/100 rig. I hope I would be able to do that!
>>
>> From what I have read on eHam Reviews, it appears that I can run the
>> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
>> as well?
>>
>> I cannot find any mention of the coax requirements, from the radio/combo
>> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
>> able to use 8X coax.
>>
>> Will I still be able to use that coax cable with up to 500 Watts output?
>>
>> What other considerations do I need to make?
>>
>> Thanks in advance,
>>
>> Carter Craigie, N3AO
>> Blacksburg, VA
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Mark Musick

Re: KPA500 Coax size requirements

Yes Bob the manual says that, but that statement in the manual was not revised after the 4.9x firmware update.
If you look at the manual revisions, that wording has been in the manual since the problem was initially discovered and before the 4.9x firmware update.

73,
Mark, WB9CIF

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Bob McGraw K4TAX
Sent: Tuesday, August 20, 2019 21:11
To: [hidden email]
Subject: Re: [Elecraft] KPA500 Coax size requirements

Because in the manual, page 4, item 2 states "Connect to the station 11 to 15 VDC power supply with the white striped lead to the positive terminal."

I view it best to always follow the manufactures instructions and not re-engineer the product or rewrite the manual.

73

Bob, K4TAX

On 8/20/2019 3:27 PM, Ken K6MR wrote:

> "The KAT500 can be {should be} powered from the radio 12V supply."
>
>
>
> Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.
>
>
>
> I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.
>
>
>
> Ken K6MR
>
>
>
>
>
> ________________________________
> From: [hidden email]
> <[hidden email]> on behalf of Bob McGraw K4TAX
> <[hidden email]>
> Sent: Tuesday, August 20, 2019 12:59:11 PM
> To: [hidden email] <[hidden email]>
> Subject: Re: [Elecraft] KPA500 Coax size requirements
>
> Carter:
>
> The KAT500 can be {should be} powered from the radio 12V supply. I
> don't suggest a separate wall wart.
>
> The KPA500 can be powered from either 120VAC or 240VAC, your choice.
> It should drive on all bands with 20 to 30 watts output from the K2 to
> reach full 500 watts output from the amp.
>
> As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low.
> The Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
> Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
> power ratings are matched conditions.
>
> What is the SWR on your wire loop on the feed line for all bands? Per
> Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50
> ohms, i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms,
> i.e. 10:1 SWR, is 500 volts. So to answer your question, YES and NO,
> depending on SWR on the coax between the tuner output and the loop antenna feed point.
>
> In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
> will get "warm" to the touch. "Warm" is created by loss which is then
> heat generated from RF. And that is RF which is not getting to the
> antenna.
>
> Personally I'd opt for a balanced open wire feed to the loop and a
> very good 1:1 balun rated for legal limit or more at the KAT500 tuner output.
>
> 73
>
> Bob, K4TAX
>
>
> On 8/20/2019 2:11 PM, Carter Craigie wrote:
>> Hello friends,
>>
>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving
>> it from my Elecraft K2/100 rig. I hope I would be able to do that!
>>
>> From what I have read on eHam Reviews, it appears that I can run
>> the amp/tuner combo on 117v. from the convenient wall socket. Is that
>> correct, as well?
>>
>> I cannot find any mention of the coax requirements, from the
>> radio/combo out to our 80-meter wire loop antenna. Right now, using
>> only my K2/100 I am able to use 8X coax.
>>
>> Will I still be able to use that coax cable with up to 500 Watts output?
>>
>> What other considerations do I need to make?
>>
>> Thanks in advance,
>>
>> Carter Craigie, N3AO
>> Blacksburg, VA
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
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Mark Musick

Re: KPA500 Coax size requirements

In reply to this post by Bob McGraw - K4TAX

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Bob McGraw - K4TAX

Re: KPA500 Coax size requirements

And since I have my KAT500 and KPA500 and K3S all on the desk within
easy reach and view, and all interfaced with the ACC buss, thus keeping
leads short and using one common supply makes lots of sense to me, and
many less issues to deal with.

I've told many folks, with the system as configured, I have a 500 watt
transceiver and an antenna system that is effectively flat from 160M
through 6M.   All I do is change RX frequency on the K3S and every thing
else follows. No RF required to switch things to the correct
configuration for band, frequency and antenna.

As to manual revisions, I see mine is C5, March 31, 2015.   My KAT500 is
s/n 1807 purchased 7/21/18.   I haven't kept up with paper revisions.
However I have firmware 1.075 in the KAT500 and 5.67 in my K3S. Looks
like all of that is up to date.

73

Bob, K4TAX

On 8/20/2019 4:21 PM, Mark Musick wrote:

> Yes Bob the manual says that, but that statement in the manual was not revised after the 4.9x firmware update.
> If you look at the manual revisions, that wording has been in the manual since the problem was initially discovered and before the 4.9x firmware update.
>
> 73,
> Mark, WB9CIF
>
> -----Original Message-----
> From: [hidden email] <[hidden email]> On Behalf Of Bob McGraw K4TAX
> Sent: Tuesday, August 20, 2019 21:11
> To: [hidden email]
> Subject: Re: [Elecraft] KPA500 Coax size requirements
>
> Because in the manual, page 4, item 2 states "Connect to the station 11 to 15 VDC power supply with the white striped lead to the positive terminal."
>
> I view it best to always follow the manufactures instructions and not re-engineer the product or rewrite the manual.
>
> 73
>
> Bob, K4TAX
>
>
> On 8/20/2019 3:27 PM, Ken K6MR wrote:
>> "The KAT500 can be {should be} powered from the radio 12V supply."
>>
>>
>>
>> Interested why this is true. Can the KAT500 tell the difference between Elecraft 12V and Generic 12V? Seems odd.
>>
>>
>>
>> I ran two KAT500s on generic 12V from a DIN rail power supply for 5 years. Necessary because the tuners and the amps were remoted in a closet 20 feet from the operating desk. No problems.
>>
>>
>>
>> Ken K6MR
>>
>>
>>
>>
>>
>> ________________________________
>> From: [hidden email]
>> <[hidden email]> on behalf of Bob McGraw K4TAX
>> <[hidden email]>
>> Sent: Tuesday, August 20, 2019 12:59:11 PM
>> To: [hidden email] <[hidden email]>
>> Subject: Re: [Elecraft] KPA500 Coax size requirements
>>
>> Carter:
>>
>> The KAT500 can be {should be} powered from the radio 12V supply. I
>> don't suggest a separate wall wart.
>>
>> The KPA500 can be powered from either 120VAC or 240VAC, your choice.
>> It should drive on all bands with 20 to 30 watts output from the K2 to
>> reach full 500 watts output from the amp.
>>
>> As to coax, yes RG-8X is OK up to 30 MHz as long as the SWR is low.
>> The Belden Power rating is 1000 watts up to 10 MHz, 370 watts at 50 MHz.
>> Loss is 0.9dB / 100 ft @ 10 MHz and 2.1 dB / 100 ft at 50 MHz. These
>> power ratings are matched conditions.
>>
>> What is the SWR on your wire loop on the feed line for all bands? Per
>> Belden, the UL voltage rating is 300 V RMS. Thus 500 watts at 50
>> ohms, i.e. 1:1 SWR, is 158 volts. However, 500 watts into 500 ohms,
>> i.e. 10:1 SWR, is 500 volts. So to answer your question, YES and NO,
>> depending on SWR on the coax between the tuner output and the loop antenna feed point.
>>
>> In general, R-8X is OK at 500 watts below 30 MHz. From experience, it
>> will get "warm" to the touch. "Warm" is created by loss which is then
>> heat generated from RF. And that is RF which is not getting to the
>> antenna.
>>
>> Personally I'd opt for a balanced open wire feed to the loop and a
>> very good 1:1 balun rated for legal limit or more at the KAT500 tuner output.
>>
>> 73
>>
>> Bob, K4TAX
>>
>>
>> On 8/20/2019 2:11 PM, Carter Craigie wrote:
>>> Hello friends,
>>>
>>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving
>>> it from my Elecraft K2/100 rig. I hope I would be able to do that!
>>>
>>> From what I have read on eHam Reviews, it appears that I can run
>>> the amp/tuner combo on 117v. from the convenient wall socket. Is that
>>> correct, as well?
>>>
>>> I cannot find any mention of the coax requirements, from the
>>> radio/combo out to our 80-meter wire loop antenna. Right now, using
>>> only my K2/100 I am able to use 8X coax.
>>>
>>> Will I still be able to use that coax cable with up to 500 Watts output?
>>>
>>> What other considerations do I need to make?
>>>
>>> Thanks in advance,
>>>
>>> Carter Craigie, N3AO
>>> Blacksburg, VA
>>>
>>>
>> ______________________________________________________________
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>>
> ______________________________________________________________
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Nr4c

Re: KPA500 Coax size requirements

In reply to this post by N3AO

RG-8X will be fine. LMR-240 is also a good choice, a little less loss.

Sent from my iPhone
...nr4c. bill

> On Aug 20, 2019, at 3:11 PM, Carter Craigie <[hidden email]> wrote:
>
> Hello friends,
>
> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
> from my Elecraft K2/100 rig. I hope I would be able to do that!
>
> From what I have read on eHam Reviews, it appears that I can run the
> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
> as well?
>
> I cannot find any mention of the coax requirements, from the radio/combo
> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
> able to use 8X coax.
>
> Will I still be able to use that coax cable with up to 500 Watts output?
>
> What other considerations do I need to make?
>
> Thanks in advance,
>
> Carter Craigie, N3AO
> Blacksburg, VA
>
>
> --
> Carter, N3AO
> Blacksburg, VA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Ted Edwards W3TB

Re: KPA500 Coax size requirements

The 110 Volt AC will be fine and draw 9 amps key down — within a 15 amp
circuit breaker with plenty for more uses. If VSWR is ok then RG-8X is
fine. I have used LMR-240 as well but is intended for higher frequencies
up to UHF.

Have fun out there!

On Tue, Aug 20, 2019 at 17:50 Nr4c <[hidden email]> wrote:

> RG-8X will be fine. LMR-240 is also a good choice, a little less loss.
>
> Sent from my iPhone
> ...nr4c. bill
>
>
> > On Aug 20, 2019, at 3:11 PM, Carter Craigie <[hidden email]>
> wrote:
> >
> > Hello friends,
> >
> > I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
> > from my Elecraft K2/100 rig. I hope I would be able to do that!
> >
> > From what I have read on eHam Reviews, it appears that I can run the
> > amp/tuner combo on 117v. from the convenient wall socket. Is that
> correct,
> > as well?
> >
> > I cannot find any mention of the coax requirements, from the radio/combo
> > out to our 80-meter wire loop antenna. Right now, using only my K2/100 I
> am
> > able to use 8X coax.
> >
> > Will I still be able to use that coax cable with up to 500 Watts output?
> >
> > What other considerations do I need to make?
> >
> > Thanks in advance,
> >
> > Carter Craigie, N3AO
> > Blacksburg, VA
> >
> >
> > --
> > Carter, N3AO
> > Blacksburg, VA
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
> ______________________________________________________________
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--
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
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Elecraft mailing list

Re: KPA500 Coax size requirements

It is a shame to see folks go cheap on the cable. My rule of thumb is
1dB or less between the rig and the antenna at the highest frequency of
operation.

Warm coax is lost rf which we have paid heavily to generate.

Regards,

Mike VP8NO
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Mark Goldberg

Re: KPA500 Coax size requirements

In reply to this post by N3AO

Take a look at this coax loss calculator. It will tell you how much loss
there is in the coax, including extra loss due to SWR. You will have to
determine how much loss you can tolerate.

https://www.qsl.net/co8tw/Coax_Calculator.htm

73,

Mark
W7MLG

On Tue, Aug 20, 2019, 12:19 PM Carter Craigie <[hidden email]> wrote:

Jim Danehy

Re: KPA500 Coax size requirements

Losses in COAX is KEY DOWN CONDITIONS.

ONE DB loss is the LEAST DETECTABLE amount a human can detect. Hardly if not impossible to notice.

Jim
W9VNE/VA3VNE

Sent from my iPhone

> On Aug 20, 2019, at 11:28 PM, Mark Goldberg <[hidden email]> wrote:
>
> Take a look at this coax loss calculator. It will tell you how much loss
> there is in the coax, including extra loss due to SWR. You will have to
> determine how much loss you can tolerate.
>
> https://www.qsl.net/co8tw/Coax_Calculator.htm
>
> 73,
>
> Mark
> W7MLG
>
>> On Tue, Aug 20, 2019, 12:19 PM Carter Craigie <[hidden email]> wrote:
>>
>> Hello friends,
>>
>> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
>> from my Elecraft K2/100 rig. I hope I would be able to do that!
>>
>> From what I have read on eHam Reviews, it appears that I can run the
>> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
>> as well?
>>
>> I cannot find any mention of the coax requirements, from the radio/combo
>> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
>> able to use 8X coax.
>>
>> Will I still be able to use that coax cable with up to 500 Watts output?
>>
>> What other considerations do I need to make?
>>
>> Thanks in advance,
>>
>> Carter Craigie, N3AO
>> Blacksburg, VA
>>
>>
>> --
>> Carter, N3AO
>> Blacksburg, VA
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
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>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
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Jim Brown-10

Re: KPA500 Coax size requirements

In reply to this post by Nr4c

On 8/20/2019 3:49 PM, Nr4c wrote:
> From what I have read on eHam Reviews, it appears that I can run the
> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
> as well?

The KPA500 runs on 120V or 240V. The KAT500 runs on 11-15VDC. My two
K3s (original model) run on a 100Ah Bionenne LiFePO4 battery, which
stays above 13V for 90% of its charge capacity; the IMD (clicks,
splatter) of a K3 increases with lower DC voltage, and lead acid
batteries stay below 12V for most of their discharge curve.

The rest of the 12V gear in my shack, in addition shack lighting, runs
on a 100Ah sealed lead acid battery. Both batteries are float-charged
using Genasun charge regulators from spare Thinkpad power supplies. The
Genasuns are MPPT chargers, so they step down the 20V from the power
supplies to the battery voltage.

> I cannot find any mention of the coax requirements, from the radio/combo
> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
> able to use 8X coax.

Has nothing to do with the amp -- study the ARRL Handbook and Antenna
Book to learn these fundamentals. As others have mentioned, the major
reason for using bigger coax is reduced loss, whether mismatched or not.

Someone suggested open wire or two-wire line with a balun at the tuner.
That can transmit OK, but unless you're lucky enough to live in the
middle of nowhere, that's a recipe for lots of receive noise. You can't
work what you can't hear. The quietest antennas are resonant and
reasonably well matched to the coax that feeds them, and with a serious
common mode choke at the feedpoint (that is, up in the air). Lots of
specific advice atk9yc.com/publish.htm. Look for the HF choke cookbook,
the RFI tutorial, and how to chase receive noise.

73, Jim K9YC

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Jim Brown-10

Re: KPA500 Coax size requirements

In reply to this post by Elecraft mailing list

On 8/20/2019 6:58 PM, Mike Harris via Elecraft wrote:
> It is a shame to see folks go cheap on the cable. My rule of thumb is
> 1dB or less between the rig and the antenna at the highest frequency
> of operation.

RIGHT!

73, Jim K9YC

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Jim Brown-10

Re: KPA500 Coax size requirements

In reply to this post by Jim Danehy

On 8/20/2019 9:18 PM, Jim Danehy wrote:
> ONE DB loss is the LEAST DETECTABLE amount a human can detect.

Not true. One dB IS approximately the smallest change in LOUDNESS that
most listeners can hear, but what matters in radio is signal to noise
ratio, and 1 dB can be the difference between making an not making a
QSO. More important, losses throughout the signal chain add up. Losses
also increase with mismatch.

> Hardly if not impossible to notice.

We notice these small things when signals are on the edge of being able
to copy or not. Like when the DX station is trying to pull your weak
signal out his noise.

73, Jim K9YC

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Elecraft mailing list

Re: KPA500 Coax size requirements

In reply to this post by N3AO

Carter;

Welcome to the world of higher power. The information you have received from others is very good. There is one other thing to watch for, it is something that most hams who upgrade to higher power experience. When we operate at low power, there are a lot of things we can get away with such as relatively poor connectors, cheap coax and the like. When we add power, things change, and many of these things start having problems. Things like arcing across connectors (watch the elbows), whether at the antenna or along the path, heating of components (low-power baluns are especially bad), and many other things can give you fits. These will be noticed as faults, either in the ATU or the KPA, and make you wonder what is going on.

The answer is to use good quality components in your antenna path from the ATU all the way to, and including the antenna. That will make the system, including the KAT and the KPA much happier, and with it, your use of it.

As for the KPA500, it can indeed run at 120V quite well. Both of mine (which includes the first prototype) have run that way for many years. Both the KPA and the KAT monitor their environment extensively, and will report issues if they see any problems with the antenna system, usually in the form of high reflected power. Many hams use the units daily. We believe you will enjoy them as well!

If you have any questions, just ask!

73,
Jack Brindle, W6FB
Elecraft Engineering

> On Aug 20, 2019, at 12:11 PM, Carter Craigie <[hidden email]> wrote:
>
> Hello friends,
>
> I am contemplating buying a KPA500 amplifier/tuner Combo, and driving it
> from my Elecraft K2/100 rig. I hope I would be able to do that!
>
> From what I have read on eHam Reviews, it appears that I can run the
> amp/tuner combo on 117v. from the convenient wall socket. Is that correct,
> as well?
>
> I cannot find any mention of the coax requirements, from the radio/combo
> out to our 80-meter wire loop antenna. Right now, using only my K2/100 I am
> able to use 8X coax.
>
> Will I still be able to use that coax cable with up to 500 Watts output?
>
> What other considerations do I need to make?
>
> Thanks in advance,
>
> Carter Craigie, N3AO
> Blacksburg, VA
>
>
> --
> Carter, N3AO
> Blacksburg, VA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

David Gilbert

Re: KPA500 Coax size requirements

In reply to this post by Jim Danehy

That's not a universally true statement.

Several years ago I was trying to decide which antenna to buy, and my
choice came down to two antennas that were 2 db apart. I created some
audio files by recording typical band noise and then overlaying them
with recorded CW messages at various strengths. The difference between
1 dB above the noise level and 2 dB above the noise level can make the
difference between no copy and copy. The files and testing methodology
can be found here:

http://www.ab7e.com/weak_signal/mdd.html

If you're ragchewing it doesn't matter, but if you're trying to make a
contact and your signal is at the level of the mud it does.

73,
Dave AB7E

On 8/20/2019 9:18 PM, Jim Danehy wrote:
> ONE DB loss is the LEAST DETECTABLE amount a human can detect. Hardly if not impossible to notice.
>
> Jim
> W9VNE/VA3VNE

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