[Elecraft] KPA500 Coax size requirements

[hawley, charles j jr]

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 <k6mr at outlook.com> 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: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> on behalf of Bob McGraw K4TAX <rmcgraw at blomand.net>
> Sent: Tuesday, August 20, 2019 12:59:11 PM
> To: elecraft at mailman.qth.net <elecraft at mailman.qth.net>
> 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:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k6mr at outlook.com
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to c-hawley at illinois.edu