KPA500 swr tolerance
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Greetings,
In viewing the info on the KPA500, I see a spec for input swr of 1.5/1 but I cannot find any numbers for what the amp will tolerate from the antenna load. I assume it is low because it's a solid state amp but what exactly will it tolerate before it soft or hard faults? Perhaps I am misunderstanding the input swr as being from the transceiver? Tnx es 73,Jim W5QM ______________________________________________________________ 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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In my experience, it does not like anything near 2:1.
It can trip out at just over 1.6:1, depending on the band and the type of load (reactive part) and power out. I got the KPA-500 which makes the amp happy. Jim W6AIM . -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Jim Hoge Sent: Wednesday, May 6, 2015 1:43 PM To: Elecraft Reflector Subject: [Elecraft] KPA500 swr tolerance Greetings, In viewing the info on the KPA500, I see a spec for input swr of 1.5/1 but I cannot find any numbers for what the amp will tolerate from the antenna load. I assume it is low because it's a solid state amp but what exactly will it tolerate before it soft or hard faults? Perhaps I am misunderstanding the input swr as being from the transceiver? Tnx es 73,Jim W5QM ______________________________________________________________ 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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a KAT500 will make it happier in this case... :)
________________________________________ From: Elecraft [[hidden email]] on behalf of jim [[hidden email]] Sent: Wednesday, May 06, 2015 2:31 PM To: 'Jim Hoge'; 'Elecraft Reflector' Subject: Re: [Elecraft] KPA500 swr tolerance In my experience, it does not like anything near 2:1. It can trip out at just over 1.6:1, depending on the band and the type of load (reactive part) and power out. I got the KPA-500 which makes the amp happy. Jim W6AIM . -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Jim Hoge Sent: Wednesday, May 6, 2015 1:43 PM To: Elecraft Reflector Subject: [Elecraft] KPA500 swr tolerance Greetings, In viewing the info on the KPA500, I see a spec for input swr of 1.5/1 but I cannot find any numbers for what the amp will tolerate from the antenna load. I assume it is low because it's a solid state amp but what exactly will it tolerate before it soft or hard faults? Perhaps I am misunderstanding the input swr as being from the transceiver? Tnx es 73,Jim W5QM ______________________________________________________________ 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] ______________________________________________________________ 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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Ur right.
Typo on my part KAT-500 (Tuner) makes the amp happy Jim W6AIM . -----Original Message----- From: Chris Tate - N6WM [mailto:[hidden email]] Sent: Wednesday, May 6, 2015 2:35 PM To: jim; 'Jim Hoge'; 'Elecraft Reflector' Subject: RE: [Elecraft] KPA500 swr tolerance a KAT500 will make it happier in this case... :) ________________________________________ From: Elecraft [[hidden email]] on behalf of jim [[hidden email]] Sent: Wednesday, May 06, 2015 2:31 PM To: 'Jim Hoge'; 'Elecraft Reflector' Subject: Re: [Elecraft] KPA500 swr tolerance In my experience, it does not like anything near 2:1. It can trip out at just over 1.6:1, depending on the band and the type of load (reactive part) and power out. I got the KPA-500 which makes the amp happy. Jim W6AIM . -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Jim Hoge Sent: Wednesday, May 6, 2015 1:43 PM To: Elecraft Reflector Subject: [Elecraft] KPA500 swr tolerance Greetings, In viewing the info on the KPA500, I see a spec for input swr of 1.5/1 but I cannot find any numbers for what the amp will tolerate from the antenna load. I assume it is low because it's a solid state amp but what exactly will it tolerate before it soft or hard faults? Perhaps I am misunderstanding the input swr as being from the transceiver? Tnx es 73,Jim W5QM ______________________________________________________________ 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] ______________________________________________________________ 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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In reply to this post by Jim Bolit
This may be a case where two directional couplers (or SWR bridges) may not be created equal.
The KPA500 uses a directional coupler, which needs no calibration, and measures the forward and reflected voltages that are sampled simultaneously. This allows us to have a rather accurate measurement and calculation. The limits are in the directional coupler itself, as to how well the windings are coupled. Having said this, the KPA500 makes most of its decisions based on reflected power, not on SWR. The only SWR decision is for very high SWR protection - the amplifier will fault at or above 18:1. This provides short- or open-circuit protection. The amplifier protection kicks in with 60 watts reflected power (for a short while), and we will fault at 100 watts of reflected power. What this really means depends entirely on the output power, antenna matching and any other signals in the area that are going in to the KPA’s antenna port. If you are running relatively low power into a relatively high SWR, the KPA probably won't fault unless it sees an SWR above 18:1. Other than that, what is coming back from the antenna determines what happens. The higher the output power, the more reflected power for a given match. Want to test it? Set things up with 65 watts reflected power, then watch as the KPA protests itself by inserting the attenuator, cutting output power in half. The KPA will continue amplifying, periodically dropping the attenuator to see if the antenna match changed, then reprocessing itself when it sees that it hasn’t. Something else of note. Non-choked RF currents on the outside of the coax shield will also have an effect on reflected power (usually makes it worse). Proper choking will have a very good effect when it is needed (and it usually is). Also, strong nearby signals may add to the reflected power, causing a higher reading, and thus causing the KPA to protect itself more quickly than if that signal is not present. Folks who build high-power multi-transmitter stations routinely deal with this scenario. This is a bit long-winded, but I hope it answers the question. We simply cannot give a valid answer to the question of SWR limits, but rather do have very valid specifications for reflected power limits. As usual, then answer is in your antenna system. Design it properly and the KPA500 will run just fine for a long time. - Jack Brindle, W6FB > On May 6, 2015, at 2:31 PM, jim <[hidden email]> wrote: > > In my experience, it does not like anything near 2:1. > > It can trip out at just over 1.6:1, depending on the band and the type of > load (reactive part) and power out. > > I got the KPA-500 which makes the amp happy. > > Jim > W6AIM > > > > > . > > -----Original Message----- > From: Elecraft [mailto:[hidden email]] On Behalf Of Jim > Hoge > Sent: Wednesday, May 6, 2015 1:43 PM > To: Elecraft Reflector > Subject: [Elecraft] KPA500 swr tolerance > > Greetings, > In viewing the info on the KPA500, I see a spec for input swr of 1.5/1 but I > cannot find any numbers for what the amp will tolerate from the antenna > load. I assume it is low because it's a solid state amp but what exactly > will it tolerate before it soft or hard faults? Perhaps I am > misunderstanding the input swr as being from the transceiver? > > Tnx es 73,Jim W5QM > > ______________________________________________________________ > 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] ______________________________________________________________ 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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In reply to this post by Jim Hoge-2
On Wed, 6 May 2015 20:43:20 +0000 (UTC), Jim Hoge wrote:
> I see a spec for input swr of 1.5/1 but I cannot find any numbers for > what the amp will tolerate from the antenna load. Like have others, I'd say it is not very tolerant. In fact, I won't let it have access to anything over 1.2, without hitting the tuner. On six meters, I've found it to be fairly sensitive to reflected power, especially at higher power settings. Do have a tuner available, even on a resonant band, when operating off the resonant frequency by a significant amount. Although pricey, the KAT500 fills the bill quite nicely. I'm not a drinker of the eKool-Aid. I'm a heavy Kenwood fan. But I really like the KPA for ease of operation, all the way to six meters, and so far, the reliability. I've been in electronics since I was in 9th grade in the 50s, and I am now wanting to simplify my life. I don't want to work on things, I just want to enjoy the hobby that was responsible for my entire career. The integration of the KPA/KAT package to my TS590 have made it so simple, I just love it. When I change bands, the amp dutifully follows without my input. 73, Gary ______________________________________________________________ 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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