Mike: > On Sep 2, 2018, at 1:27 PM, Michael Blake <k9...@mac.com> wrote: > > Dick from Elecraft answered my question. The short answer to my question was > “no”. > > To answer your question, yes the key line interrupt is set for 3.0:1 as it > should be.
Thanks for the update and glad to hear that your question was answered. That said, my reply was only based upon reading the KAT500 and KPA500 manuals. So I’m wondering how my attempt to be helpful resulted in a “misinterpretation” of what are in the manuals. Does the VSWR threshold not work in Bypass mode, or is it something else that is in play? I’m also wondering (perhaps Dick can answer this) at what point(s) the KPA500 “soft” and “hard” faults kick-in on VSWR. If you’re running at 3.0:1 VSWR with no issues, what are the set points for fault detection? 73, Barry, WD4ASW > > Mike - K9JRI > >> On Sep 2, 2018, at 13:01, Barry Baines <bbai...@mac.com> wrote: >> >> Mike: >> >>> On Sep 2, 2018, at 11:27 AM, Michael Blake via Elecraft >>> <elecraft@mailman.qth.net> wrote: >>> >>> When the KAT500 is powered on but in the Bypass mode will it still open the >>> key line to the KPA500 at the preset level (3.0:1 in my case) if the load >>> suddenly goes above 3:1? >> >> To confirm, is your SWR 3.0:1 or 2.0:1?? >> >> According to the KAT500 manual (page 21) you can use the KAT500 Utility >> Program to set VSWR thresholds for keying an amplifier, “Also, you can set >> an SWR threshold at which the key line will not close to enable the external >> amplifier to protect it from excessive SWR.” These thresholds can be set >> for all bands or individual bands. This would presumably work with bypass >> mode as bypass is defined as bypassing the tuning elements in the tuner’s >> matching network while the tuner’s SWR meter continues to function and the >> antenna selector will still switch to the antenna chosen for a particular >> band. >> >> I haven’t made adjustments using the Utility Program so I cannot speak from >> personal experience nor do I know what the default values are for VSWR >> threshold as I’m not currently where my ham station is to confirm. You will >> need to experiment carefully to ensure that you get the intended results. >> >> Also keep in mind that the KPA500 protects itself. See page 19 of the >> KPA500 manual (“Fault Conditions”) which discusses SWR measurements by the >> KPA500 itself where “minor faults” in VSWR will result in a 3 dB reduction >> in output (“Attenuator Faults”) and continues to operate (if the SWR >> improves the attenuator is removed). In the case of severe SWR problems the >> amplifier goes into standby (“Hard Faults”). Hard faults require >> intervention by the operator to place the amplifier in ‘operate’ presuming >> that the cause of the excessive SWR has been resolved. >> >> The more basic question is what SWR levels the KPA500 will operate. >> According to the KPA500 manual (page 17) the amplifier is designed for 1.5:1 >> or less (the amplifier SWR LEDs are green). Between 1.5 and 2.1 the LEDs >> are yellow, and above 2.1 the LEDs are red. I could not find a reference in >> the manual that defines at what SWR level an “attenuator fault” or a “hard >> fault” due to high SWR are generated, but this suggests that an attenuator >> fault presumably happens when SWR is above 2.1 which is why I’m wondering if >> there’s a typo in your first sentence regarding current SWR. >> >> The KAT500 manual (page 21) also notes, “The Elecraft KPA500 amplifier also >> works efficiently into a load SWR of 1.5:1. Suggested values are 1.8:1 to >> launch an automatic tuning operation and 1.2:1 for bypass.” >> >> >> Hope this helps, >> >> Barry Baines, WD4ASW >> (Currently in Boston, MA) >> >>> >>> The situation is a remote autotuner connected to a 33’ vertical that I use >>> for bands that I do not have a resonant antenna. On those bands the KAT500 >>> is in the BYP mode. A remote switch brings all of the antenna choices in >>> on a single coax which connected to the KAT500. >>> >>> 73 - Mike - K9JRI >>> >>> >>> >>> >>> >>> >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@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 bbai...@mac.com >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@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 arch...@mail-archive.com
