FWIW, below are my notes - from before I sent mine in for repair. Something happened that caused an LDG AT-1000Pro to toast the protection Diode, and an Icom IC-756 Pro 2 to burn one of the contacts off of the antenna 1 / antenna 2 change over relay.
I had already taken the K3 out of line for unstable output before trying the Pro II. We found one of the drivers bad on the K3. It is looking like the amp is common to all items that were affected. I am in luck in that I can replace the driver on the K3, and the relay on the Pro 2. Dwayne at LDG will treat me right on the 1000Pro, so all I am really stuck with so far is the $65.00 to ship and insure the LPA500 to Elecraft, and whatever they find wrong, plus return shipping and insurance. Here is what I wrote: "MFJ Analyzer shows (worse case at 50 MHz) 1.5:1 in standby and 1.1:1 in operate with dummy load connected directly to amp output." My problem is that the amp shows high SWR and REFL HI error whenever it is keyed; no matter what the power or load or band. I am guessing whatever went wrong with the amp sent a fair size spike out to both the rig and external tuner. If you are going to die, you may as well take a few with you :) I will find out soon enough. David KD4NUE -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of zen...@netspace.net.au Sent: Friday, October 19, 2012 7:54 PM To: 'Elecraft Group' Subject: [Elecraft] KPA500 input SWR in standby ...a question. Hi All, Thanks for the messages about the power up LCD blink - it's the way it should be. Now another question: my KPA500 replaces an old AL811. I noticed, when I connected the KPA500 in line, that the K3 SWR meter was giving slightly higher than expected readings with the amp in standby. Given that nothing else in my transmission chain had changed, other than swapping over the amps, I thought this was strange. I also noted that my LP100 meter would show an SWR of 1.0:1 (on the rig side of my manual tuner) while the K3 meter would show an SWR of 1.2:1. The KPA500 SWR meter agrees with the LP100. Looking at this, I put a dummy load on the output of the KPA500 and with the amp in standby, I found that on 20m and above, the KPA500 input SWR is around 1.2:1 with a maximum of 1.3:1 on 6m, measured by an Antenna analyzer on amp's input. Also, taking the amp out of line by physically disconnecting it and using a coax barrel connector to join the input and output lines causes the K3 and LP100 meters to agree. So, is this input SWR variation in standby mode, within spec for the KPA500? I didn't see this with my AL811 in line, but then I'd carefully adjusted its tuned inputs. Please tell me I'm fly specing here and to stop obsessing :) Cheers JohnVK7JB ______________________________________________________________ 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 ______________________________________________________________ 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
