I put my K3 on 20M and put out 20 watts into the KPA500 in operate connected to a Bird dummy load and the K3 shows 1:1 SWR.
Chuck, KE9UW Lionel Trains, TCA, LCCA, LRRC aka Jack, BMW Motorcycles BMWMOA #224 ________________________________________ From: [email protected] [[email protected]] on behalf of ARRL - N6MQL [[email protected]] Sent: Sunday, December 09, 2012 4:19 PM To: [email protected]; [email protected] Subject: [Elecraft] KPA500 presents high SWR to radio driving it Randy, I'm not sure if it's normal or not, but I do find that if you use an analyzer on the input of the KPA500 and a 50ohm dummy load on the output, you will see a good 50 ohm 1.0:1 SWR on the analyzer in the Stand by mode. However, when you put the amp into the Operate mode you get somewhere in the neighborhood of a 2.8:1 SWR (on the 20 meter band). When you put in around 10W to the input of that KPA500 while in operate (or at least mine) than I find that I see an increase of about .5 in the SWR. IE. If I have a 50 Ohm Dummy load on the output and I put the amp on operate and transmit the 10w into the input, I see a 1.5:1 SWR on the rig connected to the input. I would see that the input level determines the SWR on the input when the amp is in the operate mode. It doesn't seem to have a fixed 50 Ohm load on the input as I would have expected it to. Now, if someone else who knows better than I would like to explain why that is, or if this is NOT normal I would love to know as well. I think that Randy's question is a very fair and reasonable one. An answer from an authority would be helpful. If you DON'T know the answer but would like to guess... I prefer you NOT, just let someone who does know do the answering. Thank you, Michael N6MQL > Hello, > > I just spent a most enjoyable afternoon assembling SN 1213 KPA 500. Took my > time and double checked every connection, wire, etc. Everything is in the > right place and there are no faults, errors etc. when I power it up. However > both my radios (a KX3 with ATU in bypass, and a Flex 5000 without an ATU) > report high SWR with KEY DOWN. I put my SWR meter on the input side and sure > enough, most bands present a 1.9:1 or higher. I have discharged the unit and > removed the rear panel just in case the RF input wires were disconnected some > how in assembly-both input and output are secure. I am at a loss. Anyone > have any ideas? Also, I should mention on receive all bands seem VERY quiet. > > Also, my KX3 with ATU enabled works really hard but does make it tune-still > no auto band switching and no RF out that I can see. > > I was really hoping to work the 10M contest this weekend with my new amp.... > > > RANDY DIDDEL > [email protected] > Follow me on APRS at: http://tinyurl.com/k5rhd-2 > Homepage: http://blog.randydiddel.com > -- ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
