KPA500 Issue
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My KPA500 has just developed an issue. Specifically when I switch it from
Stby to Oper, the level of received signals drops by around 5 or 6 s points. It still transmits fine and there are no adverse SWR indications or loose co-ax plugs. It does the same on all bands. I switch back to Stby and the received signals return to normal. I seem to recall that someone else posted details of a similar such problem some time ago. Any suggestions would be helpful before I email the Elecraft hot line. Barry Simpson VK2BJ ______________________________________________________________ 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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Hi Barry,
There is an asterisk that appears on the left side of the KPA500 display whenever the key out signal from your transmitter is present. You should not see the asterisk when you are receiving. If you are then is it possible that you are using the key out signal to operate some other device in addition to the KPA500? 73, Mike K2MK
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Yes, that was the problem when it happened to me. It was a cable problem
that was inadvertently closing the key in ("PA Key") input on the back of the KPA500. Clearing that up restored normal operation. 73, andy ae6y -----Original Message----- From: Mike K2MK Sent: Friday, January 30, 2015 5:34 AM To: [hidden email] Subject: Re: [Elecraft] KPA500 Issue Hi Barry, There is an asterisk that appears on the left side of the KPA500 display whenever the key out signal from your transmitter is present. You should not see the asterisk when you are receiving. If you are then is it possible that you are using the key out signal to operate some other device in addition to the KPA500? 73, Mike K2MK Barry Simpson wrote > My KPA500 has just developed an issue. Specifically when I switch it from > Stby to Oper, the level of received signals drops by around 5 or 6 s > points. It still transmits fine and there are no adverse SWR indications > or > loose co-ax plugs. It does the same on all bands. I switch back to Stby > and > the received signals return to normal. > > I seem to recall that someone else posted details of a similar such > problem > some time ago. Any suggestions would be helpful before I email the > Elecraft > hot line. > > Barry Simpson VK2BJ -- View this message in context: http://elecraft.365791.n2.nabble.com/KPA500-Issue-tp7597707p7597710.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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 Barry Simpson
> .... when I switch it from > Stby to Oper, the level of received signals drops by around 5 or 6 s > points. It still transmits fine and there are no adverse SWR indications or > loose co-ax plugs. It does the same on all bands. Sounds like bad PIN DIODE situation, but I'll let those who are more expert at them take that on. > I switch back to Stby and the received signals return to normal. Just for reference, on six meters, using WSJT10 for FSK441 MS, I see one db drop in my JT measured band (white) noise between the KPA STBY and OPER modes. Gary -- http://ag0n.net 3055: http://ag0n.net/irlp/3055 NodeOp Help Page: http://ag0n.net/irlp ______________________________________________________________ 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 Mike K2MK
Good morning to those who responded to me on the Elecraft reflector. Here
is the interim outcome. I did not mention that the problem arose after connecting my brand new (yesterday) TS590SG to the KPA500. The TS590SG has different linear switching facilities from the TS590S in that there is now provision for solid state switching to avoid a clicking relay. I was using the solid state switching set up. I use the same set up with my TS990S and that works perfectly with the KPA500. I checked and resoldered the connecting cable and then I interchanged the cable I use with the TS990S as the Din pin connections are identitical with the TS590SG. The outcome was exactly the same with the loss of received signals when the KPA500 is switched to Oper and the little asterisk appears on the left side of the display. However, the set up still keys the KPA500 perfectly. I then changed over to the TS990S and with that rig, the KPA500 works perfectly with the solid state switching. The conclusion is therefore that from an initial OK position in Stby and Oper as soon as the first character is keyed, the solid state switch in the TS590SG "hangs" resulting in the KPA500 being permanently in the transmit state. The situation only clears when rig and amp are turned off, the Din plug is removed from the TS590SG and reinserted and both are turned back on. I can then switch the amp back to Oper and all is fine until the very first morse character when it all happens again. So as it stands, there appears to be incompatibility between the TS590SG solid state amp switch and KPA500. As an interim measure, I have rewired the Din plug to use the noisy relay for the amp control and that works fine. The TS590SG does output 12V to the solid state switching pin in certain configurations as did the TS590S. I had a TS590S and I wired a single transistor solid state switch inside the Din plug and that worked perfectly so I am going to do the same again, which should solve the issue. Unfortunately, I gave away the TS590S cable I had made up to the guy I sold the TS590S to. I never got the very bad spike issue fixed but the buyer did not mind as he doesn't use a linear. It really is a pity as I thought that the new linear switching circuitry in the TS590SG was a real step forward but it is not to be, at least not with the KPA500. For information and to avoid others having a similar head scratching issue, I am copying this to the TS590 list as well. As a final point, I can confirm that the TS590SG has no power spike issue whatsoever and the average audio level in SSB seems much improved from the TS590S. Once I have wired and implemented the transistor switch, I will report back with the result. 73 Barry VK2BJ On 31 January 2015 at 00:34, Mike K2MK <[hidden email]> wrote: > Hi Barry, > > There is an asterisk that appears on the left side of the KPA500 display > whenever the key out signal from your transmitter is present. You should > not > see the asterisk when you are receiving. If you are then is it possible > that > you are using the key out signal to operate some other device in addition > to > the KPA500? > > 73, > Mike K2MK > > > Barry Simpson wrote > > My KPA500 has just developed an issue. Specifically when I switch it from > > Stby to Oper, the level of received signals drops by around 5 or 6 s > > points. It still transmits fine and there are no adverse SWR indications > > or > > loose co-ax plugs. It does the same on all bands. I switch back to Stby > > and > > the received signals return to normal. > > > > I seem to recall that someone else posted details of a similar such > > problem > > some time ago. Any suggestions would be helpful before I email the > > Elecraft > > hot line. > > > > Barry Simpson VK2BJ > > > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/KPA500-Issue-tp7597707p7597710.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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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Hi Barry,
While your experience suggests that a transistor switch will probably save the day I also wonder if the problem is the result of the absence or presence of a pull-up resistor or perhaps a floating common connection between the rig and amp. Maybe a resistor in the plug would help. I suppose there is some way to check this out. 73, Mike K2MK
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In reply to this post by Barry Simpson
Looks like the Kenwood switches high during transmit and the KPA500
requires a low for transmit. KPA500 specs in my manual say +5V max, open circuit on receive, closed to ground on transmit. My old KPA500 manual doesn't show Kenwood interconnections. Only the K3, Yaesu and Icom. Yup, ya need to supply a low to the amp. Joe ( AJ8MH ) http://webpages.charter.net/aj8mh-radio/ ______________________________________________________________ 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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