KPA1500 hum - problem solved
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No hum using a dummy load.
No hum using a dipole. Hum only with my all band vertical. Thanks for the suggestions. 73 K8NU ______________________________________________________________ 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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I would bet your coax shield is acting like a radial and bringing RF
back into the shack. Need a choke. k4ia, Buck K3s# 11497 Honor Roll 8B DXCC EasyWayHamBooks.com On 4/5/2020 5:33 PM, Carl Yaffey wrote: > No hum using a dummy load. > No hum using a dipole. > Hum only with my all band vertical. > Thanks for the suggestions. > 73 > K8NU > > > ______________________________________________________________ > 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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It turned out to be using the 4-position Alpha-Delta coax switch. No problem until I connect both the vertical and the dipole to it.
> On Apr 5, 2020, at 5:37 PM, Buck <[hidden email]> wrote: > > I would bet your coax shield is acting like a radial and bringing RF back into the shack. Need a choke. > Carl Yaffey K8NU 614 268 6353, Columbus OH http://www.carl-yaffey.com http://www.grassahol.com http://www.bluesswing.com Https://www.columbusfolkmusicsociety.org http://www.timbrewolves.carl-yaffey.com http://www.folkramblers.carl-yaffey.com Http:www.clintonvillegrass.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] |
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In reply to this post by Carl Yaffey-2
"No hum using a dummy load.
No hum using a dipole. Hum only with my all band vertical." I don't understand how that information results in "problem solved". The problem didn't go away. It could perhaps be RFI but isn't it more likely that the hum is dependent on the load presented by the antenna system? Does the hum come the PSU or the RF unit? KPA500 hum level is directly related to PA current which is, in turn, related to output power and PA efficiency. PA efficiently is strongly dependent on antenna system load therefor hum level is dependent on antenna system load. A bored and cynical observer might perhaps say that KPA500 hum is "normal" so why wouldn't the KPA1500 be expected to hum. Perhaps you should be investigating the conditions for which it does not hum? 73, Andy, k3wyc ______________________________________________________________ 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] |
Re: KPA1500 hum - problem solved
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In reply to this post by Buck
If it worked correctly before then why would one need to add a choke?
Check connections, feed line, matching unit, and radial ground system at the antenna. Bob, K4TAX Sent from my iPhone > On Apr 5, 2020, at 4:52 PM, Buck <[hidden email]> wrote: > > I would bet your coax shield is acting like a radial and bringing RF back into the shack. Need a choke. > > > k4ia, Buck > K3s# 11497 > Honor Roll 8B DXCC > EasyWayHamBooks.com > >> On 4/5/2020 5:33 PM, Carl Yaffey wrote: >> No hum using a dummy load. >> No hum using a dipole. >> Hum only with my all band vertical. >> Thanks for the suggestions. >> 73 >> K8NU >> ______________________________________________________________ >> 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] |
Re: KPA1500 hum - problem solved
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In reply to this post by Carl Yaffey
If it was a switch in line to the vertical, I’d think you would observe a SWR increase when that antenna was selected.
Bob, K4TAX Sent from my iPhone > On Apr 5, 2020, at 5:12 PM, Carl Yaffey <[hidden email]> wrote: > > It turned out to be using the 4-position Alpha-Delta coax switch. No problem until I connect both the vertical and the dipole to it. > >> On Apr 5, 2020, at 5:37 PM, Buck <[hidden email]> wrote: >> >> I would bet your coax shield is acting like a radial and bringing RF back into the shack. Need a choke. >> > > Carl Yaffey K8NU > 614 268 6353, Columbus OH > http://www.carl-yaffey.com > http://www.grassahol.com > http://www.bluesswing.com > Https://www.columbusfolkmusicsociety.org > http://www.timbrewolves.carl-yaffey.com > http://www.folkramblers.carl-yaffey.com > Http:www.clintonvillegrass.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] |
Re: KPA1500 hum - problem solved
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In reply to this post by Bob McGraw - K4TAX
When he added the amplifier, the return currents on the coax became much greater.
The second problem is that the switch then added the return currents of the vertical to those induced into the dipole and made things worse. I see the need for chokes on BOTH antennas. Makes sure they are heavy duty. The best advice is in the choke handbook at K9YC’s web site. 73! Jack, W6FB > On Apr 5, 2020, at 3:17 PM, Bob McGraw K4TAX <[hidden email]> wrote: > > If it worked correctly before then why would one need to add a choke? > > Check connections, feed line, matching unit, and radial ground system at the antenna. > > Bob, K4TAX > > > Sent from my iPhone > >> On Apr 5, 2020, at 4:52 PM, Buck <[hidden email]> wrote: >> >> I would bet your coax shield is acting like a radial and bringing RF back into the shack. Need a choke. >> >> >> k4ia, Buck >> K3s# 11497 >> Honor Roll 8B DXCC >> EasyWayHamBooks.com >> >>> On 4/5/2020 5:33 PM, Carl Yaffey wrote: >>> No hum using a dummy load. >>> No hum using a dipole. >>> Hum only with my all band vertical. >>> Thanks for the suggestions. >>> 73 >>> K8NU >>> ______________________________________________________________ >>> 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] ______________________________________________________________ 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] |
Re: KPA1500 hum - problem solved
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In reply to this post by Buck
On 4/5/2020 2:37 PM, Buck wrote:
> I would bet your coax shield is acting like a radial and bringing RF > back into the shack. Need a choke. Yes -- the clue was the info about the switch. But it also indicates a lack of proper bonding. http://k9yc.com/2018Cookbook.pdf What model of vertical? Some designs require radials, some do not. 73, Jim K9YC ______________________________________________________________ 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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On Apr 5, 2020, at 7:19 PM, Jim Brown <[hidden email]> wrote:
> > What model of vertical? Some designs require radials, some do not. Cushcraft R-8 1/2 wave vertical. No radials needed. > Carl Yaffey K8NU 614 268 6353, Columbus OH http://www.carl-yaffey.com http://www.grassahol.com http://www.bluesswing.com Https://www.columbusfolkmusicsociety.org http://www.timbrewolves.carl-yaffey.com http://www.folkramblers.carl-yaffey.com Http:www.clintonvillegrass.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] |
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