KPA-100 spur on 160M?
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Has anyone who experienced oscillation with their KPA-100 (internally or externally mounted) seen a spur about 1Khz up from the main signal?
If I crank up my power to 100W a very "brrrrrippy" spur pops up just above my signal only on 160M. If I keep the power at 95W or less it is not there. I do not hear it in my external rx when the amp is bypassed. I keep it at the 90W level if I am operating barefoot on 160M of course but if this is not normal or never before seen then I'd be tempted to look into a wiring error in the PA. I eventually want to wire the PA externally. Elecraft recommends troubleshooting the KPA-100 while it is mounted in the K2 so I'd like to clean this up before extending the PA away from the K2 and a new can of worms gets opened. 73 de Tom K2TA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Tom, K2TA wrote:
Has anyone who experienced oscillation with their KPA-100 (internally or externally mounted) seen a spur about 1Khz up from the main signal? If I crank up my power to 100W a very "brrrrrippy" spur pops up just above my signal only on 160M. If I keep the power at 95W or less it is not there. ----------------------------------- How "old" is the amp, Tom? There have been a couple of shield upgrades that have to do with stability issues. I've never noticed a problem with mine, so I'm not certain of the exact symptoms. One "upgrade" added a new shield with side clips that better grounds the shield to the case on the edges. A second one adds a lower-inductance ground to the shield right at the SO-239 output connector using two ground lugs, one under one of the connector screws replacing the lock washer there and the other under the closest shield screw. The two ground lugs are soldered together to form a "strap" from the connector ground screw to the shield mounting screw. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Ron! It was a Jan 2004 production release that was unbuilt when I
bought it 2 weeks ago. Elecraft was kind enough to ship me the new shield, firmware and upgrade mods to bring it up to spec so it's up to snuff including the mu-metal speaker shield. I received a very interesting e-mail from Ron ZL1TW with a possible fix that corrected a spur he had on 80 and may have had on 160 as well. If it works I'll repost it to the group. I'll put it in today when I get home from work and report back if successful. 73 de Tom K2TA ----- Original Message ----- From: "Ron D'Eau Claire" <[hidden email]> To: "'Elecraft'" <[hidden email]> Sent: Tuesday, November 30, 2004 10:35 AM Subject: RE: [Elecraft] KPA-100 spur on 160M? Tom, K2TA wrote: Has anyone who experienced oscillation with their KPA-100 (internally or externally mounted) seen a spur about 1Khz up from the main signal? If I crank up my power to 100W a very "brrrrrippy" spur pops up just above my signal only on 160M. If I keep the power at 95W or less it is not there. ----------------------------------- How "old" is the amp, Tom? There have been a couple of shield upgrades that have to do with stability issues. I've never noticed a problem with mine, so I'm not certain of the exact symptoms. One "upgrade" added a new shield with side clips that better grounds the shield to the case on the edges. A second one adds a lower-inductance ground to the shield right at the SO-239 output connector using two ground lugs, one under one of the connector screws replacing the lock washer there and the other under the closest shield screw. The two ground lugs are soldered together to form a "strap" from the connector ground screw to the shield mounting screw. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Tom Althoff
Is this spur present when running full power QRP?
Try 15watt to see if the spur is made by the K2 itself . Turn PA off in menu or power K2 from it's DC barrel jack. If it's gone you know it's made by or with interaction of the KPA100. Tom LA1PHA ----- Original Message ----- From: "Tom Althoff" <[hidden email]> To: "Elecraft" <[hidden email]> Sent: Tuesday, November 30, 2004 9:07 AM Subject: [Elecraft] KPA-100 spur on 160M? Has anyone who experienced oscillation with their KPA-100 (internally or externally mounted) seen a spur about 1Khz up from the main signal? If I crank up my power to 100W a very "brrrrrippy" spur pops up just above my signal only on 160M. If I keep the power at 95W or less it is not there. I do not hear it in my external rx when the amp is bypassed. I keep it at the 90W level if I am operating barefoot on 160M of course but if this is not normal or never before seen then I'd be tempted to look into a wiring error in the PA. I eventually want to wire the PA externally. Elecraft recommends troubleshooting the KPA-100 while it is mounted in the K2 so I'd like to clean this up before extending the PA away from the K2 and a new can of worms gets opened. 73 de Tom K2TA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Tom Althoff
Maybe the current limiting on your power supply is starting to cut in at 95W on 160m?
73 de Paul ZL3IN > If I crank up my power to 100W a very "brrrrrippy" > spur pops up just above my signal only on 160M. > If I keep the power at 95W or less it is not there. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Tom Arntzen
No Tom..only when running the KPA/100 did we hear the spur. I fixed it
with the help of Ron ZL1TW but it may be considered an untested/experimental mod and as such did not get posted to the Elecraft reflector. I've e-mailed Gary and told him of my successful experience with it. There are 5 of us who have done the mod and it has worked for all. Hopefully it will get posted here for others to see. It did not show up when I searched the old archives. Thanks to everyone for all the e-mails on this. 73 de Tom K2TA K2/100 #1117 ----- Original Message ----- From: "Tom Arntzen" <[hidden email]> To: <[hidden email]>; "Tom Althoff" <[hidden email]> Sent: Tuesday, November 30, 2004 2:03 PM Subject: Re: [Elecraft] KPA-100 spur on 160M? > Is this spur present when running full power QRP? > Try 15watt to see if the spur is made by the K2 itself . > Turn PA off in menu or power K2 from it's DC barrel jack. > If it's gone you know it's made by or with interaction of the KPA100. > > Tom LA1PHA > > ----- Original Message ----- > From: "Tom Althoff" <[hidden email]> > To: "Elecraft" <[hidden email]> > Sent: Tuesday, November 30, 2004 9:07 AM > Subject: [Elecraft] KPA-100 spur on 160M? > > > Has anyone who experienced oscillation with their KPA-100 (internally or > externally mounted) seen a spur about 1Khz up from the main signal? > > If I crank up my power to 100W a very "brrrrrippy" spur pops up just above > my signal only on 160M. If I keep the power at 95W or less it is not > there. > > I do not hear it in my external rx when the amp is bypassed. > > I keep it at the 90W level if I am operating barefoot on 160M of course > if this is not normal or never before seen then I'd be tempted to look into > a wiring error in the PA. > > I eventually want to wire the PA externally. Elecraft recommends > troubleshooting the KPA-100 while it is mounted in the K2 so I'd like to > clean this up before extending the PA away from the K2 and a new can of > worms gets opened. > > 73 de Tom K2TA > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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