K2 trouble on 160M
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Now that I have my K3 at home I moved my K2/100/KAT100 to our lake cabin. Last weekend it started to shut down on 160 only when transmitting over about 70 watts. All other bands are fine, the antenna (160M dipole fed with ladder line thru 4-1 balun and about 6' of coax into the cabin) is fine and the ground seems fine. It was shutting down the MFJ 4125 switching power supply so thinking maybe RF was getting into the supply I took the rig home and it worked just fine there. Brought it back this weekend with an Astron linear supply and while that PS is not shutting down the rig still wants to. I have used this same setup before here with no problems and this started happening suddenly last weekend. I tried the rig without the KAT100 thru a manual tuner and it still wants to shut down. My Icom 706 works fine on 160 with the same configuration.
Ideas? 73, Bill NZ0T |
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Bill,
What does that K2 do when working into a dummy load? If it still fails, the problem is definitely with the K2. If it behaves, then you need to look at your antenna system - you may be better off with a 1:1 choke balun than your 4-1 balun. I really don't know why hams persist in using a 4-1 balun when driving ladder wire feeders - the 450 ohms is only the characteristic impedance of the line and that says nothing about the feedpoint impedance - the ladder line acts as a transmission line transformer. Measure the feedpoint impedance of the 450 ohm line with an antenna analyzer (operate it on batteries) where you connect the balun. If the impedance is high, then use the 4-1 balun, but if it is low a 1-1 choke balun will be a better choice. Which balun is better depends on the electrical length of your feedline. The K2 can behave differently in the presence of RF-in-the-shack than your 706, so that is not a fair comparison. Look at what you have connected to the K2 and ask what is different - the routing of the paddle cable? How is the power supply cable routed? Do you have a microphone connected? Have you grounded the microphone jack shell on that K2? If you have a K2 problem, ask again with details of the failure with a dummy load. Get it working with a dummy load before adding the extra element of the antenna into the problem. All we can say right now is that your problem is either with the antenna, power supply, any cable attached to the K2 or the K3 itself. Which one is pure guesswork until you reduce the number of variables. 73, Don W3FPR NZ0T wrote: > Now that I have my K3 at home I moved my K2/100/KAT100 to our lake cabin. > Last weekend it started to shut down on 160 only when transmitting over > about 70 watts. All other bands are fine, the antenna (160M dipole fed with > ladder line thru 4-1 balun and about 6' of coax into the cabin) is fine and > the ground seems fine. It was shutting down the MFJ 4125 switching power > supply so thinking maybe RF was getting into the supply I took the rig home > and it worked just fine there. Brought it back this weekend with an Astron > linear supply and while that PS is not shutting down the rig still wants to. > I have used this same setup before here with no problems and this started > happening suddenly last weekend. I tried the rig without the KAT100 thru a > manual tuner and it still wants to shut down. My Icom 706 works fine on 160 > with the same configuration. > Ideas? > > 73, > > Bill NZ0T > > 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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Thanks Don,
The rig behaves the same into the dummy load in all configurations with or without the KAT100 in line, with or without the mike or paddles connected, with or without attached and I even tried a different coax jumper. 160 is the only band it occurs on. What is confounding me is that it workrd fine at home but not here with the exact same configuration.
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Bill,
Since it misbehaves with the dummy load, you will most likely find the problem in the base K2 160 meter Low Pass Filter. I am surprised that you do not also see Hi Curr messages. 73, Don W3FPR NZ0T wrote: > Thanks Don, > > The rig behaves the same into the dummy load in all configurations with or > without the KAT100 in line, with or without the mike or paddles connected, > with or without attached and I even tried a different coax jumper. 160 is > the only band it occurs on. What is confounding me is that it workrd fine > at home but not here with the exact same configuration. > > > > Don Wilhelm-4 wrote: > >> Bill, >> >> What does that K2 do when working into a dummy load? If it still fails, >> the problem is definitely with the K2. If it behaves, then you need to >> look at your antenna system - you may be better off with a 1:1 choke >> balun than your 4-1 balun. I really don't know why hams persist in >> using a 4-1 balun when driving ladder wire feeders - the 450 ohms is >> only the characteristic impedance of the line and that says nothing >> about the feedpoint impedance - the ladder line acts as a transmission >> line transformer. Measure the feedpoint impedance of the 450 ohm line >> with an antenna analyzer (operate it on batteries) where you connect the >> balun. If the impedance is high, then use the 4-1 balun, but if it is >> low a 1-1 choke balun will be a better choice. Which balun is better >> depends on the electrical length of your feedline. >> >> The K2 can behave differently in the presence of RF-in-the-shack than >> your 706, so that is not a fair comparison. Look at what you have >> connected to the K2 and ask what is different - the routing of the >> paddle cable? How is the power supply cable routed? Do you have a >> microphone connected? Have you grounded the microphone jack shell on >> that K2? >> >> If you have a K2 problem, ask again with details of the failure with a >> dummy load. Get it working with a dummy load before adding the extra >> element of the antenna into the problem. All we can say right now is >> that your problem is either with the antenna, power supply, any cable >> attached to the K2 or the K3 itself. Which one is pure guesswork until >> you reduce the number of variables. >> >> 73, >> Don W3FPR >> >> NZ0T wrote: >> >>> Now that I have my K3 at home I moved my K2/100/KAT100 to our lake cabin. >>> Last weekend it started to shut down on 160 only when transmitting over >>> about 70 watts. All other bands are fine, the antenna (160M dipole fed >>> with >>> ladder line thru 4-1 balun and about 6' of coax into the cabin) is fine >>> and >>> the ground seems fine. It was shutting down the MFJ 4125 switching >>> power >>> supply so thinking maybe RF was getting into the supply I took the rig >>> home >>> and it worked just fine there. Brought it back this weekend with an >>> Astron >>> linear supply and while that PS is not shutting down the rig still wants >>> to. >>> I have used this same setup before here with no problems and this started >>> happening suddenly last weekend. I tried the rig without the KAT100 thru >>> a >>> manual tuner and it still wants to shut down. My Icom 706 works fine on >>> 160 >>> with the same configuration. >>> Ideas? >>> >>> 73, >>> >>> Bill NZ0T >>> >>> > 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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I do briefly see a high current message - forgot to mention tha.
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