[Elecraft] K3 Display voltage?
All this talk about TX IMD and monitoring voltage, etc got me to check out my K3. I usually run @ 50w into small amp and I see 13.7V on rcv and 11.5 while xmit. If I run the power up to 100w, I see 13.7 and 10.8; do I have a problem? I am using an unmetered Astron RS-35 into our standard 220v house supply. 73 Tom CX7TT ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3 Display voltage?
Tom CX7TT wrote: All this talk about TX IMD and monitoring voltage, etc got me to check out my K3. I usually run @ 50w into small amp and I see 13.7V on rcv and 11.5 while xmit. If I run the power up to 100w, I see 13.7 and 10.8; do I have a problem? I am using an unmetered Astron RS-35 into our standard 220v house supply. I should say so! I suppose you are using the internal voltmeter in the VFO B position? For me it reads 13.9V off-load (DMM reads 13.94V at the PSU output terminals). At 100W key down on 20m, rig draws about 18.5A, voltage drops to 13.5V. This is using a Diamond GSV3000 PSU and the standard weedy K3 power cable, cropped down to the shortest length possible to get from A to B, no more than a couple of feet. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-Display-voltage--tp2223487p2223633.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3 Display voltage?
I usually run @ 50w into small amp and I see 13.7V on rcv and 11.5 while xmit. If I run the power up to 100w, I see 13.7 and 10.8; do I have a problem? I am using an unmetered Astron RS-35 into our standard 220v house supply. You definitely have a problem, Tom, but it has nothing to do with the power supply you are using. You have excessive resistance somewhere in the DC distribution between the power supply and the K3. Either your cable is using conductors that are too small in diameter, the cable is too long, or you have a loose connection somewhere. First of all, if you have any connections such as a terminal strip or binding post, make sure that they are screwed down tightly. Also check your solder or crimp connections. The K3, like all 100W class rigs, will demand peak currents in the range of 20 amps. Distributing this amount of current without excessive voltage drop takes care. I use an Astron 30A switcher here and have the nice and convenient RigRunner type PowerPole distribution/fusing panels for most of the equipment in the shack. But for the K3 power feed I go directly from the power supply to the K3 with only 3 ft of AWG 10 cable, and only see a couple tenths of a volt change from zero load to 100W CW key down. This is what you should be aiming for if you want maximum performance from the rig. I will take this opportunity to opine further, since this is an important issue for me. Remote sensing is almost always used in industry when delivering this amount of current over distances of two feet or more. It is amazing that the amateur market has not used this simple and effective solution. All it requires is a small twisted pair cable along side the DC cable. I don't even think there are ANY power supplies marketed for amateur use that include remote sensing capability! It would only add a couple dollars to the cost. Thinking in broader terms for the future, we are at or have exceeded the technical capability of a nominal 12V input power system. It is time to think about higher voltages for rigs used in the home environment, perhaps 48V. If there ever is a K4 (never say never, Wayne and Eric ;), please design for 200W with an internal or dedicated eternal Elecraft higher voltage power supply!!! 73 ... Craig AC0DS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3 Display voltage?
Tom, You do have a problem. I recommend that you first check the voltage during transmit at 100 watts at the power supply terminals. If there is more than a few tenths of a volt drop there, you will have a power supply problem - the power supply terminals have connections on the inside as well as the outside and they must be tight and free of corrosion. A few milliohms of resistance at 18 amps will create a significant voltage drop. Next thing to investigate is the power cord and its terminating connections. The APP connectors are quite good as long as the crimp to the wire is tight enough to be what is considered 'gas-tight' If there are any doubts about the quality of the crimp, solder the connectors. Whatever termination you use on the power supply end is suspect too, the same criteria should be applied as for the APP connectors - good crimps or solder if there is any doubt. Be certain the power cord is tight on the power supply output terminal bolts. Lastly, if the power cord is much longer than it has to be, shorten it, every inch of wire has some resistance. If you need to use a long length, consider using #10 wire instead of the #12 supplied by Elecraft. Don;t get me wrong, #12 is entirely adequate if all other conditions are good, but 5 feet of #12 does have 8.1 milliohms resistance, but the return path also adds to the voltage drop, so the entire resistance is 16.2 milliohms which translates to 0.3 volts drop at 18 amps due to the copper. The drop using #10 wire will be about 2/3 of that seen with #12. From all that, you should conclude that the most significant voltage drop from light load to 18 amps load will be in the connections, but about 0.3 volts will be contributed by the wire. 73, Don W3FPR TMorton wrote: All this talk about TX IMD and monitoring voltage, etc got me to check out my K3. I usually run @ 50w into small amp and I see 13.7V on rcv and 11.5 while xmit. If I run the power up to 100w, I see 13.7 and 10.8; do I have a problem? I am using an unmetered Astron RS-35 into our standard 220v house supply. 73 Tom CX7TT ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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 No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.176 / Virus Database: 270.10.14/1918 - Release Date: 1/27/2009 7:26 AM ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3 Display voltage?
Craig D. Smith wrote: Thinking in broader terms for the future, we are at or have exceeded the technical capability of a nominal 12V input power system. It is time to think about higher voltages for rigs used in the home environment, perhaps 48V. If there ever is a K4 (never say never, Wayne and Eric ;), please design for 200W with an internal or dedicated eternal Elecraft higher voltage power supply!!! The K3 was designed with portability in mind, hence the decision to make it a 12V radio. However I guess that many (if not most) of them have never moved from the owner's shack. Since the K3 PA is a separate module that could have separate power connectors on the rear panel, couldn't someone make a higher voltage version as a drop-in replacement? I guess the lack of a commercially available power supply would deter many potential buyers, but I'm sure I recall mention of a matching K3 power supply being offered some time back, so perhaps this could be one of its options. It's be quicker than waiting for a K4. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-Display-voltage--tp2223487p2226064.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] K3 Display voltage
Thanks for the many responses, both private and via the forum. I substituted a metered Astron PS and went directly from the PS to the K3 with Elecraft supplied power cord.. Now the measurements are: 100w 13.9v to 12.9v; 50w 13.9v to 13.3v. this I can live with... My previous setup was the Astron to Rigrunner to K3...approx cable was 4ft from PS to Rigrunner and 4 to 5 ft to K3; PLUS, Rigrunner had LP-100, SixPak and Steppir tuning relay...K3 is supplying power to microKeyer II via 13.6v back panel accessory. Pardon the pun but, voltage drops, it all adds up Que intersante! I learn so much from the erudite members of this reflector (look that up in your Funk n' Wagnalls!) Just another reason why Elecraft is simply the best... 73 Tom ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
