Re: [Elecraft] [K3] K3 Off Grid
My K3, on receive, with the KAT500 in-line, the P3, and my massive 70A Astron p.s. powering the K3, drew about 20A DC. Putting the K3 in transmit mode, with just under 12W drive (so as not to kick in the 100w amp) required about 30A DC. Boosting the output to 50W drew about 70A DC. Running it wide open, at 100W out, required about 80A DC. And finally, turning on the KPA-500, with 15W drive to yield 300W out, required 150A DC. I haven't made any measurements myself, but I do believe there must be some error in your numbers. If RX draws 20A and TX at 100W draws 80A, that means 60A x 12V = 720W input power to create 100W RF output. The other 620W must be dissipated into heat, which, I guess, would melt the K3 over time :) There clearly must be an error somewhere. Also, 20A on RX seems way too high for me. The K3 by itself draws 2A on RX, IIRC. Add an extra 1A for the P3 and the KAT500 maybe, and we're still missing 17A. Was your measurement device faulty, or do you have an error in your maths? 73 de Frank PA4N __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
Hmmm. Thanks for the comments. It may be that the amperage indicator on my new main line surge protector is faulty. I will try again, this time using a Kill-A-Watt power consumption meter on my various power strips and adding up the readings of power drawn. More news as it happens... -Paul, N1HEL _ - Original Message - From: Frank R. Oppedijk fr...@qrd.nl To: elecraft@mailman.qth.net Sent: Wednesday, March 05, 2014 2:06 AM Subject: Re: [Elecraft] [K3] K3 Off Grid __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
Paul, I have been wondering where you got your information. It now sounds like you have been using peak currents that are designed to prove to you that you need the surge protector equipment rather than any kind of metering to predict battery life or any other type of average current or electric meter charges. Such surges are common with power supplies with large capacitance that are turned off then on and the capacitors charge. These have to do only with the internal resistance in the power supply and the resistance of the electrical lines and nothing to do with your battery requirements. Your battery capacity, I would estimate to be the receive current x the required operation time x the average power x 2 x transmit duty. Receive current should be about 0.5 amps for the K2, 1.0 for the K3 with one receiver and 2.0 with two receivers. The average power should be about 0.3 X peak power for CW and a bit less for SB. The duty cycle should be about 0.7 for a contest station calling CQ down to almost nothing for a station mostly listening to a net. The efficiency for a battery would be best predicted by manufacturer's data, but should be high for a reasonable sized battery. A 60 amp-hour battery is fairly small. My station battery is rated at 122 amp hours. A contest station calling CQ for 48 hours with a K3 using two receivers and transmitting at 100 watts should require a battery capable of 48 hours x 2 amps +48 X (100 watts/12v) x 0.7 x 0.3 = 180 amp hours or two fully charged batteries. Of course, you would want a big amplifier, a computer, some lights and a refrigerator for food and drink, so the K3 will be the least of your worry. If you use an ice chest and an LED light and hunt and pounce a single well charged battery should handle a CQ WW unless you want a rotary beam or an amp. You will note that you can cut your battery requirement in half with only one receiver in your K3. This estimate makes a lot of reasonable assumptions, so it would require some empirical data to be very accurate, but it shows that operating on a weekend camping trip is very reasonable because you are unlikely to call CQ all night, particularly if your XYL is along to dictate some of your activity. Willis 'Cookie' Cooke, TDXS DX Chairman K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Paul (N1HEL) n1helra...@gmail.com To: Frank R. Oppedijk fr...@qrd.nl; elecraft@mailman.qth.net Sent: Wednesday, March 5, 2014 8:43 AM Subject: Re: [Elecraft] [K3] K3 Off Grid Hmmm. Thanks for the comments. It may be that the amperage indicator on my new main line surge protector is faulty. I will try again, this time using a Kill-A-Watt power consumption meter on my various power strips and adding up the readings of power drawn. More news as it happens... -Paul, N1HEL _ - Original Message - From: Frank R. Oppedijk fr...@qrd.nl To: elecraft@mailman.qth.net Sent: Wednesday, March 05, 2014 2:06 AM Subject: Re: [Elecraft] [K3] K3 Off Grid __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
OK, here are some new readings, taken with a Kill-A-Watt power consumption meter. The readings in transmit mode were taken by keying down in CW for a few seconds and waiting until the meter reading stabilized. I have an Astron 70A power supply powering a Rigrunner that then supplies a K3, a KAT500, and a PigKnob. The P3 is plugged into the K3. There is a set of speakers, which draw .06A AC as well. K3 in RCV mode .92A AC, or 84W 6 DC at 14v K3 in XMIT, 15W out 2.7A AC, or 240W17A DC K3 in XMIT, 50W out 3.7A AC, or 342W24A DC K3 in XMIT, 100W out4.7A AC, or 438W31A DC How do these look to everyone? I'd like to get them close to right so that I can calculate my battery needs for emergency operation. Something else I don't understand is the ammeter on the front of the Astron. When the K3 is turned on, the Astron's meter jumps up about 1A DC. When the K3 is transmitting at 15W, the Astron's meter reads about 7A DC. At 50W transmitted power, it reads 11A DC. And at 100W out, it reads 15A DC. Quite a difference from the measured and computed DC amps listed above. What is going on here? Simply an innaccurate Astron meter? Thanks, -Paul, N1HEL On Wed, Mar 5, 2014 at 2:06 AM, Frank R. Oppedijk fr...@qrd.nl wrote: My K3, on receive, with the KAT500 in-line, the P3, and my massive 70A Astron p.s. powering the K3, drew about 20A DC. Putting the K3 in transmit mode, with just under 12W drive (so as not to kick in the 100w amp) required about 30A DC. Boosting the output to 50W drew about 70A DC. Running it wide open, at 100W out, required about 80A DC. And finally, turning on the KPA-500, with 15W drive to yield 300W out, required 150A DC. I haven't made any measurements myself, but I do believe there must be some error in your numbers. If RX draws 20A and TX at 100W draws 80A, that means 60A x 12V = 720W input power to create 100W RF output. The other 620W must be dissipated into heat, which, I guess, would melt the K3 over time :) There clearly must be an error somewhere. Also, 20A on RX seems way too high for me. The K3 by itself draws 2A on RX, IIRC. Add an extra 1A for the P3 and the KAT500 maybe, and we're still missing 17A. Was your measurement device faulty, or do you have an error in your maths? 73 de Frank PA4N __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html -- Paul N1HEL Half Moon Bay, CA __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
The current readings on the Killowat are showing AC into the power supply. losses in the Astron there and with additional loads it will be drawing more power than the K3 alone. The other question is the Killowatt reading peak currents or RMS.In a perfect world with a 100 percent efficient power supply connected to a K3 drawing 15A at 13.8V. The power supply will draw 1.7A. At 120 V ac.But even the best power supplies especially analogue are far from 100 percent efficient. So your readings are reasonable onto that, and I am sure someone will correct me if I am wrong, the K3 will draw somewhat more than 15A. Key down at 100W so the am meter on the Astron may be reading a little low. Sent wirelessly from my BlackBerry device on the Bell network. Envoyé sans fil par mon terminal mobile BlackBerry sur le réseau de Bell. -Original Message- From: Paul Grigorieff n1helra...@gmail.com Sender: elecraft-boun...@mailman.qth.net Date: Wed, 5 Mar 2014 12:16:23 To: Frank R. Oppedijkfr...@qrd.nl Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] K3 Off Grid OK, here are some new readings, taken with a Kill-A-Watt power consumption meter. The readings in transmit mode were taken by keying down in CW for a few seconds and waiting until the meter reading stabilized. I have an Astron 70A power supply powering a Rigrunner that then supplies a K3, a KAT500, and a PigKnob. The P3 is plugged into the K3. There is a set of speakers, which draw .06A AC as well. K3 in RCV mode .92A AC, or 84W 6 DC at 14v K3 in XMIT, 15W out 2.7A AC, or 240W17A DC K3 in XMIT, 50W out 3.7A AC, or 342W24A DC K3 in XMIT, 100W out4.7A AC, or 438W31A DC How do these look to everyone? I'd like to get them close to right so that I can calculate my battery needs for emergency operation. Something else I don't understand is the ammeter on the front of the Astron. When the K3 is turned on, the Astron's meter jumps up about 1A DC. When the K3 is transmitting at 15W, the Astron's meter reads about 7A DC. At 50W transmitted power, it reads 11A DC. And at 100W out, it reads 15A DC. Quite a difference from the measured and computed DC amps listed above. What is going on here? Simply an innaccurate Astron meter? Thanks, -Paul, N1HEL On Wed, Mar 5, 2014 at 2:06 AM, Frank R. Oppedijk fr...@qrd.nl wrote: My K3, on receive, with the KAT500 in-line, the P3, and my massive 70A Astron p.s. powering the K3, drew about 20A DC. Putting the K3 in transmit mode, with just under 12W drive (so as not to kick in the 100w amp) required about 30A DC. Boosting the output to 50W drew about 70A DC. Running it wide open, at 100W out, required about 80A DC. And finally, turning on the KPA-500, with 15W drive to yield 300W out, required 150A DC. I haven't made any measurements myself, but I do believe there must be some error in your numbers. If RX draws 20A and TX at 100W draws 80A, that means 60A x 12V = 720W input power to create 100W RF output. The other 620W must be dissipated into heat, which, I guess, would melt the K3 over time :) There clearly must be an error somewhere. Also, 20A on RX seems way too high for me. The K3 by itself draws 2A on RX, IIRC. Add an extra 1A for the P3 and the KAT500 maybe, and we're still missing 17A. Was your measurement device faulty, or do you have an error in your maths? 73 de Frank PA4N __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html -- Paul N1HEL Half Moon Bay, CA __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
I think measurements using this protocol will include the losses in the Mains Voltage to 12 Volt power supply. If you are running off batteries, then you have 12 volts already and don't suffer any conversion losses. Cheers - Bill, AE6JV On 3/5/14 at 6:43 AM, n1helra...@gmail.com (Paul (N1HEL)) wrote: Hmmm. Thanks for the comments. It may be that the amperage indicator on my new main line surge protector is faulty. I will try again, this time using a Kill-A-Watt power consumption meter on my various power strips and adding up the readings of power drawn. More news as it happens... --- Bill Frantz|Security, like correctness, is| Periwinkle (408)356-8506 |not an add-on feature. - Attr-| 16345 Englewood Ave www.pwpconsult.com |ibuted to Andrew Tanenbaum| Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
There are so many things to consider when you try to calculate battery requirements for emergency operation, is it really possible to accurately predict how long a given battery will last? Here are a few of the variables I'm aware of - - battery type amp/hour rating - starting charge state of battery - age condition of battery - environmental conditions - temperature - loads other than K3 on battery, and whether constant or intermittant - mode(s) of transmission, i.e., PSK, CW, SSB - transmit power used for each mode - percentage of time for each mode vs. receive time - total operating time desired For me, a subjective approach makes the most sense. I would make some rough calculations but really pay attention to suggestions of those who have real world experience. One or two of deep cycle golf cart batteries would probably be all I ever would need. Then remember to keep them charged! Oh, and don't assume you need 100W to make contacts! :) Steve AA6VO __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
Paul, It looks like you are ignoring the fact that your power supply is less than 100% efficient. Power into the supply does not equal power out of it. The readings from your Astron current meter are more realistic for the DC Current requirement. 73, Don W3FPR On 3/5/2014 3:16 PM, Paul Grigorieff wrote: OK, here are some new readings, taken with a Kill-A-Watt power consumption meter. The readings in transmit mode were taken by keying down in CW for a few seconds and waiting until the meter reading stabilized. I have an Astron 70A power supply powering a Rigrunner that then supplies a K3, a KAT500, and a PigKnob. The P3 is plugged into the K3. There is a set of speakers, which draw .06A AC as well. K3 in RCV mode .92A AC, or 84W 6 DC at 14v K3 in XMIT, 15W out 2.7A AC, or 240W17A DC K3 in XMIT, 50W out 3.7A AC, or 342W24A DC K3 in XMIT, 100W out4.7A AC, or 438W31A DC How do these look to everyone? I'd like to get them close to right so that I can calculate my battery needs for emergency operation. Something else I don't understand is the ammeter on the front of the Astron. When the K3 is turned on, the Astron's meter jumps up about 1A DC. When the K3 is transmitting at 15W, the Astron's meter reads about 7A DC. At 50W transmitted power, it reads 11A DC. And at 100W out, it reads 15A DC. Quite a difference from the measured and computed DC amps listed above. What is going on here? Simply an innaccurate Astron meter? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Off Grid
Here is how I'd do it, your mileage may vary. I'd measure the power draw at 100 watts key-down, and the power draw for receive. I'd assume 50% duty cycle. You can skip a lot of math by either ignoring the receive power draw (if it's low enough) and dividing by two, or adding them together and dividing by two (averaging them together). Multiply that number by the number of hours you need to be able to operate -- and that's your target capacity in amp-hours. That should over estimate the battery, so if that size wasn't economical, I'd buy one slightly smaller. That should insure that the battery does the job for years, even when it's starting to fail. It should also make sure you can keep operating if the emergency was longer than initially planned. Yes, there are a lot of factors, like operating mode that this appears to ignore. I'm simply assuming things like full power or nothing when the operator might be running SSB or PSK-31 at 20 watts. I'm also ignoring portability, which I would not do if I was operating for fun. 73 -- Lynn On 3/5/2014 1:15 PM, Steve Baum wrote: There are so many things to consider when you try to calculate battery requirements for emergency operation, is it really possible to accurately predict how long a given battery will last? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
