RE: [Elecraft] KPA3 for QRP
But I think we missed the point of the original post. I believe the question was not how much dead weight is the KPA3 when I run QRP. That has been answered. The question was wouldn't the rig be a better QRP rig if the KPA3 was used even at QRP levels?. With the K2, current drain was an issue and shutting down the after burner for QRP made sense. With the less portable K3, current drain is largely a non-issue so shutting down the big finals below 10 watts isn't an obvious good thing in my book. Of course, if I were smart enough I could just answer the question. As it is, I'm barely able to simple rephrase it :-) - Keith N1AS - - K2 5411.ssb.100 - - K3 Wave 3 - -Original Message- People talk about the extra current drain. How much is it? If you go by what W0CZ measured you get this: *snip* ___ 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: Subject:,Re: [Elecraft] KPA3 for QRP
Hi Kenneth A couple of people have measured their K3s without the KPA3 and again with it. The difference seems to be as follows. In receive, no difference with or without as far as current drain goes. When transmitting at QRP levels with the KPA3 in bypass mode, the TX current drain is approx 600 mA more than if the KPA3 were not installed. So, for a base station with an ac power supply, no big deal. However, for a Field Day rig, if you plan to run a QRP entry, those extra 600 mA will all have to come from your battery. That either reduces the time you can operate from that battery, or cause you to change batteries sooner than you would have to otherwise. That seems to be the essential difference, Kenneth. I had hoped to use my K3 (still to come) on FD, but I think I'll stick with my K2 at 5W. Much easier on my battery and solar panels. 73, Bob N6WG - Original Message - From: Kenneth A. Christiansen [EMAIL PROTECTED] To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; elecraft@mailman.qth.net Sent: Tuesday, March 18, 2008 5:25 AM Subject: Subject:,Re: [Elecraft] KPA3 for QRP Subject: Re: [Elecraft] KPA3 for QRP From: WILLIS COOKE [EMAIL PROTECTED] Date: Mon, 17 Mar 2008 08:44:15 -0700 (PDT) To: Robert Tellefsen [EMAIL PROTECTED], G4ILO [EMAIL PROTECTED], elecraft@mailman.qth.net CC: People talk about the extra current drain. How much is it? I don't have my K3 yet to make any tests and I seldom run QRP (only when the other station wants 2 way QRP), but it would be of interest to us all if anyone had measured the current draw of the K3 at receive with and without the KPA3, transmit at 5 watts without the KPA3 installed and transmit at 5 watts with the KPA3 installed. I am sure that Elecraft has the information, but I don' recall seeing it published. My guess is that the KPA3 does not require much if any current when it is switched out. Anybody do any tests to know for sure? + I measured my currents at the 12 watt part of my build and again when the K3 was finished. on 14.05 MHZ I measured TX 2.73 amps as a 12 watt K3 On 14.05 MHZ I measured TX 2.93 amps as a 120 watt K3 The receive current is 0.9 Amps either way. The receive current can jump as high as 1.1 amps if the fans are running. The extra 0.2 amps is only taken in transmit mode. If the XMIT button is hit it takes the extra 0.2 once the 120 watt amp is installed. If full break in is used than the extra 0.2 amps is only used when the key is down. If you did a field day using S and P and full break in the extra current would be about an extra half amp hour. If you were calling CQ at 50 percent transmit and full break in it would be about an extra two amp hours. If you hit XMIT each time it would add about an extra 0.5 amp hourto the two amp hours. The K3-100 in receive for a 24 hours field day will use about 24 amp hours plus 5 to 24 extra amp hours in transmit depending on duty cycle. That makes a total of 29 to 47 amp hours for a full 24 hour field day. A K2 can do the same field day in about 12 to 26 amp hours. I find the K3 to have so much better receiver and I operate S and P so it will plan to spend the extra 17 to 18 amp hours for my field day. 73 Ken W0CZ ___ 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] KPA3 for QRP
I run QRP out of practical necessity. I'm forced to use attic antennas and I don't wish to induce more RF into the domestic electrical equipment (or me, for that matter) than I absolutely have to. Nevertheless, I'm thinking about getting a KPA3, because it probably will never be cheaper than it is now, and the occasion might arise in future when I might be able to use it. I'm just wondering if there are any advantages to using the PA when running QRP. As I understand it, the PA is switched out of circuit until you dial the power above 10W, just as in the K2. There is no option for class A operation at a lower power level to produce a cleaner signal. If I run 10W of FM, the QRP PA will do all the work, and warm up very quickly, instead of letting the KPA3 do most of the work and barely getting warm. If I run 5W of PSK31, the IMD generated by the low power PA running at half its rated power will be higher than the KPA3 loafing along at the same power level. Unless I'm missing something, there would be no benefit to me at the moment from having the KPA3 unless I want to wind the power control above 10W. Am I right? - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf -- View this message in context: http://www.nabble.com/KPA3-for-QRP-tp16091280p16091280.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] KPA3 for QRP
From my understanding of it the radio has the KPA3 switched out of the loop until you cross the 12W mark. Then it starts actually putting it into the signal path. Until you crank the power up beyond 12Watts the KPA3 is nothing more than an added current drain. But if you turn things up to 12 or 13 watts you're probably still quite fine with those levels for RFIing yourself and the rest of the house / neighborhood and your KPA3 will have TONS of headroom for you in that configuration. Yet as far as the low power amp its still probably still rated at the same 100% duty cycle at full power for 10 minutes. I say probably because the only technical spec listed is that it will handle 100 watts for 10 minutes easily on the web site and in the manual. I'd imagine that similar margins are used on both PA's being that both are designed to have a 20% overhead which is more than you get from Yaecomwood out of the gate! One big advantage is that getting the KPA3 now is a smart investment as it is probably only going to go up in price and you have a great advantage with the current exchange rate as it is. Not to mention that if you were ever to want to sell your K3 the fact that a KPA3 is already installed makes it much more attractive to many more people. My motto has always been its better to have than to want. ;) On Mon, 2008-03-17 at 02:55 -0700, G4ILO wrote: I run QRP out of practical necessity. I'm forced to use attic antennas and I don't wish to induce more RF into the domestic electrical equipment (or me, for that matter) than I absolutely have to. Nevertheless, I'm thinking about getting a KPA3, because it probably will never be cheaper than it is now, and the occasion might arise in future when I might be able to use it. I'm just wondering if there are any advantages to using the PA when running QRP. As I understand it, the PA is switched out of circuit until you dial the power above 10W, just as in the K2. There is no option for class A operation at a lower power level to produce a cleaner signal. If I run 10W of FM, the QRP PA will do all the work, and warm up very quickly, instead of letting the KPA3 do most of the work and barely getting warm. If I run 5W of PSK31, the IMD generated by the low power PA running at half its rated power will be higher than the KPA3 loafing along at the same power level. Unless I'm missing something, there would be no benefit to me at the moment from having the KPA3 unless I want to wind the power control above 10W. Am I right? - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf ___ 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] KPA3 for QRP
G4ILO wrote: I'm just wondering if there are any advantages to using the PA when running QRP. As I understand it, the PA is switched out of circuit until you dial the power above 10W, just as in the K2. The switch point in the KPA3 is actually 13W. For 12 and less it'is switched out. Unless I'm missing something, there would be no benefit to me at the moment from having the KPA3 unless I want to wind the power control above 10W. Am I right? Nothing I'm aware of. -- View this message in context: http://www.nabble.com/KPA3-for-QRP-tp16091280p16091715.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] KPA3 for QRP
Hi Julian There is one drawback, however. Increased current drain, even though the KPA3 is not in use at QRP levels. If this isn't a problem for you, then go right ahead. However, if you want to take your K3 out to the field for a Field Day operation, that extra drain can create battery problems. Good luck and 73 Bob N6WG - Original Message - From: G4ILO [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Monday, March 17, 2008 1:55 AM Subject: [Elecraft] KPA3 for QRP I run QRP out of practical necessity. I'm forced to use attic antennas and I don't wish to induce more RF into the domestic electrical equipment (or me, for that matter) than I absolutely have to. Nevertheless, I'm thinking about getting a KPA3, because it probably will never be cheaper than it is now, and the occasion might arise in future when I might be able to use it. I'm just wondering if there are any advantages to using the PA when running QRP. As I understand it, the PA is switched out of circuit until you dial the power above 10W, just as in the K2. There is no option for class A operation at a lower power level to produce a cleaner signal. If I run 10W of FM, the QRP PA will do all the work, and warm up very quickly, instead of letting the KPA3 do most of the work and barely getting warm. If I run 5W of PSK31, the IMD generated by the low power PA running at half its rated power will be higher than the KPA3 loafing along at the same power level. Unless I'm missing something, there would be no benefit to me at the moment from having the KPA3 unless I want to wind the power control above 10W. Am I right? - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf -- View this message in context: http://www.nabble.com/KPA3-for-QRP-tp16091280p16091280.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 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] KPA3 for QRP
People talk about the extra current drain. How much is it? I don't have my K3 yet to make any tests and I seldom run QRP (only when the other station wants 2 way QRP), but it would be of interest to us all if anyone had measured the current draw of the K3 at receive with and without the KPA3, transmit at 5 watts without the KPA3 installed and transmit at 5 watts with the KPA3 installed. I am sure that Elecraft has the information, but I don' recall seeing it published. My guess is that the KPA3 does not require much if any current when it is switched out. Anybody do any tests to know for sure? --- Robert Tellefsen [EMAIL PROTECTED] wrote: Hi Julian There is one drawback, however. Increased current drain, even though the KPA3 is not in use at QRP levels. If this isn't a problem for you, then go right ahead. However, if you want to take your K3 out to the field for a Field Day operation, that extra drain can create battery problems. Good luck and 73 Bob N6WG - Original Message - From: G4ILO [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Monday, March 17, 2008 1:55 AM Subject: [Elecraft] KPA3 for QRP I run QRP out of practical necessity. I'm forced to use attic antennas and I don't wish to induce more RF into the domestic electrical equipment (or me, for that matter) than I absolutely have to. Nevertheless, I'm thinking about getting a KPA3, because it probably will never be cheaper than it is now, and the occasion might arise in future when I might be able to use it. I'm just wondering if there are any advantages to using the PA when running QRP. As I understand it, the PA is switched out of circuit until you dial the power above 10W, just as in the K2. There is no option for class A operation at a lower power level to produce a cleaner signal. If I run 10W of FM, the QRP PA will do all the work, and warm up very quickly, instead of letting the KPA3 do most of the work and barely getting warm. If I run 5W of PSK31, the IMD generated by the low power PA running at half its rated power will be higher than the KPA3 loafing along at the same power level. Unless I'm missing something, there would be no benefit to me at the moment from having the KPA3 unless I want to wind the power control above 10W. Am I right? - Julian, G4ILO K3 s/n: 222 K2 s/n: 392 G4ILO's Shack: www.g4ilo.com Zerobeat Ham Forums: www.zerobeat.net/smf -- View this message in context: http://www.nabble.com/KPA3-for-QRP-tp16091280p16091280.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 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 Willis 'Cookie' Cooke K5EWJ ___ 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] KPA3 for QRP
Yes Julian - you are right. There is no advantage in having a KPA3 for QRP working. In fact, there is a bit of a disadvantage as it takes up space in the case which you might be able to use for something else, like a battery or a VHF transverter. Regarding the price, at $450 + VAT it is not particularly cheap compared to any other broadband 100W HF amplifier you might buy. Couple it with the KAT3 at $300 you are into the $750 territory and I am sure there are cheaper and more flexible alternatives. A good example being the K2 100W PA and ATU in an external case. If you really want a very clean signal, an external amplifier fed with a few watts and in class A would be a better bet. You could then use a device like an MRF151G with a 45V supply and if you wish to home brew check out the CCI website for amplifier kits. A 200W amplifier running off 28V or 48V will be very clean at 50W or so in class A. Mike -- View this message in context: http://www.nabble.com/KPA3-for-QRP-tp16091280p16094199.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] KPA3 for QRP
People talk about the extra current drain. How much is it? If you go by what W0CZ measured you get this: The current tests before I put in the KPA3. Receive 0.94 to 1.1 A TX (NO POWER) 1.56 A TX 5W 2.56 A TX 10W 3.07 A TX 12W 3.23 A The same test after the KPA3 was installed, Set up and working fine. Receive 0.94 to 1.1 A TX (NO POWER 2.16 A TX 5W 3.10 A TX 10W 3.62 A TX 12W 3.78 A ___ 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] KPA3 for QRP
post from the past ref K3 current draw. Fri, 22 Feb 2008 21:53:25 -0600 From: Kenneth A. Christiansen [EMAIL PROTECTED] Add Mobile Alert To: elecraft@mailman.qth.net Subject:[Elecraft] K3 NR 457 now working in Fargo ND I got a pleasant surprise yesterday when K3 457 arrived. It was ordered June 13 and I got my Lisa Gram last week end. It has KAT3, KBPF3, KXV3, 500 hz filter, 2700 hz filter, 6000 hz filter and the FM filter on back order. I made a special test on it because I wanted to know how the KPA3 changes the current draw. I know others have asked the same question here and never did get an answer so here it is. . The current tests before I put in the KPA3. Receive 0.94 to 1.1 A TX (NO POWER) 1.56 A TX 5W 2.56 A TX 10W 3.07 A TX 12W 3.23 A The same test after the KPA3 was installed, Set up and working fine. Receive 0.94 to 1.1 A TX (NO POWER 2.16 A TX 5W 3.10 A TX 10W 3.62 A TX 12W 3.78 A All the above testes were done with a digital meter on the 10 amp scale. I would say the KPA3 adds a constant 0.6 Amp for any given power level below 12.1 Watts. I started the inventory last night about 6:00 PM and finished it tonight about 8 PM. I had a fire run, slept, went to a meeting etc. so my build time must have been about the magic 10 hours. I sure do like the receiver but have just scratched the surface of what it can do. It was worth the wait. 73 Ken W0CZ - Hope this helps. 73, Ty, W1TF, K1 #1423 waiting for a K3 __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.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
