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
