Re: [Elecraft] K2: KPA100 Removal

2011-04-10 Thread Don Wilhelm
John If the board has not been removed a few times, it often sticks on the screw threads - I suspect that is the problem. I usually use a flat-blade screwdriver between the heatsink and the board to carefully nudge it up. Watch where the screwdriver is going (peer between the board and the

Re: [Elecraft] K2: KPA100 Removal

2011-04-10 Thread Jon Perelstein
Don, I'm trying to replace D16 and D17 in the KPA100 but I'm having trouble removing the heat sink so that I can get at them (it looks to me as if I have to remove the heat sink to get at the bottom of the PC board to unsolder them). I have removed the three black pan head screws that attach the

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Richard Ferch
A couple of other points to consider: 1. I find that my K3's finals get hotter in PSK31 at 50% power than they do in RTTY at 100% power, but that's very likely due to the fact that my RTTY QSOs are in contests, with very short transmissions, whereas my ragchew-style transmissions in PSK31 last

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Don Wilhelm
Jon, Your 1/3 rule is right for continuous duty data modes like RTTY, but I understand (and have not tried to figure out the details for myself) that plain PSK31 does not come up to a full duty cycle - something about the coding, so you might go up to 1/2 the normal rated power - 6 or 7 watts

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread jon . perelstein
Duh! Sorry, I wasn't thinking when I asked that. The KAT100 is out of the circuit completely. All my testing has been with the MFJ-941E. I just removed the KPA100 and tested. My power levels are as commanded (usually a little better, but not double) AND my PSK31 signal looks like a PSK3

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Don Wilhelm
Of course it is Jon, one diode rectifies the forward power and the other the reverse power. BUT - I hope you do not have the KAT100 in line between the KPA100 and the external wattmeter when you make that evaluation - if it is, you should first put it in CAL mode using the K2 menu. 73, Don W

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Jon Perelstein
OK, thanks Don. I'll order the diodes (local Radio Shack doesn't carry them anymore). In the meantime, I think I will remove the KPA100 anyway to see what impact that has on the RFI problem. Do you think that this is also impacting the SWR reading that I'm getting in tune? Both the MFJ and the

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Don Wilhelm
John, I believe after you replace diodes D16 and D17 in the KPA100 (both are 1N5711), you will find the problems go away. What appears to be happening is that they are not fully open nor shorted, but are at some state in between, so you do get some control, but it is just not right. Replace

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Jon Perelstein
Don, Thanks as always for your reply. But you don't seriously believe that my problems with electronic equipment could be THAT simple, do you?? After all, I'm the guy whose dog ate one of the ICs while I was building the K2 (no joke). I ran 5 watts and 2.5 watts, and ran each test five times (f

Re: [Elecraft] K2: KPA100 Removal

2011-03-27 Thread Don Wilhelm
Jon, You have the KPA100 removal steps correct, but I suggest that you do not do that yet. Instead do a quick test - remove the APP connector from the KPA100 and power the K2 from the coaxial power jack. Then set the power at 5 watts and measure the power output with your external wattmeter

[Elecraft] K2: KPA100 Removal

2011-03-27 Thread Jon Perelstein
I would like to put my K2/100 back to a basic K2 as part of debugging some problems I've had around power and RFI distortion. I have the K2, KPA100, KSB2, and KNB2 installed. My plan is to only remove the KPA100 at first to see if that corrects the problems I've been having. As I understand it,