Re: [Elecraft] K2 Won't power on

Q7, Q8, Q11 and Q13 are all now replaced, and everything seems to be working normally again. Thanks everyone for all the help. 73, Jeremy VA3ZTF JeremyJones wrote Yes that was an Alkaline battery. That makes me feel better about installing the new finals once they arrive. In the mean time

Re: [Elecraft] K2 Won't power on

Hi Don, I always use Nabble to reply to postings. Do you not see the response to Jeremy below and then the rest is snipped off? AB2TC - Knut Don Wilhelm-4 wrote Jeremy, Remove the tuner and you will not be bothered with the LowP messages. In fact when testing the base K2, you should

Re: [Elecraft] K2 Won't power on

Knut, Yes, that made it through OK. I usually see posts through Nabble that contain no reference information, and sometimes the subject line is not relevant. I was blaming the way Nabble works, but I guess that is not the issue. Apparently the poster has a choice of leaving a bit of

Re: [Elecraft] K2 Won't power on

I don't know how much over 0.64 volts is bad, but I am getting 0.656. I didn't realize that a web reply was cutting off what I was replying to. I always hit the reply button and assumed it included the original text. Jeremy Don Wilhelm-4 wrote Jeremy, A power reading of 0.1, 0.2 or 0.3

Re: [Elecraft] K2 Won't power on

Jeremy, Make a quick check on your voltmeter - measure a new Alkaline battery, you should see quite close to 1.50 volts. Are you making the measurement by using TUNE? If not, you should be. Is this an older K2 with a trimpot at R60? If so, it should be turned fully counterclockwise. Check

Re: [Elecraft] K2 Won't power on

A new AA battery right from the package is giving me 1.615V on the fluke meter. This is a newer K2 (#7405). I had some issues when building it which caused me to go through a couple of sets of PA finals before I had to send it to you to get sorted out. It was working great until now, so

Re: [Elecraft] K2 Won't power on

Jeremy, That voltage is close to what I would expect from a new Lithium battery. If you are measuring an Alkaline battery, then your voltmeter is a bit on the high side. So if Alkaline battery, then your 0.65 measurement is likely OK, but if that battery is a Lithium type, the bias is a bit

Re: [Elecraft] K2 Won't power on

Yes that was an Alkaline battery. That makes me feel better about installing the new finals once they arrive. In the mean time I have a KAT100 and KPA100 to build. Jeremy Don Wilhelm-4 wrote Jeremy, That voltage is close to what I would expect from a new Lithium battery. If you are

Re: [Elecraft] K2 Won't power on

With the tuner disconnected, I'm still getting 600mV at the base of Q8 while doing a tune. The display on the radio shows power of 0.3. -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-Won-t-power-on-tp7584083p7584365.html Sent from the Elecraft mailing list archive at

Re: [Elecraft] K2 Won't power on

Jeremy, A power reading of 0.1, 0.2 or 0.3 is only residual noise on the power detection circuits. Since you do not have Q7 and Q8 installed, your real power output is zero. Yes, go ahead and change Q11 and Q13. That is not certain to change anything, but it will do no harm. A slightly

Re: [Elecraft] K2 Won't power on

I'm still getting 600mV and LowP during the tune, so it looks like I'll be replacing Q11 and Q13 as well. -- View this message in context: http://elecraft.365791.n2.nabble.com/K2-Won-t-power-on-tp7584083p7584328.html Sent from the Elecraft mailing list archive at Nabble.com.

Re: [Elecraft] K2 Won't power on

Jeremy, Remove the tuner and you will not be bothered with the LowP messages. In fact when testing the base K2, you should remove the tuner and operate the basic K2 into a dummy load. Where are you measuring 600mV? That is one problem with replying using Nabble, it strips off what you are

Re: [Elecraft] K2 Won't power on

There is no indication on the cheap meter for an out of scale reading. I've borrowed a Fluke meter from work, and after watching the capacitors charge up, the resistance reading is 2.7k ohm. This is will all of the resistors still connected as above. I'll reconnect them one by one and check the

Re: [Elecraft] K2 Won't power on

So after reassembling everything minus Q7/8, resistance from ground to collector pad for Q7/8 starts at 600k ohm then gradually drops down to 54k ohm before reseting and spiking back up to 600k and dropping again. I believe this would be a capacitor charging up and then biasing a transistor?

Re: [Elecraft] K2 Won't power on

Jeremy, From those resistance readings, I would say you are OK. If you have all except Q7 and Q8 installed, do a TUNE and re-check the voltage on the base solder pads of Q7 or Q8. If you do not see a voltage between 6.2 and 6.4 volts, replace Q11 and Q13 and retest before you install Q7 and

Re: [Elecraft] K2 Won't power on

Yes it is a digital multimeter, but I only paid about $10 for it. What resistance should I be seeing. I have noticed some drastic variations as I change the scale on my meter. The 200 ohm scale gives a reading of 91 ohms 2000 ohms scale reads 1500 20K scale reads 3.7 200k scale reads 10.7 What

Re: [Elecraft] K2 Won't power on

Jeremy, I would tend to believe the reading on the 2000 ohm scale. Look at the display in the 200 ohm scale and see if it shows a + to the left - If so, that indicates overrange and you should switch to a higher range. I would also believe that the 20k and 200k scales are showing you

Re: [Elecraft] K2 Won't power on

With Q7/Q8 removed, the resistance from the Collector solder pad to ground on both is 70 ohms. Doing a Tune with Q7/Q8 removed results in 1.0V on the Base pads and a Low P on the display. I do have the KAT2 installed, just in case this makes a difference. This was done into a dummy load. The

Re: [Elecraft] K2 Won't power on

Jeremy, 70 ohms is too low on the +12 volt power line, you should see a large capacitor charging and the resistance should climb if all is normal. 1 volt on the base during a TUNE is too high, so plan to replace Q11 and Q13 - they are included in the K2PAKIT. Yes, static can be induced by

Re: [Elecraft] K2 Won't power on

Lifting one end of R45 still showed 70 ohms. Lifting one end of RFC4 increased to 87 ohms. I left the leg of R45 disconnected when taking this measurement, and I want to confirm whether I should leave the components disconnected as I go through, or reconnect them before moving on to the next.

Re: [Elecraft] K2 Won't power on

Jeremy, Leave them disconnected until you find the culprit. Take notes of waht you have done if necessary so you can restore things after you have found the problem. 73, Don W3FPR On 2/12/2014 8:46 PM, JeremyJones wrote: Lifting one end of R45 still showed 70 ohms. Lifting one end of RFC4

Re: [Elecraft] K2 Won't power on

I have lifted R45, RFC4, R74, R82 and R97, with only a slight increase from 70 ohms to 87 ohms after lifting RFC4. I'll continue troubleshooting tomorrow by removing any capacitors connected to 12V. I also want to confirm that I should be doing these resistance checks with no power applied.

Re: [Elecraft] K2 Won't power on

Jeremy, Yes, you should be doing the resistance checks with no power applied. Inexpensive ohmmeter? Well, if it is a digital multimeter in resistance mode, you should be OK, but i it is an analog VOM or VTVM, it may not be showing you the real picture because the voltage may be sufficient to

[Elecraft] K2 Won't power on

So my K2, which has been running great for almost a year, no longer powers on. I had left it powered on and connected via the serial cable to a computer so that I could do PSK-31 contacts remotely while I was away from home. Unfortunately I never got the chance, and upon my return home, my K2

Re: [Elecraft] K2 Won't power on

Date: Tue, 11 Feb 2014 16:44:25 -0800 From: jjones9...@gmail.com To: elecraft@mailman.qth.net Subject: [Elecraft] K2 Won't power on So my K2, which has been running great for almost a year, no longer powers on. I had left it powered on and connected via the serial cable to a computer so

Re: [Elecraft] K2 Won't power on

Jeremy, I can't recall a loud buzz condition, but I would suspect the PA transistors in the base K2. First, check the resistance from the collectors of Q7 and Q8 to ground. If it is quite low, the PA transistors are toast - get the K2PAKIT and install Q7, Q8 as well as Q11 and Q13. If the

Re: [Elecraft] K2 Won't power on

Q7 and Q8 both read 12.3 ohms from collector to ground. The symptoms definitely resemble blown finals, as I experienced the same thing when I was building the kit, including the over current tripping the resettable fuse. I just didn't expect that from a receive only condition. Jeremy VA3ZTF

Re: [Elecraft] K2 Won't power on

To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 Won't power on Q7 and Q8 both read 12.3 ohms from collector to ground. The symptoms definitely resemble blown finals, as I experienced the same thing when I was building the kit, including the over current tripping the resettable

Re: [Elecraft] K2 Won't power on

Jeremy, OK, Q7 and Q8 are 'toast', you might as well remove them. With Q7 and Q8 removed, do a TUNE and measure the DC voltage at the solder pads for the base of Q7 and Q8. The expected voltage is 0.60 to 0.64 volts. If it is out of that range, replace Q11 and Q13 too. Those transistors

Re: [Elecraft] K2 Won't power on

Jeremy, One afterthought -- although Q7 and Q8 are the top suspects for your problem, after removing them, check the resistance from the Q7/Q8 collector solder pads to ground. If it is still low, the problem is something other than Q7 and Q8. 73, Don W3FPR