Re: [Elecraft] K2 - Low output during initial TX alignment
On 9/4/07, Mychael Morohovich [EMAIL PROTECTED] wrote: I would like to offer that I do include a note with my K2 sets instructing the builder not to pull the leads too tightly while installing K2-T2. Hi Mychael. I didn't mean to sound insulting or belittle your service in anyway. However, looking back at the email and thinking about how quickly I wrote it, I can see how it can be construed as such. So please accept my apologies. The incorrect installation of T2 was definitely my fault by pulling the leads too tight. However, had I taken to time to wind and tin the toroids myself, I may have been a bit more patient with their actual installation as well. Who knows though, maybe not. Thanks again. -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
Hi, John- Thank you for your post, as well as for the use of my service. In rereading what I had written, I believe that my post might have come with a terseness that I had not intended, so my apologies as well. K2-T2 is a little tricky to get right, as is communicating with the written word it would seem- hi! 73, Mychael AA3WF K2 #1025 ___ 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] K2 - Low output during initial TX alignment
During the initial TX alignment of my K2, I can't seem to get the output power above 0.2W - it fluctuates between 0.1 and 0.2 and doesn't change as I adjust L1 and L2. I am, however, able to tune L1 and L2 for RX just fine. I am showing 350 mV at my dummy load so some RF seems to be getting through. I don't see any obvious soldering problems and T1 through T4 appear to be wound correctly. I have not done any signal tracing yet but initial voltage check of the driver and finals appear fine. However, I am concerned about the voltage of the drivers collector. It jumps up to 14V at transmit but it's supposed to be 13.3V. I have to go out and buy a new DMM so I can do signal tracing (my cheap DMM has fixed probes and I can't adapt them properly). Any other ideas before I dive into signal tracing? Thanks -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
On 9/4/07, John Graf [EMAIL PROTECTED] wrote: One thing you might try is a relay reset. Thanks John, this was one of the first things I tried. No luck. I've done most of the checks in the 155 section of the troubleshooting guide. I'm at a loss as everything appears to be fine. Back to it.. -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
JT, The quickest and IMHO the easiest way to find the problem is to build up the RF Probe (the parts were included with your K2 kit). Then turn the manual to Preparing for Transmit Signal Tracing in the troubleshooting appendix. Follow the steps until you find a place where you have significantly lower RF voltage than expected - then *stop* because you have located the failing stage. Once you have found the failing stage, find it on the schematic and look to see which components are used in that stage - check them all for proper values and good soldering. If that effort did not solve the problem, we can be of further help. Right now, the list of things that could possibly be wrong is very long and we could only offer wild guesses. Once narrowed to the failing stage, the isolation of the failing part becomes much easier. 73, Don W3FPR JT Croteau wrote: On 9/4/07, John Graf [EMAIL PROTECTED] wrote: One thing you might try is a relay reset. Thanks John, this was one of the first things I tried. No luck. I've done most of the checks in the 155 section of the troubleshooting guide. I'm at a loss as everything appears to be fine. Back to it.. ___ 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] K2 - Low output during initial TX alignment
On 9/4/07, Don Wilhelm [EMAIL PROTECTED] wrote: The quickest and IMHO the easiest way to find the problem is to build up the RF Probe (the parts were included with your K2 kit). Yeah, I need to go buy a new DMM as I have no way to connect the RF probe to my current DMM. However, I just checked the ALC circuit and found that VPWR is reading high. It is reading 4.9V on pin 2 of U8 (control board) during key down. According to the manual, this indicates a potential problem in the RF detector stage. I'm going to poke around the detector a bit more and see if I can find any problems there. -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
Don and others, I just returned from buying a new DMM at RS and I didn't get very far in signal tracing the transmitter before I started getting some strange readings. In my previous email, I mentioned that VPWR was reading high at 4.9V. This can sometimes point to a problem in the RF output detector so I checked all the components here and didn't find anything wrong so, following the instructions, continued on with the signal tracing. Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch section - I am finding some odd voltages here. Voltages that do not match the expected results listed. These are all key-down voltages. Xmit Mixer Output: 0.181 (Expected: 0.016) Buffer Output: 2.05 (Expected: 0.200) Band-Pass Filter Output: 0.444 (Expected: 0.030) T-R Switch #1 Output: 0.439 (Expected: 0.029) I am doing the signal tracing using 40M. Do I need to worry about these? Thanks -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
JT, If you have little or no RF output, do not be concerned about the early stages having more RF voltage than is expected when the power is normal (and that is your case). Continue onward. If the K2 senses no power output, VPWR will ramp up to a high level trying to obtain more power output, and the RF voltage produced by the *working* stages will be higher than normal until the proper amount of RF is detected at the output. An added note - measure the RF voltage across your dummy load. If there is lots of RF voltage there, then the transmitter is working and the problem is with the detector (D9 and associated components) rather than the transmitter stages, but if there really is no power output (or very little) then look to the transmitter stages for the problem. - Do heed the *if*s in the proceeding statement, they are very important. Make the measurements in order and methodically as instructed in the manual and the steps will lead you to the failing stage. 73, Don W3FPR JT Croteau wrote: Don and others, I just returned from buying a new DMM at RS and I didn't get very far in signal tracing the transmitter before I started getting some strange readings. In my previous email, I mentioned that VPWR was reading high at 4.9V. This can sometimes point to a problem in the RF output detector so I checked all the components here and didn't find anything wrong so, following the instructions, continued on with the signal tracing. Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch section - I am finding some odd voltages here. Voltages that do not match the expected results listed. These are all key-down voltages. Xmit Mixer Output: 0.181 (Expected: 0.016) Buffer Output: 2.05 (Expected: 0.200) Band-Pass Filter Output: 0.444 (Expected: 0.030) T-R Switch #1 Output: 0.439 (Expected: 0.029) I am doing the signal tracing using 40M. Do I need to worry about these? Thanks ___ 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] K2 - Low output during initial TX alignment
On 9/4/07, Don Wilhelm [EMAIL PROTECTED] wrote: If you have little or no RF output Exactly, this is my problem. Continuing onward. An added note - measure the RF voltage across your dummy load. I'm not seeing any RF voltage across the dummy load. I am only seeing about 350 mV of DC voltage across the DL1 on key-down. I have just completed the Pre-driver, Driver, and PA signal tracing. Things are very interesting here. Driver voltages are very high, especially the output voltage but the PA Inputs and Detector Input are very low. Pre-Driver Output: 1.841 V (Expected: 0.120 V) Driver Input: 0.355 V (Expected: 0.026 V) Driver Output: 8.04 V (Expected: 1.8 V) PA Input (Q7): 0.030 V (Expected: 0.38 V) PA Input (Q8): 0.002 V (Expected: 0.38 V) RF Detector Input: 0.040 V (Expected: 2.0 V) Does this mean I have a problem between the Driver and PA or do I have a different problem area due the the high output of the Driver? Thanks -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
JT, Fine information. You have a problem between the collector of Q6 and the bases of Q7 and Q8. Your next step is to turn to the schematic RF Board sheet 4 of 4 and locate Q6, Q7 and Q8 and all the components between them. Check all for good soldering and be certain the 3 and 4 (green) leads of T2 are well tinned and soldered. You should have zero ohms between the end of R54 and the end of R53 (the ends that are connected to the T2 winding) - if not, T2 is not well tinned and soldered - if that is the problem, remove T2, re-strip the leads and re-install it, it is next to impossible to correct a poor lead tinning condition with the leads connected on the board (I have tried that and failed many times). The T2 3/4 winding is the most likely source of your problem. If you want to check the components with your ohmmeter, you will have to lift one end of many of the components (RF Chokes and resistors), with the RF chokes paralleling the resistors it is just not possible to check the actual resistance in-circuit, but you can usually trust the color code markings - but be certain the correct resistor is in the right place. 73, Don W3FPR JT Croteau wrote: On 9/4/07, Don Wilhelm [EMAIL PROTECTED] wrote: If you have little or no RF output Exactly, this is my problem. Continuing onward. An added note - measure the RF voltage across your dummy load. I'm not seeing any RF voltage across the dummy load. I am only seeing about 350 mV of DC voltage across the DL1 on key-down. I have just completed the Pre-driver, Driver, and PA signal tracing. Things are very interesting here. Driver voltages are very high, especially the output voltage but the PA Inputs and Detector Input are very low. Pre-Driver Output: 1.841 V (Expected: 0.120 V) Driver Input: 0.355 V (Expected: 0.026 V) Driver Output: 8.04 V (Expected: 1.8 V) PA Input (Q7): 0.030 V (Expected: 0.38 V) PA Input (Q8): 0.002 V (Expected: 0.38 V) RF Detector Input: 0.040 V (Expected: 2.0 V) Does this mean I have a problem between the Driver and PA or do I have a different problem area due the the high output of the Driver? Thanks ___ 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] K2 - Low output during initial TX alignment
On 9/4/07, Don Wilhelm [EMAIL PROTECTED] wrote: You should have zero ohms between the end of R54 and the end of R53 (the ends that are connected to the T2 winding) - if not, T2 is not well tinned and soldered Well, I am showing 12 ohms so I guess I'll have to take another look at this bugger. Thanks -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
Holy cow! I got it to work! It was definitely a improperly tinned green lead on T2. So much for buying pre-wound/tinned 'roids to save me some grief. Heh. Thanks Don. What a relief. Time to button it back up and continue 40M TX alignment. -- JT Croteau, N1ESE - Manchester, NH ___ 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] K2 - Low output during initial TX alignment
JT, The green leads of T2 are meant to be long so they can be routed under the core as shown in the manual. Mychael does a good job of tinning the leads for the proper length, but if you tug on them during installation, you can pull the untinned portion of the lead into the hole and the result is a PTTL (poorly tinned solder lead). If T2 is mounted right down on the board, there is often a drop-off of maximum power on the higher bands. Should you encounter that difficulty, consider re-winding T2 as a first solution and mounting it 1/8 inch above the board. 73, Don W3FPR JT Croteau wrote: Holy cow! I got it to work! It was definitely a improperly tinned green lead on T2. So much for buying pre-wound/tinned 'roids to save me some grief. Heh. Thanks Don. What a relief. Time to button it back up and continue 40M TX alignment. ___ 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] K2 - Low output during initial TX alignment
Hi, John- Since I am the fellow who provides the pre wound toroids, I would like to offer that I do include a note with my K2 sets instructing the builder not to pull the leads too tightly while installing K2-T2 . Its design is a little unusual insofar that the toroid is spaced slightly up off of the PCB, its green secondary leads hidden under the core. I tin most parts up to or onto the core itself, and with this part care must be taken not to distort how the lengthy green leads are positioned since this could result in pulling some enamel into the PCB. 73, Mychael AA3WF K2#1025 It was definitely a improperly tinned green lead on T2. So much for buying pre-wound/tinned 'roids to save me some grief. Heh. JT Croteau, N1ESE - Manchester, NH ___ 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
