Igor, Given the high RF voltage at the PA on 3.5 MHz, you may have an open Low Pass Filter - check for continuity on the 2 band board from P3 pin 1 to P3 pin 8 for both bands. If one or both are open, you have a poorly tinned toroid lead.
If that is not the problem, you may want to get [email protected] involved. 73, Don W3FPR On 9/27/2010 6:39 AM, Igor Lána wrote: > Hello Don, > thank you for advice. > > I check L9 and L10 again a it looks like good > (http://ok1tgi.nagano.cz/obrazky/K1/L9_L10.jpg) - 28 turns. > I check all condensators on FB for 80m band and everything is OK. > > I made new measuring. > I removed out the DRV-ground jumper and checked waveshapes on DRV and PA > pads. > Power supply 13,8V/3.5A, output power 0.1W, dummy load 15W Nagoya 0-500MHz. > Oscilloscop Createc SC-03, 9MHz > Current was 0,45A on 40m, 0,98A on 80m. > > DRV 7MHz (150ns, 1V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz.jpg > DRV 3.5MHz (150ns, 2V): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz.jpg > PA 7MHz (150ns, 5V): http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz.jpg > PA 3.5MHz (150ns, 20V): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz.jpg > > Yes, there isn't little bit nice sinusoid. But bigger surprise was measuring > in multimetr mode. > > DRV 7MHz = 650mV rms: http://ok1tgi.nagano.cz/obrazky/K1/DRV_7MHz_mm.jpg > PA 7MHz = 3.6V : http://ok1tgi.nagano.cz/obrazky/K1/PA_7MHz_mm.jpg > DRV 3.5MHz = 1V (?!): http://ok1tgi.nagano.cz/obrazky/K1/DRV_3MHz_mm.jpg > PA 3.5MHz = 14.9V (!!): http://ok1tgi.nagano.cz/obrazky/K1/PA_3MHz_mm.jpg > > This is strange values, isn't it ? > > But the biggest mystery - see lowest line on PA 3.5 MHz multimetr PA > measuring - there is 7.177 MHz !!! > I also made short checking with better oscilloscop (200MHz) at work on > friday. And it showed me the same problem. But I didn't have dummy load and > I thought that is the reason. > > Is the PA over-drived ? Does it work in class C correctly ? > > I checked "POWER" signal on pin 6, connector J1 > RX 2.2 V for both bands. TX 3.5MHz = 2.94V DC, 7Mhz = 3.17V DC. > > L1-L8 are adjusted for the best RX. Attemps in TX are complicated. On 80m I > can't setup higer otput that 0.5 W because current is too high. On 40m I can > adjust maximum 1W output with 2.0 "menu level". > > Now I don't have any ideas. > > Igor OK1TGI > > ----- Original Message ----- > From: "Don Wilhelm"<[email protected]> > To: "Igor Lána"<[email protected]> > Cc:<[email protected]> > Sent: Sunday, September 26, 2010 7:33 PM > Subject: Re: [Elecraft] K1 80/40 tx problem > > >> Igor, >> >> The waveshapes are normal. They will not be anything like a sine wave >> coming out of a mixer, but the fundemental RF voltage is still present, so >> the waveform will be cleaned up by the bandpass filters and the PA Low >> Pass Filter. >> >> Since you have excessive current draw, the first place to look is the Low >> Pass Filter on the 2 band board. Are the capacitors correct? Are the >> number of turns on the toroids correct? Count the turns carefully, >> counting each turn that goes through the center of the core - a straight >> wire through a toroid is one turn, a full wrap around the core is two >> turns. Failure to realize that fact is a common builder error. >> >> 73, >> Don W3FPR >> >> On 9/26/2010 12:06 PM, Igor Lána wrote: >>> Hello friends, >>> I built a kit K1 80/40. Everything was no problem. All values of >>> resistors >>> and DC voltages were OK. But in chapter 9, part "Band 1 Allignment", >>> transistor Q7 has been melted (2W at 80 m band). >>> I changed it and after that I measured current - 0.1 W on 3.6 MHz >>> current >>> is 1.1A! On 7 MHz, is slightly better - 0.1W is 0.4 A but the 2W is 1.3 >>> A. >>> After several attempts to find mistake, I tried to use the "Signal >>> Transmitter tracing" with DRV-ground jumper. Instead of RF Probe I used >>> the >>> old oscilloscop in multimetr mode. I performed the measurements to the >>> point >>> 15. All values looked like okay, but from the point 10, I watched the >>> unstability. >>> I switched oscilloscop to the measurement curve mode. And on OSC it is >>> not >>> pure sine wave. The point of MIX has been very vibrant. ATTN is clean. I >>> do >>> not know if the problem is on 6-7 intputs U8 or output 4. >>> Please, see videos of measuring on youtube. >>> ociloscop 150ns time raster: http://www.youtube.com/watch?v=fYTOw9DWfKI >>> ociloscop 50ns time raster: http://www.youtube.com/watch?v=9mUunLQdBuU >>> ociloscop-multimeter: http://www.youtube.com/watch?v=oFaKCssXsA >>> In every video first part is on ATTN, second on OSC, and the third on >>> MIX. >>> >>> Please, do you have some recommendations how or where to find the error? >>> Can Xtal X6 defective? >>> >>> Thanks >>> 73 Igor OK1TGI >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
