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
