Jesus, You will have to resolve that problem before proceeding. The most likely cause is something wrong with Q1, Q2, Q3 or Q4 on the control board.
First check the operation of the TX and RX signals. During Receive, RX should be near 5 volts at the gate of Q4 and TX should be near ground at the base of Q3. During transmit, the opposite conditions should be true. If both RX and TX are the same state you could have a bad microprocessor. Next check the output of the 8 volt regulator. It should be within 10% of 8 volts. Be certain Q1 and Q2 are 2N3906 and are properly oriented. Also Q3 and Q4 should be 2N7000 and must be properly oriented. Check and recheck the soldering. With the K2 in receive (RX at 5 volts) check that the drain of Q4 is at ground potential. Then check to be certain the drain of Q3 is not at ground potential, it should measure about 8 volts. Both the base and emitter of Q1 should be at 8 volts and the Q1 collector voltage should be at 0 volts. Q2 should have 8 volts on its emitter and about 0.7 volts less on the base which should make the collector close to 8 volts. When the K2 is in transmit state, the conditions at Q3 and Q4 listed above should be reversed from that shown in the paragraph above (Q3 conducting and Q4 not conducting) also the conditions at Q1 and Q2 should also reverse (Q1 base at 8 volts, collector at zero) and Q2 base at 7.3 volts and collector at 8 volts. If these conditions are not correct at Q1 and Q2, check the soldering of RP1 on the control board. As one other item is Q23 on the RF Board. During receive the gate should be zero volts and the drain should be 8 volts. During transmit the gate should be at 8 volts and the drain would be at zero. Be certain Q23 is oriented correctly and is a 2N7000. Good luck with it. 73, Don W3FPR > -----Original Message----- > > Hello all, i am in the adjust phase of build my K2. My main problem not > solved yet is that 8V tx voltage line is with 5.1 v permanet. > Microprocesor tx order is down and rx is up, so here all is rigth, > colector of Q1 is with 5.1. Also RX voltage seem to be down, not 8V but > 6.5. Receiver work, i receive the signal from a external generator, but > display not show agc indicator. Calibration of display also seem to work > fine. Can someone ligth me in a good direction, Thanks. > > Jesus, EA1DAV. > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.28/672 - Release Date: 2/6/2007 10:22 AM _______________________________________________ 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
