Don, thanks for that information.
Here's what I have. TX appears fine. With 12.3V supply I get the following output: 80m 3.3W; 40m 2.9W, 30m 3.8W, 20m 3W. All measured by an Oakhills Labs QRP meter and a 50 Ohm dummy load. The RX seems to have a problem. I have done a careful check of all trimmer settings. Measuring across the volume control (all controls fully clockwise); XG2 set to 50 microvolts (battery checked!); Fluke 175 true RMS meter (by a lucky coincidence): 40m: 163mV with earbuds connected; 185mV without 20m: 140mV with earbuds connected; 158mV without Leaving the earbuds in, I then tried injecting the XG2 directly on the junction of L6 and the top of the RF gain pot. The difference in audio level is dramatic, particularly on 20m, but I still don't get anywhere near your figures: 40M: normal antenna input 163mV; direct to top of RF gain pot 275mV 20m: normal antenna input 140mV; direct to top of RF gain pot 550mV - getting closer! Other checks I've done: - Made sure that the break in the PCB and subsequent link is OK for the addition of the KXB3080 - Checked L6 for continuity - Checked connections to KXB3080 - and ensured that A & B are as shown in the manual i.e. B goes nearest to T1. - Checked all voltages on U6 - within spec - Checked connections of T2 and re-soldered joints (this was supplied by the Mychael) - Checked L3 is the later version with the right number of turns This feels like it may be a problem with the pin diode switches, but that still doesn't really explain why I can't get anywhere near your 0.8V figures across the audio pot. 73 Bob G3YIQ On 18 Mar 2009, at 23:39, Don Wilhelm wrote: > Bob, > > OK, I finished the KX1 up to the point where I am able to give you > some numbers. > With a 50 uV input at 7040 from my XG2 signal generator, I find > 0.866 volts measured across the AF Gain control (control set to > maximum) with a high impedance load at the headphone jack. If I > plug in headphones (Sony MDR series), the voltage drops to 0.836 > volts. > Of course, the AGC should be active which will keep the voltage down > a bit. The KX1 has the KXB3080 option installed, and the receiver > front end is a little more sensitive than either the original KX1 or > with the KXB30 installed. > > With a 1 uV input, I read 38 to 40 mV at the same point - AGC should > not be as active at that level. > > The voltage readings were obtained with a Fluke True RMS reading DMM. > > 73, > Don W3FPR > > Don Wilhelm wrote: >> Bob, >> >> I can't give you a measurement number right away, I do not have a >> working KX1 here at the moment, but that value may be possible >> tomorrow or Friday. >> If you do not hear quite a loud signal with the 50 uV output from >> the XG2 (or XG1 with a 20 meter crystal) - with the RF Gain at >> full clockwise and the AF Gain between 25 and 35% of rotation, then >> there is something wrong. >> >> How is the transmit power output? If that is OK, then the low pass >> filter is likely OK, and you might want to look at T2. >> >> The KX1 audio is not super strong, and having good volume does >> depend on using sensitive headphones. If your headphones do not >> have an sensitivity rating greater than 108 dB/mW, then your >> headphones may be the major problem, see the KX1 manual page 62. >> >> 73, >> Don W3FPR >> >> Bob Jones wrote: >> >>> I've just completed a KX1 build with the 80/30m option and auto atu. >>> >>> It works on all bands but 30m and 20m require the volume control >>> to be fully clockwise and even then it's quiet. I've carried out >>> the recommended checks and everything appears to be fine. >>> >>> Having read the previous posts on 'low audio' there's an element >>> of subjectivity regarding what this means. >>> >>> Does anyone know of a definitive measurement I can make to see if >>> this radio is working as well as it should? >>> >>> For example, I have the XG1 and can inject a 14.060 MHz signal at >>> 1 microvolt or 50 microvolts. With the bandwidth set to maximum, >>> what level of signal should I expect on the input or output of the >>> audio amplifier, or at any other point in the circuit? >>> Any advice gratefully received. >>> >>> Bob, G3YIQ >>> >>> >>> >>> ______________________________________________________________ >>> 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 >>> ------------------------------------------------------------------------ >>> >>> >>> No virus found in this incoming message. >>> Checked by AVG - www.avg.com Version: 8.0.238 / Virus Database: >>> 270.11.18/2009 - Release Date: 03/18/09 07:17:00 >>> >>> >> ______________________________________________________________ >> 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 >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com Version: 8.0.238 / Virus Database: >> 270.11.18/2009 - Release Date: 03/18/09 07:17:00 >> >> ______________________________________________________________ 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
