Thanks Don, Problem was with D36 (SMT1B) - used pad 1 and 2 not 2 and 3
RTFM! 73 David EI9EUB On 20 May 2009, at 17:38, Don Wilhelm wrote: > David, > > When making the Transmit Signal Tracing tests, stop at the *first* > place where the RF voltage is substantially *lower* than the > expected value. That stage has inadequate output. In other words, > if the transmit mixer has low output, one can expect low output at > all points in the transmit chain beyond the mixer - even though > those following stages may be working fine. > > Since your first failure stage seemed to be the transmit mixer, > check all components shown around U10 on the schematic. Be certain > you are getting enough RF voltage from the VCO to U10 pin 6 (0.5 > volts minimum). Additionally, you must have a good signal into U10 > pin 1 - check the amount of RF voltage at TP2, then both sides of > C167 and finally U10 pin 1. There should be only a small dropoff of > the BFO signal as you progress along that path. Use the level at > TP2 for the reference level. > > 73, > Don W3FPR > > David Gilmartin wrote: >> Hi, >> >> This is my second K2 build >> >> Just got to Alignment and Test Part III and can't get RF out. >> >> >> >> Receiver tests OK >> >> Supply is 13.8V >> >> 8V regulator gives 7.59V >> >> 5V regulator gives 4.99V >> >> AGC threshold is 3.6V (highest voltage I can get) - same as first >> K2 built. >> >> >> >> No measurable power out - display says 0.1 W in Tune mode >> >> Indicated current: >> >> 220mA - RX >> 520mA - TX >> >> Indicated Voltage: >> >> 13.4V - RX >> 13.2V - TX >> >> 4.97V on VPWR at pin 2 of U8 with key down >> >> RF detector components and soldering checked OK >> >> >> >> >> Basic Voltage Checks: >> >> D6 anode goes to 240mV on TX >> >> D7 anode goes to 7.49V on TX >> >> >> >> >> I am having difficulty with the Mixer, Buffer, Band Pass Filter, T- >> R Switch and subsequent tests. >> >> I have built the RF probe and it works OK. All of the measurements >> for the tests above show a trace of voltage on switching to TX >> which then disappears. >> >> >> >> >> Problem in the T-R Switch or am I missing something obvious? >> >> Any help appreciated. >> >> David >> EI9EUB >> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
