Don: I brought home a DSO5054A (very nice 500 MHz Agilent scope!) and I was able to take the better measurements. My measurements were in P-to-P but I have divided them by 2.8 for RMS comparison:\ (all measurments Keydown)
1.) VPWR line (pin 2 of U8 on control board): 5.0 volts this is HIGH 2.) Xmit Mixer Output (pin 4 of U10): 28 mV 3.) Buffer Output (pin 6 of U9): 121 mV 4.) Band-Pass Filter Output (W6): 42 mV 5.) T-R Switch #1 Output (anode of D1): 41 mV 6.) Pre-Driver Output (collector of Q5): 34 mV this seems LOW 7.) Driver Input (base of Q6): 34 mV 8.) Driver Output (collector of Q6): 179 mV this is VERY LOW 9.) PA Inputy (base of Q7): 80 mV this seems HIGH 10.) PA input (base of Q8): 80 mV this seems HIGH 11.) RF Detector Input (anode of D9): 143 mV this is VERY LOW on my own I also measured: 12.) base of Q5: 43 mV 13.) out of C107 43 mV all of the DC voltages in column 1 on page 17 are normal Anything look new? Thanks for any help!! Brian http://home.comcast.net/~b.denley/index.html ----- Original Message ----- From: "Don Wilhelm" <[email protected]> To: "Brian Denley" <[email protected]> Cc: "Elecraft Reflector" <[email protected]> Sent: Tuesday, September 07, 2010 12:59 AM Subject: Re: [Elecraft] [K2] No Transmit Power > Brian, > > Since you are unable to measure any RF voltage, I am going to start at the > beginning - proper assembly of the RF Probe. > > The RF probe voltage is not read "across" the 4.7 meg resistor, it is read > between the end of the 4.7 meg resistor and ground. That is an important > difference. In other words, the 4.7 megohm resistor is in series with the > detector. Since the nominal input resistance of a DMM is 11 megohms > (established in the "old days" of VTVMs), that resistance in series with > the 11 megohms will cause the DMM to indicate the RMS value of the RF > voltage being measured. There are other techniques that will provide DMM > readings that indicate the zero to peak RF voltage, but the RF probe parts > provided with the K2 will indicate the RMS voltage values when used with > most DMMs. ______________________________________________________________ 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
