Thanks Don. Will run through the suggestions.
I'll take a peek at the filters through a VNA too. Is there an 'ideal' freq vs transmission plot anywhere? Two other suggestions off list for the 'deafness' points at the RX RP resistor banks so I expect a dry joint might explain some of this. 72 Dom M1KTA ----- Original Message ---- > From: Don Wilhelm <[email protected]> > To: Dominic Baines <[email protected]> > Cc: [email protected] > Sent: Thu, 27 May, 2010 21:14:02 > Subject: Re: [Elecraft] K1 build alignment. > > Dom, Yes, that K1 would appear to be deaf - most can hear a -130 dBm > signal well above the receiver noise floor. To troubleshoot it, use your > oscilloscope (with a 10X probe). First check the crystal oscillator output > on each band You can check that at the 2 band board P1 pin 4. You > should have at least 200 mV peak to peak on each band. If that test is > successful, put the oscilloscope probe on P1 pin 6 and tune the PreMix > Bandpass > Filters for maximum deflection on the 'scope. Note, that will give you an > "almost correct" setting of the inductors, but you will want to peak them > during > transmit while monitoring the RF output with your scope across the dummy > load. OK, the PreMixer bandpass is adjusted close enough to go on to the > next step - this time you will have to be in TUNE. Monitor the 2 band board > P2 pin 8 with your scope and adjust the inductors for maximum RF. If the > power output goes above 3 or 4 watts, tap the WPM- Button to bring it down - > you > cannot observe the peak if the power level is anywhere near the maximum > because > the transmit stages hit their maximum gain, so keep the power output > low. If you find output at the antenna in the step above, connect the > oscilloscope across the dummy load and re-peak the inductors - you will then > be > done tuning the bandpass filters - if there is subsequent trouble, have faith > in > the tuning of those filters and look for another problem. I believe what > you will find in the end is a bad solder connection somewhere. If it > worked at one time and then stopped working, that is usually an indication of > an > intermittent solder joint. 73, Don W3FPR Dominic Baines > wrote: > Ok this has me a bit stumped... > > First I could > get 40m working on RX and TX, but 20m was deaf as a post and no TX, now it's > the > other way around. I needed to tweak L7 and L8. > > 40m is band 1 > and 20m is band 2. > > Anyone else had this got any ideas? > Yes been through 62 and the relays do switch. > None of L1, L2 L5 and L6 > seem to be open circuit. > C's all still C and not shorted (lifted leads, > tested and resoldered). > I reset the 40m L completely withdrwaing the > cores and then going through testing with the screwed in with various turns > but > the signal generator signals are not detected now. But are on another > radio. > I have checked continuity and for solder bridges etc... and the > filter board default without power is band 1. > > Short of sticking > the filter board on a VNA as J7 pin 1-8 should be the BPF, J6 pin 1-7 should > be > the pre-mix BPF and J8 ping 1 and 8 should be the LPF (No ATU so J2 bridged). > Interested in ideas. > > BTW FT817 will easily pick out a 1uV > signal but the K1 cannot seem to manage anything until about 2.5uV but the > spec > sheet says 0.15uV which seems something is wrong is this usual? > How am I > measuring the signal: callibrated 50uV signals from xtal oscillator, step > attenuator and an oscilloscope. > > 72 > > Dom > > M1KTA > > ______________________________________________________________ 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
