If we were in a period of higher sunspot activity, we would not have this problem. If there were good signals on the 17/15 meter bands, we could use those to adjust the K1-4 to the correct band. Unfortunately, we are in a time when solar activity does not produce a lot of signals on the 17/15 meter bands, so the use of a known frequency signal source is almost mandatory. Yes, there are 'workarounds', but those should be used wtth a degree of awareness for the consequences.
73, Don W3FPR Alexey Kats wrote: > Don, > > You are absolutely right - the biggest trouble I had with my K1-4 was > on 17m band. With 20m I used XG2, but for 17m I ended up tuning it > after transmitter was fully built - I first tuned it roughly on low > power transmit with dummy load and watt meter, then using noise > generator on receive (with attenuator on), then again with watt meter > on transmit. And as a result I had to re-tune 20m again. > > On Wed, May 26, 2010 at 6:04 PM, Don Wilhelm <[email protected]> wrote: > >> Alexey, >> >> Using the noise source or "dead band noise" with the K1-4 is problematic for >> the 15/17 meter and 20 meter bands. >> The real world situation is that it is possible to tune the 15/17 meter >> Pre-Mixer bandpass trimmers to the region of 29 MHz rather than 23 MHz. The >> usual result is that 20 meters cannot be tuned properly (and the frequency >> that 15/17 meters is tuned to is incorrect). >> >> The way to avoid that situation is to use a known signal source when tuning >> 15/17 meters. >> >> The manual states that the initial position for the Trimmer capacitors is to >> be with the slots parallel with the long side of the board. The final >> adjustment ot the trimmers will be no further than 20 degrees away from that >> position. If the 'peak' occurs further away from that range, it is at the >> wrong point. >> >> Using a signal source of a known frequency will avoid this problem, but >> using a wideband noise source can certainly produce this false response. >> >> Note that this condition does not occur as readily with the 2 band board. >> >> 73, >> Don W3FPR >> >> Alexey Kats wrote: >> >>> Greg, >>> >>> You can use XG2 kit from Elecraft as a signal source for K1 on 80m, >>> 40m and 20m bands (it'll also give you a chance to adjust S-meter as >>> well). 80m might be a little problematic if you selected 80kHz tuning >>> range because it is close to the upper end of the band, but you should >>> still be able to use it unless your VFO is misaligned. >>> >>> Or you could use N-gen kit too, but be careful with it - it's easy to >>> adjust all filters on receive so it will look like you reached the >>> peak, while in reality your IF will not align properly with center >>> frequency of crystal filters. This is because it produces relatively >>> strong noise signal. If that happens (the giveaway is that you can >>> hear noise generator, but nothing from the antenna) - move all >>> adjustments for the problematic band to their neutral positions and >>> start over. >>> >>> But the easiest method is to use another QRP rig or a signal generator >>> as a signal source. >>> >>> >>> > > > > ______________________________________________________________ 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
