QCX 1485 is alive!


Kirby Cave WB3BBC
 

So after two years I've finally gotten around to building the QCX for 40 meters.  And it works!  Like many, I found building T1 the most challenging.  But I followed the suggested method in the manual and it turned out fine.  I applied 14 volts from an old Radio Shack 2.5 amp power supply and it lit right up.  Made the alignment adjustments, and measured the power out to be 4 watts into a 50 ohm dummy load.  Looking forward to making my first QSO with it.  I haven't been on the air in years, but 40 meters hasn't sounded very active to me over the last few days.

I do have one concern.  After peaking the BPF, I see that the trimmer cap is fully unmeshed.  According to the manual I should remove 5 turns from the secondary 3 winding (currently 38 turns) and try again.  Really?  I certainly don't look forward to doing that!  What improvement should I expect if I do that?  Do I really need to remove 5 turns?  Could I possibly remove the enamel from some of the windings on the top of the secondary 3 winding of T1 and short across them?  Would this reduce the inductance?

Thanks to those responsible for a nice little transceiver and thanks in advance for any advice.  73

Kirby


Alan G4ZFQ
 

According to the manual I should remove 5 turns from the secondary 3 winding (currently 38 turns) and try again. Really?  I certainly don't look forward to doing that!  What improvement should I expect if I do that?  Do I really need to remove 5 turns?
Kirby,

Easy, just unsolder one end gently unwind a few turns, resolder, test. Maybe take a few more off then cut and tidy up. (Once unwound the free wire makes no practical difference), Depending on the version you may not notice much difference but without a proper comparison it's difficult to tell, best get it right.

73 Alan G4ZFQ


Kirby Cave WB3BBC
 

 Alan,

Thanks for the reply!  I went ahead and removed 5 turns from secondary 3 of T1 as you suggested and that seems to have done the trick!  Now the trimmer cap is about half meshed when the BPF is peaked.  In my impatience in unsoldering the wire of T1 I lifted the pad off the board!   But once I verified I had removed enough turns I was able to scrape the mask off the adjoining trace, bend the T1 wire over to make contact with the tinned trace, and resolder.  Must have worked because once I fired it up again I promptly made my first QCX QSO with a station in this weekends SKCC Sprint!  He gave me RST 529, but hey, I’m running 4 watts!  Thanks again...

73 - Kirby  WB3BBC