update on my KX1 progress
Locked
 
|
After being stuck at stage 2 for some time, and pulling my hairs out one
at a time, Jim Younce, K4ZM rescued me (in a big way) - Thanks Jim! - and I recently completed the Stage 3 assembly. I would love to report success, but the war is not over... a couple of items stand in the way. 1. Completing the alignment: I have incorrectly assessed the difficulty of alignment; in that I am having trouble locating a few tools adequate to the task; the "tuning wands" I am finding here are either too large a diameter (won't fit down in there), or not insulated (and either short to the plated through holes, or couple my body capacitance (not insubstantial by the way), or are made of stuff too soft for the task of torquing those pesky trimmers... and to make matters more frustrating, the pesky trimmers have a high static friction, so that when you do turn them, they twist far more degrees than intended... So folks, share your secrets of source of said tuning tools... 2. My 20 M. output is about 2 watts; 40 is about 3.5 watts. Yes, R4 is fully clockwise. supply voltage is at 13.8 Volts. I am suspecting the windings on some toroids, or other form of joy... Hints? Looking forward to successful completion and some first QSOs to report... 73 de W5SV, Dave -- David F. Reed - W5SV - cell: 512 585-1057 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: update on my KX1 progress
|
|
Dave, W5SV wrote:
I have incorrectly assessed the difficulty of alignment; in that I am having trouble locating a few tools adequate to the task; the "tuning wands" I am finding here are either too large a diameter (won't fit down in there), or not insulated (and either short to the plated through holes, or couple my body capacitance (not insubstantial by the way), or are made of stuff too soft for the task of torquing those pesky trimmers... and to make matters more frustrating, the pesky trimmers have a high static friction, so that when you do turn them, they twist far more degrees than intended... 2. My 20 M. output is about 2 watts; 40 is about 3.5 watts. Yes, R4 is fully clockwise. supply voltage is at 13.8 Volts. I am suspecting the windings on some toroids, or other form of joy... Hints? --------------------------------------------------- The page numbers in the manual referenced below are for the Rev B manual, November 3, 2003. TRIMMERS You are absolutely right, the holes giving access to the KX1 trimmers are too small for most alignment tools. That's why a small metal blade screwdriver with an insulated handle is recommended for this adjustment (Page 10 "Tools"). If you don't have an insulated handle on the screwdriver, you'll need to make one by wrapping it with tape (Page 46 first step). One thing not mentioned in the manual is that it is often useful to exercise the trimmers first. That helps reduce any residual "stickiness". Also, some trimmers come from the factory making poor contact between the moving and stationary contacts that can cause an intermittent. Rotating the trimmers a few times will help them 'seat'. They will be fine indefinitely after doing that. Only a few trimmers require "seating" but it turns up from time to time in all the Elecraft rigs. Shorting the signal path to ground won't hurt anything (see the note on page 46), so it's not necessary to wrap tape around the screwdriver where it passes through the board if you have a small enough screwdriver. The last I heard, only the B and B1 rev's of that board have grounded plated-through holes. My KX1 was the second unit built (Wayne's was the first) and I've not see the later boards. Finally, there is some small interaction caused by the metal of the screwdriver that is evident when it is removed, but I found it quite easy to compensate for that, moving the trimmer to one side of the peak and listening for the signal to come back up as I removed the screwdriver as described in the note on page 46. If the signal increases then drops off as the screwdriver is removed, you went too far. Of course, that's true only of the trimmers whose rotors are not grounded. I believe that's only B and B1. 20 METER POWER OUTPUT Yes, check your toroid turns carefully: one turn is when the wire passes through the center. There are no partial turns on a toroid. L1 and L2 must each have 14 turns on a Yellow T37-6 core. Be sure you didn't use the grey ferrite cores by mistake. I have found that adjusting 20A and 20B for best signal-to-noise ratio rather than maximum noise produces more sensitivity and more RF out on 20. The two points are about 1/8 turn apart. Set at maximum noise, my KX1 makes about 3.1 watts on 20 meters and 4.2 watts on 40 meters with a 13.8 vdc supply. That's within spec, but I find that if I adjust 20A and 20B for best S/N (listening to a very weak signal) my 20 meter output rises to 3.8 watts and the 40 meter output is 4.0 watts. This requires a weak signal! I find that the output of the XG1 signal generator, even set for 1 uv output and listening to its second harmonic on 20 meters, is much to strong. I put a short piece of wire in KX1 antenna jack and laid it near the XG1 to produce a suitable weak signal. Too strong of a signal makes it very difficult to hear the true peak or setting for best S/N ratio. Also check the spacing of the turns on L1 and L2, especially T2. They should be as shown in the book (Figure 16, page 40). You might try spacing L2 our a bit wider to increase the 20 meter output. With L1 and L2 set up correctly for best harmonic suppression, you should expect the output on 20 meters to be 0.3 to 0.6 watts below the 40 meter output (see 40 Meter Transmitter Test, page 59). Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: update on my KX1 progress
|
|
In reply to this post by David F. Reed
Oops... Mychael (the toroidguy) caught me looking at old documentation
yesterday. He wrote me: "On yesterday's reflector you wrote to Dave W5SV: ... L1 and L2 must each have 14 turns on a Yellow T37-6 core. Be sure you didn't use the grey ferrite cores by mistake. Actually, L1 consists of 13 turns while L2 should have 14 turns. I recall early in production that both L1 and L2 had 14 turns. Sometime after that the specs on these parts changed and I adjusted my sets accordingly. ----------------- Mychael has the current info. I was looking at the wrong documentation! My apologies for the confusion for Dave or anyone monitoring this thread! Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |