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Author Topic: RESTORATION SWAN 700CX ALIGNMENT HELP  (Read 823 times)
AC0FA
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Posts: 298




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« on: February 21, 2007, 07:07:22 AM »

Hi, Fellow hams,
It finally happened I got my self kind of stuck. Maybe one of you old timers can help me out.
After replacing some bad caps in and around the finals.  

I have gobs of power 300w cw key down average output on 75 and 40 right where it should be.

I also have several hundred watts on 20 15 and 10 but It is too darn high. 20m peaks at 14.350 and the others also peak way at the top of the band.

I knew if I kept filing my head with knowledge something was bound to fall out.

I restored a swan several years ago with the same problem, but I can't remember what I did to fix it.

Erik AC0FA        
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N2VWW
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Posts: 242




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« Reply #1 on: February 21, 2007, 09:30:46 AM »

Start by neutralizing the finals. That may solve your problem.

Gary n2vww
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KA5N
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Posts: 4380




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« Reply #2 on: February 21, 2007, 10:20:53 AM »

Hi Erik,
If the high bands are peaking too high in frequency, then the individual inductors on the VFO buffer and the driver are probably mistuned.  With a non-metallic tuning tool (while working on one band at a time) adjust the slugs lower into the windings.  You should use a dummy load and very low power.  Adjust the plate and load caps for max output at say 14.200 MHz for 20 meters and then adjust the VFO buffer coil and then the driver coil.  Go easy as it may not take more than 1/2 turn to 1 turn to get things on track.  If you try tuning and it isn't working then stop and make sure you are tuning the correct coils.  As always, the problem could be something else but I don't think so.
Good Luck Allen
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AC0FA
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Posts: 298




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« Reply #3 on: February 21, 2007, 12:00:48 PM »

Thanks Allen;
I swapped out the 8950's with 6LB6's and outsmarted myself.

I reviewed the tube data and might need to add another 10 puff capacitance to bring the resonance back down.

Erik AC0FA  
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KA5N
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« Reply #4 on: February 22, 2007, 03:16:08 AM »

Well for the 8950 I see G-P cap .6 pf,input 36 pf, and output 18 pf.  6LB6 G-P .4 pf, 33 pf and 18 pf. That's hardly any difference so I am not sure where you are going to add capacitance.  I am not sure now what you meant by "peaks high".  The plate and load capacitors should be in resonace somewhere between fully open and fully closed. If you can only get rated power at the high ends of the bands then the tuning of the drive signal is what I would suspect is the trouble.  
73 Allen
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