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Author Topic: Swan 350 VFO End of Band Tracking  (Read 597 times)
AC0FA
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Posts: 298




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« on: April 04, 2007, 08:12:15 AM »

Hi All:
Aquired a Swan 350 and love it. This is a bare bones model and does not have a calibrator kit or dial set knob installed.

The owners manual indicates tracking on 80 meters is not perfect near the ends of the bands. And there may be a trade off In accuracy between the ends and the middle.

The owners manual mentions tracking through the range will be SLIGHTLY inaccurate OR the band edges will be a FEW khz off.

I noticed near the end of the bands on my 350. The dial reads 40khz too high. 3990 shown 3950 actual.  

Would this be considered a MINOR frequency adjustment that can be fixed by tweaking the 80 meter coil?

Or does this require a alignment procedure?

Erik AC0FA





Can this be corrected with external 410 vfo?al        
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KA5N
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Posts: 4380




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« Reply #1 on: April 04, 2007, 03:45:58 PM »

" noticed near the end of the bands on my 350. The dial reads 40khz too high. 3990 shown 3950 actual"
This sounds like 40 kHz low (reads 3990 and is 3950 actual frequency).  
First if the manual says it will be off a small amount I would judge 40kHz a bit much (eiher high or low).  I have no idea how finicky the adjustments are but I would try turning the coil about a half turn and see the effect.  You may have to go back and forth between adjustments to get it close.  How close?  Probably 10 kHz is OK.
allen
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AC0FA
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Posts: 298




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« Reply #2 on: April 04, 2007, 05:53:30 PM »

FB;
As always thanks allan
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AC0FA
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Posts: 298




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« Reply #3 on: April 04, 2007, 05:59:16 PM »

Oh, Sure It is labeled if you read the plate under the cabinet. 80 meter trimmer. Not shown in the owners manual at all. Not even in the picture. Oh well off I go to fix.
Erik AC0FA    
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AC0FA
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Posts: 298




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« Reply #4 on: April 05, 2007, 09:15:07 AM »

Ok,
To follow up and let every one know what fixed it.
the rig was tracking on a curve from +40khz at 3600 to +60khz at 3800 and +40khz at 4000.

I centered the dial on 3800 and turned the trimmer 1/4
turn counter clock wise.  

Until I heard the same qso on the 350 as I did on the other rig.

After the adjustment 3800 was right on, 3600 was
-10 khz and 4000 was +5 khz.

This dosen't take into account any tracking error in the other rig 700cx.

The 80 meter band now tracks about the same as 40 and 20 meters. Even though 20 meter band shares the same Trimmer coil as 80M . The Power output and alignment were not affected on any band.

The trimmer WAS mentioned in QST Magazine in the original review of the swan 350 in 1965.

Will a 410 exterrnal vfo help the 350 to track even better?

Erik AC0FA        
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