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37-690 band 2 troubles
#6

Like Ron says, if you rewind you will have problems.

Getting the proper inductance is not the problem- that's relatively simple. The problem comes about in something called distributed capacitance- that's the capacitance between the turns and it can be substantial.

With a rewound coil you will be able to set the bottom of the dial and adjust the trimmer for the high end but the middle will be terrible.

If you can remove the oscillator coil for band 2, and you have a good magnifying glass or stereo scope, look for a wire break on the outside layer of the coil; carefully follow the wire back from it's solder connection. The wires nearly always break where the person winding the coil made a 90 degree bend at the end of the coil as it runs to the solder joint. It's going to be under a tape or paper covering usually. If you find the break you will be able to remove one or two turns without any problems.

From the old coil winding department of Boonton Radio-

Pete AI2V


Messages In This Thread
37-690 band 2 troubles - by wonderwrench - 10-14-2007, 10:59 PM
[No subject] - by Sean - 10-15-2007, 08:12 AM
[No subject] - by wonderwrench - 10-15-2007, 12:36 PM
[No subject] - by Carl Travis - 10-15-2007, 02:50 PM
[No subject] - by Ron Ramirez - 10-15-2007, 04:51 PM
Coil rewinding for lower bands - by AI2V - 10-15-2007, 06:06 PM
[No subject] - by wonderwrench - 10-15-2007, 06:35 PM



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