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New here, an 89B I'm repairing
#4

Sparkydave, you might first check the feedback winding of the oscillator coil in series with the 36 tube cathode. This winding is notorious for opening up as it is wound on the outside of the main coil with a nitrocellulose insulating sleeve. The nitrocellulose decomposes over time, releasing nitric acid and corroding the copper wire. This is the usual cause of osc failure in the 89/19 moder radios.

Check the voltage on the cathode of the 36, If it is more than a few volts, them the winding is probably open. It is fairly easy to rewind this section of the coil to restore operation.


Messages In This Thread
New here, an 89B I'm repairing - by sparkydave - 06-20-2014, 07:45 PM
RE: New here, an 89B I'm repairing - by Mondial - 06-20-2014, 08:47 PM
RE: New here, an 89B I'm repairing - by gregb - 06-20-2014, 08:49 PM
RE: New here, an 89B I'm repairing - by morzh - 12-01-2014, 03:38 PM
RE: New here, an 89B I'm repairing - by AI2V - 12-01-2014, 05:12 PM



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