For reports of RF feedback from the external speaker, especially when using a vertical antenna, or a linear amplifier, check for correct installation of capacitor C16 on the EXT SPKR jack.
C16 should go from ground to the white wire on the opposite side of the jack. Some units have the capacitor soldered to the middle terminal in error!
Note: This bulletin is applicable to radios with serial numbers prior to 3070420. Time required for this procedure is ½ hour or less.