Batboard

I need some help. I have a GP300 that squeals real bad when you turn up the volume all the way. It appears that the radio is microphonic. ANy suggestions on how to repair this problem, or what the problem might be, also when I tap the radio I can hear the tapping thru the speaker. When the speaker microphone is attached it still squeals. Please help.

Thanks :cry:

It is most likely just a bad connection with the speaker/ mic connector, but I have found that it is best to clean all the metal to metal contacts, just to be sure. Open the case and clean all the pins on the speaker connector. Use a fiberglass brush, or an eraser. Make sure you remove all the shielding and clean those connections too. Reconnect everything tighly and you should be on your way.

Cheers

First let me say that the rx howling i had was with the gp300 uhf portable and not the vhf version.

The radio would howl on rx when the volume was full open but when turned down would go away.

It turned out that motorola didnt use a heavy enough shield (shield #101 and shield #105 by component view in the repair manual)
I was told by m tech that these shields should be replaced and that would solve my rx howling at full volume setting.

But the tech also advised replacing coil #L258 since it could be causing some problems also and its under shield 105 too.

The replacment shield he said was heavier than the original=however from my view it appeared the same.

But low and behold after replacing the shields and coil L258 my problem went away and has not returned.

I did notice that the vhf version according to my repair manual also uses a coil in this location so i suspect it could be true for a vhf howl suspect and its shield replaced .

The uhf L258 coil is motorola part number =2480145s08

The vhf L258T coil is motorola part number =2480145s04

Shield number 101 is motorola part number =2680970y04

Shield number 105 is motorola part number =2680968z04

The L258T coil is the same for a vhf 136 to 162 or the 146 to 174 band

The L258 coil for the uhf was for the 438 to 470 band

It is not the easiest shield to unsolder and remove so plan on carefully destroying the old shield without damaging the board and solder on the new which in itself was easy.

Good luck

EKLB

Thanks fot that information guys. I will try both of your suggestions. I just ordered the parts referenced. I just ordered parts online at MOL and should have them here at the shop by Friday. Thanks again :D