GP300 RX PL problem

VA3XDJ · Post by **VA3XDJ** » Wed Jan 17, 2007 2:12 pm

Hi

I've recently come across a 2ch UHF (438-470MHz) Radius GP300 which, despite being programmed, verified and reprogrammed over and over again refuses to go into PL mode on power up despite RX TPL tones being programmed in both channels.

The side buttons have been programmed as Vol Set and Monitor and despite pressing the Monitor button, the radio remains in Monitor mode from power up constantly.

Has anyone ever seen this before? I'm totally puzzled!

Thanks for your help.

Mike

AEC · Post by **AEC** » Wed Jan 17, 2007 10:53 pm

You may have a bad side button....

The 'popples' in those switches are somewhat cheesy and are prone to failure, with the most common being 'flattened' by excessive presses over time.

They also shift inside of the switch housing, which makes detecting the problem even more of a pain...meter the switch to see if it's in the normally open condition or closed, then you'll know for certain.

Proper position for all the side buttons is N.O (Normally Open).

Of course, if you programmed CSQ for all channels, that's what you'll get, same for TX, but it's rare to have the tone not functon unless it's defective, then it's off to the reflow station.

Tony Soprano · Post by **Tony Soprano** » Thu Jan 18, 2007 9:44 am

Does the radio transmit PL?

VA3XDJ · Post by **VA3XDJ** » Thu Jan 18, 2007 1:25 pm

Thanks for the info AEC

I'll program it again leaving both buttons unassigned and see if that works.

As far as I know both buttons click when pressed so if the above attempt doesn't work I'll open it up and check it out.

It does transmit PL fine and both channels are programmed for TPL TX and RX.

Unlike most of the GP300's this customer has gotten off eBay, this one is in impeccable condition! No scratches, cracks or crackly TX audio.

Thanks again

Mike

Tony Soprano · Post by **Tony Soprano** » Thu Jan 18, 2007 1:31 pm

Do you have a schematic diagram and board layout? Check C413, I have seen solder failure and even breakage of this cap cause no PL decode. It is a tantalum electrolytic, and it resides at the board edge next to the AFIC. It's the top one. And check C412 while there.

VA3XDJ · Post by **VA3XDJ** » Thu Jan 18, 2007 1:48 pm

Thanks for the info, Tony.

I don't work on the inner guts or do any alignment work - I just program them as requested.

I leave that work to my friend who works in a radio shop - and charges much more than me

I'll pass the info onto him if customer decides its necessary.

Its used on a community repeater and they're the only users on it at night so its no biggie - and they're used to listening to the repeater ID anyway

Mike