P1225 construction question

[kf4sqb]

How are the shields attached to the board inside a P1225? I'm assuming solder, which means I have no way to remove them (unfortunately). I have one with almost no RF output, and was wondering if I have any hope of getting to the PA section.

[Will]

Check the switched TX voltage going to the PA module. The transistor that turns on that voltage 'dies' easally.

[kf4sqb]

Will, I don't have a schematic. Where do I measure this voltage, and what should it be under what conditions?

[jackhackett]

There's also a power resistor near the antenna connector that sometimes breaks away from the board, look for a large resistor, thin white ceramic with black coating.. I believe it is .1ohms. Newer units may have a thicker greyish resistor, I'm not sure if those ones get the same problem. If the resistor has come loose you will get very little output power.

[kf4sqb]

Jack, I just checked the resistor that I think you are referring to, and one end of it is indeed loose from the board. Now to re-flow the solder and see if it fixes the problem!

[kf4sqb]

Jack, that was just the ticket. What a PITA to re-flow the solder on the "channel selector" end of that thing! The solder pads on the board aren't really spaced far enough apart to properly mate with the ends of the resistor. I had to "expand" the pad area on one end to be able to properly re-flow everything, but its done and working properly again. Thanks for the help!

[Satelite]

Hello :
On a P1225 UHF portable .
Can sombody tell me the schematic reference number for the transistor mentioned above /
Also what is the schematic reference number for the resistor near the antenae conector.
I have a P1225 repaior manual coming soon and have a P1225 with low to almost no output and would like to look it up first before destroying the radio.
Thank you
satelite

[kf4sqb]

Satelite, I can't give you the numbers, but I can tell you where the resistor is located. With the board removed from the metal chassis, turn it with the antenna connector facing up and away from you. The connector should be in the upper right of your perspective. To the left of the antenna connector, between it and the channel switch, there should be a large surface mount resistor, app. 1/8" wide X 1/4" long. On all I have been in so far, it has "R100" printed on the top of the resistor, and is a slate blue color. Try measuring for continuity from the trace on either side of the resistor, should be about 1 Ohm, if memory serves. Measure from the trace (you may have to scrape off some of the green coating to get contact), not the ends of the resistor. If you don't have a complete path, you may have to scrape off some of the green coating on one end or the other to get a large enough area to resolder it to. Hope this helps, and good luck!

[Lake Effect]

The resistor is R150 and the transistor is Q150.

L.E.