President Washington no transmit!

[liquidh8]

Help guys. I have a president Washington 858pll. It all of a sudden stopped transmitting tonight. At first I thought it was the final, but I had a 2166 driver and 1969 final from another radio and nothing. It receives fine, and the relay clicks. I hooked up external speakers to the PA jack and the recieve comes out of it, and i can talk out of it. I am sorta stuck here, anyone have any ideas"s Thank you!

 

[Robb]

Hook up another radio w/o an antenna and set it to the same channel as the radio in question. Then key the transmit on your Washington and see if you hear anything in the second radio.

Or, just hook it up to a meter bridge if you have one.

Just for a start.

http://www.worldwidedx.com/tech-repair/124433-president-washington-no-transmit.html#post323249

 

[liquidh8]

I did, I have a small old realistic handheld, i hear something on the same chanel, on ssb and am. just no power or modulation on the dosey or digital.

 

[Robb]

If the output of the Washington is weak; then it might be that the final transistor has failed.

That is a guess at this point.

 

[Double R]

i agree with robb on that , i do the cover-ion to the mossfet 2030's n and f , instead of 20 watss you will get 40 or 50 depending on how you tune it

 

[liquidh8]

Well, it ended up being a messed up cold solder joint that took me hours to find, after resoldering and testing every cap and transistor in the radio, lol

 

[liquidh8]

also, my original 1307 final, have a 47ohm 1/2 resistor going from ground to the base. do they all have this? I cant seem to find it on the schematic? It has that clear tubing over it, looks original but not sure.

 

[ExitThirteen]

Yep, that's supposed to be there, it bridges the emitter of the transistor (ground) to the base. It's part of the feedback loop circuit.


~Cheers~

 

[liquidh8]

copy that, I have a question, on the schematic I have, it has R204, a 10ohm 1/2 watt resistor. mine doesn't have that, does yours? The reason I ask, is I can't get the bias to the final any higher than 50mA, when it is supposed to be 70mA. I never could and I cant figure out why.:headbang

 

[liquidh8]

Well, to close out the thread for the searchers.

After going through more than half the parts with my capacitor and transistor tester, I accidentally found the the trace, right at the solder joint line or the TP3-TP4 pin was cracked, this feed the bias voltage to the driver. Since this was intermittent, I couldn't find it, , but now I am good to go.

Concerning the VR for the final bias, I put a new style plastic one in there of a bit higher value, and was able to adjust the final to the recommended 70mA.