faulty ranger ar3500

[geordie]

hi there i have a ranger ar-3500 works 100%on am/fw/cw but on ssb its ok for 5 minutes then it just drops output power
an idea?
this radio is driving me crazy
thanks

[5XX]

I have exactly the same problem and its driving me nutz as well.
I must be thermal instability somewhere but I can't find where.

I also notice that vr15 the SSB ALC preset is non responsive
so it leads me to think that the intermitant fault lies in that chain somewhere.

Any ideas folks..

[steve_corkett]

i came across this fault once on another radio i found it to be a resistor at fault when it got warm the resistor acted more like a thyristor its probley one thats taking a fair amount of current might be worth a look at the one of the resistors coming off the output or driver transistor as that area will tend to warm up after about 5 mins probley worth replaceing them as using a meter on them wont tell you much unless there hot hope this helps you out

[Rick]

hi there i have a ranger ar-3500 works 100%on am/fw/cw but on ssb its ok for 5 minutes then it just drops output power
an idea?
this radio is driving me crazy
thanks

Apply a two tone test while monitoring the collector of Q27 and adjust VR15 if the voltage stays the same then replace Q27 and try again. Low output on this radio is normal due to Q27 going short.

[5XX]

Thanks Rick, that seems to have done the trick. Couldn't source a C1923 but a general purpose NPN BC548 is sitting quite happily in its stead for now.

73's nd Tnx fer info..

de 5XX qrx