HR 2510 NO TX WATTAGE

[CBC544]

Hr2510 rx good but has no tx power shows about a half watt on AM if I keep the mic keyed that half watt goes to 0 watts in a couple of seconds ,I have already replaced the final mrf497,the driver 2sc2166 also Q124 audio driver Q134 pre driver ,changed C95 and C97 and C75 ,all voltages on ic104 are correct,checked voltage on Q125,Q126 and Q136 all check out according to service manual now I am stumped any help would be great

 

[Robb]

As a guess; I would have to say that a resistor or cap in/near the final stage is changing values under load.
Just a guess...

 

[TonyV225]

I have one here that did the same thing!!!

 

[dxhound]

Do you have an oscilloscope? If so probe the output of the final transistor at the transistor leg. Watch the power and see if it fades. If so do the same to the driver-then pre driver and so on. If it doesnt fall off at the final then it sounds like a bad filter or inductor, maybe the SWR PCB.

 

[Rogerbird1]

bias

What are the Bias readings on TP2, 3 and 4?

Did you use a MRF477 or MRF497?


Roger