I will assume that you have the input and output measurements reversed. Even with that modification, the output pin of U2 (the 78Lo5ACZ) should be 5volts +/- 0.15volt.? There is something wrong with either your measurement, the regulator is bad, or there is something else pulling the voltage higher than it should be.? It is a surface mount device, so tricky to replace without a hot air surface mount rework station.
As far as I can tell, the input is to the right of U2, and the output is to the left as shown in the board picture I sent before.? The center pin is at ground, 0volts.
You can measure the drains of the IRF510s on the large tab connected to the heatsinks.? The 12volts is there all of the time.? You do not need to key the PTT switch to take the measurement.? Switching the gate bias off puts them in a high resistance mode, such that only a few milliamps of current is drawn for both of the devices.
Double-check the U2 voltages.? If you are truly getting almost 8 volts on the output of the regulator there is something really wrong with the circuit.? My only suggestion is to order a replacement before you try to remove it for testing.? When ordering get the IRF510s as well.? I believe that you will need to pull them to verify that they do not have a drain to gate short that is pulling the regulator output up.? Do this before you try to remove U2.? If that is the cause of the U2 output voltage being over 5volts, then with both IRF510s removed you should get 5volts on the outpput of the U2 regulator.? Replace the IRF510s if that is the case.
There are others on this board who will do the repair that have the proper tools and experience.? I have done this type of replacement once (I thought I had an issue with one of the BAT54SL used in the product detector, that is the only removal experience. I had 4 transistors to install in a filter kit that were surface mount that went well), however I am not confident on my capabilities to work on someone else's uBITX, even at no charge and the owner taking all of the risk.? The best option would be to find a nearby ham or club that could help with the measurement and problem solution.
Hope the above helps, and good luck in finding and fixing the issue.
73
Evan
AC9TU
