Another option is to take the output of the one amp regulator and feed it into the base of a much larger NPN transistor. Tie the collector of that transistor to the unregulated voltage and the emitter will supply much higher current at regulated voltage. The transistor will cause a 0.6 volt drop in the output voltage, which can be compensated by adding a diode in line with the grounded terminal of the voltage regulator.
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XForce 1KW supply voltage.
- Thread starter BJ radionut
- Start date
With the output tuning capacitor still installed the outer and inner are ringing common. Do I need to unsolder one end and recheck?
Yes you need to disconnect the capacitor to test it for a short because, it will read a short through the combiner and secondary winding of the output transformers. If that part checks out along with the three capacitors across the input coil, you should consider running a low-power test where you just drive it with the radio and see if you can feel any temperature at the transistors. This will tell you right away if the failure is on the input side or the output side of the amplifier.
Thanks shock wave. I’m working 12 hour shifts and drive 1 hour each way. So I’m having little time to work on it. I’ll post what I find. Your awesome.
The 3 input caps I'm talking about are all in parallel with each other and connected from the copper input coil, to ground.
Will unsoldering the 3 caps from ground and doing a quick key with low power input should show some output on the meter. Right? I did the low power input from the radio and no transistors created no heat. So like you say it has to be on the input side. I’m considering replacing the relay. And the small coax that feeds the input coil. Thoughts.. Thanks for your patience.
Sorry to go on&on with this thing. Did you get a chance to read my last post? And one other thing is it possible for the input splitter to go bad and send the drive wattage to ground? I would think it would send the reflect to the moon if that was the case. Thanks again y’all have been super helpful. Happy Thanksgiving and 73s!
If one of the three input capacitors is shorted, it is likely to show that short at DC on an OHM meter. It is also likely that lifting them out of the circuit will restore some output if they are defective, although it will be out of tune. I wouldn't drive it hard or operate it long in this condition. Just a test.
The coax feeding the input coil could also be shorted. It looks like it may have been heated and squished a little bit with the soldering iron at the ground end near this coil. You can disconnect the center wire on the coax from the coil and see if that shows the coax is shorted to ground. The coil should show a short to ground and that's why you need to isolate the coax and capacitors from it, to test them with an OHM meter. It's unlikely that the relay would burn up its input contacts, before its output contacts.
I tried every thing up to the point of replacing the relay. So I ordered a new one and removed it. I realized the keying circuit was still in it. Like I said I use an external keying module. The original keying components was still there just disconnected from the ground pin of the relay. Could these components cause my problem? Or perhaps the preamp circuit?
The likely culprit is the preamp circuit. It functions as a switchable device in and out of the bypass of the main relay.
I have tested and replaced everything I can think of except transistors. Is it possible some transistors are shorted and preventing drive to reach other transistors? And how can I test them?
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...runna pile-up on 6m SSB