?The amp was previously adjusted for the correct bias and was in use with a QCX radio. I don¡¯t believe it should have needed adjusting just to use a different radio source, the QDX. Maybe I am wrong with this assumption.
I checked the finals, and both are shorted across all pins. Will order the parts needed to repair the amp, but still don¡¯t have a good reason for the QDX not trigging the amp, and/or causing the amp to fry.
The power supply used did clamp the current, but did not prevent the finals from blowing. I am not worried about repairing the amp, but how to have a QDX that works with an amp.
NT5AT - will
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On Aug 13, 2022, at 8:09 PM, Adam via groups.io <qrp-labs@...> wrote:
?Wilson Little <wilsonlittle66@...> wrote:
Bad News is that trigger the amp immediately caused the amp to fry, and
also killed a power supply. Using another p/s, the amp immediately
pulls 10 amps, triggered or not. oops... Something went way wrong.
Did you adjust the bias voltage (R5)? Amp shouldn't be keyed without
setting it to minimum (counter-clockwise) first.
Fortunately most probably nothing drastic happened, you just killed the
final transistors (Q1 and Q2, IRF510). It happens, fortunately they're
cheap and you'll be able to replace them. I'd also replace R5 and IC1
just in case, because failing transistors could've damaged them too.
It's a good idea to add a fuse between the PSU and the amp anyway.
