Petr,
There may be nothing wrong. The POWER control line originates at the U2
DAC on the front panel and is applied to Q5 on the RF Board.
You should check all components associated with Q5 to be certain of the
value and good soldering.
Since the POWER signal line is derived digitally from data out of the
MCU, it may be that the "problem" is simply one of digital resolution.
If the real value is in between 2 DAC steps, the POWER output signal can
vary between the two DAC steps causing the situation that you observed.
73,
Don W3FPR
On 5/10/2019 8:24 PM, Petr, OK1RP/M0SIS wrote:
Hi all,
so all TX part alignment went ok. All resistances, voltages and finaly power
re-peaking is in spec.
Also 5W test seemed ok until I noticed strange behavior > the power
fluctuation on key down as same
as after band switching...
Short vid is here:
https://youtu.be/lpf8GT09wv8
I am dissapointed as we thought to finish all work this evening successfuly.
I have no idea what could be wrong as I replaced K1-3 relays on band module,
checked all coils,
caps, also diodes on RF board... :(
Will be happy for any hints,
Mni thanks in advance.
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