On Mon, Jan 13, 2025 at 03:55 PM, Damon wrote:
The new PA’s were placed and I powered up again with 12v and current limited to 250mA.?
On the display, I have a blinking “6” low voltage alarm.?
Damon, blinking "6" only in TX mode or also in RX mode before try to TX or after try to TX? For TX mode 250 mA is much to low and the power supply will hit the limit. When the power supply is going below 6 V the QMX is disabling the PA, the current is below 250 mA again and the voltage comes up to the value from before. (Such a fast down and up of the supply voltage is dangerous for the QMX.)
12V rail at 6.68Vdc
How much external voltage?
6.68 V in which mode (TX, RX)?
Good VFO clock output from CLK0 & CLK1 into IC503.?
I guess you mean IC403.
Good and expected values shown from IC’s 501-503.
Like described in
QMX QMX_plus PA problems, broken BS170? With or without BS170?
PA’s dropping 980mV as measured at T501.
Dropping in which way?
980 mV DC or AC rms or AC pp or what?
Measured at which point of T501.
What is your oscilloscope showing at the drains of the BS170 (AC and DC, RX mode and TX mode)?
?
73 Ludwig
