Good evening everyone, I have the same problem as Burt, but I bought the high band QMX already built, I did a few CW QSOs with friends nearby and everything was fine, then I transmitted for 10 hours in WSPR on the 10 m and it stopped delivering RF, now it absorbs 90 mA in reception and 190 mA in transmission, previously it was from 5 W to 6 W on all bands, the antennas are all single band with SWR less than 1, I don't know what it is happened, I also replaced the bs170, but the absorption remained the same, I hope some of you can help me.? thank you very much 73
Il Lun 4 Mar 2024, 17:40 John Z <jdzbrozek@...> ha scritto:
Burt, I'll check out you screen shots later. Thanks for posting them.
On Mon, Mar 4, 2024, 11:37?AM John Z via <jdzbrozek=[email protected]> wrote:
Burt,
That current draw in TX is quite low. Check continuity through L502.
In TX the four PA transistors will have an RF square wave signal at the gates . The magnitude of that signal is 5 volts and an oscilloscope will show that. As the duty cycle is 50% a multimeter will read 2.5 volts.
The primary side of T501 should have a DC potential in the range of 9-12 volts on each of 3 pins but during transmit the drain terminals will also have an RF signal riding on that voltage of approximately 45V p-p. At the secondary side? in TX you should see? 15-25 volts p-p RF voltage with no DC bias. These are all from memory and are approximate.?
Hope that helps and GL? 73 JZ KJ4A?
On Mon, Mar 4, 2024, 9:24?AM Burt Wizeman <burt@...> wrote:
Hey John, thanks for the reply:
All bands no power out. Verified that no input exists to the antenna tuner. 12 Volts for power.
I did a jeweler's loop inspection and checked continuity for the Transformers.? Was wondering what the voltage readings should be at the pads for T501 and T507.? Also, do you know the expected Bias on Transmit for QW503-Q506?? Will check C526 specifically.??
