😂

Bipolar stuff

yes

Thank you

Thanks

The same here 😑 When I saw Peter with the hammer I thought Peters VSWR went off the scale 😵‍💫😎👻☘

Thank you my friend!

Glad to hear that!

thank you!

fully agreed

Thank you

Thank you. I agree, but you do not find always a reason for a fail, you should know that. In this case, we assume a failing part by normal selection in the first half year after taking the unit into service. We all know that this is consumer electronics, and vendors don't buy parts which were running through a binning process for a lot of money. Bias don't get tracked in this design. We have a fixed Bias level for MOS FET's. The varistor is taking the environment temperature and it is an adjustment question only to track the temperature.

Thanks for the explanation. 73@@TRXLab

Exactly what I'm wondering too. Xiegu isn't know for handing them out. At least not for the G90.

Of course lol

lol

I refer to them as "Fleas"

Very easy, follow my explanations. What you see is the reaction of pushing the on/ off button and the MCU which is switching off. That is consequently the collector voltage at the digital transistor.

No, it is not a stronger MOS FET needed. If you watch the current capability of this part, you know that it is only a fraction of its capability which this FET has to handle.

@@TRXLab that is absolutely true, in normal operating conditions. But at startup, when all the electrolytics on board are empty, the switched current is brutally high for a few microseconds. It's enough to overstress the junction of that switching MOS.

Hello Steve - Not too sure if you are correct. Hers is a list of the XIEGU XPA-125B PA's features. 1. Built-in Automatic Antenna Tuner: The automatic antenna tuner and power amplifier unit of XPA125B can be used independently of each other as either an automatic antenna tuner or a separate power amplifier. The tuner handles 14-500 ohm loads in the HF bands 1.8-30 MHz and 6-meter band 50-54 MHz. 2. 100W Power Output: The XPA-125B is the perfect amplifier for QRP radios or SDR transceivers with low power consumption （like a 5-watt transmitter） when 100-watt output is needed. Its maximum power output is 125 watts. 3. Safety & Protection: The XPA125B has a variety of intelligent protection circuits to ensure the safety of the amplifier and connected transceiver. When abnormal operating conditions appear like SWR is too high, too much drive power, or too high temperature, the amplifier enters bypass mode and displays an alarm message. 4. New Enhanced Version: After improving its shape and size from XPA125, it is smaller than the old version and can be worn on a bracelet like a small bag. 5. Large Screen Display: The 2.7 inch large backlit LCD display shows input/output power, SWR, Voltage, Current, Temperature, amplifier status as well as warning messages making the operation of this modern amplifier simple and also user friendly. 6. Note: The XPA125B is with FCC & CE certificates. FCC ID: 2ANLH-XPA125B1 Looking at the circuitry it looks like a very well designed and built amplifier. I have recently bought the Xiegu G90 Transceiver, and to be honest it's one fabulous rig especially on CW which is why I bought it, the filtering is really great as is the sensitivity of the SDR RX. 73 de EI6DO

in this case, normal selection during warranty.

It is a very well-designed 100W PA. There is nothing complicated nor useless simply good stuff.