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Mike, What you are seeing sounds like correct behavior to me for Q508 when in receive mode with RX at 3.3v. L502 holds the source pin at ground for DC, any received signal is in the microvolts, and

Stan, I’m seeing 0 on S and D, and 3.3 on the gate.

Keith, you should be able to get a good 4 or 5 watts out on that band. Have you tried adjusting the lowpass filter toroid windings yet? I would suggest that you start with L3 and spread the turns as

Mike, I can see several cold solders and tiny bridges in your photos. I suggest you clear those first. 73! de Bekir TA2RX 21 Nis 2025 Pzt 19:49 tarihinde Mike, KL7MJ via groups.io

Perhaps try checking Q508.? With QMX on in receive mode, you should see close to your supply voltage on both D and S.

I'm not sure about what the Farnell catalog shows, but the suffixes on the BS-170 by on-semi start with a D, and all refer to lead-forming and packaging (reel vs whatever).? Ones with no suffix are

I misread the value for L503, so I replaced it with a 47uH inductor, with no change in the receiver.

I concur with the previous recommendations. SWR into a dummy load from the QMX should show 1.0x:1 on the lower bands, increasing to perhaps 1.1x on the highest band.

I replaced L503 with a through hole 330uH inductor (I don't have any smd parts available).? It looks ugly, but I think there are solid connections to the PCB.? Unfortunately, the RF still isn't

Oops, I need to read more carefully before responding.? If you put the QMX+ in CW mode with wsjt-x receiving, you will see the CW filter bandwidth at a high volume.? This is because wsjt-x

The high-amplitude at 700Hz looks like you have I/Q mode enabled on the QMX+ . It must be disabled for digi mode use with wsjt-x

Hi Jan, Check the winding count of the transformer T507. Check for its proper soldering to the PCB.

My QMX Plus is approximately 25% down on the Test Certificate power, so I am looking to replace one of the BS170 FETs. The Farnell catalogue has many different suffixes to their BS170 devices. Should

Lee and Hans! I will see if I can find some info on these. I have made some experiment using the QMX USB output, which a feed through the proposed filter. The attached C-program runs on Linux.

Yes, I don’t hear it on my QMX HB either.

On 4/21/25 I had a CW practice / rag chew session on 20 meters. I worked no stations: Conditions were OK. SSN = 108, SFI = 156, A = 14, K = 5. I heard several very weak stations calling but they

Hans, Thank you. Peter LaRue AI7YN

Matti, please read QMX QMX_plus D109 ( /g/QRPLabs/wiki/37922 ). So you should use only (SMT) 3.6V 500mA. I don't have a QMX+ here in the moment. I'm not sure there is enough place to

Randy, in your situation VDD is basis to calculate the shown voltages. It is assumed VDD is 3.3V. Because of the existing difference the shown voltages are calculated wrong. To change something here

Kai, there is a way to check CLK2 from IC204. Use Terminal - Hardware tests - Rf filter sweep. As long as you are in this function CLK2 is on. Check voltage at IC501 and IC502 pin1 and pin4. Each