Oops, never mind, I can't read.? Didn't notice that there are both SMD and axial 47uH ones.
--
Cheers,
Chuck

While working on my intended LPFs I've also looked briefly at an LPF for 80m & 60m. A quick linear simulation using QUCS shows that close to 20dB attenuation at 7MHz might be possible for 0.6dB insertion loss at 5.45MHz. (Circuit attached). This might be worth more effort.

But of course it is just a linear simulation, and the QUCS response plots assume a 50ohm Thevenin source impedance. In practice an RF PA output stage isn't a 50ohm source impedance. So the real response is going to be different. So what's the best way to model the QMX RF PA output in order that (theoretical) harmonic levels at the filter output can be calculated?

If this is the one you need?



--
Cheers,
Chuck

I asked GPT4 and it gave me a complete code segment written in C using the Hilbert transform, which creates a 90° phase shift and mixes it with original signal. I'm not a C expert so can't say how valid the code is.

Paul DJ0CU G4ADF.

On Thu, Aug 31, 2023 at 07:53 PM, PHILIP GRAITCER wrote:

D103 ? 2.426 when unit on instead of -3.3V ?as you suggested.
Grounding the 78M33 (middle pin) turns the unit off

Phil,

The output of D103 should be "approximately" 3.3V (that's not a minus sign) and 2.426V is way on the low side. Grounding the LIN_REG_EN pin and turning the 78M33 OFF is good. Does it stay OFF when you remove the grounding ? That would indicate control had been handed to the processor and it enabled the 3.3V SMPS.

Speaking of firmware and loading new firmware have you reloaded the latest code AND checked the USB-C connector for good solid connections.?Hans recently released video (52 things....) shows relatively good soldering on the 16 USB-C connector pins but there are apparently a number of boards out there which are not nearly as well soldered and have "iffy" connections. I have posted details in other threads. The reason I call it an "iffy" connection is because the GCT USB4085 connector has 62mil length pins and the board is about 62mils thick. The pins also measure 0.15mm x 0.22mm and the plated via hole is 0.40mm+/-. That's not like "a BB in a rain barrel" but it does indicate good solder wicking between the pin and the via barrel is required. Since soldering those 16 pins is very difficult for the manufacturing facility it generally picks up a little solder from the via barrel plating ......but many times there is too much space between the via barrel and the pin. The result is poor or no electrical contact. Fortunately the 16pin USB-C connector is "reversible" and there are 2 pins for each signal which Hans wired together on the artwork ....so the chances of making a "good connection" are better but not 100%. Sure hope I didn't confuse anyone more.... just trying to help.

73 Kees K5BCQ

Ron,?
I failed to ask in the last post... how did you derive that value to set?

Presumably when ssb is implemented other modes like psk31. and the like will become available?? or am I on the wrong track?
. Paul DJ0CU G4ADF?

This might give some idea:

It is already done.

73

Barb WB2CBA

Pretty sure the idea is to use an EER (envelope elimination and restoration) technique similar to what Guido PE1NNZ implemented on his QCX modification and later (tr)uSDX. There's a big thread here talking about: /g/QRPLabs/topic/29572792
--

73
Andrew KI7FXL

I know it's not implemented yet, and it's unknown if it ever will be, and
I have very little interest in SSB anyway, but I can't help to wonder.
What is the original idea?

There's a synthesizer that can produce a single frequency, and a way to
modulate this frequency with amplitude modulation, and that's really all
there is.

Is it even theoretically possible for the MCU to do some magic with this
modulation that will result in voice on a USB or LSB, without any other
hardware tricks?

My QMX kit arrived with the short in place. ?

I removed Q104 (the little one) and the pad was still shorted to Q103’s tab. ?

Using just a soldering iron I first lifted Q103’s two leads. ?Then I heated the tab until I could pull off the part with tweezers. ?

At that point the pads were no longer shorted. ?

I reinstalled the devices at the edges of their pads to increase their spacing. ?All is well. ?

I had no problem with the procedure using just a couple of Metcal soldering tips, one small and the larger one for the tab. ?

Disclosure: ?I did this work using a 7 power stereoscope. ??

Jerry
N6JH

开云体育

OK, but how is FT8 a beacon mode? ?Just call CQ and never answer, and then scrape spots off pskreporter or some such? ?Or are you listening for FT8 and doing some kind of reverse beacon thing?

Andy it's exactly what they are guaranteeing they won't do, but that is off topic so won't expand further.

I uploaded photos of my soldered QMX boards and asked it to check for problems, solder bridges, out gave me a whole raft of tips where to look regarding Rx problems, so yes it's very much on topic with qrp-labs.

Thanks for you ticket reply to my question, Hans. I've ordered one of each Progrock2 and QLG2. It would certainly be considerably cheaper than the alternatives! They will be boxed with a stable psu and I will see if buffering and filtering are required. Would be a great solution for Pluto based QO100 transceivers where even with a new, high stab tcxo, on tx it still drifts.

Regards,

Roger (G8VLR).

Yes Bob but before 2021, where exactly it was trained is a bit of a secret, but for sure the internet as well.

Paul DJ0CU G4ADF?

My impression is that is due to the QMX reporting a 3200 Hz receiver bandwidth, i.e. the digi bandwidth, instead of the actual CW bandwidth.
Gary
W9TD

Hi Willie,

Thanks for prompt response!

I will try to expand current scenario, are you sitting comfortably? <grin>

Short version:
During the monthly beacon team meeting last night mention was made of a paper being presented at the upcoming IARU Region 1 conference (screen shot of title page attached) which discusses using FT8 and that our project team should revisit the modes we intend using.

As an aside, one of our VHF beacons is being used for meteor scatter research by several hams and the plan is to try and optimise the mode(s) being used to help support their efforts.

Am looking forward to further feedback on this forum for sure!

73

Nigel ZS6RN ex G8DEV