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Im building? the U3S now and was thinking of dropping the 5v main through a diode to the super cap pads with the idea that as long as its plugged into power, it will hold its place.

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Does this sound reasonable?

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I read about using a coin battery, say a 2032 but at 3v that seems kinda on the low end. I did try a 2 AA holder on my qrp-labs clock, but voltage drop thru the diode allowed even lower voltage and only a short while of support. By morning the gps had to start from scratch anyway, so I dropped that idea.. Maybe my AAs were on the way down already. Or my diode choice had too much leakage??

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regards,
Bryan, N0LUF

Thanks for getting back to me!?

No practice mode is disabled. I’m able to transmit when I plug into my laptop no issues.

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I will briefly see the microphone icon in the upper left of my phone, so I’m pretty sure the receiving side is good to go.?

I shouldn’t hear any sound right? That’s not just an artifact of iFTX?

Skipping past "no one will ever hear the difference at the other end"

You could certainly build a more powerful power amp stage into the QMX circuit.? ?You might find yourself upgrading other components (LPF's, TX RX switching etc).? ?From my experience the 10W linear is not flat gain over the full HF bands so programable or frequency contoured attenuation might still be needed and that might need a T501 /buffer/amp stage.? ?The power control part will certainly need re working and that's probably not as easy as it sounds

Overall I think you'd need to build the QMX board into the same box as a PA board and that would make it a lot less neat and tidy and considerably hotter so throw a fan in too.

So in short - just connect them together? NO
Just bridge the 10W pa board into the QMX plus PA stage space? ?Complicated
Remove the 10W PA's drivers and feed the QMX+ PA output there before returning to the switched LPF's Also complicated, still needs adjustable /contoured attenuating etc?

In short if you want to use the QMX+ and 10W PA circuits /boards as the source / inspiration for a quite complicated project and have the necessary knowledge and test gear it is possible to build a 'QMX+10W'? ?However if you have the necessary knowledge and test gear you probably wouldn't need to ask? . .?

Lets end with "no one will ever hear the difference at the other end"

I’ll ask the obvious: is CW “practice mode” enabled? That’ll prevent transmit.?

2nd thought
we lose the amplitude modulation
use transistors with lower voltage
it is solveable
73 DE muhsin TA1MHS

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Hi
What if
You take the power transistors out?
and?
use 74ACT68D's output to drive the 10Watt PA?
Through the LPFs of course
73 DE muhsin TA1MHS

Thanks Ron! I sent you an email so we can set it up.

On Tue, Feb 25, 2025 at 06:16 PM, Corey KC9RAV wrote:

assembling a QRP labs kit doesn’t require ESD protection. It doesn’t hurt, but there isn’t any major ESD risk.?

And that is why some people have failures in their assembly, or after operating for a time (due to a weakened part).

There is indeed ESD risk.

Yes, the ESD risk is minimized since most of the parts have ESD protection on their input pins, and are pre-assembled onto the CCA.?

And the risk is not as critical (like Jerry mentioned) since we are hobbyists, not making mission critical gear - and we can easily fix it if it breaks.

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But the highly integrated parts in the Q*X with fine internal lithograpy (all of the ICs except the 3.3V regulator) can indeed be damaged with careless handling.?? ESD may not cause failure immediately, but may weaken a part that may then fail later.? Yes, even with the ESD protection on their pins - it just takes a larger ESD event.? The pins are typically ESD protected to 2000V, which protects well if handled carefully.? But picking up a styrofoam coffee cup from your work table and brushing it against the cuff of your shirt can generate well over 20,000 volts of static on your hands - then touching one of those devices without discharging yourself will indeed damage it.? Thankfully most of us don't use styrofoam on or near our work surfaces, but many other materials, including carpeting, the covering on your chair, your chair's roller wheels, and even your clothing can readily generate high static charges, unless these materials are of the anti-static variety.? And how many of us have checked??

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Sorry for the tirade, but I had to take ESD refresher training every 6 mo during much of my career.? And it was interesting to learn of the common materials and simple body movements that can generate static tens of times greater than the typical 2000V ESD protected device can withstand.? So unless you know you are safe, use an ESD mat and ground yourself after moving or wear a wrist strap.? Assembly areas where I worked have chairs and floors that are known not to generate static.? And we still had to wear our wrist bands or shoe straps, and work on ESD mats that were tested and qualified every 3 mo.? Yes we worked on mission critical devices, and we had to avoid all ESD risk, unlike hobbyists.?

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After the item is assembled, the risk is lower, because there are many paths to dissipate ESD, and you usually don't directly touch an ESD sensitive device without previously discharging the ESD through a benign path.? And maybe that's why we don't often kill the ICs in qrp-labs kits.

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But please don't believe that there isn't any ESD risk unless you are specifically minimizing it in some way.

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Stan KC7XE

My two cents, assembling a QRP labs kit doesn’t require ESD protection. It doesn’t hurt, but there isn’t any major ESD risk.?

On Tue, Feb 25, 2025 at 11:24 AM, Stan Dye wrote:

On Tue, Feb 25, 2025 at 05:17 AM, spaine wrote:

A good ESD work surface is conductive

The correct word here would be "dissipative" - something that quickly dissipates static charge, but has a very high resistance to normal electrical currents.??

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As Allison said, inexpensive ESD mats are safer, and they are easy to get and use.? And even the $20 ones on Amazon, complete with wrist strap, will last a very long time.? I encourage all assemblers of qrp-labs kits to get one and use it.

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On Tue, Feb 25, 2025 at 05:43 PM, Bryan Curl wrote:

the 1mohm resistor Don Brant mentioned is important for the purpose of allowing static charge to go to ground somewhat slowly in order to not make a spark.

It is also a personal safety item, in series with the wrist strap it limits your current to ground in the event you contact a hot wire; it is best not to have a grounded conductor around your wrist when working with electricity.

73, Don N2VGU

I too have bought bad Chinese irons.? The first one I bought showed the "intended" temperature,

from the moment you plugged it in, giving no idea how hot the tip really was.

It was also too weak to deal with something like the QMX ground plane connections.

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This one addressed both those issues: ?

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A well chosen Weller or Hakko might work better, at 10x the cost.

There might well be Chinese irons out there that are of equal quality, but not at $16

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Jerry, KE7ER?

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On Tue, Feb 25, 2025 at 01:43 PM, Bruce Akhurst wrote:

In a high value manufacturing environment, you do everything you can to avoid static damage.

Even rarely occuring failures can cost big money, perhaps even the loss of a large sale.

I think most hobbyists are a bit more relaxed than that.

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I'd bet an honest survey of Q*X kit builders would find that less than half have a static mat.

Most of the parts we use are either not inherently sensitive to static or they have protection

devices at each IO pin.? Protection is typically a Schottky diode from pin to ground and another?

from pin to Vdd, these discharge any hit that exceeds normal signal voltages.

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I guess the most sensitive part that we regularly work with would be the gate of the BS170's.

Be especially careful with static control when replacing those.? Once parts are soldered down

to the board, they are usually connected to other stuff that helps discharge a static hit.

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When I approach sensitive gear, I first touch a ground point to bring the device to the same potential?

as my body.? If static is in the air, I continue touching that equipment ground while working on it

as much as I can. Static sensitive parts such as the BS170's should be kept in the anti-static?

bag till you are ready to solder them into place.? If you first touch the bag (perhaps to open it)

before touching the sensitive part, no damage will occur. Then with the other hand I'd touch

the equipment ground before bringing the part to the equipment.? If you follow procedures?

such as this, most hobbyists should not have trouble with static damage.??

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My workbench does have a static mat, but I am not always at my workbench.

When at my bench, I generally don't strap in with a wrist strap, but instead lay an arm across

the static mat to establish a connection.??

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Now retired, but at work in an engineering environment, we generally followed procedures

like those above without getting yelled at.? It was generally our own design, and if something

were to fail we were well qualified to fix it.? I can't think of a single case where I felt I had

caused static damage over several decades of work.? Procedures in manufacturing

were somewhat more strict.

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When designing a board I often add a series resistor of perhaps 100 ohms to each sensitive

IO pin that goes out to a customer accessable connector if that won't compromise the intended

purpose.? The combination of the series resistor plus the protection diodes makes it pretty much?

bullet proof, unless they plug that wire into a wall socket.

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Jerry, KE7ER

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I had to use 4.6.2 hamlib it solved my QMX issues 4.6.1 hamlib QMX is broken.

Hi Justin. I’d be happy to repair that for you if you like. I’ll write you off the group with details.?

Ron

Hey all!

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Just got a cheap lightning to usb “camera adapter” to try to do some ft8 while on lunch break using iFTX.?

I’ve noticed I can receive and decode ft8 no problem, but when I call cq audio only comes out my phone and doesn’t go into the radio.?

I have VOX enabled and all other settings are standard. Is there some config item in the radio I’m missing?

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72

Jeff

KB3TVP

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Adapter in question:

IVSHOWCO Lightning to USB Adapter... https://www.amazon.com/dp/B09H2PZTG2?ref=ppx_pop_mob_ap_share