Re: question 50 watts amp
Many thanks Bojan for the information.
Good to hear it works fine.
I would like to make the QMX with PA ?my second station besides my IC7300.
The main reason is the full break in, i really like this.
?
73 hanz
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Re: question 50 watts amp
Many thanks Adam for the information.
?
73 hanz
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Here's what I would recommend assuming you're doing CW with the QMX:
?
Battery: This is all pretty low power so you can get away with as little as 3AH of power which will get you more than a couple hours of time.
?
Key: Bring what you know how to use, I will say that using a key made to be taken out in the field is a good idea. You can use a "desk" key but you might not like it.
?
Headphones: Whatever you like here.
?
Antenna: I highly recommend bringing a resonant end-fed antenna - something that will get you 10/15/20/40 or similar. I like the K6ARK if you can get them. They're easy to get one end up somewhere but remember to bring a mast or some throw line (you can use a weight you bring or a rock you find).
?
Tuner: If you do not bring a resonant antenna, you will need a tuner like the Emtech ZM-2 (a personal favorite). Don't forget a patch cable if you use a tuner.
?
Other:
- You might want to bring a short length of coax to connect your antenna to the radio. Here's my own thoughts: if using an end-fed with a counterpoise, you can either use no coax or coax with a choke at the feed point. If you don't have a counterpoise, connect a bit of coax. The QMX is less than 5W but being gentle with it is good practice.
- Bring extra connectors and adapters. You might not "need" it but if you have them with you it's very easy for you and a buddy to try out each others stuff on Field Day or something.
- Make sure you can log effectively with all your little fiddly bits up and running and a key in your hand(s), a kneeboard style writing surface is very popular.
- Test everything beforehand. Everything. Don't just connect stuff, turn it all on and use it including logging contacts. Do it in the mud.
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Len - a PD capable powerbank 20,000 mAh will provide 36 hours of listening time. Less time if you are the object of a pile-up.
I do like my EFHW antennas, but it's a bit of work to get them high in the tree, if that is even an option. You could try starting with a cheap ground mounted vertical. Inductors can be built or purchased for this antenna...
72 es POTA on de va3rr
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On Thu, Jan 9, 2025 at 01:02 PM, Len wrote:
- battery
- antenna
- tuner
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Re: QMX - Power supply off line test Process
Stan, thanks for your impressions. I will check voltages on Q110 and Q111 also on Q101 and Q102.
Osvaldo LU3MAM
Something is wrong with your 3.3V input regulator circuit.? Inspect carefully for solder blobs or shorts, near the connector pins you soldered or anywhere else - it should not operate this way.? ]
?
1. Measure the voltages on each terminal of Q110 and Q111 when lin_reg_en is grounded, and check to see if pwm_3v3 is floating high (it should be 0V) - maybe somehow Q109 is getting enabled (activating the switched mode supply) like is supposed to happen in Step 3, and you are transferring the input voltage to VDD.
?
2.? Otherwise, VDD should never be able to go above 3.3V - it is the output of a 3.3V regulator, IC101.? But it seems to be regulating fine when you did step 1, so something in step 2 is causing the input voltage to be shorted to the output.? Q101 should turn off Q102 when lin_reg_en is grounded, preventing any voltage from getting to VDD (unless Q109 is on, which it should not be).? So something is not right here.? You can check the voltages on each of the terminals of Q101, Q102, and IC101 when you ground the lin_reg_en pin.
?
Stan KC7XE
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Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
The 833 Hz is low-frequency oscillation, likely being generated in IC202. R207 (470K) is providing a DC bias at the input of the gate which can cause the gate to operate in its linear region, acting as a high gain amplifier rather than a logic buffer. I’m not sure why this gate has a feedback resistor as we never do this for logic gates for the very reason we don’t want them operating in the linear region.
It's a quite common technique to effectively DC bias the gate's input at almost exactly the midpoint between it's 0 and 1 input voltage thresholds. An AC coupled small signal connected at this input is then very well "amplified" by the gate, with very high gain, converting it as perfectly as possible to a 3.3V square wave. It's very effective.?
If there is no input signal at all, the gate will oscillate at some extremely high frequency, somewhere at VHF. But as soon as even a small input signal is applied, the gate locks onto it and amplifies it near-perfectly with very high gain (creating the square wave). Which is another way of looking at it.?
You will find in QMX if you remove this resistor, the gate will probably not operate. Zero output. Or certainly not reliably. Because now the small signal from the TCXO (about 1Vpp) is centered on what? Zero maybe? You have to provide some DC bias. You could put 1M to ground and 1M to Vdd or something. It would probably also work (modern CMOS are quite symmetric). But a better way of achieving the same thing is the feedback resistor.? 73 Hans G0UPL
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Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
Hi Adam
Downstream of IC202 there isn't any "almost", this is the very reason why IC202 is there. You will have a 3.3Vpp output at IC202 output.?
Can you take a similar video please for the signal at IC202 output?
I'm still having trouble trying to convince myself that the 25 MHz TCXO is at fault here rather than - sorry to say it - some weird artefact introduced by the measurement itself (at the TCXO output / gate input).
73 Hans G0UPL
Hans Summers via <hans.summers=[email protected]> wrote:
> Several things I don't understand. I asked about if you could connect just
> because I wanted to know if the USB connection was working; If it is, that
> kind of means that the 25MHz signal must be present.
It's working and stable. But the 25 MHz signal is present. That's why the
waveform lines are "thick" -- it's because of the 25 MHz signal, it
appears when I zoom in.
The problem is that the 25 MHz signal is modulated by this weird, ~833 Hz
one. So it's severely distorted. The scope's time base on these photos was
set to show this low-frequency modulation.
Here's a video of TCXO output (before the gate) when I switch the time
base:
Maybe it's enough for the PLL in the CPU to lock, but *almost* enough for
the PLL in the sync chip (so most of the time it's locked, but falls out
of lock here and there, and that's why CLK outputs are momentarily
disabled)?
> It looks like the vertical division on your 'scope is 100mV/div in which
> case the waveform also isn't the 3.3Vpp expected at the logic gate
> output... so are you sure of your measurement? It's confusing to me...
It's correct. I set the switch on the probe to 1:10 (to have greater
impedance of the probe), but forgot to switch it in the scope's menu, so
the scope still thinks it's 1:1.
So it shows 100 mV / div, but in reality it's 1 V / div.
In the video above it's set correctly and shows 1 Vpp (but it's TCXO
output, not gate output -- gate output is around 3.3 Vpp).
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Re: Ultimate 3S reciever question
Ian,
So I wouldnt need bpf for each band. Unless of course I needed to filter out other radios TXing in the shack.
--
regards,
Bryan, N0LUF
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Re: QMX - Power supply off line test Process
Something is wrong with your 3.3V input regulator circuit.? Inspect carefully for solder blobs or shorts, near the connector pins you soldered or anywhere else - it should not operate this way.? ]
?
1. Measure the voltages on each terminal of Q110 and Q111 when lin_reg_en is grounded, and check to see if pwm_3v3 is floating high (it should be 0V) - maybe somehow Q109 is getting enabled (activating the switched mode supply) like is supposed to happen in Step 3, and you are transferring the input voltage to VDD.
?
2.? Otherwise, VDD should never be able to go above 3.3V - it is the output of a 3.3V regulator, IC101.? But it seems to be regulating fine when you did step 1, so something in step 2 is causing the input voltage to be shorted to the output.? Q101 should turn off Q102 when lin_reg_en is grounded, preventing any voltage from getting to VDD (unless Q109 is on, which it should not be).? So something is not right here.? You can check the voltages on each of the terminals of Q101, Q102, and IC101 when you ground the lin_reg_en pin.
?
Stan KC7XE
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I can tackle this but remember, YMMV.
- I am using battery packs purchased on Amazon.? I have "AA"
packs, 8 cells for 12v and 6 cells for 9v.? I am using
rechargeable lithium 1.5v cells.? The 12v pack puts out 12.1v
and the 9v pack is very very close to 9v.? The nice thing is
that these batteries maintain voltage pretty much until they go
dead.? Don't go super cheap on the rechargeables.? Look at the
reviews and spend a few more buck if need by.? Contact me
off-list if you want links to what I am using.
- 20-10 meters I use a vertical whip, ground mounted, with 5
ribbon wire radials.? Not quite the equivalent of 30 radials but
it works well even with low power.? NO loading coils and NO
tuner needed.? You merely lengthen and/or shorten for the
appropriate band. For the QMX you will want a way to check SWR
for multiple bands.? For QCX, you'll probably be fairly close if
you set up the same way each time.? You will need to determine,
at least initially, the appropriate lengths using an analyzer.?
Then you can verify at half power or so, at least on the QMX to
be sure your SWR is good.
- 60-40-30 meters choices are End Fed Half Wave (EFHW) or a
dipole.? Linked dipole will give you multiple bands.? Dipole in
inverted V configuration is more efficient than an EFHW, and
better suited for NVIS (near vertical incident skywave) for more
"local" communication at a few hundred miles.? Personally, I
rarely get on 60m or 40m and occasionally operate 30m if
conditions dictate it.? With a dipole I also recommend using a
1:1 current balun (not a voltage balun).? Common mode
currents on your coax can change your SWR every time you touch
your radio or your key (ask me how I know!)
- Leave the tuner at home.? You're working QRP and you want to
get as much signal out as possible.? Use resonant antennas that
match the frequency your are operating.
Of course one thing to keep in mind is
that asking these things opens a can of worms.? You will have as
many opinions as there are operators on the forum. ?Yes, many
other configurations will work.? You can use random wires and
tuners and they will work.? But I recommend staying away from
setups that take a very small signal and immediately reduce it by
50%.? Remember, only 3 dB of loss represents half of your output.?
A typical QRP labs transceiver will put out 4 watts, give or
take.? Why reduce that to 2 watts before your signal leaves your
site?? I speak as a very experience portable op with over 10,000
QSOs in the log in 2023 and over 8000 in 2024.? 2024 was 100% QRP,
so I think I can speak with a little authority on the matter.
BTW, the QDX and QMX are awesome rigs
for digital work in the field as well.? FT4 & FT8 for POTA
will rack up contacts pretty quickly if you do it right, even at
just a few watts.
72
Charles - NK8O
On 1/9/25 10:43, Len via groups.io
wrote:
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Show quoted text
?
Firstly...apologies to all for such a newbie question, but I
only just ordered a QMX and am just now learning CW :)
?
I was hoping to put together a rig for POTA while doing AT
section hikes and was looking for recommendations for:
?
- battery
- antenna
- tuner
- plus anything else that I haven't even thought of yet :)
?
Thanks!
?
Len S
KC3PWB?
--
Len S
KC3PWB
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Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
Adam,
The 833 Hz is low-frequency oscillation, likely being generated in IC202. R207 (470K) is providing a DC bias at the input of the gate which can cause the gate to operate in its linear region, acting as a high gain amplifier rather than a logic buffer. I’m not sure why this gate has a feedback resistor as we never do this for logic gates for the very reason we don’t want them operating in the linear region.
Tony
Hans Summers via <hans.summers=[email protected]> wrote:
> Several things I don't understand. I asked about if you could connect just
> because I wanted to know if the USB connection was working; If it is, that
> kind of means that the 25MHz signal must be present.
It's working and stable. But the 25 MHz signal is present. That's why the
waveform lines are "thick" -- it's because of the 25 MHz signal, it
appears when I zoom in.
The problem is that the 25 MHz signal is modulated by this weird, ~833 Hz
one. So it's severely distorted. The scope's time base on these photos was
set to show this low-frequency modulation.
Here's a video of TCXO output (before the gate) when I switch the time
base:
Maybe it's enough for the PLL in the CPU to lock, but *almost* enough for
the PLL in the sync chip (so most of the time it's locked, but falls out
of lock here and there, and that's why CLK outputs are momentarily
disabled)?
> It looks like the vertical division on your 'scope is 100mV/div in which
> case the waveform also isn't the 3.3Vpp expected at the logic gate
> output... so are you sure of your measurement? It's confusing to me...
It's correct. I set the switch on the probe to 1:10 (to have greater
impedance of the probe), but forgot to switch it in the scope's menu, so
the scope still thinks it's 1:1.
So it shows 100 mV / div, but in reality it's 1 V / div.
In the video above it's set correctly and shows 1 Vpp (but it's TCXO
output, not gate output -- gate output is around 3.3 Vpp).
|
On Fri, Sep 8, 2023 at 06:27 AM, terps707 wrote:
the biggest powerboard get really hot ..Coil 331 start smoking after 5 second.
This means you have a strong short on your VCC (5V) supply.? Something has failed internally.? If you are lucky, it is just a component on the SMPS board.? Some potential shorts happen due to the close spacing between the display board and the smps board components.? 12V and 5V goes to the display board, and if the little black mounting tab didn't get bent down far enough, or the long row of display connector pins didn't get trimmed enough, they can short with items below them.
?
You need to inspect for such potential shorts, and also measure the resistance between the VCC(5V) and GND on the main board (with smps removed).? Also measure resistance between VDD (3.3V) and ground with smps removed.? Both of these should be a few kilo-ohms, if either one is much lower, it indicates a short or failed component on the main board.
?
Note that sometimes a mechanical short, like describe above with the display board, especially a short between 12V and 5V, can cause the 5V supply coil to 'burn' as you have described, as the 5.6V zener diode tries to sink all of the current.? If shorted for a long duration repeated several times it can 'blow' that diode, which can then result in failure of 5V components on the main board (mainly the receive circuits).
?
Good luck - Stan KC7XE
?
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On Thu, Jan 9, 2025 at 10:02 AM, Len wrote:
?
Most? know of that hike the AT go for minimum weight
as basic supplies food, and, water, and shelter take precedence.
?
SOTA, IOTA, you have to carry in everything..and out
so weight is a consideration.
?
For POTA, weight generally is less an issue, sometimes.
?
HINT: pack everything you _think_ you need and set up
in the back yard for a few hours.? I have seen people
do this and find they needed an adaptor, cable, mic, or
adequate clothes (too cold) or sun protection
(umbrella or sunblock).? Make a list of needed items
(every last little thing).
?
?
So your list:
- battery
?
How big, for how many operating hours?
Rechargable and how to do that?
AA alkaline cells as they are available anywhere.
?
- antenna
?
keep it simple 20M and maybe 40M.
Plus cord to support it.? A way to get it over a branch.
Dipole or end fed half wave (EFHW) are the common choices.
A vertical may be used but allow for significant inefficiency.
?
- tuner
Depends on antenna and if its more or less sensitive
to how its deployed.? Tune if it in a real world
configuration.?
?
Use a simple manual unit with built in SWR display.
Auto tune is more weight and spare battery?
?
Maybe a 25-30ft collapseable mast for setups where
carrying it far is not needed but trees are scarce.
?
coax RG174 for weight, adaptors for BNC and Pl-series.
RG58 or RG8X is weight is not an issue. Bring about 20Ft!
?
- plus anything else that I haven't even thought of yet :)
?
headphones, key,? for FT8/data you need a computer(weight and battery)
with cables.
?
Packing material, bags, box or waterproof box as needed
Pack frame and pack for longer trips.
?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Holiday season and family time slowed things a bit but i was able to finish speaker enclosure to acomaccompanie the main case for my qmx+. Amplifier module is TDA2030 and speaker is from old Compaq branded pc. Decent sound power and nice base for the size.
Selection of free files to print will be available this time tomorrow.
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Re: New silicone enclosure feet
Hi John, all Thanks, but $16 shipping for a package of pads and QCS + power button cover??
QRP Labs shipping has always been charged at - as close as I am able to estimate - actual cost.?
FedEx shipping for 1 gram is the same as for 500 grams. It goes in 0.5kg increments. Note that we have pretty good discounted rates at both FedEx and DHL Express due to guaranteeing to ship several hundred packages per month with each. For an individual walking into a FedEx office in US you'd pay more for shipping an item domestically than we do from several continents away.?
DHL Express is the same - 500 gram increments - (and around 50% more expensive than FeeEx in the case of US shipments).?
Post office airmail used to be a good option. But 5 years ago the then US president unilaterally withdrew the US from the International Postal Union agreements on international mail pricing, allowing the United States Postal Service to charge whatever it wished for "last mile delivery". Airmail prices to US tripled overnight, becoming more expensive than our FedEx rate. Several other countries followed over subsequent years. Since Covid19 the global airmail systemed seemd to also got very unreliable (slow and lost packages). To most destinations it's now more expensive than the couriers, as well as very slow and unreliable. That's why we no longer have post office airmail as an option on the website.
So yes - there isn't anything I can do about it - but sadly it isn't likely to be worthwhile for anyone to order a set of sticky feet on their own. But they're there for someone who may wish to add them an existing order.? 73 Hans G0UPL
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Re: New QMX+ build not powering up/accepting new firmware
Do you have a DMM or other method of measuring the Voltage and Current from your battery?
The voltage and current before you press power-on, while you are pressing it, and after you release it are very interesting to help diagnose problems.
The click in your speaker is probably normal.
If you haven't done so, try a USB-A to USB-C cable that you have verified supports data (many are for charging only).? Some have reported problems when using a USB-C to USB-C cable, depending on the computer.
Also, carefully check all the connections between the front panel and the main board - perhaps you are not getting VCC to the panel, so it is not showing anything.? If there is no firmware loaded, it is normal for the display to be dark/no data displayed.? But QMX+ kits shipped in the past few months have had firmware pre-loaded.
Stan KC7XE
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3x18650 cell pack. I use 3200mAH ones.
homebuilt 40-10m doublet antenna fed with 300 ohm line
something like the EMTECH ZM-2 QRP tuner
?
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Re: Ultimate 3S reciever question
Now,? does one need 2 of the 6 band relays to be able to switch bpf and lpfs together? or can only one or the other be controlled in operation??
--
regards,
Bryan, N0LUF
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Go to YouTube. Search on ham radio sota. Spend hours watching. Lots of good stuff
Ed
AB8DF
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Re: Ultimate 3S reciever question
Should work fine Bryan.? I have been very impressed by the receive module.? I am currently using it with no front end filtering for receiving wspr and FT8 with no problems. I am using an auduino controlled vfo but Hans' vfo would be fine.
?
Regards
Ian G3VAJ
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hanz YL3JD
Jason KE8WSI
va3rr
Dan
Ivica - YU1QRP