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Re: 10 watt linear HF amplifier - stability issue/question #10W_PA

 

Thank you all for the information and knowledge you shared, I really appreciate!
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Laszlo
Re: QMX+ High Current and Self Start

 

The 80/60m LPF has a temporary 10uH in place for testing until replacements are ordered.?

Q105 source (left leg) or Q104, I did initiate a power on by probing D101 with my DMM as well.?

JP102-7 is open line and short with encoder press. JP102-1 remains open line.?
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I will report back on the startup findings…
Re: New Build but can’t get firmware to load

 

I’m probably about to get yelled at but I have to ask. Theoretically speaking, could excess flux cause a short?

Re: QMX+ High Current and Self Start

 

On Mon, Sep 16, 2024 at 07:02 PM, Damon wrote:
So, What in the world would cause the PA’s to be gated and dump all that power to overload?
Damon, with default settings the PA voltage is high in RX mode (see here). With one problem in the PA stage a current may flow also in RX mode.
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Additionally, pressing the encoder to turn the radio on does not work. I actually have to press my fingertip to Q105 to latch it on. Pressing the encoder to power down the radio “works” but there is a current draw of 0.065A until I remove the plug. Trying to restart the radio does not work until it is unplugged.?
I guess something is wrong related to QMX QMX_plus Startup section 2 #1 and section 3 #3.
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I’m starting suspect IC503 and the MCU. I’m not wanting to reinvent any wheels so any and all advice to move forward is graciously appreciated!
Thats not my first place.
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Further tests show poor 80/60m performance and there is a significant voltage drop compared with the other LPF’s.
Read QMX LPF section for debugging the LPF section.
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All together it looks to me like more than one failure. So a remote debugging is very difficult. It would be good to sort out one of the problems to start. I think the best is to start with the switch on / off problem.
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Like I wrote before
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QMX QMX_plus Startup? from the QRP Labs Wiki contains a description for the switch on process. Following this you may find the wrong part. I guess there could be something wrong around Q103...Q105. I would check Plug-in PCB #1 off line first (see QMX QMX_Plus Power supply test Process ).
Additional remove SMPS and check resistance from PWR_ON (mainboard) to GND with and without left encoder depressed.
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I actually have to press my fingertip to Q105 to latch it on.
Which contact of Q105?
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73 Ludwig
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Re: #bug #qmx QMX SWR protection not working when QSK is enabled? #bug #qmx

 

On Mon, Sep 16, 2024 at 10:42 PM, @Ludwig_DH8WN wrote:
Adrian, I guess this is a problem. For the original design ADC_FWD should be around 2 V @ 5 W out. For your design it should have around 4 V. AFAIK the highest input voltage for an ADC input is a bit more than 3 V for right measurement. For your QMX ADC_FWD is above the limit. This may cause calculation errors for both the output and also the SWR.
The SWR value displayed by the QMX in the diagnostic screen seems to be consistent with my Daiwa SWR/power meter (probably because the measured voltages are equally off, so their ratio remains the same). But I think you're right about the ADC input voltage! Will change the windings as soon as I have a bit of time.
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> I understand "S" were shown and no sidetone (for SWR protection) but you had output at the same time. Is this right?
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Yes, that is correct. Sidetone was suppressed as soon as the "S" appeared, then I saw both needles on the swr/pwr meter still wigling (I accidentally left my tuner in bypass mode). As soon as I switched QSK from "Auto" to "None", SWR protection operated correctly, killing the output.
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Regards,
Adrian
Re: #bug #qmx QMX SWR protection not working when QSK is enabled? #bug #qmx

 

On Mon, Sep 16, 2024 at 08:20 PM, Adrian YO3GFH wrote:
There is one mistake I did when building my QMX and haven't corrected yet, but I don't think it would have any effect on this: each of my SWR bridge (T507) secondaries have 2 turns instead on one :-)
Adrian, I guess this is a problem. For the original design ADC_FWD should be around 2 V @ 5 W out. For your design it should have around 4 V. AFAIK the highest input voltage for an ADC input is a bit more than 3 V for right measurement. For your QMX ADC_FWD is above the limit. This may cause calculation errors for both the output and also the SWR.
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I'm not sure about the situation.
To my surprise, the SWR protection didn't trip - although the S was displayed on the screen and the sidetone gone silent, the QMX happily countinued to emit RF.
I understand "S" were shown and no sidetone (for SWR protection) but you had output at the same time. Is this right?
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73 Ludwig
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Re: QMX+: The trifilar toroid torture test

 

If I thought i was going to use it for anything else, I'd just pick up three spools in three different colours :-D

On Mon, Sep 16, 2024, at 14:32,?kf7rcm@... via groups.io wrote:
I followed the instructions to the letter. BUT, I also left a couple of inches of excess wire to unravel. That extra length makes it way easier. Get a spool of .33 bell wire so you can waste a bit of it and keep from becoming frustrated.?
Re: QMX+: The trifilar toroid torture test

 

I followed the instructions to the letter. BUT, I also left a couple of inches of excess wire to unravel. That extra length makes it way easier. Get a spool of .33 bell wire so you can waste a bit of it and keep from becoming frustrated.?
--
Wayne S.
KF7RCM
Re: 10 watt linear HF amplifier - stability issue/question #10W_PA

 

I did the measurement with known RF sources (minicircuits and Qbit brick amps),
power measurement by BIRD, and HP8568B, Rigol DSA815T.? The numbers
I gave were better than 1db accurate.?
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For output power I use the SA (one of 4) as they are calibrated to better
than 1db (typical is .1) and even the bird is 5% of full scale.
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Nominal is 13.8V, using less than 13V seriously? limits power and bluntly
it wasn't meant to run at 12.0V... or 11!
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Over driving the input will result in gain compression and that makes the
gain look lower.
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Gain is flat (+- 1db) from 1.8 to over 30mhz for the 4 I have.
One case known to me the source as not flat over that range.
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Oscillation... make sure the coax used to deliver the signal in and power out
have the shield connected to ground on the board.? ?At least one person
reversed that, really!? ?Similar case the coax was not grounded at all.
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One built with the transformer leads were very long, reducing output
at the upper frequency.
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One builder manged to swap the BN43-2402 with the BN61-2402.
They are similar but onei s 43 ferrite and the other 61... impacted
bandwidth and gain.? They all sorta look the same.? One is grayish
and the other is shiny.? That and they were packaged separately.
RTFM the manual points that out.
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Low power... T203 only one side actually soldered.
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One builder called it the 10W amp but actually built the
50W CW monoband amp. built for 40M and was testing at 20M!
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--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
Re: QMX PUTTY and a fault or two

 

开云体育

Should have mentioned the PC is running Win10

On 16 Sep 2024, at 18:52, Chris - KC0TKS <kc0tks@...> wrote:

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Try also:
/dev/ttyACM0

/dev/ttyUSB0

/dev/ttyUSB1

Of course this only applies to Linux.


On 9/16/24 12:30 PM, Lindsay Pearson via groups.io wrote:
which give a couple of lines of text to enter (/dev/ttyACM1)
Re: #bug #qmx QMX SWR protection not working when QSK is enabled? #bug #qmx

 

Hello Ludwig,
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Thanks for answering, I gave Hans's post a read and then tested the SWR sweep in the terminal HW tests and Tune SWR in the QMX menu, with 50% voltage. In both cases I got around 1W, compared with the 4W under normal conditions. I also checked the Diagnostics screen in the terminal and PA voltage is 0.8V on idle and 10V on key-down (I have the 12V low band QMX). Also, "Mod high on RX" is enabled. So all seems good, apparently?
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There is one mistake I did when building my QMX and haven't corrected yet, but I don't think it would have any effect on this: each of my SWR bridge (T507) secondaries have 2 turns instead on one :-)
This affects the QMX internal power reading (I get 8-9W in the diag. screen and the LCD power bar is always full), but not the SWR. I don't see how this could be the cause, but I'll happily stand corrected :-)
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73,
Adrian
#QMXplus Issues with latest firmware 1.00_27 with newly built qmx+ #QMXplus

 

Hi All,
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I completed my QMX+ and went to load the latest firmware (1.00_27).? The loading process went normal and I did get the initial setting to setup the bands.? I picked 160M-6m.? But what I found is that this did not initialize the QMX+ correctly.? I also noticed that the hardware tests looked strange (lpf, sweep).? I verified that the band options were set correctly, and still only got 80-20M,? I then did a factory reset, got prompted for the band selection again, and again picked 160m-6m.? But this still failed to have the correct band setup.??
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I then loaded firmware 1.00_26 and when through the process again, but this time the band settings were correct, the band configuration menu was correct, and the hardware tests look good.? I haven't tried to reload 1.00_27.? I suspect something is not being initialized with the QMX+? from a factory reset/new install.??
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Cheers,
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Chris, w0anm
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Re: QMX+: The trifilar toroid torture test

 

Nail polish works great.
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Tisha, AA4HA
Re: QMX+: The trifilar toroid torture test

 

This is what I did with paint-pens. I colored the lengths of wire and let them really dry before using the drill chuck to make them in a bundle.
It also looks really pretty when you get it installed on the board.
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Tisha, AA4HA
Re: u4b not transmitting

 

Hi Dave and John,
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All good now, everything is working.
Run Program does transmit while connected to USB power / Console.
I figured out the HP=1 setting before complaining the outputs were still in phase.
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The confusion started with the CW (and HELL etc) commands not working *in the console*. Just on this unit it seems.
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Thanks for the suggestions. 73 Thomas
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Re: QMX+ High Current and Self Start

 

Further tests show poor 80/60m performance and there is a significant voltage drop compared with the other LPF’s. I set the band to 6m and found 10.47V at the switching diodes and their respective nodes except for 80/60m which measured at .557V No solder shorts were visible and no hot components found. Input RX current is around .100mA @12.0V When 80/60m is active, the voltage goes to 4.73V instead of the expected 33mV as the others measure. L507 appears open line, I will need to replace it but I fail to see if this could be related.?

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Re: 10 watt linear HF amplifier - stability issue/question #10W_PA

 

Glad it’s stable.?

I saw similar and went round the gain puzzle?
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It drops off at highest and lowest frequencies?
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It reduces with low supply voltage ( I was using 13.5 V)?

It reduces as output level increases (gain compression)?
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Accurate Gain Measurement with hobby level equipment ?is complicated as the input impedance is literally anything but 50 ohms so your input source and/or any input pad/attenuator will not be working to spec..?


Basically it’s probably working fine?
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Re: Winding toroids with a chopstick?

 

开云体育

I use this method and this realy work.

Tarmo K?lli
ES4RTK

16.09.2024 20:45 Chris Raine W3PB kirjutas:
I saw this method used on a Youtube video. ? It looks to me as though the builder has created the mythical “3rd arm growing out of the middle of my chest” with this lashup. ?A vice holds a sharpened chopstick vertically. ?The toroid is placed on the chopstick, and slides up and down as needed, leaving both hands free to wind the wire.
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While this is new to me, perhaps some of you have experience with this method? ?

73,
de W3PB. Chris

Virus-free.
Re: QDX and QMX+ (soon at least) what is the max safe swr?

 

My 4SQRP seems to make my SWR on 20M worse.? I think I can get it less that 2:1, but I finally put the analyzer on my antenna clean (no tuner) and am about 1.2:1 so I figure that is okay.
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Bob,
The 4SQRP tuner is great for matching most antennas, but I agree that it doesn't do well with an already close matched antenna.?
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--
73, Dan? NM3A
Re: QMX PUTTY and a fault or two

 

开云体育

Try also:
/dev/ttyACM0

/dev/ttyUSB0

/dev/ttyUSB1

Of course this only applies to Linux.


On 9/16/24 12:30 PM, Lindsay Pearson via groups.io wrote:

which give a couple of lines of text to enter (/dev/ttyACM1)
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