|
At startup I get:
~70 mA for ~1 second
Then 260mA
After a transmit command 97 mA (command can be from Key or over the USB bus)
Other observations:
Same effect for starting in cw or digi
Hardware diagnostics, voltages & duty cycle, do not change?
I do see a higher drop, 108v between between Supply Voltage and Transmitter (PA) Voltage than expected.
Any thoughts before I start probing?
|
Everything there sounds about right, except the 108v drop between?supply and PA. Did you mean 108 mV? If so, that's really small and not a problem. Is the 97 mA the receive current after ?the first transmit activation? If so, that's good too. This device comes on with more than 200 mA current draw until things wake up and the buck converters start working. You should see a significant?drop in idle (receive) current down to the 100 mA range after boot up. If that's transmit current, then it is way too low.?
73 .. .Ron
On Thu, Aug 10, 2023 at 8:18?AM Chris KB1NLW via <chrisrey1= [email protected]> wrote: At startup I get:
~70 mA for ~1 second
Then 260mA
After a transmit command 97 mA (command can be from Key or over the USB bus)
Other observations:
Same effect for starting in cw or digi
Hardware diagnostics, voltages & duty cycle, do not change?
I do see a higher drop, 108v between between Supply Voltage and Transmitter (PA) Voltage than expected.
Any thoughts before I start probing?
|
The voltage drop between supply and the Transmit (PA) voltage is 1.8v.
The additional 200ma receive current exists until a transmit command.? Since this is on 12.1V supply it is about 2.5W.
Also I am only transmitting 2W, I believe I was transmitting 4W? when I first built it.
Notes:
The SWPS duty cycles do not change between the 260ma and 97ma situations.
No difference between firmware 7 & 9
|
From Section 2.31 of the QMX Assembly Manual............
>9. When you apply power to your QMX?for the first time, it is a very good idea to use a lower supply voltage than you intend to run at, perhaps 7V for example; and use a current-limited supply if possible, perhaps limited to say 250mA. If there are any problems, this will minimize the probability of damage.<
After that, you go to Section 2.33 of the Manual for Firmware Installation instructions since the kits are shipped with the Bootloader code only.?
Since the?Assembled Kits?Hans sells are fully tested, I "assume" they will already have the latest Firmware installed.??
73 Kees K5BCQ
|
Chris,
As crazy as it sounds, it's like the handoff from linear 3.3v
regulator to buck 3.3v regulator doesn't happen until you poke the
transmit function. Can you probe LIN_REG_EN and see when it drops?
That effects the hand-off.
JZ KJ4A
toggle quoted message
Show quoted text
On Thu, Aug 10, 2023 at 12:54?PM Kees T <windy10605@...> wrote:
From Section 2.31 of the QMX Assembly Manual............
9. When you apply power to your QMX for the first time, it is a very good idea to use a lower supply voltage than you intend to run at, perhaps 7V for example; and use a current-limited supply if possible, perhaps limited to say 250mA. If there are any problems, this will minimize the probability of damage.< After that, you go to Section 2.33 of the Manual for Firmware Installation instructions since the kits are shipped with the Bootloader code only.
Since the Assembled Kits Hans sells are fully tested, I "assume" they will already have the latest Firmware installed.
73 Kees K5BCQ
|
Chris,
What do you see on the "Power On" point on JP101 as you push the Power On (Left Encoder pushbutton).
73 Kees K5BCQ
|
Chris,
Yes.....something between "Power On" and "Power Hold" does not seem correct. This WILL happen if you had the "Q103 and Q104" short discussed on another thread.
73 Kees K5BCQ?
|
More diagnosis:
Q507 is turned on at power up and turns of following a transmit command.
CW keying envelope appears correct (~5ms rise and fall), thus the PA control circuitry is OK.
?
However the the Diagnostic/Transmit (PA) voltage is low by 1.5v, measured with a scope and meter it is close to the supply voltage as expected.?
The PA voltage is 0.4V in receive - I would think the DAC should be fully turning off the control circuit.? Is this why my current on receive is higher than expected ~100ma.
Is this a firmware issue?
|
Some more test data.
PA voltage from power up through post transmit.
It looks like Q507 is not being fully turned off.? (I'll check if R507 id open)
The initial high current may be that one or both of the PA pairs of BS170 is on, possibly the <TX> signal is present until after the first transmit.? In the scope plot this would pull the voltage down.
Could be a firmware issue
|
Seems like turning the unit "ON" by pushing the left rotary encoder PB would first turn on the Linear Regulator IC101 to supply ~3.3V VDD which will draw about 200mA while the microprocessor initializes itself and the Buck Converters (3.3V and 5V) spin up. Then the microcontroller drops the Linear Regulator and enables the Buck Converter (less than 1 second later). There should be a resultant drop in current to about 100mA when using the Buck Converter. This is all in "Receive" mode (no key).
73 Kees K5BCQ?
|
Chris,
Why does your QMX come up in Transmit mode ?
73 Kees K5BCQ
|
The QMX comes up in the receive mode drawing ~250ma until it is keyed into transmit, when it goes back to receive the current drops to 100ma. It does appear to me that the firmware has a startup issue.? If turned on it will stay drawing 250ma indefinitely.? While starting in this high current mode the diagnostics page shows normal parameters.? The only exception is during transmit the "Transmit Voltage"? drive to the PA is about 1v low.
More tests tomorrow.?
|
Wonder if anyone else sees that ? Sure looks like the 3.3V Linear Regulator is not being turned "OFF" after the Buck Converter is initially turned "ON". Can you see what the Gate pin on Q110 (LIN_REG_EN) on Plug-in PCB #2 reads while this is going on.
There are several possibilities if the (LIN_REG_EN) is not present.
73 Kees K5BCQ
|
? I may be seeing this. I have one of the power supply boards that had the short, found with DMM before power on. With some encouragement from Mike, W1MT, I repaired the short and successfully powered up the QMX, downloaded the firmware successfully, and things started working. I was powering the rig with 7 volts as recommended and was so excited that no smoke escaped that I didn’t pay any attention to current draw. There were a couple of minor issues - the backlight adjustment wasn’t working and the small push-buttons were intermittent- but I was hearing CW on 20m. Next day I pulled the boards apart and touched up the soldering on the LCD adjustment and the push buttons, plugged the boards together and powered up again. The LCD adjustment and buttons now work, but I’m no longer hearing anything on any band. Another rig confirmed that there are signals that I should hear on the QMX. After reading this thread, I noticed that the current draw, in receive only, Is 190ma. Also, if I power down with the left encoder (“Shut Down”), the rig still shows about 130ma current draw. If I unplug the power from the QMX and plug it back in, the current drops to 0ma. While the rig is drawing 190ma, nothing seems even warm to the touch. Not sure what to look at! Would I learn anything from the terminal access tests? I don’t have an o’scope.
73, Randy KS4L
toggle quoted message
Show quoted text
On Aug 10, 2023, at 8:38 PM, Kees T <windy10605@...> wrote:
? Wonder if anyone else sees that ? Sure looks like the 3.3V Linear Regulator is not being turned "OFF" after the Buck Converter is initially turned "ON". Can you see what the Gate pin on Q110 (LIN_REG_EN) on Plug-in PCB #2 reads while this is going on.
There are several possibilities if the (LIN_REG_EN) is not present.
73 Kees K5BCQ
|
To eliminate a variable can you try a different battery power supply
and different power cable?
-mike/w1mt
|
As Chris JZKJ4A pointed out in his Aug 10 note, it may be that the 3.3V Linear Regulator is not being turned "OFF" when the 3.3V Buck Converter is turned "ON". I don't know if Hans' power supply sequencing scenario is fully implemented in the current firmware. Please check my following note and tell me what the Gate pin on Q110 (LIN_REG_EN) does during "power on".
73 Kees K5BCQ
|
Mystery Solved:?
Bad Q505 (BS170) was conducting when off.? During startup, before the first transmit,? the PA voltage control provides full voltage to the PA transistors even though the QMX is in receive? (this is a firmware anomaly).? This was the cause of the extra current.??
Replacing the bad BS170 corrected both the startup current and low transmit power.
Also, I did check the transition from the 3.3V linear and the buck regulators which was correct.
|
Hans took the time to created a great QMX schematic on the QRP Labs website including component numbering which corresponds to the page number of the schematic. For those of us trying to help and to follow the posted information flow, it would help if everyone please double checks the component numbers they use to describe the problem/fix.
73 Kees K5BCQ
|
Chris,
What took out Q505?
JZ
Hans took the time to created a great QMX schematic on the QRP Labs website including component numbering which corresponds to the page number of the schematic. For those of us trying to help and to follow the posted information flow, it would help if everyone please double checks the component numbers they use to describe the problem/fix.
73 Kees K5BCQ
|
I didn't notice the failure for a while, since I was still making contacts at 2W.?? Note two failure indications for anyone else with low power:
- Higher current before transmission (although Hans may change the firmware and remove the anomaly that the PA transistors are powered? in the initial receive prior to the first transmission.)
- Lower power.
On investigation I saw a smaller signal on the Q503/Q505 than Q504/Q506.? Then I noticed Q506 was warmer than the others. Cause: Two possibilities (1) SWR transients during my autotuner finding a match (2) did I try to transmit without an antenna or dummy load ( I don't recall doing this, but maybe).?? Hans:? A low power mode for tuning would be useful.? I thought about dropping the supply voltage during tuning With diodes switched in series with my 12v supply but then I worry about the transient to full voltage. I think 4 or 5 diodes would drop the power to 2.5w.? Any thoughts?
|
Ronald Taylor
Randy