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Re: #QMX Rev4 v27, kit just built not working
#qmx
Okay - I take it back. Step #3 states that you cannot do this via the terminal program. You can. Toggle the Relative/Absolute function in "CW Keyer" and back out. It will make the transmitter function and not lock up the radio when the paddles are closed. At least on my QMX.
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Myron WV0H |
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Re: #QMX Rev4 v27, kit just built not working
#qmx
Okay - I finally found what I was looking for. A way to do a factory reset and enable the transmitter in 1 parameter change. This is strange and is the common denominator for when I was able to get the transmitter to function.
This is so obscure. (Rev 4, v27)
Step 1: Remove power to QMX.
Step 2: Remove USB cable but leave the speaker, paddles and dummy load attached.
Step 3: Reattach DC power cable, turn on QMX. The computer is NOT attached and leave it detached. You cannot do this via the terminal program.
Step 3: Do a factory reset on the QMX itself in its internal menu system by long press of left button. Rotate the right encoder to "Factory Reset". Click the left button to bring up the "Sure?" display, click the right encoder (TUNE). The QMX should show "Reset . ."? on the display. Once reset, turn right encoder to select 60-15m (my version of radio). Click left button to store it.
Step 4: Enter the Menu (long press of left button), navigate to "CW Keyer", click left button again to access sub menu and Keyer Mode should be displayed. Rotate right encoder to "Sidetone abs/rel". Click left button to enter this sub-menu, use right encoder to change it from "Absolute" to "Relative". Click right button three times to exit this third sub-level and it should be back at VFO frequency display.?
Step 5: Squeeze the paddle and enjoy a transmitting QMX... at least for me.
But once again, still no receive through all this...
This is repeatable.
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Myron WV0H? |
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Re: Reciever Module - Why cut the LO in 1/4th, how does it work?
To anyone else with a similar question, the tayloe detector uses a two phase (90deg apart) clock AT the receive frequency, not 4x above. The 4x LO is simply a common method to generate two different signals that are 90 degrees apart while being at the receive frequency. That's where I had it wrong. |
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Re: Reciever Module - Why cut the LO in 1/4th, how does it work?
IC2 in that module is a couple of flip flops and is there to take a single signal and make a pair of signals that are 90 degrees apart and at the desired receive frequency. Unfortunately, that chip also divides the input signal by 4 as part of the process of making two signals 90 degrees apart. But, the FST3253 only requires 2 90 degree offset signals at the desired?receive frequency going into pins 2 and 14. It is possible to have the Si5351 clock chip generate?two signals that are 90 degrees apart so they don't?have to first go through the flip flops. If you only have a single frequency LO then it needs to be at 4 times the operating frequency and go through the flip flops. If you have two LO outputs 90 degrees apart, feed them?directly to pins 2 and 14 of IC1 and set them to the operating frequency. This is how it is done on all the QCX series radios. Ron On Sun, Sep 29, 2024 at 4:11?PM fccdrmail via <fccdrmail=[email protected]> wrote:
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Re: Reciever Module - Why cut the LO in 1/4th, how does it work?
开云体育The Tayloe detector wants two LO signals that are in quadrature (phase shifted 90 degrees) to one another. ONE way to get this phase shift is to have a signal at 4X what you want to receive, and then to count it down. That's what's done in the original design. What Hans has done is to program the 3532 (using his bag of tricks!) to directly generate two LO signals directly that are shifted 90 degrees relative to one another. So no divide by 4 is required! Short story: He used different way of generating the quadrature LO, but the detector works the same way as described in the papers you're reading. 73, Paul -- AI7JR On 9/29/24 16:11, fccdrmail via
groups.io wrote:
-- Paul -- AI7JR |
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Reciever Module - Why cut the LO in 1/4th, how does it work?
Hello,
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After assembling the RX module it has been working great, and i'm really happy with the performance aswell, a wire in my basement was able to pickup FT8 across the sea!
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Anyway, I'm confused as to how it even works, as the manual says this: "The two outputs of this circuit (at pin 6 and pin 9) have the same frequency as the receive frequency (1/4 the LO frequency), but are offset from each other by a 90-degree phase difference", I know it is how the chip is setup, to make the frequency 1/4th of the LO, but why? Every paper I have read about the tayloe detector mentions that the MUX (FST3532 in this case) requires a 4xLO in to see a quarter cycle of the input at each output. It's on the first page of the tayloe mixer PDF. Is there something I missed, or am I interpreting the schematic wrong? Because how I am looking at it now makes me believe the receiver should actually be receiving 1/4th freq of the already 1/4th cut 4x LO.
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Anything will help, thank you very much. |
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Re: #QMX Rev4 v27, kit just built not working
#qmx
Hi Ludwig - Yes, the encoders show the little right and left arrows when rotated the proper direction and the remaining switches check good. All Green.?
When I enter terminal mode Main Menu/Configuration/Hardware Tests/Diagnostics: all switches and encoders check fine. Depressing (p) results in 30mA of current to toggle on. Release the p key the PTT goes off, normal. When I press the T key, the QMX locks up. Have to cycle the power supply to get the QMX unlocked.
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I read the links you sent and my PCM1804 shows between 2.5 to 3.5 Kohms resistance on each Vdd and Vcc pins respectively. The chip does get a little warm according to my FLiR gun readings it shows about 25°C temp rise and per the datasheet: a thermal resistance JA of 100°C/W at ~0.26W dissipation equates to about 26°C temp rise. I would call that normal, however, at times I have heard the screeching noise come from the speaker but is really short-lived and very intermittent. If it happens again, I will try to measure the chip temp and see if it gets hot. That screeching has come and gone in the past but never has lasted very long and it doesn't happen much...maybe occurred 5 times.
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As for RF sweep, I can never execute the test because it will lock up the QMX and has to be power cycled.?
Yesterday, when I did get it to transmit, terminal HW Diagnostics showed good power out on all bands except 17m where it was about 4.1W and SWR sweep of what looks expected from a dummy load.
The Image sweep shows flat line at -165.
AF sweep shows flat line at -165.
The IQ Sweep shows flat line of all zeros.
The LPF Sweep shows nice shape and good amplitude (between 0 and 2) in the respective ham bands. Skirts show nice roll-off.
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I did manage to get the transmitter going again by going into the terminal mode and toggling VFO MODES from OFF to ON. Just don't know what they were. Maybe in the CW encoder and VFO tuning steps area. Hard to recreate it in my mind. Now, it's back to just locked up and no TX. Cycled power, no TX or RX.
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Myron
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Re: 50w PA oscillations
On Sun, Sep 29, 2024 at 02:33 PM, Jonas Sanamon wrote:
Guess I have to find schematic?+ component placements for the QMX+ next to follow Your advice.?Or you could build a small buffer to go between the QMX+ and amp keying input.? Then there would be no need to dig into your radio, plus it would afford a measure of protection for the radio. 73, Don N2VGU |
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