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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
n4qa at_hotmail.com
EUREKA !
Now we're getting somewhere ! I use three PCs around here for various purposes - two Dell core i3 machines w/ Win 11 Home and this one, a Dell core i5 machine running Win 10 Home. Hmmm... Now, my antenna switch has at its nr 3 position, a Bird model 10-A-MFB-10 attenuator/dummy load. Lots of intervening coax too ! Both 'Tune' and normal FT-8 xmsns run for as long as I wish ! I *do*, however, have an 'rf in the shack' issue (but not on the dummy) and will have to look into that further. Many thanks for all of your help, guys - it is much appreciated ! Lookout now, WW2FLY, here comes N4QA ! 73, Bill, N4QA |
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
Thanks for the post, printing custom decals, how cool.
I have a lot of homemade cases and don't always remember which jack or knob is which. Here is the knob that I printed. It uses 3mm or 1/8" set screws and is designed around a 1/4" shaft. The finger grips really help turning stiffer turning controls.? direct link: -- 73 Dave AD0B |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
n4qa at_hotmail.com
Tnx, Ken.
The only program I have tried to key QDX with is WSJT-X. And, I still can't seem to find any audio setting, slider, Windows etc that is not already set to maximum. Someone suggested trying to use a different PC. Maybe it's time I tried that... 73, Bill, N4QA |
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Re: QDX PTT to QRP LABS Amp
Hi all,
Time to confess... I have deleted my last message because I made some mistakes at writing my measurements results in post.? Here they are: 1) I measured now the voltage at the PA PTT line when unconnected: +2.1V.? It should be at 0V through 10k resistor. That is why I used a 1k parallel to GND in QDX to pull it down when inactive. 2) When simulating the QCX PTT output by using +5V from PS the current into the PA PTT line was: - at inactive PTT 0V: -3.3mA - at active PTT +5V: +19mA 3) When using the QDX modified PTT line (100R||470R) the current into the PA PTT line was: - at inactive: -3.4mA - at active (+4V): 13mA So, yes Ron, you are right, something is wrong here at the PTT line input.? I was just rectifying the consequences not the cause. But it works well.? Now I have to open it again and find the faulty one. The choice is very narrow: Q5 or Q6.? But faulty and not dead. Anyway I would recommend to use parallel 100R to 470R to get higher PTT voltage at TX. 73 Bojan S53DZ |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
Bill, this may be completely a red herring, BUT, are you trying to control your QDX remotely, ie VNC /SSH to it?
I found that using this method to use the Terminal program to key the tx would only give a short tx burst. This is because the ¡®held key press¡¯ action to hold the tx on does not work in this situation. I just wondered if you were seeing a similar problem but using whatever programme you are using to key the tx? 73 Ken g4apb? |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
n4qa at_hotmail.com
Thanks, fellows.
toggle quoted message
Show quoted text
On Sun, Aug 14, 2022 at 07:43 AM, Alan G4ZFQ wrote: I mentioned the terminal program because it offers a transmitter test. This would confirm that the transmitter works correctly.Alan, when I see this, it makes me think that I could actually test the transmitter ! Now I know why some folks refer to me as being hard-headed ! 73, Bill, N4QA |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
QDX consistently xmits great but only for 250 ms each attempt. I have to believe the ops manual when it describes the remedy for this anomaly, which is to increase the 'gain' that the PC sends to the rig via 'AG' commands i.e.? AG00 thru AG99. But in order to do that, apparently I must use some sort of terminal program ? What am I missing here ?Bill, This adjustment is explained in the manual. BUT it is not relevant to you as it concerns receive only. I mentioned the terminal program because it offers a transmitter test. This would confirm that the transmitter works correctly. However the most likely thing is sound settings on your computer. Windows? Every setting for the QDX must be maximum, including the WSJT-X Pwr slider on the right. 73 Alan G4ZFQ |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
Hi Bill? I think I mentioned before, and I believe it is also in the manual: 1. The audio again theoretically controlled by the AG command applies only to the QDX in receive mode. It is irrelevant for TX.? 2. The CAT AG command doesn't work anyway, due to a bug. I fixed it in my 1_05_003 beta here but you guys don't have that yet. So you couldn't set receive audio gain by CAT anyway.? 3. Two flashes of the LED, reared once per second, indicates the PC volume is not set to full volume..? 4. There isn't anything wrong with your QDX. You need to fix the sound settings in your PC, to make sure all three settings are at full volume (WSJT-X slider, the specific output device QDX in the sound manager, and the master volume).? 5. If the QDX was in transmit properly (3 flashes repeated once per second) but briefly only. Then dropped back to RX... That would indicate RF issues (grounding, common mode currents, etc). But from what you've said this isn't the problem.? Conclusion: the fault is just in the PC sound settings.? 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl -------- Original message -------- From: "n4qa at_hotmail.com" <n4qa@...> Date: Sun, Aug 14, 2022, 1:51 PM To: [email protected] Subject: Re: [QRPLabs] QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds. GM, Geoff and the gang. |
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Re: Qdx terminal tx test
#qdx
73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl -------- Original message -------- From: KEN G4APB <lfoofui.nbz42@...> Date: Sat, Aug 13, 2022, 2:01 PM To: [email protected] Subject: Re: [QRPLabs] Qdx terminal tx test #qdx Hi Hans, Should anyone want to know this, I figured out a way to keep the QDX tx on during a remote terminal tx ptt test. On my Raspi 4 loaded a keyboard programme called 'Onboard', then configured from its own menu for a 'long key press' to give 'repeating keys'. This allows me to keep the tx on longer for spectrum and other power measurements. Now another 'feature request' for you to consider....I have modified my QDX to cover from 80m to 10m but I need to switch antennae as I change bands. Could a band dependent configuration option be added to allow the PTT output to give either polarity (as already has) but in receive mode as well? i.e NOT just a PTT function only on transmit. For those wanting to use the PTT function as original, just disable the rx ('PTT') mode. This would allow me to switch antenna three changeover relay drivers (from pull up, pull down and disable states). whadderya think? 73 Ken G4APB |
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
On Sun, Aug 14, 2022 at 02:40 AM, Mark KB0US wrote:
Turns out my 67 year old self isn't much better with decals than my 11 year old self! I think I need to not move them as much? and trust?the force.?I'm trying a bit more acrylic spray as well.?Acrylic spray will only dissolve decals or what we call Good luck removing that stuff if it's on a plastic case ;-)) ? - 73 de Andy - |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
n4qa at_hotmail.com
GM, Geoff and the gang.
Mark explicitly said that the QDX was in good working order so I? must presume that any issues are with my setup here. QDX consistently xmits great but only for 250 ms each attempt. I have to believe the ops manual when it describes the remedy for this anomaly, which is to increase the 'gain' that the PC sends to the rig via 'AG' commands i.e.? AG00 thru AG99. But in order to do that, apparently I must use some sort of terminal program ? What am I missing here ? Thanks & 73, Bill, N4QA |
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Re: Artwork for "Manual Days" Chinese Antenna Tuner
Here's another hint if you haven't built the little tuner yet. Check the DPDT toggle switch with an ohmmeter before you solder it to the circuit board!! Suppliers seen to have gotten a great deal on defective switched and I just had to pull mine and replace it. I'm pretty sure i had to do that on the first one i built, but you can't expect me to remember that after 5 years. Right?
73 JS6TMW |
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Re: #qdx for 40, 30, 20, 17 +
#qdx
Sverre,
here is a photo of how I modified the 80M winding to a 26MHz winding. Look closely and you may see I cut the tap at the end of the 40m winding on L12 (at 36 turn point), removed the last 5 turns and wound a new 15 turns overlapping to fit, in the space left. The START of this new wind goes to the original start (0), and the new end to the 80m tap point (END). I then reconfigured the 80m setting to cover 17mhz to 35mhz etc, set bpf to 0, and lpf to 0. Hope this makes sense. Ken g4apb |
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Re: #qdx for 40, 30, 20, 17 +
#qdx
Hi Sverre,
remember this is work in progress.... I chose the values from ELSIE to give a 5 order elliptical LPF. You will see I have attempted to cut off the third harmonics on Tx from 18mhz to 30mhz, and the Rx BPF is centred around 26MHz to cover the same bands, which you see as a response not seen by the Tx. The markers show fundamental and third harmonic points. The rx BPF response I chose other values than your original values to get a broader response but ended up back to your values. I physically measured the responses using my NanoVna connected between the antenna port on the junction of C33/C34 via a 100nF cap. Then powered the QDX into rx mode at the various bands to check. I get 3 db loss indicated and Tx power on 28MHz is 2.5W and not the flat lossless response I hoped for, as I said- work in progress. However, the radio does tx/rx on these new bands so great fun just playing with it as is for now. Have fun. Ken g4apb |
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Re: #qdx for 40, 30, 20, 17 +
#qdx
Hi Ken
That¡¯s interesting! I got my own QDX last week, and am halfways through the build now. I¡¯m leaving the 80 m filters out for the moment, getting ready first for the input BP filter. it would be very helpful to see a scan of your new BP filter! -- Sverre LA3ZA |
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Re: QDX PTT to QRP LABS Amp
Will,?
I am sorry to hear that PA is dead.? The PA bias is needed to be adjusted as per assembly manual, so just a bit back from the finals to conduct.? To be class C amplifier.? No matter what the RF drive is QCX or QDX.? However the input power to this PA is different for different modes.? But the puzzle is how the PA was working good with the QCX, where the maximum output current of a 74ACT00 in PTT line is 75mA. 73 Bojan S53DZ |
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Re: Qdx terminal tx test
#qdx
Hi Adam, re tx testing¡
I did not mention it but I was using Putty on the raspi to enter terminal mode in the first place. I have just found out that you can¡¯t do continuous key press over VNC. Anyway, I have found a get around now. different subject now, Alan, re antenna changeover ¡.. thanks but here is no mention of this in any QDX documentation. I guess some form of physical drivers/buffer devices would be needed to connect to X6 and then a connector to bring it out of the case. My request would require no physical mods as the ptt driver is already available and a connector to the external world is already there. Just a another ¡®simple¡¯ firmware mod for Hans, hi hi¡.. 73 Ken g4apb? |
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Re: QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
Bill,
My comment on using a dummy load reduces the chance of RFI causing the QDX to cause the drop out of the transmission.? The dummy load is not an issue; it is a way to help isolate the problem. 73 Evan AC9TU |
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Re: QDX PTT to QRP LABS Amp
Wilson Little <wilsonlittle66@...> wrote:
The amp was previously adjusted for the correct bias and was in use withHmm, then you're right -- it shouldn't happen. At least not if the load was properly matched (but I was running this PA with a severely mismatched antenna, VSWR above 3:1, and it still didn't blow up). I checked the finals, and both are shorted across all pins. Will orderI saw your measurements: #v+ On the QRP Labs' QDX with the PTT connected - Voltage input to R10 mesures 5.00 v ref to ground - Voltage output of R10 measure 0.86 v ref to ground - Voltage drop across R10 is 4.13 v #v- I just checked and it's 3.3 V in my (working) setup. Something must be loading the PTT line in the PA. Looking at the schematic the only possibility (other than some weird short-circuit on the board) seems to be Q5. Can you try unsoldering Q5 and checking if it makes any difference in voltages and the LED? Unsolder Q1 and Q2 as well (I'd do it even if they were functional -- without Q5 the receive diode switch will be turned on even during TX). |
_Dave_AD0B
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