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QDX: Receiving great but needs more audio output gain in order to xmit for more than 250 milliseconds.
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n4qa at_hotmail.com
Hey gang. Received my assembled QDX today...Thanks Mark !
OK, so the receiver is plenty hot...I'm playing on 40m first. When I attempt to transmit - either by the 'Tune' button or by actually calling someone, the rig transmits for about 250 ms and then just stops xmitting. I found that I must operate the WSJT-X gain slider at 0dB to even achieve this truncated xmsn. The red LED blinks twice repetitively as it is indicating insufficient audio drive...I think ?! I see in the ops manual where it suggests that the slider be operated at 0 dB and that there are audio gain commands which may be sent to QDX, such as AG21 etc. I think I need to send AG99 or so. Exactly how do I do that ? Please give me the step-by-step here ! WW2FLY is getting away and I really want to work them before the special event ends in a few days ! Many thanks for any help ! 72 / 73, Bill, N4QA |
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Hi Bill QDX isn't an SSB transmitter, there is no concept of audio gain or volume level affecting transmitter power output. It's all or nothing. You should always have all the volume settings on your PC at 100% so as to get best possible accuracy on the zero-crossing audio frequency measurement.? The audio gain setting only affects the receive audio level. You need to set that in the terminal applications. The CAT AG command has never worked on QDX, including in the current latest firmware 1_04... however I did fix that in the next firmware version that I'm running locally?here (currently 1_05_003 beta). If your LED flashes only twice that indicates your QDX is not getting enough volume from the PC. I find that regardless of Windows or Linux, there are three places the volume has to be set to 100%. First is in WSJT-X itself (the slider at the bottom right); then the device volume, and finally the master volume. What?you get out is the product of these three (multiplied together).? 73 Hans G0UPL On Fri, Aug 12, 2022 at 11:38 PM n4qa <n4qa@...> wrote: Hey gang. Received my assembled QDX today...Thanks Mark ! |
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Did you turn off all audio processing and other special audio features in Windows? Things like echo cancellation will remove continuous tones like FT8, for instance.
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73, Willie N1JBJ
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Hi Bill,
In addition to what Hans stated, if you have the three flashes and the transmission stops, that could be an RF feedback problem.? Try transmitting into a dummy load using the terminal emulator, then using WSJT-X, and finally attaching the antenna.? If it works until you transmit with the antenna, you have RF feedback into the shack.? You can try snap-on ferrites on all the leads into and out of the QDX.? That has helped others, including myself, until you can adjust the antenna so there is no RF getting back down the transmission line. 73 Evan, AC9TU |
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n4qa at_hotmail.com
Thanks fellas but no joy.
No rf feedback, no audio processing, all volume settings at max.? 2 repetitive Status LED flashes each time she trips until I stop the xmsn. The thing is, for a quarter of a second or so, power out is at 2 watts with 10 vdc, 3+ watts with 12 vdc. Sounds great in the FT-450D, Tune and normal xmit - can hear a couple of fq shifts b4 she drops out in normal xmit. Everything sounds beautiful, if only for a short while ! Any other thoughts? Thanks & 73, Bill, N4QA |
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On Aug 12, 2022, at 7:03 PM, n4qa at_hotmail.com <n4qa@...> wrote:
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n4qa at_hotmail.com
Hey Willie ( Willie or Will is what my dad, W4MAI,sk 2006 used to call me ).
My linear regulated supply is a 15 volt max, 2A max jobby that seems to be working nominally. Presently set for 12 vdc, 1 adc, QDX pulls 130 ma rcv, 550ma xmit. No dips in output v under load etc. 73, Bill, N4QA |
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Willie,
This first step is to do a very close and?thorough inspection of the board for shorts or bridges between traces.? What happens when you use the Terminal Transmitter Test program?? Does it still drop out? I think you might have a short occurring when you go into transmit mode.? That could be across the 5volt regulator output as it supplies all of the QDX logic ICs.? Can you monitor the output of IC2 when you go into transmit to see if there is a sudden drop, and then it comes back?? This could be an IC5 failure.? Does the LED continue with the 3 pattern flash? If you have a hot air SMD rework station, I would remove IC5 to see if the transmitter drops out after the 1/4 second.? If not,? then replace IC5 and remove the BS170s.? Try again,? If you can, test the BS170s with a transistor tester.? Replace all 4 if one is bad. The above are just suggestions.? I could be misinterpreting the symptoms you are describing.? Please proceed at your own risk. 73 Evan AC9TU |
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I know you said there's "no RF Feeedback", but this is classic symptoms of RFI, which can be disconcerting on QDX as even brief transmissions into a mismatched load (which usually causes RFI) can blow up (at least) your finals.
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73, Willie N1JBJ On Aug 13, 2022, at 9:28 AM, n4qa at_hotmail.com <n4qa@...> wrote: |
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n4qa at_hotmail.com
Hi ya same name !
That's right ! - no rf feedback. I'm confident that my Bird dummy load prevents rf feedback. Also, still getting 2 repetitive blinky LED flashes which, according to the ops manual indicates insufficient 'gain'. I understand, Hans, that this is not *audio* gain...just gain :0) The plot thickens. 73, Bill, N4QA |
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On 13/08/2022 14:58, n4qa at_hotmail.com wrote:
Also, still getting 2 repetitive blinky LED flashes which, according to the ops manual indicates insufficient 'gain'.Bill, Did you check using the terminal program as Evan suggested? This would confirm a PC problem (or not). Operation manual section 4.1 PuTTy is available for Windows. 73 Alan G4ZFQ |
开云体育Hi Other WIllie,Sorry, I misunderstood, thought it was working on 30M, but on closer reading it turns out it was only for a brief moment, my mistake. OK, now we're into shotgunning the problem: As Alan said, use a terminal program to transmit and eliminate your PC as a source of the problems. As someone mentioned (can't find it now), check the post-regulator supplies on the QX to make sure they aren't dropping as you start transmitting. Check all solder joints and visially inspect the board and all components for anomalies. Can you select speakers or a headset as the output of your WSJT-x program and try the 'Tune' function to see if it stays steady? When you say '2 repetitive blinky LED flashes' do you mean it flashes twice at the beginning of the transmission and then never again, or it flashes twice, stops, flashes twice, stops, and repeats that during the entire time it should be transmitting (either FT8 or Tune)? 73, Willie (the Other Other WIllie) N1JBJ
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n4qa at_hotmail.com
Please explain about the dummy load being an issue.
BTW, this dummy load requires no interconnecting coax- has bnc male on one end, female on the other. My combination dummy load / attenuators consist of one each Bird model: 10-A-MFB-10,? ?-20,? ?and -30 dB ten watters. I use them for running QRPp and for attenuating xmtr output for direct connection to my Spectrum Analyzer. Oh, and as a dummy load ! BTW, the XYL & I had a great time inside my old high school today ! 73, Bill, N4QA |
开云体育Oh, _that_ kind of dummy load, that everyone else in the known universe calls an attentuator. ?Makes me wonder if there's some other miscommunication going on here.Which one of those 'dummy loads' do you use when your QDX is having this problem? ?Does it change if you use different ones? 73, Willie N1JBJ
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Joshua KJ7LVZ
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