Re: QDX Extremely Low Receive Volume
#qdx
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On 10/11/2021 19:52, Karl Heinz Kremer - K5KHK wrote: Thanks everybody. I am using "Serial.app" on the Mac (I know there is a Putty, but I never had much luck with that, I do however use it on Windows and Linux). Turns out that the problem was not related to the audio settings, it was due to a bad solder joint. I used my multimeter to test the connections of the bandpass inductor, and they all looked good. I just fired up the old solder iron and touched up the inductor solder joints and the corresponding caps. Now I have the opposite problem :) I've already turned down the audio level to 500, and I am still going into?the red on the meter in WSJTX :)
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Re: QDX issues: please include info:
#qdx
Hi Alan,
I added the screenshot.
not 79 but +10 to -75 quite similar also as of it's shape.
73. Alper TA2SUA
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It's adjustable in the settings, it can be played with. Can't remember which menu offhand, as I'm not near qcx at this time.
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Re: QDX issues: please include info:
#qdx
This is my 20m chart, the scale is completely different from Evans'.
Why?
73 Alan G4ZFQ
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Re: QDX issues: please include info:
#qdx
On 11/11/2021 07:43, Suat Alper Seyhan wrote: I have very similar graphics to Evan's on rf sweep also.
Do you get exactly the same 20m chart? With the scale on the left of it going from +10 to -79? I must test again with the latest firmware. One observation I'm not sure if related to this or not but: when I was doing the change of 47uh smd's I measured the resistor type through hole inductors with a not that reliable LCR meter but it was showing 38 uh. I also measured, on a meter I trust. I also saw 38uH 73 Alan G4ZFQ
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Re: QDX issues: please include info:
#qdx
I have very similar graphics to Evan's on rf sweep also.
Connected to a 50 ohm dummy. For power output I had to squeze the LPF's a lot to get to somewere near 4w with 9v. While doing the squeezing I possibly shorted something and all 4 bs 170's puffed.
So I changed them with different ones. Before and after the bs170 change graphics are exactly same. Re-did L12 and trifiliar toroid as I tought I might? did something wrong with them. Almost nothing changed.
Running on windows 10
1.01b
I built first for 12v but then changed to 9v setup.
Currently running on 10v with 9volts setup tried with different psu's switchmode all same results. For getting around 5w output? I'm running 9v setup with 10 volts but with 9v also sweeps are same.
One observation I'm not sure if related to this or not but: when I was doing the change of 47uh smd's I measured the resistor type through hole inductors with a not that reliable LCR meter but it was showing 38 uh.?
These are %10 tolerance inductors I think so 38uh if that reading is true might be a little low. I don't have enough experience or knowledge to comment on that but just wanted to share the observation.
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Re: QDX TX power was almost zero.
syuji ota, in the years i have been reading all of the posts to [QRPLabs], yours is the most carefully constructed, informative and clear description of a problem and its solution that I have seen.
If English happens to be your *second* (or other) language, then WOW.
Thank you.
-- MC VK1MC
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Re: QDX CAT Control Issue?
Today I went into the console interface and turned on CAT logging so I can get some more data.? @Karl, it looks normal there- the QDX starts up on an out of bounds frequency, I'm assuming so that it doesn't even accidentally start transmitting. I consider this a security blanket, since I have to manually set the frequency when I'm ready to operate. My finals feel safer that way ;-)? I'll report back when I have data to share. -- Ryan Flowers - W7RLF
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QDX TX power was almost zero.
Hello. everyone.
My QDX(order #50315) arrived in Japan on November 8th.
I assembled it immediately.
And I checked the reception performance.
The reception sensitivity is good for each band.
Next, I connected a dummy load to the QDX and measured the transmit power.
The output from QDX was almost zero.
20m has more output than 80m, but it is still only a few mW.
I confirmed the soldering of the toroids etc.,
?but there is no abnormality.
I saw the signal on an oscilloscope.
And I found that the signal was attenuated at both ends of C2 (2.2uF).
When I measure the capacity of C2, it is only around 100PF.?
It was this capacitor that caused the output to drop.
I soldered a 0.47uF ceramic capacitor instead of C2.
(Because I didn't have a 2.2uF ceramic capacitor.)
As a result, each band has an output of 5W at a power supply voltage of 12V. (T1 is 3:2)
This C2 was originally 2.2uF, but it seems to have been degraded by heat during the replacement of L1.
I recommend attaching it to the back of D3 instead of C2 when replacing L1.
?
My current info:
1 - Windows 11 Pro 21H2 22000.282? ?WSJT-X v2.5.2?
2 - QDX version v1_01b
3 - Built for 12 volts
4 - Power supply 3to14V 1.5A Linear Mode type
5 - Rev 1 PCBs
?
73? syuji ota? JH3AQQ
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Re: QDX issues: please include info:
#qdx
20m seems to have no filter at all. I don't see how that happens without a bad/wrong capacitor. Evan, Looking back at your pictures I think Hans needs to comment. The 20m one is odd in all respects, the scaling is totally different from the others making comparisons invalid. My charts have always had the same range of scaling as your other three although I did not keep a record. 73 Alan G4ZFQ
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Re: OT: Congratulation JackW8TEE
Thanks, Jeff! I didn't know it was out. I take it you saw it on a digital subscription, right? I'll try my best to hold your interest!
Jack, W8TEE
On Wednesday, November 10, 2021, 06:54:19 PM EST, Jeff | VA2SS via groups.io <jeff@...> wrote:
Jack, I liked your voltage divider article in latest November CQ edition. Well explained and useful knowledge. ?
Looking forward for next month article.
Best 73.
--
Jeff | VA2SS
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Re: QDX issues: please include info:
#qdx
Evan, I hope you get a good answer. My charts look a lot like yours except for the low side of 80m. In reworking and re-examining the BPF section I found I'd crossed turns on the inner face of the T50-2 somewhere around 16. The wrapping is otherwise neat and tight enough that?I don't know that I'll be able to fix it without unsoldering the tap at 19. And no idea if it will fix anything. We'll see.?
20m seems to have no filter at all. I don't see how that happens without a bad/wrong capacitor. I've visually confirmed that C29 is the 22pF ("220") and I tested it during parts inventory and right before insertion. It was the only one out of range for my cheap parts tester, but then I remembered the fancy SmartTweezers Santa brought me. Anyway, I'm fresh out of theories for now.?
¨CBrent WT4U
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Re: QDX Extremely Low Receive Volume
#qdx
Thanks for the heads up. I wont do that ;)
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Karl Heinz - K5KHK
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Re: Order "in transit" at Grace-Hollogne for 3 weeks?
My QDX status shows packaging damaged, repacked and forwarded from .Grace-Hollogne.? I suspect that's a result of customs clearance. Hopefully,I will eventually receive everything.
Tim
Sent from my Verizon, Samsung Galaxy smartphone
Get
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Re: OT: Congratulation JackW8TEE
Jack, I liked your voltage divider article in latest November CQ edition. Well explained and useful knowledge. ?
Looking forward for next month article.
Best 73.
--
Jeff | VA2SS
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Re: Order "in transit" at Grace-Hollogne for 3 weeks?
Kent,?
It looks like you package got caught in some depot machinery for a few weeks!
Kit looks good though...? My QDX sat there for a number of days but not weeks.
73
-Mike
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Re: A couple QDX questions: 60 meters? & 9v vs 12v
WA8LMF wrote something about our presence on the 60-meter band that hams in the U.S. should keep in mind.
The 60 meter band is part of the larger 5.060-5.450 MHz band, which is a federal/non- federal shared band that is allocated to the fixed service on a primary basis and to the mobile (except aeronautical mobile service) on a secondary basis. The 5.060-5.450 MHz band is primarily used by federal agencies for ship-to-shore and fixed point- to-point communications. Non-federal use of the 5060-5450 kHz band includes state government licensees and licensees in the Industrial/Business Pool that operate standby and/or backup communication circuits for use during emergency and/or disaster situations, entities prospecting for petroleum and natural gas or distributing electric power, coast stations and aeronautical fixed stations.
The Commission added the Amateur Radio Service as a secondary allocation after determining that such frequencies could be useful to the Amateur Radio community for completing disaster communications links at times when existing frequencies in the 3.500-4.000 MHz (80 and 75 meter) and 7.000-7.300 MHz (40 meter) bands are not available due to ionospheric conditions. It concluded that such an allocation represented the best compromise available to give the amateur service access to new spectrum while assuring the federal government agencies that their use is protected.
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Re: A couple QDX questions: 60 meters? & 9v vs 12v
Whether FT8 is legal on 60 meters depends on where you live.
In the US and the other countries in the Americas that have mirrored the US rules (including Canada, but not Mexico which has a full band allocation), the legality of FT8 operations is questionable. Those rules allocate 5 channels on the 60 meter band, and it is specified that CW and digital operations must be at the center of a channel. That appears to allow only one FT8 signal per channel, right in the middle,?which is not how FT8 is normally done. The ARRL does not currently recommend FT8 operation on 60 meters in the US, but a number of hams are using the mode and are not sticking to the 1500 Hz offset. The power limit on 60 meters in the US is 100W ERP referenced to a half wave dipole; you won't exceed that with a QDX and any likely antenna on that band. (If you have an antenna on 60 meters that can exceed that limit when driven with a QDX, I want to meet you!)
The customary channel for FT8 operation is channel 3; 5357 kHz USB, with the center of the channel at 5358.5 kHz. (Set WSJT-X to an offset of 1500 Hz to be strictly legal in the US.) All of the FT8 operation I have heard is on that frequency, regardless of country. It's often busy but not overloaded, so there is no need to spread out to other frequencies.
A number of countries, including most of the nations of the EU, have a full band allocation on 60 meters rather than a few discrete channels. In most cases it's the?range from?5351.5?¨C 5366.5 kHz that was approved at WRC-15.?FT8 operation on 60 meters is fully legal in those countries with no restrictions other than license class (check your rules) and the 15W EIRP power limit in many countries. Unlike the US power limit, that's based on an isotropic antenna rather than a half wave dipole. The limit could make the use of a 60 meter Yagi or other beam antenna with your QDX illegal. If your QDX is producing 5W output, using an antenna system with more than?+5dBi gain (including feedline losses, and tuner losses if used) would exceed the power limit. You'll be fine with the usual simple wire antennas, including half wave wires with any feed arrangement.
The UK went its own way, with a number of frequency blocks of varying sizes available. One of those is 5354 to 5358 kHz, which appears to allow FT8 operation on the usual frequency IF an offset of 950 Hz or less is used. (The FT8 signal is about 50 Hz wide so you have to stay a bit away from the edge of the block.) Presumably it's legal to have a QSO with a non-UK station that is?using a larger offset. The rules also limit antenna height to 20 meters above ground, but allow 100W PEP and 200W EIRP.
Hans is in Turkey, one of the nations with the full ITU-allocated band and a 15W EIRP power limit. He doesn't have to worry about restrictions on FT8 operation while he is there but does need to be aware of the power limit.
The Wikipedia article about the 60 meter band has a list of the countries with allocations on the band:?
Just like with any other regulator design you want to use low ESR capacitors.? MLCCs usually are, tantalums usually are, and disk ceramics usually are.? Verify before whipping something together out of junk box parts.?
That schematic is fine for use with a low ripple input supply or battery.? ? If building an AC to DC linear supply much more capacitance is needed on the input and it doesn't hurt on the output.?
Fred W0FMS?
Hi Bill,
I just used the typical 78xx schematic and MLCC capacitors that I had on hand. E.g. Mouser 581-SA115E334ZAA or similar. I don't think the component choice is terribly critical, but MLCC is what I usually use and have available.
Cheers? Gregg W7GRM
I am building mine for 9V for the same reason, to use with batteries.? I have a couple of different switching converters and can always do a linear regulator for home use.
I also think that 9V will be better for the AMS1117 regulators over time than 12V will be.?
Fred W0FMS?
On Wed, Nov 10, 2021, 9:26 AM Bill Lamm < kd9mdl@...> wrote: Gregg W7GRM..? I have been thinking on the same lines.. possibly overthinking as I look at your picture.. I have some 3s LiFiPo surplus batteries that should power the QDX and Raspi for a weekend..
could you elaborate on you componeny choices? Looks like ceramic caps?
Thanks
KD9MDL
Bill
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Re: QDX Extremely Low Receive Volume
#qdx
Hi Karl,
I have exactly the same picture on 20m on mine. Re-did l12 bandpass and trifiliar transformer as I thought I did something wrong with them but nothing changed. So don't do that :)
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Re: Order "in transit" at Grace-Hollogne for 3 weeks?
Well, a day after I wrote to Hans with my concern. The package arrived at my front door a few minutes ago.? Great Job, Hans. As you can see it arrived a little worse for wear which might explain its delay. Internally, it appears OK, we will see.? So, it has arrived.? Looks like that Grace-Hollogne can a pretty tough place.
Kent.
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jjpurdum
Mike Perry, WA4MP
Shirley Dulcey KE1L
Retired Doc