Got through the build, added the firmware, booted up the rig.? Now to fit the case on!? This has turned into the most difficult part of the build.? The tongue and grove are off by a very small fraction.? I at first thought it must be the boards, so I took them out and verified that nothing was sticking up or out, the nuts were aligned etc.? Then I went back to the case and the empty case would not fit together.? Maybe a 64th of an inch or some miniscule amount but it is not a fit.? Anyone else have this fit issue?? The case was not stressed in any way and removed just prior to install.
Thanks,
Burt
K4SRQ
|
Re: RF preamp for power amp - HF and 6 mtrs. Magic silicon does all.
Generally...
video/RF amplifiers are measured the same.
Power output (undistorted and t 1db comprssion)?
Power gain (also votlage gain)
Distortion IMD, IP3, harmonics
Noise, noise figure of the amplifier.
You can use voltage gain or power gain so long as the input and output load
impedance are known.? For power the common use standard is 50 ohms and
DBW? or DBM.? Votage gain is sometimes used as well and if the load
impedance is know the conversion is easy math.??
That is an opamp amplifier so gain is the ratio of the feedback plus or minus 1.
The latter parts sign reflects if the amplifier is inverting or noninverting.
The series output resistors are for stability as most opamps are rather fussy
about reactive loads.? Fussy translated to they become unstable or can oscillate.
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)
In testing per the video cited (scrunching L4 and L10's turns closer together), I was able to get the output up to 2-1/2 watts but that only made me more convinced -- as you said -- that the BPF is the major factor in this situation.
Yes, I did.? Perhaps my surmise above was incorrect. As I said before, I'm reluctant to butcher the radio when it operates perfectly well on 20m through 12m so far as power out is concerned -- and I am fine with 2W on 10m for the moment. I have a Low Band QDX coming and I will be more circumspect about winding L12 and the LPF coils on that.? Dunno. -- William, k6whp -------------------- "Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)
William,
I count 20 turns on both of the toroid pictures.? The difference is on the 14th turn.? I count 15 turns to what should be the 14th turn and then only 2 turns between 17 and 20 on the second picture.
L12 will not impact the QDX output.? For 10 meters on a high band QDX, that is L4 and L10.? Have you tried squeezing or expanding those toroid windings?
73
Evan
AC9TU
|
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)
Evan,
Thank you for your reply. I went back to carefully review my work as well as LY2H's video covering this subject..
After carefully inspecting L12, I believe it is one turn short between "17t" and "End (20t)". I am not sure that is apparent from the pictures I posted below but using magnifying eye glasses and a harsh light, it goes to the last turn being omitted. In testing per the video cited (scrunching L4 and L10's turns closer together), I was able to get the output up to 2-1/2 watts but that only made me more convinced -- as you said -- that the BPF is the major factor in this situation.
Interestingly, I will have to "work up the courage" to extract L12, rewind, and replace it. The other bands -- 20m through 12m -- put out a robust 4-6 watts* and I am loathe to turn the whole built rig into lunch meat for the sake of 10m. I may yet gain the nerve to do so, but my recent experience on 20m and 15m compels me to manufacture a 12m and 17m vertical and see what can I see.
..all of that said, I marvel at the technology and research that went into designing the radio, how Hans has brought fire from the Gods like Prometheus of old, and how wonderfully abundant this group is with knowledgeable hams as yourself to provide support.
Thank you again.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
*which will be throttled back to about 5 watts by lowering the input voltage.
|
Re: #qmx high band harmonics
#qmx
Borrowed a tinySA Ultra and a 40dB attenuator from a friend today, and got good results using that and 10dB of attenuation inside the tinySA.? All harmonics in the radio's output are in compliance with the FCC limit.? I declared victory and buttoned the QMX into its case. Looking forward to warmer weather and taking it into the field.
73, everyone,
Eric
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Re: Older model QCX LCD lights up , but no display
thanks will do! as twisted as it sounds,? I am looking forward to trouble shooting this as my trouble shooting abilities are not what they used to be.? It will be great to exercise them again after 40 years.
|
Re: #qmx high band harmonics
#qmx
On Sat, Mar 2, 2024 at 04:07 PM, Da Amazin' man G0FTD wrote:
If you accidentally leave it it on then you'd exceed the input spec
Unless you have a specific reason to turn on the LNA, leave it off.? It will reduce the upper limit of the dynamic range of your instrument at the same time that it increases sensitivity.? Always turn it off if you are using external attenuation.? Only use it if your measurement is front-end noise limited. This is a powerful instrument and as such it requires some thought and understanding to make good measurements with it.?? There is a lot of good information on spectrum analyzer use at Keysight, Rohde & Schwarz, Anritsu and other manufacturers.?? Here are a couple to get started. 73, Don N2VGU
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Re: #qmx high band harmonics
#qmx
On Fri, Mar 1, 2024 at 12:59 PM, Evan Hand wrote:
For best results, keep the input at the TinySA under -25DBm.?
That is approximately -25dBm total power into the tinySA mixer; and gain/loss before the mixer, whether internal or external, will need to be accounted for.? -25dBm is not a hard and fast number and will vary with instrument and measurement. One way to check if the level is OK or too high is to add some more attenuation and see if the carrier to intermod/harmonic measurement changes.? If no change then the IM/harmonic is real and not internally-generated.? If it changes, add attenuation until it doesn't.?? The "sweet" spot between distortion and noise can be narrow; some commercial SAs have 1dB (or less) step attenuators for fine level control for this reason.? An external step attenuator can be handy, but watch its power rating..... I suspect that the tinySA designer made the internal LNA design such that it will saturate before it damages the mixer; that is what I would do.? What you will get instead is a screen full of massive distortion products, and, I expect, a warning from the instrument; I've never driven mine hard enough to find out.?? 73, Don N2VGU
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Re: Low Band QMX Spectrum analyzer measurments
On Thu, Feb 29, 2024 at 08:20 PM, Ronald Taylor wrote:
Chris, you technically don't meet the -43 dBc requirement
Yes he does. You clearly didn't bother reading his non US callsign which is quite clearly written at the end of his post. HINT - next time try reading the UK regs instead, there are no requirements other than making sure your tx doesn't cause undue intereference to others. Technically speaking, he can have a harmonic greater than a fundamental, and if it's not causing "undue intererence" then no rules are broken. OK, so that's an extreme example, but true. Reality is diferent, and most ops will take pride in suppressing unwanted emissions so that they don't cause problems. However, the point here is that many of us get just a bit pissed off with posts that assume the world has the same US rules. Now leave the rest of us alone to enjoy OUR regs, not yours. -- - 73 de Andy -
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Re: Older model QCX LCD lights up , but no display
The Backlight only need '12v' power applied to come on.
Most of the set runs on 5v via a regulator - but not the final few Audio OP amps which will generate some hiss..
Perhaps you ruined the first CPU (the instructions are too brief !) but the current one should have been fine.? ? I would proceed as the troubleshooting guide
in?
and?
Do all the DC checks in the build manual but start with is the 5V power there and at 5V !
?
|
Re: Older model QCX LCD lights up , but no display
Next you should probably check for continuity on all pins between IC2 and the LCD. Those are :
IC2 ? ? ? ?LCD 2 ? ? ? ? ? ?11 3 ? ? ? ? ? ?12 4 ? ? ? ? ? ?13 5 ? ? ? ? ? ?14 6 ? ? ? ? ? ? ?6 27 ? ? ? ? ? ?4
73...Ron ?
On Sat, Mar 2, 2024 at 1:33?PM Kevin Welna < kwelna@...> wrote: OK, there is more to this story.? This was a functioning QCX,? but it had firmware version 1.00g.? I in my infinite wisdom decided to upgrade the firmware my self rather than just buy the chip.......oops LOL
I get all the cables, down load the software plug it all in and press the button..... I believe I should have not been powering the radio when I pushed the button.....Anyway, afterwards,? the chip did not update and the screen,? while it lights up still displays nothing.? I have since ordered a new chip.? Which has been delivered and installed.? Alas, the same issue? is still present,? The display lights up (Backlight?) but nothing is displayed.? Regardless of the contrast adjustment. ?? When I plug in my earphones I do hear hiss,? so I think? it is receiving?? but I do not hear anything but hiss.? since I can not see to tune the radio I am not sure that it is actually receiving....Any suggestions?? I did check pin 3 and the pot does adjust the contrast between 0 and 5V.
Thoughts on where should I look?
Kevin - W5LNA
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Re: #qmx high band harmonics
#qmx
On Fri, Mar 1, 2024 at 05:08 PM, Eric W. Hansen wrote:
What isn't clear to me, from the tinySA Ultra specifications, is whether its "recommended input power below -25dBm" is before or after the SA's built-in attenuator.? How do you read it?
Tiny SA also has a 20db LNA. If you accidentally leave it it on then you'd exceed the input spec, so -25dbm should be your final target just in case. ? -- - 73 de Andy -
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Re: RF preamp for power amp - HF and 6 mtrs. Magic silicon does all.
Questions / statements on this design.
First one is how the? drafter of the schematic - not the original designer came to? his Av? results
For instance the? input transformer has a voltage gain of? 2 and? a power gain of slightly less than one.
so as a? log ratio surely the? voltage gain is? +3 dbB ? But he uses? 20 log? V2/ V1 type formula I guess and he's getting? 6 dB
THe reason this is intriguing? is I want to see where his? Av of? 13.4 for the first video op amp comes from.
I 'd say that? the way to analyse this is? to replace teh 180 R feed back resistor with two 90Rs and a? virtual tap to GND.? That's because
it is a fully balanced circuit.??
So Av would? be? 332 /90? ? +1, using the std form for an inverting in put? FB amplifier.? THis gives a voltage gain of 4.7
I we use the Incorrect formula of? ? 20 Log? 4.7? ?we get 13.4? as a the? Av as a logarithmic gain. This aligns with his table.
This query is more about? the correct way of analysing the? performance of the RF amp than picking holes in whatever formulation he?
used for the? logarithmic voltage gain.??
any comments. ?
The other comment which I wills save is those ballasting resistors on the output? - they seem to be required as per the TI? datasheet for this chip.
|
Re: High Band QDX One-Band-Low-Power Syndrome (yet again)
Hi William,
The RF sweeps combine the LPF and the BPF (L12 and one of the selected capacitors).? The most impact is from the BPF.? If the LPF is correctly built, it will be significantly above the operating frequency.? With that said, I do not use the RF sweeps to tune the LPF.? That is done by compressing or expanding the turns on the two toroid inductors in the filters.? Both can impact the output power, though, for me, the most impact was with the L2, L3, or L4 toroids.
Hans has a video on tuning a QCX LPF that can apply to the QDX.? The QCX has more toroids, but the principle is the same.
73
Evan
AC9TU
|
QMX and QCX-mini repair - Jeff W1NC
Thanks to Jeff, W1NC for the great job repairing my builds of both kits.? I didn't believe the quick turnaround and how reasonable the cost was.? He will even throw in a tactful appraisal of your kit building skills :-) along with his frequent detailed communications.?
73
Reed AA1RB
|
Older model QCX LCD lights up , but no display
OK, there is more to this story.? This was a functioning QCX,? but it had firmware version 1.00g.? I in my infinite wisdom decided to upgrade the firmware my self rather than just buy the chip.......oops LOL
I get all the cables, down load the software plug it all in and press the button..... I believe I should have not been powering the radio when I pushed the button.....Anyway, afterwards,? the chip did not update and the screen,? while it lights up still displays nothing.? I have since ordered a new chip.? Which has been delivered and installed.? Alas, the same issue? is still present,? The display lights up (Backlight?) but nothing is displayed.? Regardless of the contrast adjustment. ?? When I plug in my earphones I do hear hiss,? so I think? it is receiving?? but I do not hear anything but hiss.? since I can not see to tune the radio I am not sure that it is actually receiving....Any suggestions?? I did check pin 3 and the pot does adjust the contrast between 0 and 5V.
Thoughts on where should I look?
Kevin - W5LNA
|
Re: Brainstorm question: How to "view" QDX LED status remotely?
Hi!
Apologies for inexperience and eye sight too bad to read all these messages...??
Brainstorms-- 1. Optocoupler with a long USB cable??
2. Smoke alarm?? <grin>
73 Paul KY4XJ
On Wednesday, February 28th, 2024 at 8:41 AM, natereik via groups.io <natereik@...> wrote:
My QDX is generally "remote" in my attic at my main QTH, running off a laptop up there, 30 feet feet from where I'll sit and "operate." I like the QDX for remote digital work, because there's no audio routing involved, no other software needed to operate, and I don't need huge bandwidth if I remote desktop in.?
BUT, I have run into situations at home where I've accidentally bumped a slider in WJST-X....and eventually figured out I wasn't transmitting even though WJST-X seems to show that I am. I go up to the attic and then can see the LED status indicator and realize there's something wrong with the audio.?
? ? ?I'm looking at putting 2 or 3 QDXs to the same computer at my 2nd QTH eventually, and have realized this could be an occasional issue there, as I'll want to remote operate from home. From what I can tell, there's no way through Putty or any other native way to "see" the status LED (or read the status) via a computer... I have low bandwidth at my cabin, upload speed is slow there (600 kbps), so a camera with video is out of the question. So I'm curious as to how you think one could most easily "remote view" the status LED on a QDX or 2 without an insane amount of complexity??
Phototransistors into Arduino inputs? Somehow monitor the current of the LED, but fast enough to see what it's doing? (as in, need the resolution and speed to "Read" flashes vs the 1hz sine wave, etc) Of course this isn't an everyday need, so if it's just ridiculous to do so, I'll skip it. But was thinking there may be a simpler way than what I'm coming up with.?
Curious as to what others think, as this is not an area of my expertise.?
-Nate
N8BTR
|
High Band QDX One-Band-Low-Power Syndrome (yet again)
I am researching a low-power-on-one-band symptom on my High Band QDX, Succinctly, the power out was measured into a dummy load via a WM-2 and the rig was powered with a 5AH SLA bucked down to 12.0 VDC. Results below:
??? 20m ~6.0W 0.70A
??? 17m? 5.0W 0.66A
??? 15m ~6.0W 0.74A
??? 12m ~4.3W 0.66A
??? 10m? 2.0W 0.59A
I then did an RF filter sweep of the rig using PuTTY and got the images attached below. Here are my questions:
(1) I checked and compressed and loosened the turns on L4 and L10 to little or no effect on the sweep of 11m or 10m.
(2) To me, 20m looks like crap yet the rig puts out a healthy >5W on that band.
(3) The rest of them looks sort of OK.
(4) The 11M/10M looks great and clearly (to me) does not look like the LPF is causing the low power condition.?? ?
(5) Sorry for the ignorant question, but what do the filter sweeps show to all the trained eyes out there?
I have consulted the LY2H and EX0AA comments on the one-band-low-power matter and am still sorting through the group's anecdotal comments and other resources. Like LY2H, who could live with 3 watts on 10 meters, I could as well -- just not the one watt that my rig outputs on a 10m antenna. Also, I mainly want to get "some steerage" on how to utilize the tools and techniques to solve the problem.
Thanks in advance,??
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: looking for non-US keyer chip
Hi, yesterday I ordered a keyer kit from HamGadgets. They actually had reasonable shipping, $17 compared to $30 to send only the chips. Everything seems to be included in the kit and it should take very litle time to assemble it. Ron VE8RT On Sat, 02 Mar 2024 07:51:57 -0800 "EA4HZK" <ea4hzk@...> wrote: Attiny85 chip very affordable anywhere and you can get the software from github.
--
__________________________
.----------------. .----------------. .----------------. .----------------. .----------------. .----------------.
| .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. |
| | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | |
| | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | |
| | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | |
| | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | |
| | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | |
| | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | |
| | | || | | || | | || | | || | | || | | |
| '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' |
'----------------' '----------------' '----------------' '----------------' '----------------' '----------------' .----------------. .----------------. .----------------. .----------------. .----------------. .----------------. | .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. | | | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | | | | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | | | | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | | | | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | | | | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | | | | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | | | | | || | | || | | || | | || | | || | | | | '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' | '----------------' '----------------' '----------------' '----------------' '----------------' '----------------'
.----------------. .----------------. .----------------. .----------------. .----------------. .----------------.
| .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. |
| | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | |
| | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | |
| | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | |
| | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | |
| | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | |
| | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | |
| | | || | | || | | || | | || | | || | | |
| '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' |
'----------------' '----------------' '----------------' '----------------' '----------------' '----------------'
.----------------. .----------------. .----------------. .----------------. .----------------. .----------------.
| .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. |
| | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | |
| | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | |
| | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | |
| | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | |
| | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | |
| | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | |
| | | || | | || | | || | | || | | || | | |
| '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' |
'----------------' '----------------' '----------------' '----------------' '----------------' '----------------'
.----------------. .----------------. .----------------. .----------------. .----------------. .----------------.
| .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. |
| | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | |
| | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | |
| | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | |
| | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | |
| | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | |
| | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | |
| | | || | | || | | || | | || | | || | | |
| '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' |
'----------------' '----------------' '----------------' '----------------' '----------------' '----------------'
.----------------. .----------------. .----------------. .----------------. .----------------. .----------------.
| .--------------. || .--------------. || .--------------. || .--------------. || .--------------. || .--------------. |
| | _________ | || | __ | || | _ _ | || | ____ ____ | || | ________ | || | ___ ____ | |
| | |_ ___ | | || | / \ | || | | | | | | || | |_ || _| | || | | __ _| | || | |_ ||_ _| | |
| | | |_ \_| | || | / /\ \ | || | | |__| |_ | || | | |__| | | || | |_/ / / | || | | |_/ / | |
| | | _| _ | || | / ____ \ | || | |____ _| | || | | __ | | || | .'.' _ | || | | __'. | |
| | _| |___/ | | || | _/ / \ \_ | || | _| |_ | || | _| | | |_ | || | _/ /__/ | | || | _| | \ \_ | |
| | |_________| | || ||____| |____|| || | |_____| | || | |____||____| | || | |________| | || | |____||____| | |
| | | || | | || | | || | | || | | || | | |
| '--------------' || '--------------' || '--------------' || '--------------' || '--------------' || '--------------' |
'----------------' '----------------' '----------------' '----------------' '----------------' '----------------'
___ ___ __ _ _ ____ _ __
| __>| . | /. | | | ||_ /| / /
| _> | |/_ .|| | / / | \
|___>|_|_| |_| |_|_|/___||_\_\
___ ___ __ _ _ ____ _ __
| __>| . | /. | | | ||_ /| / /
| _> | |/_ .|| | / / | \
|___>|_|_| |_| |_|_|/___||_\_\
___ ___ __ _ _ ____ _ __
| __>| . | /. | | | ||_ /| / /
| _> | |/_ .|| | / / | \
|___>|_|_| |_| |_|_|/___||_\_\
___ ___ __ _ _ ____ _ __
| __>| . | /. | | | ||_ /| / /
| _> | |/_ .|| | / / | \
|___>|_|_| |_| |_|_|/___||_\_\
___ ___ __ _ _ ____ _ __
| __>| . | /. | | | ||_ /| / /
| _> | |/_ .|| | / / | \
|___>|_|_| |_| |_|_|/___||_\_\
73's !
-- Ron VE8RT <ve8rt@...>
|
Burt Wizeman
k6whp
Donald S Brant Jr
Bruce Akhurst
Ronald Taylor
Timothy Fidler