Re: Dire need for a part!
Hi all
FYI Digikey's cheapest?US shipping option is FedEx Ground (4 days) at $6.99. Mouser's cheapest shipping option is UPS Ground at $7.99.?
It isn't $15...??
Barb,
I prefer to buy from Tier 1 disti -- but with USA shipping higher than a cat's back on Halloween, and the large number of SMT parts needed to make an order that makes good economic?sense -- sometimes it's better to take a chance on buying direct from China, or from a second- or third-tier vendor like Walmart. ?
As their business model, Walmart sells trash bags and Cream of Wheat, not SMT inductors. ? ?But if you buy 200 SMT inductors, at least a few of them have to be good. ? And it's cheaper to bin your own from Walmart parts than to pay $15 for $0.03 of parts from Mouser or Digikey. ?
It was a sad, sad day indeed when Digikey stopped their free shipping?on prepaid orders.? I haven't tried ... if I sent them a check for $15 or $20 of hobbyist components without any shipping on the?check, would they send the parts or send back my check? ? ?Someone should try that -- alternatively, have their 12-year-old daughter?write out the order by hand, explaining her situation and the Grrrl-STEM project she needed the parts for. ?
73 Jim N6OTQ
On Mon, Sep 4, 2023 at 5:50?PM < wb2cba@...> wrote: I would buy from reputable sources like Mouser or Digikey.?
73
Barb WB2CBA
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I built one of the early QMX rigs, S/N 338, and it's done great ever since, about 2 1/2 months, until last week. I gave it the ultimate test by transmitting without an antenna and not being observant so did it a couple of times. It took it at first, but eventually gave up and shorted one of the finals.
I replaced the finals and D106 zener diode it shorted also. It came up and did fine so put it back in the case. It worked for an hour or so then the same thing, short causing the power supply to current limit to 1 Amp. This time D106 was fine. I replaced all the finals and to be safe the driver IC503, 74ACT08D, chip. Tested and all ok so back in the case. Again it lasted about an hour with FT8 and bang. Same short.
What could be causing it to repeatedly fry the finals? Actually only one of the finals shorts. The other 3 all test good. The antenna is connected with SWR of 1.0. Power out on 20M is 4.5 watts and 40M is 4 watts. Now this evening with it out of the box and just replacing the one bad BS170 it's worked for an hour and a half and still is ok. Could being in the case causes too much heat build up? I don't see anywhere where the case touches anything.
Noticed today an oddity, the QMX display kind of flickers as it powers up. No flicker once it's up, but I don't remember that occurring previously. ??? It makes me think that there is something that is putting a heavy load on the voltage as it powers up so the display isn't seeing the full voltage. I don't see that indicated on the meter on the power supply.
Ideas?
Help!
73,
Cliff, AE5ZA
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Re: Dire need for a part!
Barb,
I prefer to buy from Tier 1 disti -- but with USA shipping higher than a cat's back on Halloween, and the large number of SMT parts needed to make an order that makes good economic?sense -- sometimes it's better to take a chance on buying direct from China, or from a second- or third-tier vendor like Walmart. ?
As their business model, Walmart sells trash bags and Cream of Wheat, not SMT inductors. ? ?But if you buy 200 SMT inductors, at least a few of them have to be good. ? And it's cheaper to bin your own from Walmart parts than to pay $15 for $0.03 of parts from Mouser or Digikey. ?
It was a sad, sad day indeed when Digikey stopped their free shipping?on prepaid orders.? I haven't tried ... if I sent them a check for $15 or $20 of hobbyist components without any shipping on the?check, would they send the parts or send back my check? ? ?Someone should try that -- alternatively, have their 12-year-old daughter?write out the order by hand, explaining her situation and the Grrrl-STEM project she needed the parts for. ?
73 Jim N6OTQ
On Mon, Sep 4, 2023 at 5:50?PM < wb2cba@...> wrote: I would buy from reputable sources like Mouser or Digikey.?
73
Barb WB2CBA
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Re: Dire need for a part!
I would buy from reputable sources like Mouser or Digikey.?
73
Barb WB2CBA
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I solved an intermittent QMX audio issue and thought I would share what I discovered. I noticed the case required some effort to squeeze closed properly and for the small end screws to align. The audio problem appeared after the final assembly, but I never experienced the audio squeal when the back was off. I later found that pressing on the main board by the power supplies would recreate the problem. I then realized my case was pressing down on one of the nylon power supply mounting screws - the one closest to the middle of the board. I used my wire cutters to nip off enough of the screw to get the case to snap shut with no effort. Now the audio issue is gone and the rig is 100% complete, making dozens of great QRP QSOs on CW & some FT8 for good measure. What an amazing feat of engineering :-)?
I hope this helps someone with a similar issue. Perhaps a countersunk screw would work well here, but trimming the edge did the trick.?
?
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Re: Dire need for a part!
Sometimes when you google on the part description and include the vendor (Walmart, in this case) you will get the Walmart link in?what google returns. ?
No, Walmart is NOT an electronics component vendor, but their Borg-sized computers seem to be able to find this kind of thing.? Question is, are they Radio Shack-quality (IOW, floor ?sweepings)?
I've purchased a few electromechanical pieces from Walmart?-- mostly battery connectors and power plugs -- when they were cheapest AND fastest guaranteed delivery.? Somewhat surprisingly, I wasn't disappointed.? So don't rule Walmart out.
73 Jim N6OTQ
On Mon, Sep 4, 2023 at 4:56?PM james jones < j2@...> wrote:
Walmart shows they have 200 0805 47uh 10% smd parts for $13.49.?
I’ve not tried ordering but they certainly are listed on their website.
YMMV
Jim w0nkn?
David (WA5DJJ)
Can you please give me a detailed explanation how in the world you got through WalMart to get taped smd parts. I have tried everything
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Re: QDX - protection of BS17O PA
I have not tried them, but I like the following devices, stocked at digi-key
? (leaded)
?or?? (45V versions)
Gary
W9TD
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Hans,
I am VERY glad to hear the QSX will not be tiny like the QMX.? I am an experienced kit builder and the QMX was really tough for me to build and I'm hoping the new SMPS boards I ordered will solve my issue of "Now it works, now it doesn't" with my QMX.? If it doesn't I'll chalk the loss up to my lack of skills. Right now if someone asks me if they should build a QMX I'm telling them if you are a well experienced kit builder with a lot of good test equipment, have great eyesight and trouble shooting skills the QMX is for you.? And being at least a BSEE would be great too.? Otherwise save yourself the $$$ and heartache and get something easier to build.
Sorry Hans but that's how I feel.??
73, Bill NZ0T
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Re: Dire need for a part!
Walmart shows they have 200 0805 47uh 10% smd parts for $13.49.?
I’ve not tried ordering but they certainly are listed on their website.
YMMV
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On Sep 4, 2023, at 4:43 PM, N5SE via groups.io <bwmoore@...> wrote:
?
David (WA5DJJ)
Can you please give me a detailed explanation how in the world you got through WalMart to get taped smd parts. I have tried everything to duplicate your feat and failed miserabley. Thanks in advance.
Dear members,
I found some on line and ordered them.?? They should be here soon.?? I
will have extras when they get here so if anyone else
needs a SMD 0805 47uH inductor please let me know.?? I am willing to
share and I will have quite a few extras.
--
73 Dave WA5DJJ SUPER GRABBER WEBSITE:
--
N5SE
Billy Wayne Moore
7066 Shady Knoll Ln
Willis, TX 77318-6324
Phone: 936-537-2975???
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Re: Dire need for a part!
David (WA5DJJ)
Can you please give me a detailed explanation how in the world you got through WalMart to get taped smd parts. I have tried everything to duplicate your feat and failed miserabley. Thanks in advance.
toggle quoted message
Show quoted text
Dear members,
I found some on line and ordered them.?? They should be here soon.?? I
will have extras when they get here so if anyone else
needs a SMD 0805 47uH inductor please let me know.?? I am willing to
share and I will have quite a few extras.
--
73 Dave WA5DJJ SUPER GRABBER WEBSITE:
-- N5SE
Billy Wayne Moore
7066 Shady Knoll Ln
Willis, TX 77318-6324
Phone: 936-537-2975???
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On Mon, Sep 4, 2023 at 08:28 PM, Jerry Moyer wrote:
True but with a circular polarity antenna on one end or the other, deep multi-path cancellations are virtually eliminated because it causes each of the wave fronts to arrive at a different and constantly rotating polarity. ?As a result only one of the arriving wave fronts at any given moment will be the same polarity as the receiving antenna and all others will arrive at that moment at a lesser signal strength.
?Assumes a space wave / direct wave only. Circular or mixed polarization is good at FM broadcast, and it's used to get around a few things in the auto world. If you use the vehicle chassis as an end fed half wave at 100Mhz then you'll see a classic dipole polar response. But a dipole is also responsive to the vertical component at the the? end of a dipole. So if you transmit circular of mixed then the end feed dipole effect of a vehicle body become almost eliminated and the dipole appear as good as omnidirectional. I've got the measurements to prove it, from my own portfolio of work 25 years ago when I had to measure this stuff ;-) But not much use at HF. Once again, the reflecting medium determines the output polarization regardless of what the incident wave is. Multipath was a pet project of mine some 25 years ago when designing diversity antennas. My old workbench below, including an HP Multipath Simulator...the rack on the left. -- - 73 de Andy -
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Re: I completed the assembly of the new QMX
good evening everyone, finally this afternoon the Q103 and D101 spare parts for the QMX power board arrived, tomorrow I hope to be able to replace them but I hope more for a miracle for loading the firmware and starting it up.? 73 to all Giuseppe iu8eun
Hi Chris
One thing, Hans posted information about a secret extra
diagnostics screen which gave useful information about voltages as
read by the inbuilt ADCs. Cand someone please repost the
instructions for getting to it, the post seems to have vanished in
the multitude of others.
There's the official hardware diagnostics screen now which presents things tidily.?
Or the secret debug screen I use in development, which presents information in a haphazard way which is useful to me during development and probably not much else, but you can try it if you want! Just press d in the main menu when connected with a terminal! Remember, d is for debug. Pressing d again turns it off.?
73 Hans G0UPL
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Re: QDX - protection of BS17O PA
Hello Paul
I will be delighted to send my checklist over. I am working down in London this week but will forward it on at the weekend.
A few years back I purchased a NanoVNA which I switch onto my antenna as part of the SWR check. It will instantly show if there is anything untoward going on.
I think I paid ?32 for it and now a vital part of the shack for many other applications too.
73s Ted
2E0THH
?
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True but with a circular polarity antenna on one end or the other, deep multi-path cancellations are virtually eliminated because it causes each of the wave fronts to arrive at a different and constantly rotating polarity. ?As a result only one of the arriving wave fronts at any given moment will be the same polarity as the receiving antenna and all others will arrive at that moment at a lesser signal strength. ?There is a cost of about 3 dB in gain up front but that is more than offset by the reduction in multi-path fading. ?This should work regardless of whether or not it is VHF bouncing around a mountain or HF bouncing off the ionosphere. ?This method of reducing multi-path fading is most often used by FM broadcasters in the US to prevent “picket fencing” to a mobile receiver but I have also employed this same method to enable UHF FM 2-way NLOS communications inside and around buildings and even underground. ?But if the cause of the fading is actually due to Doppler shift then using a circular antenna would most likely be ineffective. ??
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On Sep 4, 2023, at 1:02 PM, Da Amazin' man G0FTD via groups.io <punkbiscuit@...> wrote:
?On Sun, Sep 3, 2023 at 05:43 PM, Jerry Moyer wrote:
Aren’t we really talking about multi-path cancellation? ?That commonly affects VHF and above. ?The way to deal with multi-path is to use multiple polarization or even circular polarization at one or both of the antennas. ?Am I missing something??
The reflecting media is what controls the finally emitted polarization. You can send any polarization to the ionosphere, it will take it in and then spew it out at what IT determines. Same for VHF/UHF,? not ionospheric). All down to what the reflecting *media* determines based up on it's spacial geometry, angle of incidence etc. Long and complicated subjected, but one I've got quite? a bit of both amateur and professional pedigree ;-) I've also done tests, synchronized TX's on HF separated by by 10Hz or so feeding horizontal / vertical? mixed polarization. Makes no difference what polarization you send, ionosphere is the dictator,. Ionosphere takes your input and then decides upon the "output" and we are it's slaves. -- - 73 de Andy -
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Re: QDX Rev 4 Only Shows 80M Band After Working Near T2
I seem to have a similar problem. My Rev 4 was ordered assembled and has been working fine for months.? I upgraded the firmware to 1_10 and then found the only band available is 40.? Multiple installs of different firmware and factory resets have failed to make a difference.?
n3jwj
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Re: QDX - protection of BS17O PA
I agree with Hans.? However, its more than cost or size.
From experience...
Adding protections considerably complicates the transmit section and adds
a large number of parts that can also fail or if kitted be damaged in assembly.
It also can if "broken" cause a larger number of problems that for the inexperienced
would be annoyingly difficult to repair.
Add to that the best protection is prevention and that means making sure the load is?
a reasonable approximation as high SWR can mean unusually low impedance,
or unreasonable reactance that presents a troublesome load.
From my experience in antennas the number of cases where it "works great"
usually meant an untuned antenna, out of band antenna or if more than one?
the wrong antenna. When corrected the usual response was "Wow" or "why?
did it work before?".? What is forgotten is anything can radiate, doing it well
can make a massive difference.? ?
--
Allison
------------------
Post online only, please no email.
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Re: QDX - protection of BS17O PA
Dear Hans,
I appreciate and trust? your analysis and my version 1 QDX worked really great once I solved all of the SWR and power adjustments to using a 12VDC power supply adjustments.? I understand that the testing you have done pretty well proves to me that it is some kind of external event that is blowing the BS170 FET's on some of the QDX's and it doesn't seem to be limited to one version of QDX.? Since I plan to loan out or give my version 3 QDX's and they may end up in places where the folks may not be astute to making sure the power supply is exact or the antenna SWR is less than 2:1.? I want to make them as bullet proof as I can to prevent failure.? I understand that your testing and some of mine proves pretty well that the failure of the PA section of the QDX shouldn't happen unless it is abused.? Maybe the addition of these inexpensive parts will improve the reliability for the failures that are caused by things that we can't reproduce the modes that caused the outlying failures.
So, I am going to put two 3 amp power diodes in the power line to drop the 12V to 10.5VDC.?? Since I ordered the 47V Zener diodes, I am going to add them to the QDX output amplifier and I am going to put the 1N4148 diode on L14.? I am only doing this to prevent the QDX from self destruction during the time that the new operator has time to learn to check the other killer things that causes failures.?? I want them to experience the same amazement of 40M contacts to the far east with a ground mounted vertical antenna with 3.5 watts when the station calls them.? Or working all over the USA on JS8CAL using this amazing little black box with no knobs.?
Thank you for your message.? I will be keeping track of these 5 QDX units and try to record the failures we have to build a data base.? Thanks to all who have also put their thoughts and possible solutions for the failure of the QDX's BS170 Final Amplifiers. All of the efforts have given us all some really good background on their results and cures for the rest of us to try.?
Take care and have fun.
73 Dave WA5DJJ
SUPER QRSS/WSPR GRABBER
?
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On Sun, Sep 3, 2023 at 05:43 PM, Jerry Moyer wrote:
Aren’t we really talking about multi-path cancellation? ?That commonly affects VHF and above. ?The way to deal with multi-path is to use multiple polarization or even circular polarization at one or both of the antennas. ?Am I missing something??
The reflecting media is what controls the finally emitted polarization. You can send any polarization to the ionosphere, it will take it in and then spew it out at what IT determines. Same for VHF/UHF,? not ionospheric). All down to what the reflecting *media* determines based up on it's spacial geometry, angle of incidence etc. Long and complicated subjected, but one I've got quite? a bit of both amateur and professional pedigree ;-) I've also done tests, synchronized TX's on HF separated by by 10Hz or so feeding horizontal / vertical? mixed polarization. Makes no difference what polarization you send, ionosphere is the dictator,. Ionosphere takes your input and then decides upon the "output" and we are it's slaves. -- - 73 de Andy -
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For the record, QMX kit 73569 has the Q103/Q104 short. I am attempting repairs but have ordered spare QMX SMPS boards as backup.
Pete, KH6GK
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Re: QDX Hiband , reduce power to 0dbm for xverter
Thanks for those ideas !?
Itnworks , yes but from 15 up it leaks like ~3db, and on ft8 3db when you are qrp is unfortunately a gamechanger.?
I already did the condensator mod fromnthenbig topic what permitted me with adjusting the coils to get the higher bands up to 2w/2.5w. Thats why the idea came to me tonuse itnas transverter driver . But for digi the type of xverters i have only work properly via the 0dbm ports.?
20m could do 2m and if there is a way to generate a "HI" or "Low" signal of some sort depending on bands i could switch to 4m via 10m.??
Will have a look and try to find out how much the driver puts out.?
73
Felix , df3fx/f1veo
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Barb WB2CBA
K9NUD-Steve
Gary W9TD
N5SE
Ted 2E0THH