I had run into a similar situation. And this solved it:
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Amazon.com: Digirig Shielded Short USB-A to USB-C Cable with Ferrites : Electronics
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I so use this:
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RF into the computer is gone.?
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For a vertical, a ground connection is only for lightning or static charge protection. It won't do much for rf. So without a proper counterpoise, there's going to be rf issues.?
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I use 2 raised tuned radials on my 1/4 wave vertical in the field, and the common mode choke is a nessesity for this set up.?
--
73
de Roy - KI0ER
Littleton, Colorado USA
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Re: Still no output on QMX
If you use a linear regulator, then you're correct-- It generates
heat and will "waste" power...
The buck/boost regulators are all switchers, which will
(nominally) waste less power. Consider, if you use 3
silicon diodes to bring 13.8 volts down to (roughly) 12, and draw
1 amp on transmit, that will be about 1.8 watts dissipated in the
diodes--and that loss won't change as the battery voltage drops.
Don't know what the comparative losses will be in a switching
regulator... Close maybe, but I don't know which would be better!
73, Paul -- AI7JR
On 9/22/24 02:03, James via groups.io
wrote:
Hi Paul, I initially built the 9V version of the QMX.?All my
power sources are either 13.8V or 12.8V. My thoughts were
building the 9V version with a voltage regulator inline of a
dedicated power cord. ?My
only concern, and honestly I'm not knowledgeable to know, but
I was thinking that the extra voltage would be dissipated in
heat, and the hotter the regulator would get, the more
amperage it would draw. I was going to inquire about this
theory, but then actually getting any output at all out of the
rig became the major concern. In the middle of all that, I
rebuilt it to the 12V arrangement. Right now I'm not sure why
I'm not getting any output so like I said, I will reassemble
the rig and run the test that Ludwig was suggesting and go
from there. Thank you for your input. After I tackle the
output problem, I'll check into your suggestion. I'll try to
find some information on which is better, boosting up to 9V,
or regulating down from 12V.?
?
James
KA9TII??
--
Paul -- AI7JR
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Re: Removing flux. Is it necessary? Yes/No
Hi All
It is very interesting to see so many recommendations for IPA etc. I have tried this on a kit I built and it attacked the green coating on the rear of the board.?
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John G0UBE
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Re: qmx with tiny lcd display
find a smaller display and rotate it 90deg is the first step
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The only reason I can think of for doing this, if I were to do it, is to turn the QMX into an HT. What's your plan?
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73,
Yoon KM6KJI
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Re: QDX delivery - missing 30pF
I scavenged a 30pF from my QMX+ kit to get me through this QDX build until I can get a replacement. I may contact Hans and have him add this to a GPS order...
73,
Steve AK0M
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Re: Removing flux. Is it necessary? Yes/No
I clear thick areas of flux build up with a careful and gentle scraping with the back edge of the pointy end of a #11 Xacto blade.?
Then a very used, old soft toothbrush to brush way the flux crumbs.
I follow that with frequently changed Q-Tips, one end only soaked in 99% IPA ( yes, ninety nine percent) and swiped clean with the dry end. I look for fiber wisps and take care of those.?
I clean periodically as I go, taking the time to inspect joints and touch up soldering where necessary.?
Then 99% IPA and a new, clean, cut down acid brush in sort of broader areas followed by pressing and wiping gently with cut up pieces of micro fiber cloth; also frequently changed until the IPA flashes off quickly leaving no smears.?
I do all of this over my grounded (1 M ohm) static safe building board,? wearing a proper static control wrist strap that plugs into a barrel ended alligator clip that is joined to the? board. I use that same static control setup while handling ANYTHING at any time, that includes static sensitive components while inspecting, sorting, installing components and calibrating procedures that involve touching any component. And static safe soldering irons too.
GREG
On Sun, Sep 22, 2024 at 9:34 PM, Robert AD6XJ <91710robert@...> wrote: I've been using no clean flux on my QMX+ and using 91% isopropyl UNSUCCESSFULLY. A friend recommended a product called "flux off" but it costs $30 a can (too much for me). I don't remember my old solder leaving so much gunk behind ?. I do have an ultra-sonic tank I'm willing to try, but I do agree fully that the point-by-point cleaning process is also a good inspection opportunity. The cotton swabs do annoyingly leave a lot of fibers, maybe I need nippers that don't cause burrs??? So I am still looking for a solution (pardon the pun) to get rid of this flux.
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?
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Re: QDX delivery - missing 30pF
I am just finally getting around to assembling my QDX rev 4 to take with me on a KL7 visit this week. Discovered I am missing one of the 30pF capacitors.
I have a plain ceramic 50V 30pF that I could drop in, will that type work ok in lieu of having a monolithic ceramic capacitor? I could also go to a 27pF plain ceramic if that would be better.
73, Steve AK0M
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Re: Removing flux. Is it necessary? Yes/No
I've been using no clean flux on my QMX+ and using 91% isopropyl UNSUCCESSFULLY. A friend recommended a product called "flux off" but it costs $30 a can (too much for me). I don't remember my old solder leaving so much gunk behind ?. I do have an ultra-sonic tank I'm willing to try, but I do agree fully that the point-by-point cleaning process is also a good inspection opportunity. The cotton swabs do annoyingly leave a lot of fibers, maybe I need nippers that don't cause burrs??? So I am still looking for a solution (pardon the pun) to get rid of this flux.
?
?
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Perfect. No perf board required.?
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You're welcome ... and here is a photo showing how I built it.
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Re: What's the Weakest Signal You Can Get a Response From?
I have gotten -26 reports on ft8 and still completed the QSO on my QMX+
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73
-Mike
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This looks like a great method and eliminates the box I was working on to go between the KX3 (ACC2) and the amp. ?Thank you! ?I knew there was a brain-trust out there.?
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I added this mod inside my 50W amp to add low-active PTT capability without disturbing the existing high-active PTT.? Then I wired up a PTT cable that connected the KX2's PTT signal to the tip of the cable's 3.5 mm plug.? I'm guessing it's that same as what would be needed for the KX3.
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?
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Re: QMX+ back up clock accuracy
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Re: Removing flux. Is it necessary? Yes/No
Long ago (1974, oy), I had a summer job at JPL and was sent to NASA soldering school for a week.? The teacher impressed upon us that "flux is hygroscopic" and could not be allowed to remain on any assembly.? Since then I've believed that I should remove residual flux, even when I don't.? (Have fluxes changed in fifty years?? I don't know.)
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Eric
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Get plenty of ferrites on the interconnecting cables and power cable and a good choke on the antenna feedline
Also although the QMX is low power try to get the antenna some metres from the shack?
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Re: What's the Weakest Signal You Can Get a Response From?
I work POTA exclusively 5 watt. Either with my QCX or QMX and I’ve had QSOs from coastal NC into Europe, Alaska, Hawaii, and even into New Zealand. ?Antenna is either a QRPGuys triband vertical or an EFHW.
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Usually my assigned RST is two units below what I send back. But I’ve had dozens of RSTs at 117 or so,
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QRP is all about whether the other guy can hear you. ?My POTA station is necessarily compromised, but the responder’s station is not. ?He could be using a mega element beam up 100’ + and max legal power. ?He only needs to be able to hear you and be motivated to answer. ?You can assume that if he answers, he hears you well enough.
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I don’t consider myself under equipped running QRP at a POTA activation. Usually I’m about 10% DX when I activate.
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?
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Re: What's the Weakest Signal You Can Get a Response From?
And to add for the FT-8 for example, the difference in the receiver bandwidth used for the FT-8 is 50 to 2700Hz as compared with the SSB bandwidth. It means that considering the noise alone it is?more than 17dB bellow the noise in the SSB channel.
--
73 Bojan S53DZ
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Re: What's the Weakest Signal You Can Get a Response From?
Hi,
the precise number for the receiver could be the MDS or the sensitivity. It is measured at the receiver input.
MDS - the minimum discernable (or decodable) signal
Sensitivity - the signal that is a predefined number of SNR.
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When it comes to your question as how it works on the air, how you can make the least possible QSO than you have to calculate more things.
- from you --> the correspondent
your: TX power, antenna efficiency, --- propagation, QRM, --- correspondent's: antenna efficiency, RX sensitivity.
- from him --> you:
his: TX power, antenna efficiency, --- propagation, QRM, --- your: antenna efficiency, RX sensitivity.
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In the QSO all these are in series, so whatever parameter fails - no answer, no QSO.
--
73 Bojan S53DZ
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Re: 180pf (181) Capacitor Needed
Hi all
Note that Digikey will sell you an individual resistor or capacitor if you want it. The postage cost via USPS (3 days typical) is $4.99.?
Thanks, Tisha.?
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Mouser sold me four of the caps for about 11 dollars total with shipping.
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Paul - AI7JR
Mark Palmer
Bruce Akhurst