Hi David,
This happens to my U3S as well. but U3S should transmit even without a GPS. I just set the last digit of minute manually and let U3S pick up GPS time whenever it's willing to(usually after the first TX), or briefly power cycle the U3S after GPS shows a 3D lock, similar to what you did. BTW, My GPS is a third party one.
73, Wei
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Looking at the assembly manual, page 45, 60-15 version...
L510 is 11 turns, yet the published inductance is higher than L513, which is 12 turns. The footnote says 11 turns works better in practice, but it appears that the published inductance value for L510 is for 13 turns.
As an aside, last summer I put together a set of 5B4AGN/W3NQN bandpass filters. The source for the toroids was the same as QMX. The permeability of all the toroids was higher than the specs. Took a lot of rework to get the filters right.
73,
Steve, N2IC
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On Thu, May 23, 2024 at 10:22 AM, Ted 2E0THH wrote:
don't you need the exact value of the cap for this analysis to work?
?Yes, you do - the more accurate you know the value of the cap, the more accurate you can interpret the results. -- John AE5X
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Powdered iron cores do tend to keep the same inductance at various frequencies up to HF. Q depends on the core type. I used to measure my inductors at the intended operating frequency with my FA-VA5, but the DE-5000 does a very credible job at 100kHz. Ferrite is a different matter.
I like to check my results with the VK3CPU toroid calculator.
73 de va3rr
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On Thu, May 23, 2024 at 10:58 AM, John AE5X wrote: As someone else mentioned,? the DE5000 makes these measurements at 100kHz and
that is fine even for components that will be used at HF. I had a DE5000 for a
while and it agreed closely with the VNA method.
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Great video John
Just curious, don't you need the exact value of the cap for this analysis to work?
73s Ted
2E0THH?
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Re: U4B GPS Altitude stability
Dave & Bruce: Thank you for the detailed information!
-Bob KA5MIZ
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QMX+, sorry for the typo. Here's a vid I posted some time ago:
As someone else mentioned,? the DE5000 makes these measurements at 100kHz and that is fine even for components that will be used at HF. I had a DE5000 for a while and it agreed closely with the VNA method.
--
John AE5X
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Re: Antenna tuner companion for QMX?
#qmx
The problem with PolyVaricons is not loss.? They are power limited
for two reasons..
The poly film is very thin so high power (more than QRP) is out.
The other is the mechanical construction is such that the rotor connection
can and does fail (intermittent contact).
While buying new air variables can be pricey its more of taking
advantage of the buyer. Flea markets and old radios are a great
source and usually very cheap.? Even the old "broadcast" variable
can be run at higher power.? ?Old dirty ones?? RUn them though
the dish washer.. they come out looking very good.
That said I've use them in matching units and they work and generally
if there is loss look at the tiny coils used, first.
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
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Re: Antenna tuner companion for QMX?
#qmx
Question; here in the real world, how much signal loss due to using the ubiquitous "PolyVaricons"?? With the scarcity and pricing for "air variable capacitors" the PolyVaricons are an attractive and readily available option (AliExpress).? I am building a couple of the AliExpress PolyVaricon tuner kits and also have bought parts to homebrew my own versions.
Also, PolyVaricons are "cute" !
Jim WB4ILP?
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Re: Antenna tuner companion for QMX?
#qmx
"connector saver", now I understand why male/female adapters exist.
Thanks Don !
Jim WB4ILP?
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Re: U4B GPS Altitude stability
I believe the firmware was designed to give an altitude as quickly as possible .... this is to save battery and time while flying.? So a 3D altitude solution can be computed with just 4 satellites. In flight this solution is usually computed in 15 seconds? or so, with a small dipole antenna, as reported by telemetry.? ?If a more accurate altitude was required, more satellites would be needed for the solution... and this could be a future option, but would require more time to lock on more satellites. Perhaps this could be done in the future, with a Basic call for more accurate positioning. On the ground while testing it is normal to see a variation in altitude, with a non ideal view of the sky, even though you know the U4B is sitting on the table.?
Dave VE3KCL
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Re: A couple of new 12V power options
Love this option with the Tufteln product. I have the low and mid band QMX but both are wound for 9v. I have a high band (assembled) I¡¯m still waiting on but I believe those are assembled 12v?? Either way I¡¯ll use this power supply option for other radios in my kit: a Penntek TR-45L, Mountain Topper and KX3. Thanks for sharing.?
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On Thu, May 23, 2024 at 07:09 AM, John AE5X wrote:
I think I will do that for my upcoming QCX+ build, using a nanoVNA to measure the coil's L before installing it onto the board.?
QCX+ or QMX+? Curious if you (or others) will/can share how you specifically do this. Seems to be a few different methods. Some use a capacitor in series and look at resonant frequency, some seem to use NanoVNA saver to show the L directly... (but then what frequency range?)...And I thought I saw another method as well.... On Thu, May 23, 2024 at 03:25 AM, Marek SP9TKW wrote:
My experience is to go by required inductance for LPF not number of turns. Cores might differ in AL value by +/-20%? and squeezing and spreading wires often is not enough. Recently, I used that method on MB version based on Bill's notes and straight away I got 3.5W minimum on each band without any adjustments.??
Marek, what method do you use to measure the inductance? -Nate N8BTR
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Are the inductance values in the QMX manual based on calculation or measurement? I'm in the midst of a mid-band QMX build and had to spread all my inductors to get close to the values in the manual. Even so, all of my inductors measured 5-10% higher than those in the manual, as measured at 100kHz with my DE-5000.
tnx de Russ, va3rr
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On Thu, May 23, 2024 at 04:25 AM, Marek SP9TKW wrote: My experience is to go by required inductance for LPF not number of turns.
Cores might differ in AL value by +/-20%? and squeezing and spreading wires
often is not enough.
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On Thu, May 23, 2024 at 03:25 AM, Marek SP9TKW wrote:
My experience is to go by required inductance for LPF not number of turns
I think I will do that for my upcoming QCX+ build, using a nanoVNA to measure the coil's L before installing it onto the board.? ? -- John AE5X
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The meter I used was the OHR WM-2. This is a dedicated watt meter and should be an instrument that is precise enough to do the job. It helped me a lot in many other projects so far.
Btw, currently I am travelling and can not try any optimizations in the next two weeks...
73 Hannes DL9SCO
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The ft8cn App works perfectly with qcx only using usb-c cable for both cat and Audio.?
No vox or kenwood ts-480 may be selected!
Setting in ft8cn app:
Rig: qdx
Control:cat
Connection type:usb
Leave everything else at default setting
At your android phone/tablet:
-Setting
-Sounds & Vibration
-separate app Sound
-Turn on now
+Add apps?
-select the FT8CN App in the List
-Go back
-in Audio device select "Phone" or "Tablet"
-Go back. Thats it
Media Volume: 100%
73 de DL9TX
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Re: Antenna tuner companion for QMX?
#qmx
Paul,
Since a ham license is a license to learn your comments are interesting. Most hams I know (and we have a large club) wouldn't understand your comment and few would research the literature to understand. ?All they know is that the tuner makes the SWR go down and their QRP transmitter is happy. ?
Thanks for your comment and I will read and learn more, again because at 80 I have forgotten much of the ¡°why¡± in matching to antennas. ?I started when SWR was rarely discussed in club meetings but my pi-network made the RF go out to my antenna and the world (I used to have QSL cards to prove it) and I was a happy 16 year old ham (1960)?
Again, thanks for your comment. ?I have two ZM-2 antenna matching devices and they both work well. I am also anal enough I sometimes use a modern RigExpert analyzer to adjust the matching device before connecting my QRP xcvr same as I do with my AlexLoop. ?So far haven¡¯t had to replace any finals.?
Read on my ham friends. ?Thanks to my parents for all the encouragement to read anything and everything that stops in my visual field. ?Wife of 51 years main complaint now is that I am always hiding behind a book or magazine. Ha! You can teach an old dog new tricks but at 80 you have to reteach him the same concept every day.
Be the REASON someone smiles today.
Dave K8WPE
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On May 22, 2024, at 10:25?AM, Paul Christensen <w9ac@...> wrote:
? On Tue, May 21, 2024 at 11:14 AM, Ben KO4BHX wrote:
I use the emtech ZM-2 ATU with my QMX. Similar size and style, 15 Watts, 80m - 10m, I have found it works great for my needs.
This statement from Emtech's website is a bit disingenuous:"The ZM-2 will tune all bands from 80 to 10 meters."
Meaningless. And silly. Even if it "works great."? The tuner isn't adapting to a "band" of operation.? It's adapting to a complex impedance at an operating frequency.? Emtech should either leave that marketing bullet-point out or specify a complex impedance range.? But, it's easier to sell it this way without a full complex impedance analysis. ?And gullible hams buy into it. The same inaccuracies apply to manufacturers that sell their tuners based on being able tune a 3:1 SWR or 10:1 SWR, for example.? The quoted SWR have an infinite set of complex impedance combinations.?? Paul, W9AC
?
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Re: A couple of new 12V power options
Well, I¡¯m going to give it a try, I ordered a 12v trigger cable to activate the PD.
wish me luck?
KV4TT- Mike
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Hi All,
I have a frustrating issue with my U3S, where it never seems to get the time from GPS if the GPS is slow getting a lock, even after the GPS achieves a 3D lock the U3S doesn't register the time, and therefore never transmits. But, I have found that if I power up the GPS before the U3S and wait for a lock, then power on the U3S, it registers the time straight away and then transmits normally.
Anyone else noticed this behaviour?
For now, I will continue powering the GPS first and then the U3S after a lock is achieved.
73's
--
David Thomas M0OOR
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va3rr
Ted 2E0THH
VE3KCL
Hannes DL9SCO
David Wilcox K8WPE
Mike (KV4TT)