Re: Antenna tuner companion for QMX?
#qmx
I'm a fan of the ZM-2 as well - a very close match can usually be achieved with it w/o even transmitting, by tuning for max rx noise.
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John AE5X
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Re: Antenna tuner companion for QMX?
#qmx
Barb,
I really like meeting the "Tuner" size and cost criteria with your approach. Have you looked into what component changes would have to be made to support 10W? 160m through 6m with the Digital modes ?
Sounds like a great "kit" opportunity
73 Kees K5BCQ?
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Colin,
A gate threshold of 3V is in spec (maximum) for the BS170. You should see a swing of 5V p-p at the gate pads with the FETs not installed. With them installed, you¡¯ll see slightly less swing but still above gate threshold. As others have said, 3V p-p at the gates is incorrect in either case.
What is the bandwidth of your scope and what frequency do you have set during the measurement? The scope bandwidth needs to be at least 5x the TX frequency to see a decent waveform.
Tony - AC9QY On Wed, May 22, 2024 at 10:17?AM colin.douglas via <colin.douglas= [email protected]> wrote:
The other thing is all the fets show a threshold above 3 v when tested on a transistor tester and cap of 60 pf or more which does not seem to be in spec Ive tried two different sources of supply but I expect they all come from China. Could that be the problem
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To expand slightly on Hannes response. Both the QMX and QMX+ use the same firmware.
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Re: Antenna tuner companion for QMX?
#qmx
Paul,
Emtech¡¯s statement isn¡¯t disingenuous but probably poorly worded. We all know that a tuner gives maximum return loss at only a single frequency so this statement would be disingenuous only if tuner couldn¡¯t perform its function across the entire 80 to 10 meter frequency range.?
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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Hi Ludwig,
Thank you for pointing out the mistake in reading the information from Colin.
The gates of the BS170s should see a 0 to 5 volt 50% duty cycle square wave, which is the 2.5-volt RMS that would be measured by a DVM.
Colin,
What does a DVM set for DC voltage read?
Be careful of excessive testing with a failed PA section, which can cause further damage.? In one case, for me, the MPU became damaged and made the board scrap.
73
Evan
AC9TU
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Hi Harold,
all QMX firmware is available from the QMX page. QMX plus requires 1_00_019.
73 Hannes DL9SCO
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Re: Antenna tuner companion for QMX?
#qmx
The insertion loss for adaptors from SMA to BNC at HF is insignificant.
At VHF its barely a factor.
Its not an issue save for the mechanics of it.? SMA is not a rugged
connector for multiple connect/disconnect.
As to tuner the EMtech is good I have and use a HB version of it
and its a useful tool.? For all manual tuners I use a Tennadipper
( I have both the original and the newer II version.
I also have Elecraft T1 while tuning it can easily peak 10:1
while hunting for the best solution.? ? Other include a
QRP L-Tuner also? a T tuner both work well but even manually
adjusted that can easily hit 10:1 cases.
Rather than run the radio I use that to dial in the tuner.
No risk to the radio and less RF radiated.
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
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Thanks Ron. Didn't think so but needed to check. Hope you are doing well. QCX you built for me is still going strong,
W.
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Wayne S.
KF7RCM
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Re: Antenna tuner companion for QMX?
#qmx
This and the insertion loss for any adapters used if you went BNC-->SMA
I understand SMA is small and somewhat convenient.? I would likely see if it would be possible to swap over to BNC's if I build it.
Nice design, regardless.
Todd K4MSW
On Thu, May 16, 2024 at 05:02 PM, Andy wrote:
toggle quoted message
Show quoted text
if someone can't fit an SMA connector to a cable
Andy, the question is how many times the tuner and so the SMA will be connected and disconnected, maybe (to) often. SMA is not designed for?. And is SMA a good choice for connecting in the field, in case of dust, rain or snow?
73, Ludwig
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Re: A couple of new 12V power options
Most of the 18650's I have used will come off the charger when fully charged with an open circuit voltage of around 4.5 volts (depending upon the charger, and I guess the battery manufacturer).? If you let them sit around for a couple days, the voltage will drop to around 4.08 and stay there for a long time, which gives 12.24 volts from three in series.
Even at 12.24 volts open circuit, when you attach them to a QMX, and it goes to transmit, the voltage will drop to about 11.8 or so, which keeps the finals from overheating.? Of course, after some time, TX voltages will drop to 10 volts, which doesn't effect the power output too much.? My QMX starts at around 3.5 or 4 watts and then drops to 3 watts when the battery voltage is approaching 10 volts on TX.
At this point, which takes several hours, I just trade batteries with a fresh set in less than a minute.? I always keep a few in reserve and like I said, they will hold at about 4.08 volts for a long time.? I have ten in reserve and with a solar panel to charge them, it's likely I could spend several days operating and not run out of power that I can carry in my pockets.
Having the battery monitor in the QMX makes this so easy.? Great idea Hans!
FWIW, you can buy individual 18650 batteries with a built-in battery management system (BMS) and some even have a USB mini charging port on EACH battery.? Kinda cool, although I would think it a pain to charge each individual battery.
Still very interesting that Tesla uses over 7,000 of these in the battery packs for their cars (not latest models though).
Mark KD0QYN
On Wednesday, May 22, 2024 at 08:58:59 AM CDT, Danny Bower <m0sdb@...> wrote:
On Wed, May 22, 2024 at 02:11 PM, Brian Kassel K7RE wrote:
Another great deal on a pre-built LiPo 3S battery pack is at
a place called "Battery Hookup":
?
?
Only $ 2.00 for 3S 2200 mah with BMS, enclosed in a
tube. These are surplus, but at that price a person can buy several.? They are fully protected and can be charged easily .
I have had several dealings with them, and can recommend them highly.
I have no connection with this establishment etc.
Bear in mind fully charged they're 12.6V so care is still needed when using them with a QMX
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Re: QCX+ Zero Audio Output
QCX+ AUDIO ISSUE I did replace IC10 with good results. I now have audio and it looks like everything is working.? Thanks for the help. Fred KM6riy 73
On Thursday, May 9, 2024 at 02:06:01 PM PDT, fred libby <fred.libby@...> wrote:
Ron, Eric & Rowan Thanks for your input. Ron I did check pins 3 & 7 of IC10 and read 6.7V. Previously I thought C51 was the problem, however removed it & tested ok. After reading Eric and Rowan comments related to Heil headset and ear buds I ordered set of ear buds. It looks like to me when I look the schematic, page 110 assy manual, IC10a, C51 and the resistance of the headset, or ear buds make up the Audio output circuit. At this point I think it would be best to install C51 and see if ear buds solve the problem. Fred KM6RIY 73
rowan
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The other thing is all the fets show a threshold above 3 v when tested on a transistor tester and cap of 60 pf or more which does not seem to be in spec Ive tried two different sources of supply but I expect they all come from China. Could that be the problem
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Re: Qmx MB power up and issues
You are correct it is built for 12v with the RWTST configuration. Rev 4 board.
I did figure out the encoder, one pin did not solder to the pad so the only thing left is the missing Q301 for the light.
Measurements are as follows with 12.3v power from a battery. On a dummy load, band is 60m
At rest:? .146A
Press P: .152A
Press T: .898A
Transmitter section on putty while pressing T shows
Voltage 10v
Power 6.4w
Swr 1.04
Why do I feel like the amps are on the high side?
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Hi. Evan thanks for reply. It was a 3v peak to peak reading on a scope. 73s
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On Wed, May 22, 2024 at 04:47 PM, Evan Hand wrote:
3 volts is high.? It should be 2.5 volts or slightly lower.?
Evan, I think you are talking about the medium voltage (measured with a DMM in DC mode). Colin wrote "3v peak to peak". So this seems a bit to low. But with a dead IC5 it should be 0 and I don't beleve in a half dead IC5. Like you wrote
2 - remove the 4 BS170s and test the gate pad levels again.
73, Ludwig
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Re: Kit Builder Tip - Enamel Wire Cleaning
On Wed, May 22, 2024 at 10:59 AM, Daniel Walter wrote:
The original blades are perfectly fine for 18 gauge to 30 gauge (AWG) without modifications. No need for different jaws. A number of constructors have found this to be true
Ok, thanks!? A number of comments on the Amazon page say it won't do the smaller wire.? Guess I will try it and find out.? :-)
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Re: Kit Builder Tip - Enamel Wire Cleaning
The original blades are perfectly fine for 18 gauge to 30 gauge (AWG) without modifications. No need for different jaws. A number of constructors have found this to be true.?
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73, Dan? NM3A
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Hi,
I am currently designing a transceiver that uses an encoder and volume potentiometer just like QCX mini uses. (Those of you who attended FDIM got to see it firsthand)
I am trying to slim down the form factor and thought that the potentiometer and rotary encoder that the QCX mini would be a perfect match.
Does anyone happen to know the manufacturer and part number of the pot and encoder that is used in the QMC mini (or a link on digikey/mouser/lcsc).
Thank you in advance,
-Jonathan KM4CFT
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Re: Antenna tuner companion for QMX?
#qmx
On Thu, May 16, 2024 at 05:02 PM, Andy wrote:
if someone can't fit an SMA connector to a cable
Andy, the question is how many times the tuner and so the SMA will be connected and disconnected, maybe (to) often. SMA is not designed for . And is SMA a good choice for connecting in the field, in case of dust, rain or snow? 73, Ludwig
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Hannes DL9SCO
Dj Merrill
Jonathan Kayne, KM4CFT