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(Not really)
I start my build of the QMX+ tomorrow.
12V or 9V?
Michael WD0OM
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$0 answer:? type "12V or 9V" into the search field at the upper right and browse the results.? : )
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73, Mike KK7ER
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I made both the QMX and QMX+ for 12 volts BECAUSE i have a 12 volt power supply. Well it is an MFJ switching supply that is adjustable to 12. Also got a buck device that regulates a battery output from 12.6 or higher to a stable 12 volts.
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That was my logic, anyway...
--
73
Karl
KI4ZUQ
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It comes down to what will be more convenient for you and your existing power sources, if any. The radio itself will work well either way.
The advantage of 12V is that most hams already have power supplies and batteries for it -- or think they do. The catch is that the QMX really means 12V, not 12.6V or 13.8V or whatever. You will need some way to reduce the voltage from a typical lead-acid or LFP battery, a series diode or three is one way to do it. You can also use a four cell lithium (not LFP) battery, which will be safe but produce less output because its peak voltage will only be about 11V. If you use a bench supply, turn the output down to 12V rather than the more typical 13.8V.
The advantage of 9V is that the battery is that, all else being equal, the battery will be smaller and lighter?than a 12V battery.? But it will also store less power and not last as long. You could use a three cell LFP (again with some diodes), or a six cell alkaline or NiMH battery. If you?use a bench supply, set it for 9V.?
You can use a QMX built for either voltage along with a DC-DC converter to get 12V. But those can be inefficient, and they add another source of potential noise along with the noise generated by the switching regulators in the radio.
(Not really)
I start my build of the QMX+ tomorrow.
12V or 9V?
Michael WD0OM
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Thing is, power source is a problem I've already solved: I have USB-C PD trigger cables for both 12V and 9V, and my most likely power source is an Anker Prime power bank that recognizes and adjusts to either and gives reliable voltage as specified. I have an existing QMX built for 12V for example, that works fine with this.
Therefore, let me reframe the question: availability of power sources being equal, what are the reasons to prefer one over the other. My impression from the graphs in the assembly documentation is that 9V is actually more efficient for getting to 5W reliably. Is this correct? Other than limiting what I can use for supplies, what are the downsides of 9V, if any? Does 12V present any strong advantage, other than wide availability of 12V-ish batteries in ham kit?
Michael WD0OM
On Fri, Sep 13, 2024, at 16:44, Shirley Dulcey? KE1L wrote:
It comes down to what will be more convenient for you and your existing power sources, if any. The radio itself will work well either way.
The advantage of 12V is that most hams already have power supplies and batteries for it -- or think they do. The catch is that the QMX really means 12V, not 12.6V or 13.8V or whatever. You will need some way to reduce the voltage from a typical lead-acid or LFP battery, a series diode or three is one way to do it. You can also use a four cell lithium (not LFP) battery, which will be safe but produce less output because its peak voltage will only be about 11V. If you use a bench supply, turn the output down to 12V rather than the more typical 13.8V.
The advantage of 9V is that the battery is that, all else being equal, the battery will be smaller and lighter?than a 12V battery.? But it will also store less power and not last as long. You could use a three cell LFP (again with some diodes), or a six cell alkaline or NiMH battery. If you?use a bench supply, set it for 9V.?
You can use a QMX built for either voltage along with a DC-DC converter to get 12V. But those can be inefficient, and they add another source of potential noise along with the noise generated by the switching regulators in the radio.
(Not really)
I start my build of the QMX+ tomorrow.
12V or 9V?
Michael WD0OM
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On Fri, Sep 13, 2024 at 11:44 PM, Shirley Dulcey KE1L wrote:
But it will also store less power and not last as long.
Voltage has nothing to do with capacity.
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On Fri, Sep 13, 2024 at 11:52 PM, Michael - WD0OM wrote:
what are the downsides of 9V
For me it was compatibility, all my gear home or /P is 12V and up. Building it for 9V would mean i need to build one more separate set of battery packs for qmx+ use or compromise with noisy buck converters which i managed to avoid during previous use cases.
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Only advantage in technical sens would be being on the safe side for BS170, but i did not have any issue with them and 12V in all my qrplabs builds.
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It does when you're using that voltage to drive a voltage converter, as the QMX does. The QMX draws more receive current from a 9V supply than from a 12V supply.
On Fri, Sep 13, 2024 at 11:44 PM, Shirley Dulcey KE1L wrote:
But it will also store less power and not last as long.
Voltage has nothing to do with capacity.
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That is assuming, of course, that cells of the same size are used; say, comparing a three cell 2Ah battery to a four cell 2Ah battery.
On Sat, Sep 14, 2024 at 2:35?AM Shirley Dulcey KE1L via <mark= [email protected]> wrote: It does when you're using that voltage to drive a voltage converter, as the QMX does. The QMX draws more receive current from a 9V supply than from a 12V supply.
On Fri, Sep 13, 2024 at 11:44 PM, Shirley Dulcey KE1L wrote:
But it will also store less power and not last as long.
Voltage has nothing to do with capacity.
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If you look at efficiency in this particular case then yes. In recent years mah values per cell are going wild so not much of impact on overall usage time compared to weight like 10-15 years ago. But cant say that there are no weight freaks among us where ever gram/mA counts Hi
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$200,000 is not enough, sry
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It's a question which is heavily driven by your power source preferences.? If you're flexible on power sources, the 9V gives a bit higher efficiency and probably gives a little less stress on some of the power supply components like the linear voltage regulator during the startup sequence.? 12V allows operating over a slightly wider operating voltage range at reduced power out? before the rig no longer functions.
-Steve K1RF
------ Original Message ------
Date 9/13/2024 5:20:55 PM
Subject [QRPLabs] The $200,000 Question
(Not really)
I start my build of the QMX+ tomorrow.
12V or 9V?
Michael WD0OM
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Just a thought:?
Best of both worlds:? Wind two T501s, one for 9v and one for 12v and arrange plug/socket to allow interchange.
Lots of room in a QMX+ to do this.
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I built all of my Q*X radios for 12v. My thought was that if I built it for 12 and only had a 9v battery I would be ok, but if I built it for 9 and only had a 12v battery I would be out of luck (or possibly out of a radio).?
73,
Mike, KL7MJ?
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I don¡¯t have a QMX+ yet but what I intend to do is build it for 9V and install a linear voltage regulator so that I can supply it from 12V, 13.8V power supplies, 12V lead-acid batteries (could be 13V+) or LiPo¡¯s (up to 12.6V).
My reasoning is that, within reason, I don¡¯t need to worry about which source of power I use and the QMX+ will have a steady 9V supply.
The down side is that power is wasted in the regulator.
It¡¯s a personal choice, but it suits my requirements.
Comments welcome.
73/72
John
M0JBA
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On 14 Sep 2024, at 16:08, Mike, KL7MJ via groups.io <alaskamike@...> wrote:
I built all of my Q*X radios for 12v. My thought was that if I built it for 12 and only had a 9v battery I would be ok, but if I built it for 9 and only had a 12v battery I would be out of luck (or possibly out of a radio).
73,
Mike, KL7MJ
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On Fri, Sep 13, 2024 at 02:44 PM, Shirley Dulcey KE1L wrote:
ou will need some way to reduce the voltage from a typical lead-acid or LFP battery, a series diode or three is one way to do it. You can also use a four cell lithium (not LFP) battery, which will be safe but produce less output because its peak voltage will only be about 11V. If you use a bench supply, turn the output down to 12V rather than the more typical 13.8V.
A 4S LiPo is 16.8V at full charge!? ?You need a bunch of diodes as even after
near 80% discharge it will be 12.8!!!? ?
If LFE then14.2 at full charge.
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8 NiMh might be a better fit for Q-X radios.? thats about 2.2ah and
12V full charge and 9V near dead.
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I use a boost/buck for 12V or 13.8 (two different units).? The 12V is for a
computer (MiniATX) and 12V is the preferred voltage.? For for radios
most I have are standard to 13.8V so I use that unit.? The efficiency is
better than diodes and it keeps the output voltage very constant.
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Those are Drok (10A units) in the aluminum finned cases and I've
had little issue with noise.? Likely overkill for many things.? There
are smaller 3A and 5A versions.
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By doing that I can use anything from 8 to 28V as a source to get to?
what I desire.
?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
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On 14/09/2024 16:23, John Baines via groups.io wrote: install a linear voltage regulator The 70s called and want their technology back :-)
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On 14 Sep 2024, at 17:02, Andy via groups.io <andy.mm0fmf@...> wrote:
On 14/09/2024 16:23, John Baines via groups.io wrote:
install a linear voltage regulator The 70s called and want their technology back :-)
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Old tech. but if it works why change it for something noisy? ;)
73
John
M0JBA
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Show quoted text
On 14 Sep 2024, at 17:02, Andy via groups.io <andy.mm0fmf@...> wrote:
On 14/09/2024 16:23, John Baines via groups.io wrote:
install a linear voltage regulator The 70s called and want their technology back :-)
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On Sat, Sep 14, 2024 at 11:08 AM, Mike, KL7MJ wrote:
My thought was that if I built it for 12 and only had a 9v battery I would be ok, but if I built it for 9 and only had a 12v battery I would be out of luck
My thinking was that I would be able to run my 12V Q*X radios on 12V for full power and 9V for reduced power or increased robustness into poor loads.
A 9V build would be more limited in this regard.
73, Don N2VGU
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Karl
Shirley Dulcey KE1L
Ivica - YU1QRP
Donald S Brant Jr