Re: QMX Display Brightness

I think I use 120 ohms in my builds.

-mike/w1mt

QMX Display Brightness

I am finding the brightness of the QMX display to be too high. I want to increase R306 (33 ohms) to lower that.??I'm thinking about 100 ohms. Any other suggestions as to what would be a good starting point?.?
--
73, Dan? NM3A

Re: QDX Success story

#108418

Hi Dan

RF envelope shaping requires amplitude modulation capability for the PA. QDX does not? have this, QMX does.?

73 Hans G0UPL

Show quoted text

On Fri, Aug 25, 2023 at 5:12?PM Daniel Walter via <nm3a=[email protected]> wrote:

John,
Your explanation of QDX L14 makes sense. It doesn't seem to be a serious problem for semiconductor failures tho. More of an issue for spectrum 'dirtiness'. The diode would take care of both concerns.?

I wonder why it could not be taken care of in the QDX firmware, as it has been with the QMX. There doesn't seem to be the memory and processing constraints of the QCX, even though it doesn't have the capacity of the QMX processor. ?
--
73, Dan? NM3A

Re: QDX Success story

#108417

John,
Your explanation of QDX L14 makes sense. It doesn't seem to be a serious problem for semiconductor failures tho. More of an issue for spectrum 'dirtiness'. The diode would take care of both concerns.?

I wonder why it could not be taken care of in the QDX firmware, as it has been with the QMX. There doesn't seem to be the memory and processing constraints of the QCX, even though it doesn't have the capacity of the QMX processor. ?
--
73, Dan? NM3A

Re: Power supply for pre-assembled QMX

#108416

Not too late, Bev - I added a note to your order.?

73 Hans G0UPL

Show quoted text

On Fri, Aug 25, 2023 at 4:18?PM algarveastronomy <bmes@...> wrote:

On 25/08/2023 12:49, Hans Summers wrote:
> 12V unless you specifically ask for 9V.

Hi Hans

Is it too late to ask for 9V option for QMX serial 72387?

Regards
Bev
COAA
Portugal

Re: PCB 1 and 2 Again!

g4edg

#108415

As a final test I fed the QMX with two external regulated supplies, 3.3v and 5.0v and provided for ADC_3V3 and ADC5V with two potential dividers.

Unfortunately, the QMX reacts in exactly the same way as before when using power via PCB 1 & 2.

Top row of display.... dark boxes?

Nothing happens when connecting the QMX to my laptop...all combinations of powering up and connecting the USB cable.

Maybe the firmware dosent like this arrangement....otherwise I pronounce this QMX dead.

73 Steve G4EDG

Re: Audio level limiting with diodes?

#108414

ND6T has pointed out that this can be done with an external adapter that will leave no permanent modification to your rig and could be used with any homebuilt rig.

http://www.nd6t.com/qrp/speaker.htm

Re: QMX AGC... any progress?

#108413

I don't think anyone is arguing that the diodes are the best solution to the problem long term, but they can be done now with minimal cost and effort, and will help protect your hearing.? They will also cause no problems when the eventual polished solution is released as they only have an effect at very loud audio levels.

I'm not super concerned about "bodging" a radio that is home built to begin with - I always considered that part of the fun so long as the modifications were made well, but an external adapter would solve that problem for you, and you only have to worry about forgetting it until the polished firmware solution is released.

Re: Relationship of VDD and VCC

#108412

On Wed, Aug 23, 2023 at 05:50 PM, <wb2cba@...> wrote:

I found some info on this article which explains all V?? cases pretty good:

73?

Barb WB2CBA

Link appears to be dead or broken

Bob
KG5GTE

Re: Power supply for pre-assembled QMX

#108411

On 25/08/2023 12:49, Hans Summers wrote:
12V unless you specifically ask for 9V.Hi Hans

Is it too late to ask for 9V option for QMX serial 72387?

Regards
Bev
COAA
Portugal

Re: QDX xmit one flash

#108410

开云体育

Whoppie!!!! ?

73,

Cliff, AE5ZA

Show quoted text

On Aug 25, 2023, at 07:46, Wayne Greene <wayne.greene489@...> wrote:

Hey, all! I moved my radio over to a PI and it works!!

Re: QMX step 12 continuity oddity

#108409

开云体育

Garrett,

Your results seem inconsistent to me like maybe a probe is on the wrong place.

You say B1 & B2 have continuity, and A1,2,3 to B1 is open, but to B2 is 10 ohms. Either B1 to B2 does NOT have continuity or both B1 & B2 will have continuity to A1,2 & 3.

Just an aside, the solder joint to the upper of the 3 transformer connections below point B1 does not look good. I would add flux and reheat that until it flows properly.

73,

Cliff, AE5ZA

Show quoted text

On Aug 24, 2023, at 23:55, Garrett kc3unp <kc3unp@...> wrote:

Hello fellow QRPers,
?
I am enjoying my QMX build, yet I’ve run into a snag on step 12 page 31 (the first specified continuity checks). I am hoping that someone has either seen/rectified a similar issue, or may have some tips on how I might move forward.?
?
I’m attaching a screenshot that shows the results of the continuity checks, after installation of the larger binocular transformer, and after having gone back to really ensure that the enamel has been properly scraped off prior to completing the solder joints. As you can see in the image, there is a low resistance, approximately 10 ohms conductivity showing between A and B.?
?
I have examined all of the other component connection points, and I’m not identifying any solder bridges, nor clippings, nor whiskers. As far as I can tell, my board doesn’t suffer any of the SMC bridges that have appeared on a few of the boards. I do plan to flip the orientation of D508 to make additional room for L508, but the polarity is already correct.?
?
Any tips are appreciated!
?
Thank you,
Garrett KC3UNP

<QMX Checks.jpeg>

Working QDX just lost reception

#108408

Greetings,
Using my QDX for the past year or so. Very, Very happy with the radio.
Last night I noticed I lost reception. Checked WSPR for reception of any kind..... nothing.
9 volts in and 4.2 watts out according to my meter and very limited reception.
All sorts of activity on 40, 30, 20, but no or limited reception on WSJT-X 2.6**
Any one have or know a thread on this?
(Two nights ago made 5516 mile contact and made Ukraine and Slovenia last night) so it was working fine.

Thanks
James?

Re: Power supply for pre-assembled QMX

#108407

Hello Bev

12V unless you specifically ask for 9V.?

73 Hans G0UPL

Show quoted text

On Fri, Aug 25, 2023 at 3:49?PM algarveastronomy <bmes@...> wrote:

My QMX is getting close to the head of the queue.? Will it be built for a 12V supply or a 9V supply?

Regards
Bev
COAA
Portugal

Non-Resonant antenna for QMX POTA operations

#108406

Parks On The Air (POTA) with my QMX (#133) has found a 100% activation success rate using a simple wire antenna that tunes 40M and 20M with the aid of the 4 State Tuner. 18 gauge speaker wire with one side 15 meters and the other side 7 meters is tied in an electricians knot at the center and then 10 meters is left together zip cord style terminating with banana plugs. This plugs directly into the 4 State Tuner without the need of a balun. I throw the ends into trees and support the center with a Jackite telescoping pole up 32 feet that just conveniently leans into the overhead tree foliage. I have now activated over 20 parks with this setup using a QMX and full voltage 13.8v LiFePO4 battery. Everything fits into a small box and when carrying my pole it looks like I'm going fishing!

Interestingly, the AGC issue caused me to briefly switch to using the QCX-Mini, but the non-resonant antenna has a buzzy side tone with the QCX-mini that the beautifully shaped CW envelope in the SDR QMX totally eliminates! So I just very quickly turn down the volume when a loud station follows a faint one. Signals from all across the USA come in loud and clear. Thank You Hans for the perfect POTA machine. 72, Sandy KB3EOF

Power supply for pre-assembled QMX

#108405

My QMX is getting close to the head of the queue.? Will it be built for a 12V supply or a 9V supply?

Regards
Bev
COAA
Portugal

Re: QDX xmit one flash

#108404

Yay!

Roger

Get

On 25 Aug 2023, at 08:46, Wayne Greene <wayne.greene489@...> wrote:

Show quoted text

Hey, all! I moved my radio over to a PI and it works!!

Re: QDX xmit one flash

#108403

Hey, all! I moved my radio over to a PI and it works!!

Re: QMX - Short from 5V to ground somewhere on the main board

#108402

First rule out solder bridges and stray pieces of wire on your board. ?My experience in this kind of short on a QMX main board is that it’s from a failed chip. ?5V is supplied to the chips in the receive path (mostly), a few capacitors and the display. ?Remove the display first to rule that out. ?Then it’s a matter of elimination. ?Once you find the fault, then you have to ask why. Chips don’t fail without a reason.

Re: QMX Draws 200mA when Power Applied

#108401

Hi Glenn,

There is a short somewhere. ?VCC (5V is getting pulled down). ?Also what concerns me most is the LIN_REG_EN signal. ?It is supposed to be at logic levels (0V to 3.3V) and is directly connected to the cpu. ?unfortunately, that kind of voltage on the cpu is usually not healthy for that chip.