QDX 80M Band Sweep Question
This is the band sweep of 80M on my QDX. I'm wondering if this is normal:
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What do the RF Plots look like?
-mike/w1mt
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Re: Relationship of VDD and VCC
The way I deal with this is to name my supplies with the actual voltages, e.g., +5V, +3.3V, etc. If there are analog and digital supplies at the same voltage, I use +3.3V_A, +3.3V_D. There¡¯s absolutely no confusion with this naming convention.?
Tony - AC9QY
Hi Kees
The component library names for things are sometimes different from the schematic net names. This is a case of that. The 74CBT3253 calls it's supply pins Vdd. They are on the +5V rail in QMX which happens to be called Vcc.
It IS all confusing...
The way I think of it - which I believe (perhaps incorrectly) to be the most common usage is:
Vcc is for bipolar transistors, C = Collector; going back half a century to 74-series TTL (transistor transistor logic) they ran off +5V so in my schematics Vcc is +5V.
Vdd is for CMOS/MOSFETs where D = Drain. And commonly or at least, often, ok, sometimes, this means a +3.3V supply. So in my schematics Vdd is +3.3V. 73 Hans G0UPL
Looking at the schematics, I thought VDD was 3.3V and VCC was 5V but they seem to be interconnected like on the 74CBT3253 schematic power pins.
73 Kees K5BCQ
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Re: QMX AGC... any progress?
On Thu, Aug 24, 2023 at 02:19 PM, N1EDC wrote:
I posted a couple days ago....
I saw that. Similar things were tried with the QCX and do work up to a point but they're not a proper solution. I'd rather not have to bodge the hardware when the problem can be sorted out gracefully in firmware. I'm sure Hans will get round to it during his daily spare 12 seconds.... ? Joking aside, this really should be a priority as there is very real potential to cause hearing damage with these sudden violent jumps in volume. Similar to KE0WVA, my day job is in music and sound production so I kinda need what's left of my hearing to stay undamaged. Cheers, Ronan?
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Re: #qmx Bringing up QMX, Nothing in display but terminal works, shutdown press does not
#qmx
OK, thanks! I'll add that to my things to try! :-)
Couldn't imagine that those delays should be normal, but it's odd
that so much else seems to work!
Paul
On 8/23/23 23:44, Rick NF6G wrote:
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Paul, maybe flashing your firmware, at that 180 mA limited
current, was marginal for getting a good flash. Your startup
delays, and failure to shutdown, sound more to me like software
issues than hardware. Fingers crossed that something simple like a
reflash, at normal voltage without current limits, and system
reset, will normalize your QMX's startup and shutdown behavior.
On Wed, Aug 23, 2023 at 10:12 PM, Paul - AI7JR wrote:
... I set my current to about 180 mA and it came up.
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On QMX, it's been suggested to put a 47v zener from drain to
ground on each side of the output transformer, to protect against
high SWR over voltage.
Wouldn't that also obviate the need for that commutating diode?
Paul
On 8/24/23 07:39, Jonathan Halterman
wrote:
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I read this with interest a few weeks ago and would be interested
in Hans' thoughts on a commutating diode across L14 and wondering
if perhaps there might be a future revision to the QDX?
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I'm not sure would have to check, but with 12v I'm getting between 3 and 4 Watts input on each band when connected to an aerial.
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Re: USB Device not recognized .... another one
#qmx
That, I don't know...
On 8/23/23 22:34, Rick Williams - VE7TK
via groups.io wrote:
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Thanks for getting back Paul.
You are correct! In my case it should then trip the current
limited supply. However, the QMX doesn't draw current at any time
and never goes over my pre-set limit?
To confirm, when I apply power to the 2.1mm connector and long
press the left encoder, the QMX should go into into Update mode
whether it's connected to the PC via? USB cable or not?
--
73, Rick
VE7TK
Website:
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Re: #QMX Are these Issues?
#qmx
I'll try that!
On 8/23/23 23:06, Chris wrote:
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This isn't what I'd expect, my QMX
comes on instantly when I press the power on button. It shows
the Shut down message a fraction of a second after the long
press but doesn't close until I take my finger off, then it's
instant.
Thinking a bit I wonder about the
controls board, try powering up with just the main board and
PSUs, no display, no controls. The current should remain at zero
indefinitely. If so you might try shorting pins 5 and 7 on
JP201, the connector to the controls board. That's the same as
pressing the power on button.
All these things seem to be associated with controlling things.
Chris, G5CTH
On 24/08/2023 06:06, Paul - AI7JR
wrote:
Is there some kind of log for QMX issues? Don't want to bore
anybody by reporting what's known, or my build defect!
Here's what I'm seeing (I've got Firmware version 9 loaded,
7volts, 250ma current limit):
- On application of power, initial current is 0, but goes to
around 10ma after 10-15 seconds. Stays steady after it comes
up.
- On initial power application, power on click is ignored,
until the above 10ma step in current.
- At that point, power on click "delays" for ~10sec, then
display comes on and 150ma current draw.
- Tune knob frequency only goes up?
- Long press power click displays Shutdown, but LCD never
goes off, current (150ma) never drops.
- While "Shutdown" is displayed, band and mode can be
changed!
- Going back to 3, if the power is interrupted briefly
(maybe 200mS), device turns off. Pressing power-on click
activates immediately!
I what I'm seeing "normal" at the moment? :-)
Haven't gotten so far as to transmit or receive, either one.
(Need to read that operations manual!)
Please forgive if this is the wrong place to put this!
73, Paul -- AI7JR
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I backed everything down to 80%, but nothing changed.
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Hey, Charles. I'll try adjusting the power.
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Thanks, Evan. I rebooted my machine, but still no change.
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Just FYI.? I had a problem with my QDX being overdriven with the
audio input.? It displayed similar behavior.? The transmit light
would flash once and the power output was erratic.? I can tell
when the audio is right because the red light flashes and the
power output is rock steady.? YMMV.? Prior to upgrading my
operating system, I could leave everything at 100% and it worked
fine but not now.? (Xubuntu 20.04 to Xubuntu 23.04).? I assume
this problem is not limited to Linux, especially with the bizarre
way Windows seems to handle I/O devices.
73
Charles - NK8O
On 8/24/23 10:43, Evan Hand wrote:
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Wayne,
Be sure to power cycle the QDX between settings changes.? It may
be that the settings do not take effect until power cycle and or
reboot.
73
Evan
AC9TU
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What is you transmit power into a dummy load for each band?
-mike/w1mt
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Ensure that you have 2.5v at each solder joint for T401.
-mike/w1mt
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Wayne,
Be sure to power cycle the QDX between settings changes.? It may be that the settings do not take effect until power cycle and or reboot.
73
Evan
AC9TU
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yep, that's what I'm getting. attached is audio scan, looks bad.
Paul DJ0CU?
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Re: Blue screen of death U3s
Ok,?
Probed the clock outputs, nothing, pin 13, sc has nearly 5v on it while pin 14 is very low. Pin 18, pll has 3.3v. Possibly Q7 died??
Andy?
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.
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Thanks for that catch. I changed that default, but I'm still not getting any audio to the QDX.
Wayne
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Paul - AI7JR
M0RON