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QDX SWR protection circuit? #qdx

 

Apologies if this has been discussed. I searched and did not find anything relevant.

Are there are any plans to implement the SWR protection circuit from the QMX in the QDX? The QDX is perfect for certain applications due to the absence of controls.
 

Interesting thought. I have not seen it discussed before here. Hans could switch to a 2 color LED or add a second LED to indicate when SWR protection has tripped (or add yet another blink pattern). And perhaps he could add a custom CAT command to read the SWR so it could be displayed on the host computer. Just dreaming...?

73, Mike KK7ER?
 

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But unfortunately, there's no SWR sensing in the QDX...

73, Paul -- AI7JR

On 2/24/24 20:12, Mike KK7ER wrote:
Interesting thought. I have not seen it discussed before here. Hans could switch to a 2 color LED or add a second LED to indicate when SWR protection has tripped (or add yet another blink pattern). And perhaps he could add a custom CAT command to read the SWR so it could be displayed on the host computer. Just dreaming...?

73, Mike KK7ER? 
-- 
Paul -- AI7JR
 

We're talking about potential new QDX features.?
But at this point the QMX features are a superset of the QDX features.
Realistically, I doubt Hans has time or motivation to make any big changes to the QDX design when customers can just buy a QMX.?
The only difference I can think of at the moment is that the QDX is always powered on while the QMX requires a button push.?
IIRC, there was a thread here on remotely turning on the QMX.?
That may be all that is needed to swap out a QDX for a QMX.?

73, Mike KK7ER?
 

On 25/02/2024 15:57, Mike KK7ER wrote:
I doubt Hans has time or motivation to make any big changes to the QDX
As you say it is a BIG change. Requiring new PCB to take the extra components and processor connections. Maybe a LED to show it has activated.

The QMX is slowly progressing, then the QSX...

73 Alan G4ZFQ
 

I have a project at work where I needed to simply convey a bunch of machine states. I was amazed at how much information I can share with a 3 color LED. With color and solid and blink I can easily do 20 states. My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?

Colin

? ? ? ? ??
? ? ? ?K6JTH


On Sun, Feb 25, 2024 at 8:34?AM Alan G4ZFQ <alan4alan@...> wrote:
On 25/02/2024 15:57, Mike KK7ER wrote:
> I doubt Hans has time or motivation to make any big changes to the QDX

As you say it is a BIG change. Requiring new PCB to take the extra
components and processor connections. Maybe a LED to show it has activated.

The QMX is slowly progressing, then the QSX...

73 Alan G4ZFQ






--
Colin - K6JTH?
 

On Sun, Feb 25, 2024 at 11:46 AM, Colin Kaminski wrote:
My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?
I ran into the same problem with a MIL SATCOM terminal I was working on.? Since blue-yellow is 1/10th or less common than red-green, which I also have,
we ended up using blue-yellow LEDs and different blink patterns to convey the various device states.??
I was kind of surprised that there was no guidance from the military (that we could find) regarding this issue.
73, Don N2VGU
 

Hmmm, I wonder whether implementing colored?LEDs as part of a system's Human?- Machine Interface (HMI) could run afoul of the Americans with Disabilities Act (ADA). ?

73
Jim N6OTQ

On Sun, Feb 25, 2024 at 1:18?PM Donald S Brant Jr <dsbrantjr@...> wrote:
On Sun, Feb 25, 2024 at 11:46 AM, Colin Kaminski wrote:
My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?
I ran into the same problem with a MIL SATCOM terminal I was working on.? Since blue-yellow is 1/10th or less common than red-green, which I also have,
we ended up using blue-yellow LEDs and different blink patterns to convey the various device states.??
I was kind of surprised that there was no guidance from the military (that we could find) regarding this issue.
73, Don N2VGU

 

Same issue with traffic lights that control vehicles at intersections. Red/Yellow/Green. The position of these lights, Top/Middle/Bottom is used to understand their meaning. A similar set up could apply to any coloured LEDs in a QDX assuming that it is not a single multicoloured LED.
--
Compton
VK2HRX
Sydney, Australia
 

I once set up a BIOS EPROM to flash SOS on the carry light.? Well actually any message in Morse.

Chris, G5CTH
 

Rather than try to add SWR protection circuitry, try protecting the BS170's:

I also added the zener across L14 for good measure. My Final blew for no known reason once. I replaced the BS170,s added zeners per Sverre plus the one across L14 and have had no issues since (6 + months and hundreds os QSOs). I did this to both the high and low band QDX radios.
I moved one of the antennas from the switch to the Icom so my Grandson could listen to the QDX transmit, then forgot to move the coax back. I was transmitting into an open switch port at full power ( I always operate the 12v radios at 11 volts) with no ill effects.
YMMV
 

On Sun, Feb 25, 2024 at 01:19 AM, Howard wrote:
Apologies if this has been discussed. I searched and did not find anything relevant.

Are there are any plans to implement the SWR protection circuit from the QMX in the QDX? The QDX is perfect for certain applications due to the absence of controls.
I agree that it is unlikely that Hans will want to find time for incorporate a reflectometer into the QDX with associated extra software in the controller.? Part of the problem is that, unlike the QMX, there is no easy way of reducing the supply to the final amplifier in the QDX. This would mean that the only way for a reflectometer to operate would be to completely shutdown the transmitter by removing the RF drive. By itself, this may protect the final amplifier, but would give little help to resolve the poor SWR situation.? A better way would be switching to reduced power operation, which might allow matching adjustments to be made before going back to full power.
?
It could be possible to make an outboard unit to implement such protection. Transmitter output would pass through a tandem bridge reflectometer (as at the output of the QMX).? Rather than using a processor to monitor the forward and reverse waves, I think an op-amp based circuit might be better because it would operate far faster than any processor based system.? Speed of operation is essential to give maximum protection to the output BS170 transistors (although it still may not be fast enough for high voltages across the transistors). The reflectometer circuit would be arranged to trip at an appropriate SWR (perhaps 2:1) whereupon a MOSFET switch in series with the 12V QRX supply would open to put a string of silicon diodes to reduce the supply to around 8V. This voltage would reduce output to around 1W which would lessen the stress on the output transistors. Once operating at reduced power, antenna matching could be adjusted as required, returning the QDX to full power afterwards by pressing a reset button. Note that this assumes the QDX is built for 12v operation rather than the 9V option.
?
With regard to the op-amp circuit, the simplest arrangement would be to just monitor the reverse wave detector and trip the protection when its absolute voltage exceeds that for a 2:1 SWR.? However, it may actually be better to monitor both forward and reverse wave to that the trip would operate at a defined SWR (i.e. for example 2:1). This would require additional complexity in the op-amp circuitry.
?
The diagram below shows the elements of the outboard protection unit.
?
--
Peter Lee
G3SPL

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