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QMX Feature Request - field “tune” mode
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The SWR metering and protection are features that really make the QMX a field capable radio. However, from several outings now I’m finding that I would like a front panel means to activate a reduced power transmit setting so that I could make adjustments to the antenna tuning while monitoring SWR on the QMX.
Often my antenna is a rather high Q base loaded vertical in which small adjustment to the coil position can result in big swings in feed point impedance. I’ve been using an external SWR/Power meter which presents a 50 ohm load to the QMX while measuring SWR, but this meter is twice as big as the QMX itself and means an extra piece of equipment and coax jumper to carry into the field. If I could, from the front panel menu enable, a “tune” voltage setting and corresponding tune mode SWR protection threshold, I could leave the external meter at home and dial in the the antenna tuning using just the QMX. Stretch goal request: an SWR sweep around the operating frequency shown “graphically” on the LCD. |
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Is the "Hardware Tests" -> "Tune SWR" menu item sufficient for your use case? (%voltage settable in "Protection" menu) On Wed, Feb 28, 2024 at 12:43?PM <w6csn@...> wrote: The SWR metering and protection are features that really make the QMX a field capable radio. However, from several outings now I’m finding that I would like a front panel means to activate a reduced power transmit setting so that I could make adjustments to the antenna tuning while monitoring SWR on the QMX. |
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I find that the SWR feature under the hardware tests menu works very well for tuning (and power level of that SWR test is configurable in the setup menu to boot!), though it’s a bit tedious to access for your frequency in question, even if you’ve been in the menu just a minute ago. It would be great to have a shortcut from the operating screen. For anybody doing band switching, I suspect it’s more used than the presets or the A<>B functions (the latter of which has tripped me up a few times) |
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Hi all I do think?W6CSN's request is fulfilled by the SWR feature in the hardware menu. However, it does need operational convenience improvements as Garrett KC3UNP says. It was already requested and on my list that the frequency and band should default?to the current operating parameters; then the left knob should adjust band and the right knob, frequency.? Regarding a graphical sweep display: it is my eventual plan (but after other higher priority items) that all the graphical tools in the terminal screens (Image sweep, BPF, LPF, SWR sweep) should also be available in miniature form on the LCD; remember?we only have 8 characters to use for custom graphics but it is nonetheless possible to make a quite usable display from this. Some readers may recall, dare I say it, this QSX video? that demonstrates some code I wrote for that. It just needs to be adapted?and incorporated into QMX.? 73 Hans G0UPL On Thu, Feb 29, 2024 at 8:53?AM Garrett kc3unp <kc3unp@...> wrote:
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Hi Ronan ? Could one of the front panel long-presses be made configurable? That way it could default to the present way of working but could be made to jump straight to a menu of choice if desired.... Yes, also on my list - is to make ALL the controls configurable... If people diverged from the default then of course the laser etched printing on the front panel wouldn't match the function but the flexibility will?be there for those that want it.? 73 Hans G0UPL |
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“?Often my antenna is a rather high Q base loaded vertical in which small adjustment to the coil position can result in big swings in feed point impedance.” If you’re concerned about protecting the finals while finding the right tap on the coil you might consider a different solution. An ?N7VE LED SWR bridge between the QMX and your antenna, in ?the tune position, would keep the radio from never seeing an SWR over 2:1. ? QRPguys and qrpkits (mini SWR indicator) has them. Or better yet make one, they’re very simple and low cost. Light weight, it won’t add any significant burden on your ?field operations. |
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Would it be possible to turn the power down automatically as the SWR rises to protect the PA?? Maybe start at a SWR of 2 and reduce to the specified limit by 3. Restore the power, ideally slowly, after the SWR improves.
Then a user could transmit and the PA would be kept safe automagically.? This is rather like the way my IC-7300 behaves, the power is reduced automatically at high SWRs, then as I tune the antenna the SWR reduces and the power increases. There would be no need for any user control, it's normal operation. Transmit and watch the SWR and power. Minimise one and the other will be maximised. . Chris, G5CTH |
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The schematic of the N7VE bridge is readily available from many sources. I used the one from wb3gck.com as shown on his Z-Match tuner; just implement the bridge portion if you want. There are several minor variations that others have made. Contact me off list if you’re interested in building one, I’m good on qrz.
Steve W6WU? |
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Yes, my request is technically fulfilled by the Tune mode in the Hardware Test menu. Thanks to those that pointed out the existing feature.
Also, as G0UPL and others have observed, the existing Tune mode could benefit from a quicker access method. As for building/buying an external Tune/SWR indicator, I’m really wanting to avoid an additional item in my field kit. Besides, the QMX has a perfectly good SWR detector built in, I just want to use it easily without tripping into protection mode. When using a tunable antenna such as a vertical with adjustable coil, my typical “workflow” is to reduce power if that option is is available, put the internal keyer in straight key mode, then briefly tap the key, note the SWR, adjust the antenna, repeat until happy ( SWR < 2:1 ), return to keyer mode, reset operating power. If I were to suggest a UI for this on the QMX: a simultaneous press of the pushbuttons puts the QMX into reduced power Tune/SWR mode at the current VFO frequency with an appropriately scaled protection threshold. The RF output is enabled while either paddle or left pushbutton is depressed. A press of the right pushbutton returns to normal operating mode. At any rate, I’m satisfied that easier access to Tune/SWR is on the firmware development radar. |
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I don't see how adding another SWR bridge will help things.? The QMX already has a SWR bridge, it can also control the Tx power, and all this is under the control of the QMX controller.? All the OP is asking it it's possible to make the management of this more easily accessible.
I'm wondering if the SWR monitoring and power control can be used, ideally automatically, so the QMX provides the information we need to tune our antennas and also protects itself. Chris, G5CTH |
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Chris G5CTH, The op said he wanted to protect the rig while adjusting his loading coil. If the connection to the antenna goes open while adjusting, what will the QMX finals see? Personally I wouldn’t chance it.? |
Garrett kc3unp