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Glad I didn't get a QDX!
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Hi Ken ? I'm wondering if the next version could/would have a tx control connection for something like the?10W HF? Linear, or the 50 watt version for the QCX, though I don't know if that would work directly. My worry is that the 50W PA is a single band unit. The QDX is a 4-band unit. How will that work... The QDX band can be changed by the PC. If you built an external amp arrangement, that has to be band-changed manually. It worries me that accidents would occur... any comments?? 73 Hans G0UPL |
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Assuming you have a have 2 spare IO pins.... (and I haven't looked to see if the PA needs a PTT signal or switches to TX when driven by some RF)
The reason for a hardware link rather than pure software is if the fix is purely software then some clever wag will faff about resulting in running the PA on the wrong band with whatever consequences that has for their hardware and other spectrum users.?
Fitting a hardware link forces the user into following a set of steps that makes it difficult for them to run the QDX and PA on the wrong band. To go back to normal QDX mode the use just removes the link.
My $0.02 worth
Andy
From: [email protected] <[email protected]> on behalf of Hans Summers <hans.summers@...>
Sent: Monday, December 20, 2021 2:04 AM To: [email protected] Notification <[email protected]> Subject: Re: [QRPLabs] Glad I didn't get a QDX! ?
Hi Ken
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I'm wondering if the next version could/would have a tx control connection for something like the?10W HF? Linear, or the 50 watt version for the QCX, though I don't know if that would work directly. My worry is that the 50W PA is a single band unit. The QDX is a 4-band unit. How will that work... The QDX band can be changed by the PC. If you built an external amp arrangement, that has to be band-changed manually. It worries me that accidents would
occur... any comments??
73 Hans G0UPL
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Hi Andy Nice. That's an opinion worth a lot more than $0.02 73 Hans G0UPL On Mon, Dec 20, 2021 at 1:26 PM Andy <mm0fmf@...> wrote:
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On Mon, Dec 20, 2021, at 04:26 AM, Andy wrote:
Andy, You are assuming that the user will have only one PA, or that the PA is single banded.? I have built power amps with manual switched LPF.? There are others that have modified the QRP-Labs 50watt amp to have a selectable LPF.? There is also the possibility of hardware failure.? Trying to automate the failure detection is often more of a failure mode generation (this from many years of industrial control automation experience). I would not like having the QDX limited to only one band when the power amp is attached.? I already have two 50watt QRP-Labs amps one for 40meters and one for 20meters as well as multiple eBay kit amps.? I only have 1 QDX,? Do I now need to buy multiple QDX, one for each band to go with the amp? Hans, An alternate solution is to put the band verification in the amp.? That is add a filter that will not switch the antenna if the input does not fall within the range of the amp capability (Think in terms of the QDX 30/20 meter shared LPF filter).? Even this is prone to failures so that making it the operator's responsibility is still my choice.? If I screw up I will need to fix the problems that occur.?? If you are really trying to make it foolproof, then including encoding of the band that the amp and QDX share would be better.? This could be extended to allow for automatic filter selection for those amps that have multiple band capability. If you do go with Andy's suggestion, PLEASE make that configurable as well.? That is the inhibit and band selection fully configurable so that I can get a PTT signal on any band supported without restriction. Respectfully, 73 Evan AC9TU |
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The requirement was essentially how to stop the user running an existing PA and a new QDX on different bands, because let's face it, users are stupid and do stupid things!? The solution offered works for that requirement.
Andy
From: [email protected] <[email protected]> on behalf of Evan Hand <elhandjr@...>
Sent: Monday, December 20, 2021 4:15 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] Glad I didn't get a QDX! ?
On Mon, Dec 20, 2021, at 04:26 AM, Andy wrote:
Andy, You are assuming that the user will have only one PA, or that the PA is single banded.? I have built power amps with manual switched LPF.? There are others that have modified the QRP-Labs 50watt amp to have a selectable LPF.? There is also the possibility of hardware failure.? Trying to automate the failure detection is often more of a failure mode generation (this from many years of industrial control automation experience). I would not like having the QDX limited to only one band when the power amp is attached.? I already have two 50watt QRP-Labs amps one for 40meters and one for 20meters as well as multiple eBay kit amps.? I only have 1 QDX,? Do I now need to buy multiple QDX, one for each band to go with the amp? Hans, An alternate solution is to put the band verification in the amp.? That is add a filter that will not switch the antenna if the input does not fall within the range of the amp capability (Think in terms of the QDX 30/20 meter shared LPF filter).? Even this is prone to failures so that making it the operator's responsibility is still my choice.? If I screw up I will need to fix the problems that occur.?? If you are really trying to make it foolproof, then including encoding of the band that the amp and QDX share would be better.? This could be extended to allow for automatic filter selection for those amps that have multiple band capability. If you do go with Andy's suggestion, PLEASE make that configurable as well.? That is the inhibit and band selection fully configurable so that I can get a PTT signal on any band supported without restriction. Respectfully, 73 Evan AC9TU |
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Perhaps in the future a QDX-HP (High Power) is in order with a built in PA that does the band switching? ?I wonder what the market would be for this, since realistically I rarely run digital modes above 20-30 watts since I think the point of digital was lower power comms.
As far as user error, unfortunately I¡¯ve fallen into the ¡°done stupid¡± things group, I¡¯m sure we all have. Rest assured I only do the stupid thing once (maybe twice) before I learn. Haha! Rich KQ9L |
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This is a challenging area, because I feel like part of the beautiful innovation that Hans has gifted the community with is simplicity.? ?We could likely add small things forever,? and so the cost would go up, and the board would get bigger.? ?That's not really at the heart of a QRP station, though.??
Concern for allowing tx on the wrong band of an Amp connected is a good design thought process to have. Perhaps something that could benefit the platform in many ways:? ?A small serial eeprom...? storing a variety of user preferences in attribute, value pairs... to allow forward and backward software compatibility with ease.? ?Just ignore the attributes not undersood. The hardware pin approach is also simple, and for that I really like it.? In days past we would have used a small dip switch set.? ? If I were to bring out headers for jumpers though, I would almost want to bring out the SPI bus pins to allow an eeprom to be added? by the user...? as well as perhaps run the Amp tx switch off of the spi as well.? ? A simple search for Grove or STEMMA devices shows connector and ecosystem options in the SPI world. Yet, it still seems like a TSOP-5 surface mount eeprom for 25 cents US or less could store thousands of user config options and might just possibly fit on the current board size.? ?Then the user would have to set in software what options to use.? ?Dumping the options over the terminal interface for review would be trivial.? ?Think of it as 8000 dip switches for a quarter.? ?;) https://www.onsemi.com/pdf/datasheet/nv24c08lv-d.pdf |
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On Mon, Dec 20, 2021 at 08:08 AM, Andy wrote:
If Hans can figure out "how to fix stupid" .? He and his family will be able to purchase a private island and live happily ever after!
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N3MNT
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