Re: QMX+ Military Version
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Re: QMX+ Military Version
Love it!
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73, Dan - W2DLC
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Perhaps posting a screenshot of the LPF scans and swr scans for 10m and 6m would give us some data to start with.?
Stan
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Chris, you may need to update Hamlib. I did. There is a button on version 2.7 to do so, but I had to first install OpenSSL on my Windows 10 in order to update Hamlib using the button. TS-480 worked for me.
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Hi Ron,
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It is a relieve to read this post. ?The same exact thing is happening with my QCX mini 20m because I was not using the correct “exit button”. ?For some reason I would press the encoder to exit right after selecting the keyer speed. ?Indeed it is true that it is the operator error for not following the instructions but I thought that I had built this incorrectly for the past year and a half due to the buttons getting stuck.
Since I am such a new HAM operator with no soldering experience and you can name a long list of inexperienced things in this hobby I was at loss already. ?I wish it would not be possible to “exit” or “clear” the screen after selecting the keyer speed to avoid this issue that even though it is the operator’s negligence for not reading and following instructions but for noobs like me who keeps forgetting it would help. ?I guess I will learn the hard way like many things in life. ?
Thanks for sharing the post and giving me hope that I may be able to build another QRP rig. ??
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Lidiette?
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Re: QMX+ Military Version
KUDOS.? ?Looks like something I've seen ripped from an old jeep. I LIKE IT!
73, Paul KY4XJ
On Monday, February 24th, 2025 at 22:17, W6MQI via groups.io <w6mqi@...> wrote:
Okay, I went a little crazy being a military radio guy the standard QMX case just wasn't doing it for me.? So I decided to draw up a PRC-174/CMX+ clone using Fusion 360 CAD software and my 3D printer. The radio isn't fully functional yet like the 6 holes above the LCD are for an LED voltmeter using an Ardunio Nano, and the custom built battery which will reside in the back section. The CMX board is located in the front half of the case unfortunately I wasn't able to print the case in one piece since my printer bed wasn't large enough I think the case looks okay in two pieces. For those that don't know what a PRC-174 is check out N6CC.com or RadioNerds.com site under PRC-174.
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73, Dave
W6MQI
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Okay, I went a little crazy being a military radio guy the standard QMX case just wasn't doing it for me.? So I decided to draw up a PRC-174/CMX+ clone using Fusion 360 CAD software and my 3D printer. The radio isn't fully functional yet like the 6 holes above the LCD are for an LED voltmeter using an Ardunio Nano, and the custom built battery which will reside in the back section. The CMX board is located in the front half of the case unfortunately I wasn't able to print the case in one piece since my printer bed wasn't large enough I think the case looks okay in two pieces. For those that don't know what a PRC-174 is check out N6CC.com or RadioNerds.com site under PRC-174.
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73, Dave
W6MQI
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All working well except 1 W on 10 m and 0.6 W on 6 m.? Already checked for correct winding and bad/insulated solder joints.? Anyone else have this problem or have suggestions to resolve.? Thanks in Advance.
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Re: QCX buzzing sound on key down
Thanks. It does it with a known good power supply into a dummy load sometimes. Sometimes it works for a few minutes. It’s in a die cast box with a 0.1 uF across the power connector and the power cable loops through a large ferrite. The antenna jack is fed with RG 174. It did work before. I will look some more when I get time.
-John?
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Jerry, thanks for the suggestions. I’ll give those a try. I am powering it with a battery and using a good dummy load so I can eliminate those issues. I like your idea of shorting out some of the components to see if that reduces the noise.
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Stan, I’ll try attaching the images again in a few minutes, but I don’t think that will help. Even when I use my wife’s computer, I can still see the images so I think there may be a problem with the images external to me.
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You make a very valid point about why worry if it’s working ok. I thought about that but it bugs me knowing something is wrong and I just want to figure it out.
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After another look at the schematic, I see no reason to lift the RX_IN wire of L401
or the IC402-9 wire of T401.? Just shorting those wires to ground should be sufficient.
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RX_IN might see 12vdc through R510 and Q508, but R510 is 470k so the current will be miniscule if RX_IN is shorted.
IC402 and IC403 are just analog switches, they do not have drivers and receivers inside.
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I suggested you put a 50 ohm dummy load on the antenna port to ensure the noise source is not external.
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Jerry, KE7ER
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On Mon, Feb 24, 2025 at 03:40 PM, Jerry Gaffke wrote:
What kind of power supply are you using???
Try running off a 9v transistor radio battery, or something else reasonably quiet.
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Do you have a 50 ohm dummy load at the antenna port when testing?
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I'd try cutting the receive chain in various spots.
For example, try lifting the RX_IN wire of of L401, and tying that wire to the ground plane.
If the noise has gone then the problem is back in the transmitter LPF section somewhere and subject for another post.
Should be able to tie 20 feet of magnet wire to that L401 wire and hear some signals.
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If you still have noise, try lifting the T401 wire that goes to pin 9 of IC402 and tie that wire to ground.
If you still have noise, try shorting across C416,417,419,419 so all four inputs to the LM4562 op-amps are grounded.
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If you still have noise you might short across C426 and also C427 so the left and right differential signals
into the PCM1804 are zeroed, but first check with a voltmeter that there is no significant voltage
across those caps or you may blow the op-amps.
Assuming C416-419 are still grounded, I would expect no voltage across those caps.
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Jerry, KE7ER
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Matthew, your original screenshots of the IQ plots did not come through.
Maybe if you show us the screenshots it will give us some ideas to help you with.
And if "everything works fine", is there a reason why this is important to fix? meaning does it interfere with good reception or signal decoding, or reduce receive sensitivity or clarity?? Or is it just a mystery that you want to find?
Stan
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What kind of power supply are you using???
Try running off a 9v transistor radio battery, or something else reasonably quiet.
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Do you have a 50 ohm dummy load at the antenna port when testing?
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I'd try cutting the receive chain in various spots.
For example, try lifting the RX_IN wire of of L401, and tying that wire to the ground plane.
If the noise has gone then the problem is back in the transmitter LPF section somewhere and subject for another post.
Should be able to tie 20 feet of magnet wire to that L401 wire and hear some signals.
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If you still have noise, try lifting the T401 wire that goes to pin 9 of IC402 and tie that wire to ground.
If you still have noise, try shorting across C416,417,419,419 so all four inputs to the LM4562 op-amps are grounded.
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If you still have noise you might short across C426 and also C427 so the left and right differential signals
into the PCM1804 are zeroed, but first check with a voltmeter that there is no significant voltage
across those caps or you may blow the op-amps.
Assuming C416-419 are still grounded, I would expect no voltage across those caps.
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Jerry, KE7ER
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On Mon, Feb 24, 2025 at 03:07 PM, Matthew Basanta - NE3U wrote:
I’m bumping this to see if there are any more ideas. I’ve checked everything I can think of. I rewound T401 (the trifilar toroid) and replaced the PCM1804. I’ve followed the audio chain through the receive section with my scope but can’t identify a specific issue. I’m at the guess and check stage and looking for ideas. It’s picking up noise somewhere but I have no idea where.
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I’m bumping this to see if there are any more ideas. I’ve checked everything I can think of. I rewound T401 (the trifilar toroid) and replaced the PCM1804. I’ve followed the audio chain through the receive section with my scope but can’t identify a specific issue. I’m at the guess and check stage and looking for ideas. It’s picking up noise somewhere but I have no idea where.
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?? I have a factory built 30 Meter QCX+ for sale, $80 shipped USA, contact me by my QRZ email.
?????????????????????????????????????????? W6TOM
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Re: Poor Mans ESD Safe Work Surface
Oh completely understand.
I don't actually use that worktable for actual power on testing. At most, I ohm out detailed checkpoints or other ohmic confirmations of connections. If I've removed the board from the holder to do those sorts of checks, I place it on top of another non conductive surface ( manilla folders are my friend for lots of tasks).?
Any power on testing I do at my shack operating tables.
You are correct. The mats are nice.? Just an old habit of mine from way back in the day before there were such things outside of pricey commercial sources. I think I picked it up on list of hints and kinks documents that Elecraft had in its website back when it was all kits and I built out a K2.?
GREG
On Mon, Feb 24, 2025 at 3:38 PM, Stan Dye via groups.io <standye@...> wrote: Nice idea, Greg.
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I prefer working on a non-conductive work surface, so I don't accidentally short things while testing.
There are several low-cost (under $30) ESD mats available on Amazon, including the wrist-strap, such as this $23 one:
Stan
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Re: Poor Mans ESD Safe Work Surface
I prefere a non conductive esd mat. The mat and wrist strap have resistors in. I also use a plug with just the earth connected and not had any issues in 25 plus years(apart from replacing the strap every so often ).
Nice idea, Greg.
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I prefer working on a non-conductive work surface, so I don't accidentally short things while testing.
There are several low-cost (under $30) ESD mats available on Amazon, including the wrist-strap, such as this $23 one:
Stan
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Re: QMX kit arrived w/damaged L501, is it a problem?
Maybe it is regional... My QMX+ kit arrived today in PERFECT condition. No damage to the outside packaging. The 1st thing I checked was L501: AOK inside an anti-static bag, inside a paper envelope, inside a cardboard box, and the FED-X plastic envelope.? So.... to this southeastern corner of the USA, a happy result.? FED=X people here are careful.?
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72 de N4REE, Bob Easton - QRP CW forever
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Daniel Conklin
Lidiette Lacalle
W6MQI
N4REE - Bob