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QMX/QMX+ T507 Winding Sense

 

Hi All. There has been a little bit of concern expressed in a few posts about the correct way to wind the 10 turn windings on T507 which, along with two diodes, 6 resistors and 2 capacitors make up the SWR sensing circuit in QMX and QMX+. I did an experiment today that proves it does not matter which way the windings lay down on the binocular toroid, either top to bottom on both halves (clockwise on one side and Anti-Clockwise on the other), looking at one end of the binocular, or top to bottom on one half and bottom to top on the other (both windings either Clockwise or Anti-Clockwise). The reason for this is that the actual turns direction through the center of the core and around the outside is always the same no matter how you wind it. The instantaneous current flow and magnetic field are in the same direction in both configurations.?
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I built up two binocular cores. I wound one each in each of the two above configurations and connected them to a breadboard model of the circuit used in the QMX/QMX+. I took the two output voltages (FWD and REF) to two old VU meters to show analog outputs for the test.
I put about 4 watts of RF into the circuit and attached a dummy load for one test of each and an antenna with some SWR for the other test of each. Attached are photos of the dummy load test. The meter on the left is showing Forward power and the one on the right is Reflected. The two test results are virtually identical. Results for the tests using an antenna with 2.4:1 SWR both showed less forward power and some reflected power as would be expected, again both virtually identical.?
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I hope this alleviates any concerns about how to wind T507. Best 73 .... .Ron
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Ron, Thanks for all the testing. That is good to know.

73¡¯²õ

Mike Krieger


On Mon, Aug 19, 2024 at 5:37?PM Ronald Taylor via <wa7gil=[email protected]> wrote:
Hi All. There has been a little bit of concern expressed in a few posts about the correct way to wind the 10 turn windings on T507 which, along with two diodes, 6 resistors and 2 capacitors make up the SWR sensing circuit in QMX and QMX+. I did an experiment today that proves it does not matter which way the windings lay down on the binocular toroid, either top to bottom on both halves (clockwise on one side and Anti-Clockwise on the other), looking at one end of the binocular, or top to bottom on one half and bottom to top on the other (both windings either Clockwise or Anti-Clockwise). The reason for this is that the actual turns direction through the center of the core and around the outside is always the same no matter how you wind it. The instantaneous current flow and magnetic field are in the same direction in both configurations.?
?
I built up two binocular cores. I wound one each in each of the two above configurations and connected them to a breadboard model of the circuit used in the QMX/QMX+. I took the two output voltages (FWD and REF) to two old VU meters to show analog outputs for the test.
I put about 4 watts of RF into the circuit and attached a dummy load for one test of each and an antenna with some SWR for the other test of each. Attached are photos of the dummy load test. The meter on the left is showing Forward power and the one on the right is Reflected. The two test results are virtually identical. Results for the tests using an antenna with 2.4:1 SWR both showed less forward power and some reflected power as would be expected, again both virtually identical.?
?
I hope this alleviates any concerns about how to wind T507. Best 73 .... .Ron
?
 

Hi Ron,
Based on my experience with my recently completed construction of a QMX+, I would beg to differ with your conclusion.? When I applied power to my QMX+ for the first time, during transmit there was no indication of power out or SWR on the QMX+ display.? Troubleshooting revealed that the outputs of the SWR bridge circuit were reversed, i.e. the output power measurement was appearing at the bridge REF output, and the reflected power measurement was appearing at the FWD output.? These readings apparently confused the firmware calculation of SWR, and it failed to display anything for either Power Out or SWR on the display during transmit.? ?I decided to reverse the direction of one of the 10-turn windings (I was able to do this without removing T507 - it was tedious and difficult, but doable).? After reversing the winding direction, the outputs reversed back to normal - i.e. output power on the FWD output and reflected power on the REF output, and the output power and SWR indications were displayed correctly during transmit.? My conclusion was that the sense of the two 10-turn windings does matter.? It would be good if Hans updates the T-507 construction directions to clarify the winding sense needed.
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Bob, KC9UR
 

Do you have any photos or diagrams showing what the incorrect winding scheme you had looks like.
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I realise that a number of people are concerned that it isn't clear how the T507 transformers are wound but I really can't see how there can be a problem.
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T507 is electrically two separate transformers, a top one using wires A-A and B-B, and a bottom one using wires C-C and D-D.? Wires A and D are the thin ones with 10 turns and B and C are the thick ones with 1 turn.
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For A and D wind 10 turns through each hole of the core, in each case the wire goes through the core and round the outside, then through.? Do this until you have passed each wire through the core 10 times.? Thread the thick wires B and C through the cores, one in each hole.? This should look like the photos.? Bend the thick wires down so they will fit neatly into the large holes in the board.? The thin wires come out of the core and go straight into the holes on each side.? It should look neat, no wires crossed over, thin wires at the top and bottom, thick wires in the middle.? Once it's all fitting nicely remove it from the board. scrape the wires and refit, then solder.
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That's all it is, no need to worry about clockwise or anticlockwise. all that's needed is that the wires come from the board, then through the core and from the core into the board on the other side of the core. In the case of the thin wires after going through the core 10 times.
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Chris, G5CTH
 

Thanks for the replies Mike, Chris and Bob. Well said Chris. Bob, in my testing it made no difference which way they were wound. I even tried "jumble" winding one of the?windings so it had no discernible direction of lay around the core and?it made no difference, but since you got different results I did some more testing today. I couldn't find a scenario where it would reverse outputs so I thought perhaps you had maybe had a bad solder joint on one of the wires that was possibly corrected when you rewound it, so I removed one transformer wire at a time from the circuit. I found that when I lifted either end of the C-C wire (large wire furthest from the board edge), I got full forward power on the Reflected side and nothing on the forward side, looking like a reversal of the voltages (although not exactly a reversal since there is no voltage delivered to the forward power detector in this case). The?reason for that can be seen in the schematic. When that wire is open, there is no path to D514. So I'm wondering if this is possibly what happened in your case? Did you touch up the other connections when you reversed?one of the windings and maybe corrected the problem that way unknowingly?

Best 73 .. .Ron

On Mon, Aug 19, 2024 at 8:08?PM Bob KC9UR via <rebill05=[email protected]> wrote:
Hi Ron,
Based on my experience with my recently completed construction of a QMX+, I would beg to differ with your conclusion.? When I applied power to my QMX+ for the first time, during transmit there was no indication of power out or SWR on the QMX+ display.? Troubleshooting revealed that the outputs of the SWR bridge circuit were reversed, i.e. the output power measurement was appearing at the bridge REF output, and the reflected power measurement was appearing at the FWD output.? These readings apparently confused the firmware calculation of SWR, and it failed to display anything for either Power Out or SWR on the display during transmit.? ?I decided to reverse the direction of one of the 10-turn windings (I was able to do this without removing T507 - it was tedious and difficult, but doable).? After reversing the winding direction, the outputs reversed back to normal - i.e. output power on the FWD output and reflected power on the REF output, and the output power and SWR indications were displayed correctly during transmit.? My conclusion was that the sense of the two 10-turn windings does matter.? It would be good if Hans updates the T-507 construction directions to clarify the winding sense needed.
?
Bob, KC9UR
 

I agree completely. Makes no difference with binocular T507. The BIG difference is whether it works or not and that is related to solder joints. My second try with QMX was prettier and it worked! My first try on QMX+ was successful bbecause I scraped EVERY wire to bright copper. Then made a good solder joint.
--
73
Karl
KI4ZUQ
 

¿ªÔÆÌåÓý

I have to agree. I scrape to bright copper, solder at 370C, when it flows hold it to count of five. Then remove heat and let it cool.?

I am very new and my QMX worked first time.?

Take the separate instructions for Really Twisted toroidal slowly and deliberately. I made it for 12v. ?It really makes a difference. I have to turn power down to 11v to keep output below 5watts.?

Just take every toroid like a class for a new kind of wind. Don¡¯t assume any of these can be done from previous experience.?

Like I said, I am new to radio building and my first QMX worked first time.?

This is a really cool device!

Paul Wamble
K5EBP?
214-405-5876 cell?


On Aug 20, 2024, at 11:35?AM, Karl via groups.io <karlshumaker@...> wrote:

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I agree completely. Makes no difference with binocular T507. The BIG difference is whether it works or not and that is related to solder joints. My second try with QMX was prettier and it worked! My first try on QMX+ was successful bbecause I scraped EVERY wire to bright copper. Then made a good solder joint.
--
73
Karl
KI4ZUQ
 

Hi Ron,
It could very well be that I had a bad solder joint on the winding that I reversed, because I found one previously on one of the inductors in the 160m low pass filter.? Thanks for doing the additional testing!? Best wishes!? Bob, KC9UR

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