Looks much cleaner than it did when you first cracked it open! Nice job on the coupler sorting. I'm feeling spoiled by your uploading of two videos within the same day. Thanks so much for sharing your project with us. Fred
British radio amateur G4ZNX David Stockton (or G4ZNQ - both callsigns return answers for David!) seems to have created the bridge. Rev George Dobbs, G3RJV was a British radio amateur founder of the GQRP Club. Searches return some fascinating facts for their involvement with radio, and a descriptive article presenting the design.
I would have had no idea why the bridge would not work if connected the way it is labeled. Looks like this would be an economical way to construct a useful meter. Thanks for sharing all the information and construction techniques.
Good morning. Congratulations for completing the project and uploading the video to have some solid conclusions at least for now. 1.The capacitor almost 75-80% meshed in is good for 20 meter with qrp power. 2.The dual purpose meter works though calibration is not possible. 3.The entire attempt to improvement with a large roller coaster inductor has resulted in converting it into a qrp antenna matching unit for the higher bands. 1.Stockton bridge is, like the "Monimatch", a symmetrical design coupler; you can swap the antenna ( load) and source (TX) ports. 2. It's apt for 50 (or 75 ohm) system only when a 50 ohm coax cable (with the shield braid connected to only on either of the ports, (but not on both) as the "one turn through the torroid transformer between the TX and the antenna. 3. It would allow magnetic coupling but not the possible capacitive coupling on the torroid transformer. 4. The diagram is correct but the "forward"/"reverse" ports are shown wrongly. 5. The transformer between the TX and the antenna ports is the current transformer with one turn through the torroid. 6. The secondary should be offering at least 4 times the impedance (inductive reactance) that of the characteristic impedance of the transmission line (here, 50 ohm assumed, though the circuit has just a jumper like wire through the torroid transformer) and hence you can calculate the number of turns for the secondary for the lowest band of operation. It's better to have slightly more than required on 80 meter; follow the formula for calculating the inductive reactance, 2 pi f l . But too many turns are not good for the higher end of the HF spectrum. 7. One end of the current transformer is grounded and the other end feeds the identical torroid voltage transformer's secondary; the primary being again a piece of 50 ohm coax cable whose center conductor ends offer the outputs for rectification and termination into 50 ohm resistors of carbon composition. 8. Here too the piece of 50 ohm coaxial cable must have the braid connected to ground on only one side (Faraday's shielding) to avoid capacitive coupling but the magnetic coupling. 9. The diodes must be preferably germanium but identical Schottky diodes will do good. 10. Here I can see 2N5711 diodes for rectification. 11. The diode on the TX side always provides the "forward or incident" energy and vice versa. 12. Again I would like to stress on the fact that it's, like the Monimatch a symmetrical design coupler. The ports can be swapped for your convenience. 13. W2AEW, your good friend, Allen, has made atleast one lovely video on the subject of the Tandem coupler. 14. I advise everyone to watch it. 15. You didn't mention on which port you got the "incident energy sample; maybe you forgot, I believe. You can mention it for the sake of your viewers. I am one among them, please remember. 16. And it would be a real improvement if you have a wide space capacitor with a reasonably high capacity so that you can put it to use on the lower bands too. 17. I know your radio has a 3:1 tuner. 18. The tuner can be "improved" in the "real sense" for good. 18. The coupler must be screened without fail. 19. The wires must be also screened even if you use a twin flex wire between the coupler and the meter. 20. And you must use "voltage multiplier" of the right magnitude to the meter to read full scale ; I assume it's a 100 u ampere (or less) meter, very sensitive. For a 100 u ampere meter use 10 kilo ohm per volt. You can have atleast 3 ranges like 1v, 10v and 100v fsd to read different powers like 10w, 100w and 1000w using a 3 range switch and appropriate voltage multiplier resistances in series with the forward sample voltage. You must calculate the appropriate voltage multiplier resistances for the reverse sample voltage too using dummy resistors of appropriate wattages like 25,100 ohm (to read 2:1) and 17,150 ohm (to read 3:1) SWR. But you were mentioning something like "a shunt"..!!??🙄🙄 WISH YOU ALL THE BEST...👍❤️
Thanks. I wondered why this one did not have the coax thru the toroids. I can change that. I remember watching Alan's video The capacitor plate spacing is twice as good as the one that I replaced. I never operate above 100watts so I'm sure it's good for that. looks better than the caps in my MFJ.
@@IMSAIGuy nice that you responded quickly. In the small compact board you may not be able to install a piece of 50 ohm coax with the shield braid connected to the ground on one side. Hence leave it as such. But ensure that the jumper wire is in the middle of the core in either of those transformers so as to maintain symmetry. Though you may be happy with the capacitor you have installed the roller inductor might be of real qro use only with a big capacitor. I will be pleased if you install the original one and operate it on lower bands too. It's going to be an educational video, I am sure. There are many who don't have the right components of their expectations and they would be happy to see you do the right stuff on behalf of them, I suppose. Anyway thanks 👍❤️
@Talk to the hat. Hi, I think you are confused like Imsai guy. You want to have a 100 or a 50 micro ampere meter for good sensitivity. By employing a SHUNT you don't want to pass all or majority of the tiny current you derive from the SWR bridge; the meter would read almost "0" A voltage multiplier is a large value resistor that lies in series so that the tiny current makes a deflection on the scale. You may want to refer to school physics book. De VU2RZA .
If you notice, on your schematic, in goes to a single wire on top, or the primary, then on the bottom transformer, in goes to the secondary to be inducted to the primary. One diode goes to F the other to R. So, where the F is, it is coming from primary to secondary, then to the diode. On the bottom one, secondary inducts into the primary, then to the diode for R. IN that way, the signal when coming the other way, then it yo read both, R and F. But in last case, signal goes to the primary side of the transformer. I hope this is clear.
I use a mini balun 4 cellular base station's. this is something I may test 2 check the performance! yup! looks nice & clean!! I like this theory of tuning on the card! but?
I have seen the first capacitor modified by removing plates. Wider spacing increases power handling, but reduces capacitance. That would mean using 2 or 3 sections for the proper capacitance values need to effectively worl. I had NO IDEA that the IC-7300 was capable of outputting 2.5KW! :)
The Chinese SWR bridge seems to be the same as in the David Stockton schematic, only "the tap" you said is connected at the Tx side not the Load side, and this will become forward instead of reverse... I think it's working the same, either way. You should try it... I also suggest you to watch W2AEW videos about the directional couplers he made and explained...
There is a BIG difference: The original thansfomers are shielded between primary and secondary (the one turn is the center conductor of a small piece of coax). This can make a big difference in performance.
I was looking to see if anyone had got a fix for one of these because they dont work properly at 1.8mhz. Nothing to do with which way round you connect them. But I think I've figured it out now. Totally the wrong material in the ferrite rings meaning the impedance of the coils is far too low and half your power goes into heating up the ferrite!
@@IMSAIGuy Yep, I started in late '69 and have been an inveterate DXer ever since (along with being a test equipment junkie LOL!). Love the old adage that at the top of a cycle you could tune into a bedspring and work the world on 10m!
Sir..Thank you so much for this video and the vast amount of information there in.. I have one of these swr modules, but I have tried, without success, to obtain the documentation for it.. If you have one, would you be kind enough to provide a link to that documentation for me.. Thank you .. 73..John Rees..G4EIJ..Bristol..UK
I'm talking about free with no strings. I'll pay the postage. Looking in my junk box for 7400 series nixie drivers. Might have some if I can find them.
If you read his notes the circuit is symmetrical, if you swap ‘In’ and ‘out’ then ‘Reverse ‘ and ‘ Forward’ swap.
Looks much cleaner than it did when you first cracked it open! Nice job on the coupler sorting. I'm feeling spoiled by your uploading of two videos within the same day. Thanks so much for sharing your project with us. Fred
British radio amateur G4ZNX David Stockton (or G4ZNQ - both callsigns return answers for David!) seems to have created the bridge.
Rev George Dobbs, G3RJV was a British radio amateur founder of the GQRP Club.
Searches return some fascinating facts for their involvement with radio, and a descriptive article presenting the design.
I would have had no idea why the bridge would not work if connected the way it is labeled. Looks like this would be an economical way to construct a useful meter. Thanks for sharing all the information and construction techniques.
Alan W2AEW has an excellent video #196 on how this works, with demonstration.
You should win an award for most content per day! It's amazing how much content you produce, I can hardly keep up!!! Do you even sleep?!
I do sleep! my secret weapon is being retired and locked up avoiding viruses.
Good morning. Congratulations for completing the project and uploading the video to have some solid conclusions at least for now.
1.The capacitor almost 75-80% meshed in is good for 20 meter with qrp power.
2.The dual purpose meter works though calibration is not possible.
3.The entire attempt to improvement with a large roller coaster inductor has resulted in converting it into a qrp antenna matching unit for the higher bands.
1.Stockton bridge is, like the "Monimatch", a symmetrical design coupler; you can swap the antenna ( load) and source (TX) ports.
2. It's apt for 50 (or 75 ohm) system only when a 50 ohm coax cable (with the shield braid connected to only on either of the ports, (but not on both) as the "one turn through the torroid transformer between the TX and the antenna.
3. It would allow magnetic coupling but not the possible capacitive coupling on the torroid transformer.
4. The diagram is correct but the "forward"/"reverse" ports are shown wrongly.
5. The transformer between the TX and
the antenna ports is the current transformer with one turn through the torroid.
6. The secondary should be offering at least 4 times the impedance (inductive reactance) that of the characteristic impedance of the transmission line (here, 50 ohm assumed, though the circuit has just a jumper like wire through the torroid transformer) and hence you can calculate the number of turns for the secondary for the lowest band of operation. It's better to have slightly more than required on 80 meter; follow the formula for calculating the inductive reactance, 2 pi f l . But too many turns are not good for the higher end of the HF spectrum.
7. One end of the current transformer is grounded and the other end feeds the identical torroid voltage transformer's secondary; the primary being again a piece of 50 ohm coax cable whose center conductor ends offer the outputs for rectification and termination into 50 ohm resistors of carbon composition.
8. Here too the piece of 50 ohm coaxial cable must have the braid connected to ground on only one side (Faraday's shielding) to avoid capacitive coupling but the magnetic coupling.
9. The diodes must be preferably germanium but identical Schottky diodes will do good.
10. Here I can see 2N5711 diodes for rectification.
11. The diode on the TX side always provides the "forward or incident" energy and vice versa.
12. Again I would like to stress on the fact that it's, like the Monimatch a symmetrical design coupler. The ports can be swapped for your convenience.
13. W2AEW, your good friend, Allen, has made atleast one lovely video on the subject of the Tandem coupler.
14. I advise everyone to watch it.
15. You didn't mention on which port you got the "incident energy sample; maybe you forgot, I believe. You can mention it for the sake of your viewers. I am one among them, please remember.
16. And it would be a real improvement if you have a wide space capacitor with a reasonably high capacity so that you can put it to use on the lower bands too.
17. I know your radio has a 3:1 tuner.
18. The tuner can be "improved" in the "real sense" for good.
18. The coupler must be screened without fail.
19. The wires must be also screened even if you use a twin flex wire between the coupler and the meter.
20. And you must use "voltage multiplier" of the right magnitude to the meter to read full scale ; I assume it's a 100 u ampere (or less) meter, very sensitive.
For a 100 u ampere meter use 10 kilo ohm per volt. You can have atleast 3 ranges like 1v, 10v and 100v fsd to read different powers like 10w, 100w and 1000w using a 3 range switch and appropriate voltage multiplier resistances in series with the forward sample voltage.
You must calculate the appropriate voltage multiplier resistances for the reverse sample voltage too using dummy resistors of appropriate wattages like 25,100 ohm (to read 2:1) and 17,150 ohm (to read 3:1) SWR.
But you were mentioning something like "a shunt"..!!??🙄🙄
WISH YOU ALL THE BEST...👍❤️
Thanks. I wondered why this one did not have the coax thru the toroids. I can change that. I remember watching Alan's video
The capacitor plate spacing is twice as good as the one that I replaced. I never operate above 100watts so I'm sure it's good for that. looks better than the caps in my MFJ.
@@IMSAIGuy well.. Dr subramanian.. is our teacher.. 👍👍
@@IMSAIGuy nice that you responded quickly.
In the small compact board you may not be able to install a piece of 50 ohm coax with the shield braid connected to the ground on one side. Hence leave it as such. But ensure that the jumper wire is in the middle of the core in either of those transformers so as to maintain symmetry. Though you may be happy with the capacitor you have installed the roller inductor might be of real qro use only with a big capacitor.
I will be pleased if you install the original one and operate it on lower bands too.
It's going to be an educational video, I am sure.
There are many who don't have the right components of their expectations and they would be happy to see you do the right stuff on behalf of them, I suppose.
Anyway thanks 👍❤️
@Talk to the hat. Hi, I think you are confused like Imsai guy.
You want to have a 100 or a 50 micro ampere meter for good sensitivity.
By employing a SHUNT you don't want to pass all or majority of the tiny current you derive from the SWR bridge; the meter would read almost "0"
A voltage multiplier is a large value resistor that lies in series so that the tiny current makes a deflection on the scale.
You may want to refer to school physics book.
De VU2RZA
.
The circuit has appeared several times in QRP books and articles, notably in "Sprat".
it does not matter which is the input it still works you just have to change the fwd and rev over
Good proyect! congrats! 73's Dx from Martin's LW9DTR
If you notice, on your schematic, in goes to a single wire on top, or the primary, then on the bottom transformer, in goes to the secondary to be inducted to the primary. One diode goes to F the other to R. So, where the F is, it is coming from primary to secondary, then to the diode. On the bottom one, secondary inducts into the primary, then to the diode for R. IN that way, the signal when coming the other way, then it yo read both, R and F. But in last case, signal goes to the primary side of the transformer. I hope this is clear.
I built the same Stockton circuit deadbug style and it works great. I saw that one on Amazon.. curious, are those controlled impedance traces?
Tandem Match or Stockton among QRP-ers is bidirectional, should not matter how you connect it if the transformers are identical.
I love this channel so much. I fear you're going to burn out with this much content.
I use a mini balun 4 cellular base station's. this is something I may test 2 check the performance! yup! looks nice & clean!! I like this theory of tuning on the card! but?
The fact that the POWER output indicator is so far overdriven tells me that it is actually the SWR output, and that the silkscreen is correct.
I have seen the first capacitor modified by removing plates. Wider spacing increases power handling, but reduces capacitance. That would mean using 2 or 3 sections for the proper capacitance values need to effectively worl.
I had NO IDEA that the IC-7300 was capable of outputting 2.5KW! :)
You can feed that into an Arduino for example, with a digital display for a more fancy project.
The Chinese SWR bridge seems to be the same as in the David Stockton schematic, only "the tap" you said is connected at the Tx side not the Load side, and this will become forward instead of reverse... I think it's working the same, either way. You should try it... I also suggest you to watch W2AEW videos about the directional couplers he made and explained...
There is a BIG difference:
The original thansfomers are shielded between primary and secondary (the one turn is the center conductor of a small piece of coax). This can make a big difference in performance.
I was looking to see if anyone had got a fix for one of these because they dont work properly at 1.8mhz. Nothing to do with which way round you connect them. But I think I've figured it out now. Totally the wrong material in the ferrite rings meaning the impedance of the coils is far too low and half your power goes into heating up the ferrite!
always great videos, what power do you think these can handle, Thanks Dave
probably 100w
@@IMSAIGuy ok thanks
Thanks for share, but a SWR meter should works in both directions, it is symetrical. The capacitor seems to be quite small? 73!
That's a W8DIZ board and is labeled correctly.
Lee, WA8QFE
We're starting to walk up the Cycle 25 curve so things will continue to get interesting on the higher bands!
I remember the good ol 22 cycle which got me DXCC
@@IMSAIGuy Yep, I started in late '69 and have been an inveterate DXer ever since (along with being a test equipment junkie LOL!). Love the old adage that at the top of a cycle you could tune into a bedspring and work the world on 10m!
Sir..Thank you so much for this video and the vast amount of information there in.. I have one of these swr modules, but I have tried, without success, to obtain the documentation for it.. If you have one, would you be kind enough to provide a link to that documentation for me..
Thank you .. 73..John Rees..G4EIJ..Bristol..UK
ea4nz.ure.es/swrmeter/swrmeter.html
@@IMSAIGuy Many thanks..
I have to get one of these to play with. Thanks for your vids. AB1ZI
Can you share the notes of swr meter shown in the video in pdf DE VU3IZD 73
www.sm7ucz.se/Meters/Stockton_pwr_meter.pdf
But why a big block of ABS ? looks odd
👌👌👌👍
I have some parts you might like to have such as the bridge from an hp 8502A and the variable cap from an hp 204C. How can we make contact?
I'm talking about free with no strings. I'll pay the postage. Looking in my junk box for 7400 series nixie drivers. Might have some if I can find them.
@@williamdenbeste9703 my about page has an email address
Belinya dimana gan
link is in the description
hello sir ive a request
?
The people from VU Land can't get this.