TESORO GOLDEN SABRE

[Mr.Jaick]

i've seen some people has about -6 , i think it depends on IC chips consumption

[Mr.Jaick]

I got this backwards. The Disc pot goes into the Negative comparator input so output high when input low.

Thanks for details on scope pictures.
The signal at the wiper of the Disc pot is moving up as you turn the pot. This is Not correct and why the comparator output goes to a solid high level.
What should happen is the signal should become more and more delayed as you turn the pot.

Did you CHECK the Voltages on the opamp and comparator? -4.8 is lower than typical but should work.
Re-check the Disc pot connections and component values. Check all soldering and since you have a hand made double sided PCB ensure connection are made TOP & BOTTOM where needed.

i checked the voltage +8 and -5 on all the chips, they are fine
the pcb is a custom metalized double sided , i ordered from a pcb manufacturer
but i'll check everything again, thank you

[Mr.Jaick]

Mr Jaick the phase shift between your Tx and Rx does not seem to be 20deg, there is obviously much less than that maybe 10-15 after seeing the picture you posted.

About the negative voltage, try Schotky diodes those have less on resistance and pair those transistors to have equal hFE and also low ESR electric capacitor is a must! The best I have made was around -6.7volts.

Waltr has some really good points also!

thanks sir i'll try schotky diodes , it will help
the signal occupies 6.9 blocks on the screen, so 360/6.9 = 52 degrees for each horizontal block, and each block has divided by 5 sections so each of them means 10 degrees of phase shift and the phase shift between tx and rx is 2 sections so i think it's fine, isn't it?

[Mr.Jaick]

You can also try to use ICL7660 to make negative voltage for the circuit. You need less components and it makes -7.48volts loaded, works splendid!

Do not forget that you have very asymmetrical voltages for the IC's that means that the negative peaks of the signals get clipped. I really believe that this is your problem.

regards

yes i have a bit asymmetrical waveform , and negative peaks get clipped a little
and yes something is wrong with my setup , i'll try to figure out
regards

[Nandor]

Please post the schematic you made!

[waltr]

i've seen some people has about -6 , i think it depends on IC chips consumption

i checked the voltage +8 and -5 on all the chips, they are fine
the pcb is a custom metalized double sided , i ordered from a pcb manufacturer
but i'll check everything again, thank you

thanks sir i'll try schotky diodes , it will help
the signal occupies 6.9 blocks on the screen, so 360/6.9 = 52 degrees for each horizontal block, and each block has divided by 5 sections so each of them means 10 degrees of phase shift and the phase shift between tx and rx is 2 sections so i think it's fine, isn't it?

Voltages you have are fine. They do not need to be exact.
Good checking Voltages On the pins of the Chips.

The RX phase shift is NOT important at this stage of troubleshooting. Also I played a lot with the TGSL I built and this circuit actually works very well with almost any phase shift.
This is NOT the problem yet.

The Problem is in the DISC Circuit as I have pointed out in previous posts.

[Mr.Jaick]

Voltages you have are fine. They do not need to be exact.
Good checking Voltages On the pins of the Chips.

The RX phase shift is NOT important at this stage of troubleshooting. Also I played a lot with the TGSL I built and this circuit actually works very well with almost any phase shift.
This is NOT the problem yet.

The Problem is in the DISC Circuit as I have pointed out in previous posts.

i think i discovered the problem somewhere
take a look at these pictures:

all signals reference is at the middle X axis of the scope screen.
disc pot and GB pot connected but disc switch is not connected

1- TX signal (2v/div , 10us t/dev)


2- U102(LM393) pin 6 which is inverting input , GB pot at mid range (2v/div , 10us t/dev)
output of GB section is clean square wave for the Jfet(TR5) , no problem


3- U101(LF353) pin 6 , the problem (5v/div , 20us t/dev)
actually i accidentally switched the first op_amp of LF353 with second one when i was designing the PCB, my bad but it doesn't effect anything, does it??


4- middle pin of 100k disc pot, at min (2v/div , 10us t/dev)
it's simply the TX signal from that 3.3k resistor


5- U102 pin 2 which is the inverting input of comparator (2v/div , 10us t/dev)


6- U101 pin 7 , this is the problem for that flat DC voltage (2v/div , 10us t/dev)


7- middle pin of disc pot, at max , obviously it feeds that DC signal form U101 into next stage(comparator) when i turn the disc pot to MAX and cause the problem (2v/div , 10us t/dev)


and to notice i used PN4391 instead of J107 , at that time i only found this FET and didn't know about BF245 so maybe i would change it in advance

[Mr.Jaick]

Please post the schematic you made!

how can i send the schematic sheet in altium format here?
the schematic that i made the pcb out of it is bit deference but i turned it into the original one from Dan Bowers pdf
it's the original now

[kt315]

ZIP it. open ADVANCED reply form and attach the file.

[Nandor]

This is my device, here you can see the Tx signal and the phase shifters output. Tx has 14Vpp clean sinewave
First Tx vs Geb and than Tx vs Disc square wave and last the Disc pot middle leg output as the Discrimination is at minimum and maximum level.
https://www.youtube.com/watch?v=VbjYgZoMek4

This is the video of the Jfet transistor signal vs Rx signal you can see that Geb is on the left and Disc is on the right side of the Rx signal
https://www.youtube.com/watch?v=mqPf72qbTeA

[waltr]

3- U101(LF353) pin 6 , the problem (5v/div , 20us t/dev)
actually i accidentally switched the first op_amp of LF353 with second one when i was designing the PCB, my bad but it doesn't effect anything, does it??

no problem accept can confuse us if you only state U101-7

6- U101 pin 7 , this is the problem for that flat DC voltage (2v/div , 10us t/dev)
[ATTACH]49466[/ATTACH]

This is a problem and why Disc pulse changes level.
Check for bad soldering, shorts and layout. Does this chip have -6V on pin 4?

and to notice i used PN4391 instead of J107 , at that time i only found this FET and didn't know about BF245 so maybe i would change it in advance

The PN4391 should work and is not the current problem.

[Mr.Jaick]

Taddaaaa I finally got it
when i was checking the U101 input and output , i realized that the pin 7(the original pin 1) and pin 8 are shorted!!!
i noticed the chip(LF353) is getting too hot , but i thought it is normal(yes i'm being dumb sometimes)
after refreshing all the solder joints i carefully followed the traces around inputs and output and find out that the stupid PCB manufacturer has joint the pin 7 and 8 !!!
because these two traces are a bit close to each other but not out of spec of the manufacturer, they told me they can etch down to 0.25mm at minimum , and my design was about 0.5mm !
the joint was extremely thin and somewhere very unreachable...
i ruined my 100k pot when i was trying to change it, it's a bit touchy but i saw the correct waveform for a second and i'm sure it's okay now, but couldn't capture it
i'll buy a new one tomorrow and test everything, hopefully it'll be fully functional, i'm pretty confident

so yeah fortunately it fixed, well thanks to you great people , i've learned a lot here just within a few days
truly you guys are some of the must helpful and useful people on earth, thank you very much for lessons
regards

[Mr.Jaick]

This is my device, here you can see the Tx signal and the phase shifters output. Tx has 14Vpp clean sinewave
First Tx vs Geb and than Tx vs Disc square wave and last the Disc pot middle leg output as the Discrimination is at minimum and maximum level.
https://www.youtube.com/watch?v=VbjYgZoMek4

This is the video of the Jfet transistor signal vs Rx signal you can see that Geb is on the left and Disc is on the right side of the Rx signal
https://www.youtube.com/watch?v=mqPf72qbTeA

you're posts are very helpful thanks for sharing
i don't know how youtube's search algorithm works , cuz i searched about TGSL before and watched all the videos about it but never found your videos

[Mr.Jaick]

no problem accept can confuse us if you only state U101-7


This is a problem and why Disc pulse changes level.
Check for bad soldering, shorts and layout. Does this chip have -6V on pin 4?


The PN4391 should work and is not the current problem.

god damn it , you're awesome waltr
who are you man? the next Jesus?
i appreciate your help, thank you

[Mr.Jaick]

the schematic i have build now:
i have removed all those 100nF bypass caps

TGSL_schematic.rar