Lrl from Italy

[toorani]

hi franco dear
i remove the quartz and i decreased the capacitor c13 and c14 to 50pf but the voltages are still the same as before,It has only dropped by about 0.4 volts.
Also, the r6, r8 and r11 resistances are 550 k ohm
In your opinion, where is the problem?
Thank you very much for your guide

[FrancoItaly]

hi franco dear
i remove the quartz and i decreased the capacitor c13 and c14 to 50pf but the voltages are still the same as before,It has only dropped by about 0.4 volts.
Also, the r6, r8 and r11 resistances are 550 k ohm
In your opinion, where is the problem?
Thank you very much for your guide

Surely there is a self-oscillation. This is the operation of the first version of my lrl. Touch the antenna and check if the signal varies. If so, if the signal is stable, the lrl works equally this way. To decrease the gain increases R10 / R12 (1.5K or 2.2K). Self-oscillation can depend on a parasitic coupling of the pcb and / or the excessive gain (beta) of the transistors.

[toorani]

Hello franco dear
By touching the antenna voltage dc out( emiter tr5, it is about 2.3 volt) It does not change at all.
I set the resistance of r10 and r12 to 2K ohm, but the collector voltage increased by about 0.2 volts.
Thank you very much for your guide

[abdou2014]

[FrancoItaly]

Hello franco dear
By touching the antenna voltage dc out( emiter tr5, it is about 2.3 volt) It does not change at all.
I set the resistance of r10 and r12 to 2K ohm, but the collector voltage increased by about 0.2 volts.
Thank you very much for your guide

I confirm that there is a self oscillation, the pcb is better double sided, with lower side connected to ground. Try also transistors type BC...B (lower beta than C type).

[abdou2014]

happy birthday Mr Franco

[FrancoItaly]

happy birthday Mr Franco

Thank you so much.

[toorani]

Hello dear franco
I hope you always be healthy
I found the problem circuit,Tr2 transistor was faulty.
The collector voltage is now: tr2 2.8 volt ,tr3 4.5 volt, tr4 4.5 volt
why the collector voltage tr2 is 2.8 volt?
Without the quartz, the output voltage is zero(emiter tr5) and with quartz is 4.1 volt
signal Emitter tr1 is 8 Mhz 2.4 volt pic to pic,Of course capacitor c1 is Two parallel capacitors 560p.
capacitor c13 is 200 nf and c14 is 100 nf but why The output voltage does not exceed 4.1 volts?
capacitor c2,c3 and c4 is 1.8 pf

Thank you very much for your guide

[WM6]

I found the problem circuit,Tr2 transistor was faulty.
The collector voltage is now: tr2 2.8 volt ,tr3 4.5 volt, tr4 4.5 volt
why the collector voltage tr2 is 2.8 volt?

Interesting PCB construction toorani. New PCB Art design.

Better than Manhattan style PCB construction. Bravo.

An easy way to put TR with wrong pin orientation on it too.

Did you checked well before power on?

..

[toorani]

Interesting PCB construction toorani. New PCB Art design.

Better than Manhattan style PCB construction. Bravo.

An easy way to put TR with wrong pin orientation on it too.

Did you checked well before power on?

..

hi Mr wm6
I originally plugged the pin collector- Emitter incorrectly But I've corrected it now.

Thank you very much for your guide

[FrancoItaly]

Hello dear franco
I hope you always be healthy
I found the problem circuit,Tr2 transistor was faulty.
The collector voltage is now: tr2 2.8 volt ,tr3 4.5 volt, tr4 4.5 volt
why the collector voltage tr2 is 2.8 volt?
Without the quartz, the output voltage is zero(emiter tr5) and with quartz is 4.1 volt
signal Emitter tr1 is 8 Mhz 2.4 volt pic to pic,Of course capacitor c1 is Two parallel capacitors 560p.
capacitor c13 is 200 nf and c14 is 100 nf but why The output voltage does not exceed 4.1 volts?
capacitor c2,c3 and c4 is 1.8 pf

Thank you very much for your guide

4.1V is ok. 2.8V at TR2 collector voltage is ok, as here the signal is very small. If touching
the antenna the output changes the sensor stage is ok.

[toorani]

4.1V is ok. 2.8V at TR2 collector voltage is ok, as here the signal is very small. If touching
the antenna the output changes the sensor stage is ok.

hi franco dear
with touching the antenna, How much output should change ?
Thank you very much for your guide

[FrancoItaly]

hi franco dear
with touching the antenna, How much output should change ?
Thank you very much for your guide

it's not critic, about 10mV - 1V or more.

[toorani]

[QUOTE=FrancoItaly;156419]it's not critic, about 10mV - 1V or more.[/QUOTE


Thank you very much for your guide
with touching the antenna,the output will increase by about 0.4 volts

[toorani]

[QUOTE=toorani;156420]

it's not critic, about 10mV - 1V or more.[/QUOTE


Thank you very much for your guide
with touching the antenna,the output will increase by about 0.4 volts

In your opinion, with these conditions my lrl is ok?
Can I put it inside the box?
The box with aluminum foil does not create capacitive capacities?
What is lrl reaction to the target?
Or, by placing the L1 vertically, the sensitivity to the north pole and south will decrease?