So the triode is acting as a diode and then further filtering is done by the cap connected between the filament and the transformer? Of course the grid leak resistor and the other cap also play a part.
This detector circuit was used in many different radio brands at that time. The circuit is actually performing 2 functions simultaneously; RF detector and audio preamplifier. Combining the two functions does compromise performance but, was considered an acceptable tradeoff in order to save the use of one additional vacuum tube. Detector operation: The plate voltage on this tube is so low (22 volts), the tube, even with 0 volts on the control grid, is on the threshold of being cutoff (almost no plate current flowing). Therefore, in order to get the tube to conduct, the input signal must go positive. So, as the RF signal on the grid passes the zero crossing point, the positive portion of the RF envelope is getting amplified and the negative portion fully cuts the tube off. The circuit compromise is this: The circuit operates best at a certain RF input level (I.E., a "Sweet Spot"). If you over drive the detector, the control grid will act as a rectifier diode connected to ground and will short out all of the positive portion of the RF envelope, pushing the DC level on the grid increasingly negative as RF drive increases. This will cause high audio distortion as only a portion of the positive RF envelope will be amplified. Conversely, under driving the detector will produce low audio levels and somewhat increased audio distortion.
This is one of the great benefits of that new adage "anything you post online will basically exist forever" Sure hope so, in this context. Sir, you are a gift to all of us radio guys, old and young!
I think that’s the clearest and easiest to understand explanation of grid-leak detection I’ve ver heard. Thanks!
Thank you , and your welcome.
So the triode is acting as a diode and then further filtering is done by the cap connected between the filament and the transformer? Of course the grid leak resistor and the other cap also play a part.
The triode rectifies (detects) the signal and amplifies the signal at the sometime.
@@AllAmericanFiveRadio Yeah, that is the part I left out. It is interesting the different ways detection was done over the years.
A very nice and ellegant explanation again! Thanks for sharing it.
Thank you , and your welcome.
This detector circuit was used in many different radio brands at that time. The circuit is actually performing 2 functions simultaneously; RF detector and audio preamplifier. Combining the two functions does compromise performance but, was considered an acceptable tradeoff in order to save the use of one additional vacuum tube.
Detector operation: The plate voltage on this tube is so low (22 volts), the tube, even with 0 volts on the control grid, is on the threshold of being cutoff (almost no plate current flowing). Therefore, in order to get the tube to conduct, the input signal must go positive. So, as the RF signal on the grid passes the zero crossing point, the positive portion of the RF envelope is getting amplified and the negative portion fully cuts the tube off.
The circuit compromise is this: The circuit operates best at a certain RF input level (I.E., a "Sweet Spot"). If you over drive the detector, the control grid will act as a rectifier diode connected to ground and will short out all of the positive portion of the RF envelope, pushing the DC level on the grid increasingly negative as RF drive increases. This will cause high audio distortion as only a portion of the positive RF envelope will be amplified. Conversely, under driving the detector will produce low audio levels and somewhat increased audio distortion.
Thanks
❤ super pozdrowienia z Poland
Thank you , and your welcome.
Excellent explanation!! Thank you.
Thank you , and your welcome.
Thanks sir..
Thank you, and your welcome.
Most excellent explanatioin RIck. You make understanding how circuits work so much easier. :)
Thanks Doug. Hopefully this can help keep these radios working.
You deserve a pat on the back for that explanation. Absolutely brilliant 👏👏👏
Thank you. hope this video helps.
That was a very nice explanation. Thank you, sir.
Thank you , and your welcome.
You are a natural born teacher and presenter. Go to the head of the class!
Thank You!
This is one of the great benefits of that new adage "anything you post online will basically exist forever"
Sure hope so, in this context.
Sir, you are a gift to all of us radio guys, old and young!
Thank you , and your welcome.
Excellent video, very informative. Thank you!
Thank you , and your welcome.