"Obviously there are a bunch of varactor diodes here." I think I like that line so much I'm going to start throwing it randomly into casual conversations. May I do so without attribution?
I enjoy this analysis of RF-magic. A partial explanation why these circuits seem to be out this world is that (electrical) engineers before the digital era were drilled in undertanding the math that these circuits need to get working. Nowadays we're more like Lego kiddies using function blocks (code, ic's, ...) without thoroughly knowing the basics anymore.
Fascinating. The isolation to get the needed very high stability. They are cancelling out the course frequency in the mixed output to avoid a difficult filtering? Thanks for this! Such weird construction for a commercial product.
All that talk and discussion about impedance, RF coupling and parasitic capacitance... gets swept away in an instant when you open up devices like this 😅 Thanks because this still gives me some hope of success out there in making a rf device at home by myself😅
I think perhaps those coupling inductors are actually 10 pf caps. The inductive pickup wires are the leads. That's the least of your problems. Getting those transistors out is "difficult". I vaguely recall having a similar issue, requiring a Dremel. Test the snot out of them first, of course! 73's W3IHM
Sometimes when I look at the old analog schematics, I'm starting to think that their creators were either genius or insane. Who'd use uncoupled coils to pick up nearby rf signal nowadays... But the most insane part for me is the montage. It seems that it'd take hours to assemble and test just one module.
That's when the magic happens and the naughty words get uttered, been there with this sort of construction, it can take a very long time to extricate one small part and not upset the rest of the circuit and the overall tuning stability etc.
I paused the vid at 5:02 and looked at your scope screen and I can't see any measurements like frequency or amplitude just that its 100 mV per/div. Is this just how you like it set up or what am I missing please ?.....cheers.
@@IMSAIGuy I understand this ! but most of us use the measurement facilities that are standard in all digi scopes nowadays. Some seriously powerful stuff ( you pay for ) but reading the graticule is fine, you probably have a slide rule too !..... you do you :)
@@andymouse I hope people stop relying on all the fancy stuff and learn how to estimate and use things quickly. Developing a gut feel will result in a better understating of electronics than numbers. I had another viewer who wanted me to use a fancy frequency counter for this repair. yes there is a place for the nice measurements but not at this stage of trouble shooting. final adjustments and calibration is the place.
@@IMSAIGuy I agree in reality of course and I can gather the correct information as long as I know the voltage per div and the time but the functions are there :)
for this particular measurement. I had vert set to 100mV/div. I expected a signal +/-100mV. the channel one sine wave did this great. when I went to measure channel two, I got a flat line. I expected channel to to look similar to channel one.
This generator looks home made with lots of point to point wiring and even a separate little bodge board. Almost like something a wizard would make in his laboratory. 🧙♂️🎛🎚
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"Obviously there are a bunch of varactor diodes here." I think I like that line so much I'm going to start throwing it randomly into casual conversations. May I do so without attribution?
hahaha I found it funny too :D
I enjoy this analysis of RF-magic.
A partial explanation why these circuits seem to be out this world is that (electrical) engineers before the digital era were drilled in undertanding the math that these circuits need to get working.
Nowadays we're more like Lego kiddies using function blocks (code, ic's, ...) without thoroughly knowing the basics anymore.
Fascinating. The isolation to get the needed very high stability. They are cancelling out the course frequency in the mixed output to avoid a difficult filtering? Thanks for this! Such weird construction for a commercial product.
All that talk and discussion about impedance, RF coupling and parasitic capacitance... gets swept away in an instant when you open up devices like this 😅
Thanks because this still gives me some hope of success out there in making a rf device at home by myself😅
I think perhaps those coupling inductors are actually 10 pf caps. The inductive pickup wires are the leads. That's the least of your problems. Getting those transistors out is "difficult". I vaguely recall having a similar issue, requiring a Dremel. Test the snot out of them first, of course! 73's W3IHM
The 2n5053 crosses to a NTE316, which is still available from Digikey.
Sometimes when I look at the old analog schematics, I'm starting to think that their creators were either genius or insane.
Who'd use uncoupled coils to pick up nearby rf signal nowadays...
But the most insane part for me is the montage. It seems that it'd take hours to assemble and test just one module.
FesZ Electronics just dropped a video on cavity filters which have similar couplings.
I'm pretty sure they were insane geniuses
Might be good to spend some time on the leveling part of that can.
Jeopardy Question: Micro surgery.
Answer: What are things that happen off camera.
That's when the magic happens and the naughty words get uttered, been there with this sort of construction, it can take a very long time to extricate one small part and not upset the rest of the circuit and the overall tuning stability etc.
I paused the vid at 5:02 and looked at your scope screen and I can't see any measurements like frequency or amplitude just that its 100 mV per/div. Is this just how you like it set up or what am I missing please ?.....cheers.
the screen IS the measurement, horiz and vert divisions are like rulers you use to look at the waveform
@@IMSAIGuy I understand this ! but most of us use the measurement facilities that are standard in all digi scopes nowadays. Some seriously powerful stuff ( you pay for ) but reading the graticule is fine, you probably have a slide rule too !..... you do you :)
@@andymouse I hope people stop relying on all the fancy stuff and learn how to estimate and use things quickly. Developing a gut feel will result in a better understating of electronics than numbers. I had another viewer who wanted me to use a fancy frequency counter for this repair. yes there is a place for the nice measurements but not at this stage of trouble shooting. final adjustments and calibration is the place.
@@IMSAIGuy I agree in reality of course and I can gather the correct information as long as I know the voltage per div and the time but the functions are there :)
for this particular measurement. I had vert set to 100mV/div. I expected a signal +/-100mV. the channel one sine wave did this great. when I went to measure channel two, I got a flat line. I expected channel to to look similar to channel one.
All that camera moving is frustrating!
This generator looks home made with lots of point to point wiring and even a separate little bodge board. Almost like something a wizard would make in his laboratory. 🧙♂️🎛🎚