The signal highlighting around the tubes explained so much so fast. Thanks Rick

Thankyou!! You're quite a teacher. I've been studying all weekend in preparation of a new Eico 369 sweep generator and getting my arms around where to inject and take off the signal. This video nailed it. Thanks for all your work.

@AllAmericanFiveRadio

5 жыл бұрын

Thanks

Thanks for the vid, I'm still learning (trying) to follow the signal through the schematic. Really appreciate that keep things as basic as the subject will allow and also that you don't rush through. Thanks again, Stan in SC

I can't thank you enough for all of your informative videos...Keep it up please !

@BadChizzle Sure why not. it is interesting that I can do my own discovery tours. Save up, a O-scope is a great tool to have.

Richard, you made a really useful video thanks for spending your time on everyone's knowledge.

@AllAmericanFiveRadio

4 жыл бұрын

Thanks, and you're welcome.

Thanks so much for showing all the detail in the schematic on voltage checking. I'm still learning, so this video was most helpful. I know these videos don't just shoot and edit themselves- there's a lot of time, effort and labor that goes into producing something like this. This is an older video, but the information is still very valid. Regards, Tom

@AllAmericanFiveRadio

3 ай бұрын

Thank you, and your welcome.

@CameramanLink I figured you did. I am fascinated with the discussion, if the ratio detector or discriminator is better. When both rely on the same frequence shift from center to work. The real difference is/was Sarnoff lawyers and Armstrong lawyers.

Another killer video for sure Rick. Keep em coming. I need the help! ;-)

@imfree707 Yep, it was plugged into an isolation transformer and variac.

Thanks radioland1 Hey Meyer, I'm happy that this video helps you understand FM radio. This video is the result of your question about FM. And I know there are other KZreadr who are very interested in FM circuits. Thanks for your question and it is neat to make another friend in Brazil. Rick

Thanks for another great video

My oscilloscope has an impedance of about 10megs. So if a circuit is also 10megs, the scope will drain half the power from the circuit. If the circuit under test is 100megs, then the scope will pull it down about ten times more.

@joernone Thanks John, It would be better to use a tube tracer. This solid state tracer seems to be design will, but I would want to use it on big power transformer radio. Regards, Rick

Thank you. After taking it apart, the vol pot is not really accessible .i am now thinking of building an FM transmitter to hook the microphone up and transmit through that.

Rick, Thanks. This was a really good vid...opening my troubleshooting eyes even wider. And as usual, your use of instructional aids was superb. Wish I could do even half that well. Your signal tracer is solid state. Aren't you afraid it'll be fried? How much voltage can it take? Regards. John

Thanks Mephysto65 In the RF circuit of the tracer is a diode. I did a video on it. I'll copy this and send you a message with the video.

I have a different question for you. I have a Aiwa CSD-MR1 that I would like to hook a microphone to so I can play through the amp circuit. Do you have any suggestions on where I can connect the mic input?

Your microphone would have have a fairly high output. You could try connecting a microphone across the volume control, but it doesn't look like your radio has a pre-amplifier.

Interesting video, but there is one thing I don't understand. How is it possible for measuring instruments (like an oscilloscope) to short out the signal? The inputs of scopes are high impedence, so that they should not interfer with the circuit under test. How can e.g. a 1 MOhm input impedence short out anything at all? Also, I noticed the scope didn't short out the signal anymore after the demodulation stage. How come? Thanks for all your videos.

Another big chapter in radio repairing. Could you tell me something about your signal tracer? I understood there are two modes: rf and af; is it correct? Wich is the differece inside its circuitry?

hi rick, i have a question that is not related to this video. i have to replace some capacitors on an amplifier but the amp was made in sweden and uses roe brand capacitors that i think were made in germany. these capacitors are not labeled like normal capacitors. one says 10/63 another says 22/63 and the last says 47/63. does this mean 10mf/63volts etc? they don't look big enough to handle 63volts so i am kind of guessing it means 6.3v maybe . please explain these numbers to me, thanks.

Thanks GeoN0JRJ

Thanks CameramanLink AA5 and FM was invented by the same guy, Edwin Howard Armstrong. You know about AM. FM demodulation relies on frequency shift off center of the 10.7, the intermediate frequency. It is the LEVEL of the frequency shift from center that is rectified producing the audio. Interesting isn't.

Thank 5tony

Thanks wolfhawg

Thanks 1fornone

I'm curious about how your oscilloscope was connected to perform the checks, do you have a video on the set-up?

@AllAmericanFiveRadio

7 жыл бұрын

The radio that is under test is always on my isolation transformer. The oscilloscope ground and the radio ground are connected together. The points that I tested in this radio are marked with a red arrow and on the wiring diagram you can see the pin number and tube number. In the video is a page of how to count the pins on several tube socket types. This information is also in my free e-book, here is a link to the download page. www.richardmcwhorter.com/vacuumtuberadio/

Hello Jim please excuse what could be a silly question as I have no experience with broadcast receivers and specifications. What do you use a a typical input setup for your RF signal generator. I would typical use 3khz deviation for the narrow band equipment I normal play with. But I see most FM broadcaster receiver specify 1khz mod with 75khz deviation. Have I got this right as my signal generator won’t exceed 20khz deviation but it’s really designed for mobile radio repair Marconi 2955. Is the deviation setting real 75khz. Many thanks regards Chris

@AllAmericanFiveRadio

5 жыл бұрын

What is the model radio you are working on.

@allthegearnoidea6752

5 жыл бұрын

AllAmericanFiveRadio hello Jim I don’t have the radio in front of me now but it’s a 1980s kenwood tuner, AM FM stereo. I’m not actually working on the radio as such it’s just that it is the only receiver I have that has a 75 ohm input. I noticed it was picking up my test tone 1khz 100mhz at less than 1uv but sound very scratchy, increasing the signal level did not help. I think the problem could be the deviation of my test set as it only goes upto 20khz. So I’m really just after some typical deviation and input levels you would typically feed into a stereo tuner etc with your test gear. I can find the tuner info later but it’s not really a question specific to the tuner. I think the problem is probably with my signal generator in that it’s not designed for stereo or the deviation level etc. I will find a link to my previous tuner video. Many thanks Regards Chris

@allthegearnoidea6752

5 жыл бұрын

KR-2600 kzread.info/dash/bejne/kX2C2MShfKq9grg.html

Thanks laredostan

Thank you for this This may be a bit of a dumb question but what is the difference or advantage between having an oscillator tank circuit or an oscillator vacuum tube Thanks

@AllAmericanFiveRadio

Жыл бұрын

The tank circuit is the resonant frequency part of the circuit. The vacuum tube supplies enough enery to the tank circuit to keep the entire circuit oscillating. Positive feedback. The Oscillator Mixer kzread.info/dash/bejne/lm1q2NmaoqvJo8o.html

@alexinnewwest1860

Жыл бұрын

Ah ok thank you. I think what confused me is that perhaps some radios. (Maybe older ones) will have 2 separate tubes for this. One for the oscillator and one for the mixing where some radios will have it on in one tube?

@AllAmericanFiveRadio

Жыл бұрын

@@alexinnewwest1860 The higher end radios and military radios usually have a separate oscillator tube. Making the radio more accurate and stable, but more expensive.

@alexinnewwest1860

Жыл бұрын

Ah thank you for clearing that up for me. Makes total sense :-)

Hey, Rick You know I dig your videos, and always learn new stuff. But really, I've got to say, I just want to go through all your stuff and rifle through your parts and junk drawers. Is it ok to say that? Oh well, I already said it! And... I need to find an old O scope that's going for $5.00. Not asking for much am I?!

Does having a negative voltage on the grid clearly prove that the oscillator is running? What if a Schematic calls for 7 V negative but you have 4 V negative what was that suggest?

@AllAmericanFiveRadio

5 жыл бұрын

For FM I would use an Oscilloscope to determine if the FM oscillator is working.

@fredfabris7187

5 жыл бұрын

AllAmericanFiveRadio In your video you mentioned that checking at the oscillator tube is often impossible. So would you suggest checking it farther down the chain? That seems fine but if one of the I F stages are inop it would be inconclusive right?

very useful video. One Q, is your oscilloscope isolated from the mains?? thanks

@AllAmericanFiveRadio

6 жыл бұрын

The Chassis is isolated The Vacuum Tube Shortwave Radio -- Free Ebook www.richardmcwhorter.com/vacuumtuberadio/

Hello sir I'm Mohammed from India I need philips prestige 556 transistor radio service manual pls help me sir tq

@AllAmericanFiveRadio

3 жыл бұрын

I'll be glad to help if I can. Contact me at allamericanfiveradio@yahoo.com

Thanks laredostan