How the capacitor was a big help to me I had problems too and this solved a lot of my problems and I thank you very much it was a great

A point about the tuning capacitors in vintage equipment. As John mentioned, the rotor is electrically - and mechanically - connected to the frame. BUT the rotor's electrical signal must pass through bearings (sometimes bushings) in the rotor mount. These bearings can often corrode and/or disintegrate, causing intermittent or completely failed electrical connection. And it is equally important to note that almost all off the shelf lubricants are insulators, and if applied to the bearings during maintenance will insulate the rotor from the frame! IF you need to lubricate, you need to use an ELECTRICALLY CONDUCTIVE grease. Silver bearing. It is expensive :)

Thank you for making this video. Your description is way clearer and easier to understand than many other way I have heard the air capacitor explained.

Thanks John! That was really straightforward and simple to understand.

Thanks, I don't remember learning about tuning capacitors, how they are connected and why, but you did an amazing job making it understandable

Nicely done Mr. Richter. I’ve been playing with radio for over 50 years. I’ve been an engineer for over 30 years. Your description of a variable capacitor and explanation of its function is concise, accurate and easy to understand. Well done! Keep up the good work. Howie WA3MCK.

Thanks mate..my radio interest started in 1957 and continues. My favorite component was always the tuning condenser. 24NOV2017

Good information! Many of us hams/radio enthusiasts have beat our heads in the wall deciphering some parts of old schematics. It's also amazing how we went from say cycles (kc, mc etc..) to using Hz...many old schematics will use those mc or kc to represent Mhz or Khz. Good job, someone has to keep history of how it worked alive or those old radios will be dead.

As always, very helpful, John. Since I can't have someone by my side, videos like this are the next best thing. Cheers!

Thank you very much for the information! You have helped me so I can continue helping the planet. So thank you for your contribution of knowledge and the time you took to make the video. Its the small things like this that can really make a difference.

Thank you for making and posting this tutorial video. It was very much needed by myself, and no doubt, many others!

This video will make a huge difference in the success of my projects. Thanks,

GREAT STRONG VOICE AND VIDEO PRESENTATION AS WELL . THANK YOU SIR .

Good information, thanks for sharing John!

Per your request, you need to make a correction to your explanation of the Red and Blue capacitors. The capacitors with the dashed line between them are the main tuning. One for the RF signal from the antenna, the other for the oscillator circuit. The Red capacitors in the drawing are the trimmers.

Nicely done. Thank you.

Nice work. Exactly what I wanted to know. Thanks.

Hi, thank you for teaching me!!!

Greetings: The tuning capacitor has one section that forms half of a "resonant tank circuit" that requires an inductor that together with the tuning condenser resonates at frequencies that cover the broadcast (medium-wave) band from about 550 kilo-Hertz to about 1700 kilo-Hertz (aka 1.7 MHz). In the absence of a loop or loopstick antenna a longwire external antenna is used to collect radio broadcast carrier waves that are used with the local oscillator tank circuit to create the Intermediate Frequency (IF) in the convertor tube, also known as the mixer tube. That local oscillator tank circuit is formed by a separate inductor paired with the other portion of the ganged tuning condenser. BTW: The local oscillator portion of the tuning condenser can be of the same capacitance range as the other half or it can be lesser in capacitance while it is paired with an appropriate inductor such that the local oscillator frequency range produces a difference frequency that tracks with the frequency range of the antenna portion of the tuning condenser tank circuit in a way that always results in a difference frequency that becomes the IF frequency in the convertor tube's output. Typically the maximum capacitance of the antenna section is historically about 365 pico-farads. In the schematic shown, the loop antenna is the inductor that forms the tank circuit with the larger section of the tuning condenser. That tank circuit is tuned so that the impedance top to bottom is greatest when the frequency matches that of a broadcast station's carrier frequency. That high impedance keeps the desired carrier from draining off to ground and instead goes into grid 3 of that tube. In addition to the antenna signal, the antenna loop will later be the path for the DC AUTOMATIC LEVEL CONTROL to reach that same grid to reduce the gain of strong station signals (strong signals produce a more negative DC level that has the affect of reducing the gain of that portion of tne convertor tube as well as that of the IF tube - Hazeltine patent). The local oscillator connects to grid 1 where it gets amplified for the mixing process. The RED capacitor adjacent to the capacitor used for antenna tuning is the trimmer capacitor affixed next to the lug of the stator. The trimmer capacitor is formed by a sandwich of two plates separated by a mica dielectric. As the screw on the trimmer is turned clockwise the capacitance increases as the two plates of the trimmer are forced together. That capacitance is added to that of the larger movable section indicated by the trimmer being drawn in parallel to the larger section.

Hey John- Love the video and your explanations. When is part 2

Many thanks!

Thank you!

now we have the video!! :)

thanks man

Wonderful presentation Sir. However I have a old model 5 pin tuning capacitor. What is its pin configuration and how to connect it with the circuit, if I want to make a old model transistor set.

nice vid

Thank you sir !

A smaller gang is for the oscillator section the larger gang is for the antenna

thanks!

Mr. Richter can you give a main use of the tuning capacitor into the tuner section

Your video helped me very much. I see why now I'm getting weak signals. ? Should I use one variable capacitor that's much larger and a small 365 variable for fine tuning or do you have a better suggestions? Thanks, I hope you keep producing more info.🤔

Thanks.

I always thought that the ganged air capacitor (M1) was the ones joined with the dotted lines while the mica (trimmer) capacitors were the ones in red.

Nice video. But at 6:43, I'd expect the dotted line to connect the air capacitors, rather than the mica ones, given that the air caps are linked together. Seems that for a while, the better-made receivers still had variable air capacitors for tuning, while the cheaper ones had those mini tuning caps with plastic (mylar?) liners. I've always wondered if the air capacitors had better performance, or if they were just part of the a design that hadn't been updated. The plastic lined ones were probably more reliable, on the average.

Hey, thanks for getting back to me. I see, in a radio the capacitor IS completely isolated from the chassis. But the case, the rotor and the shaft are electrically the same point and they are collectively the opposite side of the capacitor from the antenna's input to the stator plates ... correct? And therefore, control over the shaft movement must be done through an insulator ... correct? I'm planning on using a matching pair to trim capacitance at the input to a record player's moving magnet cartridge amplifier. The standard impedance is usually right around 200pF 47K ohms. Some amps have a few steps you can choose from but the steps are entirely too large ... making those steps basically a gimmick or for some exotic cartridge. I'd like to trim by about +/- 50pF from the standard. I have about 50 cartridges to work with ... it should be educational and perhaps even find each ones sweetest spot. Whatchya think?

Cool

For a 2-gang rated 12 - 495 pF, with 2 lugs on each gang, if I connect all 4 lugs, would that make capacitance 24 - 990 pF? I wasn't aware that antenna gets hooked up to chassis lug. Thanks.

sir can you give definition on what is a tuning capacitor. i really need it for my assignment. hoping for your response. thank you

I realize when I watch these type of videos that they are very intriguing but I know nothing.

I’m a complete novice to this stuff. Still, I would like to use a tuning capacitor in a small circuit so, which is the ground and where do I connect the power/signal, is the stator the ground, and the rotor the input, or vice versa? Please let me know. I want to learn. Thank you kindly

Of signal tracing coming?

Soooo ...... the rotor (rotor plates, rotor shaft and frame .... IS the minus side .. and .. IS ground. Is this correct? And rotor plates actually make continuity (their electrical path for current to them) through those little spring washers/holders and through the associated grease. Is that right? If not, how does current get to those rotor plates reliably? That's the part I'm not understanding ..... because .. I have actually found another use for them other than a radio .... and I don't yet own a capacitance checker. And it's not as a paper weight ; ) Go ahead .. ask me what I'm gonna use it for. Cuz it absolutely blows me away that nobody else that I can find has ever used them this way.

can hook up some wires to the var. cap, to show how it's hooked up, where do the wires go on the actual capacitor

Do you know which one of the two capacitors (small or large) has high frequency, either VHF or UHF, I still request you hook up those Rotor and stator to so me wires that are color coded we we viewers can see, I appreciate your explanation but it should have green/blue/red wires to show what is going ware not just nration with the diagram of the schematic. it's hard to understand from that diagram symbol which which rotor is the big and and which rotor is small

Can the mica.cap in the tunning capacitor ever go bad

John Richter goodnight my name is Ronny Brenes of Costa Rica I want to make a homemade antenna tuner but I have capacitors as video and occupied capacitors for this application can help calculate 2 x 100 pf and 100 pf single x

That's not true the red ones are the Tremors they're stationary the one with the dotted line shows the mechanical gang of the two air capacitors

Comment in my comment pls...