Electronic component identification help please

[Danzik]

Hello, I was wondering if you guys could help me identify these components and or inform me on what type they are ? Resistor, diode, and capacitor perhaps ? But not sure of their types, values or what to call them to order or find them. Thanks

 

[144inBama]

Is this a keying circuit?

 

[Danzik]

Is this a keying circuit?

No sir, they go from ground to a pill transformer corner

 

[144inBama]

I believe they are tuning caps.

 

[brandon7861]

Thats what I thought too, especially given the location. Looks like a 100nF, a 10nF and a 2.7nF.

Edit: I changed the values in my response. When I looked at the pictures, somehow I had 103, 102 and 272 in mind, but SuperLid's post made me realize the error.

 

[AudioShockwav]

Looks like a XForce Amp.
Epoxy dipped caps.

73
Jeff

 

[Danzik]

I had one set of them burn up along with a pill that I have already replaced, it is a XFORCE

 

[Danzik]

Anyone have a recommendation on what ones I should replace the capacitors with, would one cap be sufficient or not ? These are mostly just for filtering out noise arnt they ? Thank you guys for the help

 

[SuperLid]

272 = 2700pF, 103 = .01uF, 104 = .1uF the look like monolithic ceramics, probably high voltage, like 500v or more.

 

[brandon7861]

Anyone have a recommendation on what ones I should replace the capacitors with, would one cap be sufficient or not ? These are mostly just for filtering out noise arnt they ? Thank you guys for the help

Read my edit in post 5. Sorry for the mixup, SuperLid got it right..

 

[Danzik]

Thanks fellas, I appreciate it !

 

[nomadradio]

They are connected from the 12-Volt (?) power to ground, at the center-tap point of each push-pull output transformer. Textbook name for this would be "decoupling", or just "bypassing" capacitors. They keep the RF from leaking upstream into the power supply.

This is a strategy to filter harmonic frequencies as well as the 27 MHz RF energy. Putting three capacitors in parallel with widely different capacitance ratings becomes a wider-band RF filter than a single capacitor can deliver.

The larger capacitance values become less effective above 27 MHz. The smaller value caps are more effective for harmonic frequencies 54, 81, 108 MHz and up.

If they get hot and burn up, a larger component is called for. It's all about the capacitor's resistance. Bigger cap has more metal in it. More metal means lower resistance. Easiest way to do this with ceramic capacitors is a higher voltage rating. Naturally, a 12-Volt circuit doesn't "need" a 1000 or 2000 Volt cap. But those parts will be physically larger. Larger means more metal. More metal means lower resistance.

73

 

[Danzik]

They are connected from the 12-Volt (?) power to ground, at the center-tap point of each push-pull output transformer. Textbook name for this would be "decoupling", or just "bypassing" capacitors. They keep the RF from leaking upstream into the power supply.

This is a strategy to filter harmonic frequencies as well as the 27 MHz RF energy. Putting three capacitors in parallel with widely different capacitance ratings becomes a wider-band RF filter than a single capacitor can deliver.

The larger capacitance values become less effective above 27 MHz. The smaller value caps are more effective for harmonic frequencies 54, 81, 108 MHz and up.

If they get hot and burn up, a larger component is called for. It's all about the capacitor's resistance. Bigger cap has more metal in it. More metal means lower resistance. Easiest way to do this with ceramic capacitors is a higher voltage rating. Naturally, a 12-Volt circuit doesn't "need" a 1000 or 2000 Volt cap. But those parts will be physically larger. Larger means more metal. More metal means lower resistance.

Thank you for the explanation of this Nomadradio, that described that perfectly! This whole situation began when a 2879 transistor went south, along with the 10 ohm resistor of coarse, and apparently took these caps out right along with it .