So, many of the plate chokes I have seen described in home brew
amplifiers and those in use in Ameritron, Henry, Alpha and QRO are
single layer wound solenoids, many like the one I built. These do not
exhibit resonant peaks (High Z) in the ham bands as far as I can tell
based on my limited experience. I am very confused by the assertions
that I need to build something materially different than these examples
or face a very inefficient and perhaps flaming amplifier.
Michael Tope wrote:
>----- Original Message -----
>From: "Jim Forsyth" <jim@forsyth.net>
>
>
>
>>This mini thread is about a case where the resistance of the inductor WAS
>>significant and possibly DID affect the resonant frequency appreciably.
>>
>>Jim, AF6O
>>
>>
>>
>>>At the risk of sticking my foot in my mouth again, R generally
>>>doesn't effect the resonant frequency of an RLC circuit appreciably
>>>provided that the Q is reasonably high. On the other hand, a plate
>>>choke when you look at it very closely is really a distributed RLC
>>>circuit, so one has to be careful about applying simplified 3 component
>>>lumped element models. I'd love to see a rigorous analytical treatment
>>>of this if anyone knows of a good reference.
>>>
>>>73 de Mike, W4EF........................................
>>>
>>>
>
>Yes, I understand that, Jim, but I was having a hard time believing that
>you could get away with deQing a choke enough to shift the resonant
>frequency significantly without turning it into a fireworks display. I did
>some google searching and there seems to be little in the way of
>analytical information on plate choke design. Mostly it seems to be
>an empirical art (e.g. use X # of turns closewound on a D diameter
>form kind of thing). My best guess of the equivalent circuit would be
>a bunch parallel RLCs in series, but even that I suspect is oversimplified.
>The fact that it has multiple staggered parallel and series resonances,
>for instance, can't be explained by a simple 3 component lumped RLC
>model.
>
>73 de Mike, W4EF..............................................
>
>
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