[Amps] grid resonance

[Will Matney]

On 8/7/06 at 1:43 PM Ian White GM3SEK wrote:

>Phil Clements wrote:
>>
>>> But that resonance belongs to the whole circuit, involving the anode and
>>> cathode and all their associated components. There are too many unknowns
>>> in that loop to understand what the frequency of the observed dip might
>>> be telling us about reverse feed-through from the anode back to the
>>> cathode.
>>
>>Ian,
>>Are you saying that a GDO can only dip a "circuit?"
>
>I'm saying you can't even have an L-C resonance without a circuit - 
>literally a closed, hard-wired loop.
>
>For example, if you simply connect an L and a C in series, with opposite 
>ends floating, you don't have a closed loop so you don't have a resonant 
>circuit yet.  Before you can see a resonance and a dip, you must make 
>some other connection that closes the loop and completes the circuit.
>
>But the resonance then belongs to the entire circuit you have made - not 
>just the obvious inductor and capacitor, but also all the strays that 
>you don't know about.
>
>That requirement for a hard-wired circuit only begins to break down if 
>components are physically large enough to have significant 
>electromagnetic interactions between different parts of themselves - 
>antennas being the obvious example, and large anode chokes being 
>another.


A choke doesn't have to be large to have a self-resonant frequency. That is 
caused by the chokes inductance and distributed capacitance. However, 
the choke has to be shorted out to complete a circuit in order to read it with 
a GDO. The smallest of wound chokes have these say 1 uH, etc. A GDO can 
only dip at some resonance, it's up to the user to figure it out.      


>
>
>-- 
>73 from Ian GM3SEK
>
>_______________________________________________
>Amps mailing list
>Amps at contesting.com
>http://lists.contesting.com/mailman/listinfo/amps

Best,

Will