[Amps] grid resonance

[Tom W8JI]

>>Parallel resonance only approaches series resonance when 
>>the
> L to C ratio is very large. <
>
> Is that a general statement or one just applying to the 
> mobile whip example? Sorry, Tom, but I don't understand: 
> can you elucidate, please?

It's a general statement.

A series resonant circuit doesn't change modes until the 
stray capacitance effectively shunting the inductor from 
end-to-end is equal to inductance. A short mobile antenna 
with a large loading coil is a good example of this.

In the series resonant mode an 80 meter mobile antenna might 
be resonant on 3.5MHz  for example. The parallel resonance 
of that coil could approach 4 or 5 MHz for a very bad 
design. In a very good design, it would be on some frequency 
well over that....as high as possible.  My best 40 meter 
mobile antenna goes into parallel resonance on 45 MHz, the 
poorest one I have at 20MHz.

The grid dip meter dips on both modes.

73 Tom