Topband: 160 Shunt-Fed Tower Readings

[Larry K4AB]

>I would like to know how you can get 15893pf from a 1000pf capacitor.  That
>has to be a mis-read value there...gary  maybe rounded off to 159pf??

That's a great question.  Where is the analyzer actually getting that reading?

73,
Larry K4AB


On 12/10/14, Tom W8JI <w8ji at w8ji.com> wrote:
>> I'm concerned about a few things:
>>
>> 1) I'm thinking the antenna is electrically too short.  After all, the
>> Yagi at the top really isn't adding too much top loading.  And I'm
>> thinking
>> adding a couple of top loading wires connected to the tower
>> might be beneficial.
>
> If you run any power, you will likely start to have problems with arcing at
>
> the Yagi antenna elements where they cross the boom.
>
> This is because of the poor insulation, and because of the high voltage at
> the boom when on 160.
>
> The cure for that is to ground the elements to the boom though  air coil
> inductors. Just five or ten uH would work OK, and not upset the antenna
> operation. This would also add 160 top loading.
>
>
>> 2) What exactly is the analyzer telling me when it says C:15893pF?
>> I'm far from an engineer, but something tells me that's way high.  Or is
>> it?
>
> It is meaningless. It just means you are measuring almost where the antenna
>
> is resonant.
>
> 73 Tom
>
>