Thank you Jim!!!!
de ns9i
On 2/1/2011 10:05 PM, Jim Brown wrote:
> On 2/1/2011 1:57 PM, DGB wrote:
>> And is it acceptable to enclose them in a non-conductive enclosure Jim,
>> even at high power (1500w)? We can get ice 3" thick sometimes!
> It depends entirely on the degree of imbalance in the antenna, and to
> some extent on the electrical length of the transmission line. Greatest
> stress is placed on a straight through choke when there is significant
> imbalance. The strongest cause of imbalance is feeding the antenna far
> off center. An antenna with fairly good balance (for example, where the
> only imbalance is non-symmetrical proximity to earth or to surrounding
> conductive objects would not cause much dissipation in the choke, even
> at high power. On the other hand, running high power into a strongly
> unbalanced antenna (like a Windom) would likely put enough common
> voltage across the choke to fry it, and putting it in an enclosure would
> make it more likely to happen, and to happen at lower TX power, because
> it inhibits heat transfer.
>
> I agree with Jim Lux -- the primary concern is dissipation.
>
> 73, Jim K9YC
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