On Thu, 8 Apr 1999 15:07:27 -0400 "Tom Rauch" <w8ji@contesting.com>
writes:
>> How incorrect? My handy dandy hand held Wavetek LCR meter cant even
>read
>> that low when I just tried to measure a few minutes ago. The
>insulator is
>> a standard 502 with 1/4" guy grips. Should I drag the HP-4271B
>outside or
>> is the actual C too low to be of any concern except to stimulate
>> discussion on the reflector?
>
>I'd toss that Wavetek over on the audio bench. Maybe that is the
>same meter you used to determine the inductive metal film
>resistors Mouser has are non-inductive?
NO, I think I used some junk from MFJ for that old test. The Wavetek is a
recent addition that works well.
When I want to do serious measurements I get hung up on HP.
>
>The measured capacitance of a 502 insulator with the strand-loops
>only (grip cut off at the point where it starts to lock) is 12 pF.
My measurements today say you are off by a factor of 10 at least. Are you
using a Wavetek, MFJ or a real instrument?
So I can duplicate please detail what you are doing.
>> I would also expect the loss of galvanized steel guy wire to have
>an
>> increasing absorbtion effect as frequency increases. Has that been
>> factored into the modeling programs?
>
>Resistance wouldn't be a problem, as long as the line isn't
>resonant or electrically long compared to the operating frequency.
>
>Unfortunately, that isn't the case. Resistance might be a factor, de-
>Q'ing the lines and making them broadband absorbers.
Hmmm, all I I got out of that was doublespeak.
>
>Why do you think AM BC stations break up lines every 50 feet or
>so on the AM band? Because of insulator capacitance, something
>totally overlooked in the "non-resonant length" tables we vainly
>follow.
Gee Whiz. After all these years Johnny Ball capacitance is important?
Why didnt the "experts" mention this years ago?
IMO...HOG WASH.
73 Carl KM1H
>
>
>73, Tom W8JI
>w8ji@contesting.com
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