On Tue, 15 Sep 1998 20:48:36 -0400, "w8ji.tom" <w8ji.tom@MCIONE.com>
wrote:
>
>Hi Tom,
>
>> I want to make a linear loaded inverted L for 160. The vertical part
>> would be 65 feet long, and the linear loaded part would be 30 feet. I
>> want to hook one side of the stub to the top of the vertical wire, and
>> then short the other end of the stub. Would 300 ohm ribbon be too
>> narrow for the stub, or would I have to make some kind of open wire stub
>> for the linear loaded portion.
>
>Linear loading never seems to work as well as models indicate. That would
>especially be true with twinlead as the loading stub. I'd opt for a good
>hi-Q loading coil and maybe a multiwire top hat.
>
>In any event, 30 feet of twinlead hung out on the end as a shorted stub sho
>nuf won't act like 60 feet of wire, you'll be lucky if it acts like 65 feet
I agree, model it and it becomes clear.
An oft used variant of the inverted L is to let the far end of the
flat top drop down, as in up 67, over 37, down 30, becoming an
inverted "J". This keeps one from the losses of a base loading coil.
Adjust the length of the 30' down part to get resonance. There is some
interaction between the two vertical pieces which makes simple
arithmetic not work so good for lengths.
Again, modelling it will get it close before going after it with the
snips.
>
>73 Tom
73 y'all. Guy.
Guy L. Olinger
k2av@qsl.net
Apex, NC, USA
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|