开云体育In a message dated 12/6/2005 7:11:12 AM Central Standard Time,
pewomail@... writes:
?
>I'm new to ham radio and plan to buy some equipment soon (Xmax's
>comming up ;-) ?
I have the FT-857D and the FC-40, no experience with the Buddipole.
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>FC-40, I'm wondering if I can use it to fine-tune a dipole
antenna.
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The FC-40 will work with random wires, dipoles, loops and other
configurations of wire antennas, BUT there is probably no single wire length
that will allow operation on ALL bands.? There is no "free lunch" involved
-- shorter antennas WILL be much less efficient radiators (and receivers) on the
80 and 160 meter bands, even with a perfect "match" by the FC-40.
?
As I understand the Buddipole, (from reading only) one is able to change
coils to change bands, and match to different frequencies within the band by
means of movable taps on the coil.? How far "out of (coil) band" one might
be able to venture with the FC-40 is something you might want to email the
Buddipole folks about.?
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>I gather there is a difference between balanced and un-balanced
>antennas; let me see if I get this straight: since solid-state >transceivers feature unbalanced final stages, it is desireable to >insert a balun between the radio and the dipole, which is a balanced >antenna (I guess this is to avoid currents on the outer side of the >coax cable). The FC-40's output is geared towards wire antennas and is >probably un-balanced, right!? ?
The Coax feed from the FT-857-D is unbananced into the FC-40.? The
FC-40 is expecting to feed a balanced antenna -- one side hot, one to
ground/counterpoise.? In the (in my experience) LIKELY event that you are
experienceing RF on the coax, line isolaters (see radioworks.com or others -- no
I don't work for them) will eliminate that problem.? Some snap-on ferrites
can be used on the supplied 16-foot control cable between the CAT port of the
FT-857D and the FC-40 to preculde RF pickup on the control line.
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The FC-40, and the similar-function products by SGC,?are more
properly termed "antenna couplers" and are located?at or very
near?(fewer inches are better) the antenna feed point.
?
Some other products, more properly called "tuners" sit at/near the
operating position and may not require a CAT connetion.? Additionally, some
feed out with coax.
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Yaesu sends one 16' control cable that must be connected between the CAT
ports on the radio and the FC-40 (extensions of 16' length are about $35US from
Yaesu).? OK for mobile installations, but for fixed use one will probably
need more control cable length (remember to use ferrites to avoid RF
pickup).? With the FC-40 plugged into the CAT port?of the FT-857D,
there is no provision for using?a?computer to control the
transciver.?
Hope this helps with your decision.
?
73.
Gary
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