longwire for portable?
 

Hiya,

I have an MFJ 9040 and want to make it totally portable. No tuner, etc. I
am thinking about a longwire cut to frequency but how do I connect it?
Won't I need to use some feedline? If so, how do I connect it to 20-22gg
wire? I need to make this as cheaply as possible. Interested in just
throwing the antenna up or down a balcony etc.


Thks
greg

"G. Doughty" wrote
I have an MFJ 9040 and want to make it totally portable. No tuner, etc.
I
am thinking about a longwire cut to frequency but how do I connect it?
Won't I need to use some feedline? If so, how do I connect it to 20-22gg
wire? I need to make this as cheaply as possible. Interested in just
throwing the antenna up or down a balcony etc.

=============================

You forgot to say what an MFJ 9040 is. I've never heard of it. Does
everybody except me always have one?

But you have no problems.

Just throw some wire over the balcony or out of the bedroom window, cut to a
length of about 1/4 or 3/4-wavelengths at the frequency you intend to use it
at, and plug the near end of it into the coaxial output socket of the
transmitter.

At least as important is the ground connection. For that use large aligator
clips at the ends of shortish lengths of 18-gauge, plastic-insulated,
flexible, multi-strand wire and connect to the domestic plumbing system.
Hot or cold water or central heating pipes, or preferably several of them,
will do fine.

To save yourself the inconvenience of withdrawing the antenna to prune it,
make the antenna wire length a little longer than 1/4 or 3/4-wavelengths and
connect it in series with a 300 pF variable capacitor.

Don't worry about the SWR if the transmitter doesn't mind.
----
Reg, G4FGQ

On Sat, 8 Jan 2005 11:32:58 -0500, "G. Doughty"
wrote:

I have an MFJ 9040 and want to make it totally portable. No tuner, etc. I
am thinking about a longwire cut to frequency but how do I connect it?
Won't I need to use some feedline? If so, how do I connect it to 20-22gg
wire? I need to make this as cheaply as possible. Interested in just
throwing the antenna up or down a balcony etc.

Hi Greg,

Both your description above AND the manual scream "use a tuner."

A "tuned" antenna is only tuned to its environment, and unless you
take that environment with you on the road, that antenna is NOT going
to be tuned. However, there is much to be said for sloppy
installations being so lossy as to match every time. A low dipole
often so qualifies. However, a longwire cut to frequency (something
of a contradiction in terms, by the way) would then depend on the
ground path attached to your MFJ. If you are thinking of cut to
frequency in the sense of a halfwave, then you are driving a severe
mismatch (which that manual also screams may lead to spurs).

Get the drift?

73's
Richard Clark, KB7QHC