Re: New K3 User and New Ham

Posted by N5GE on Jan 05, 2010; 2:49am
URL: http://elecraft.85.s1.nabble.com/New-K3-User-and-New-Ham-tp4253024p4253287.html

On Mon, 4 Jan 2010 17:19:39 -0800 (PST), KC2VNI <[hidden email]>
wrote:

Howdy Steve,

>
>Folks: I am a new ham. I just purchased a K3 100W radio with an auto-tuner.
>Several basic questions:
>
>1) Wire antennas- Do you guys have suggestions for a multi-band wire antenna
>pre-made by someone like MFJ or similar that I could hang in a tree?
>

You can save 70 to 90% of what you would pay for a ready made antenna
by building your own.  We are going to build a 40m dipole or inverted
vee:

1. Go to Lowe's or Home Depot and buy some of the yellow egg shaped
electric fence insulators, about 75 or 80 feet of #14 insulated
stranded copper wire and a package of 3/16 inch nylon rope.  Also get
a 3 inch piece of 1/2 inch PVC pipe.

2. When you get home, drill a 3/16 inch hole about 1/4 inch from each
end of the PVC pipe.  This is you center insulator.

3. Use one of the following formulas based on the mode you want to
use: 468 / 7.035 for the CW and Data end of the band (66.5 feet) , or
468 / 7.170 (65.3 feet) for the SSB end of the band.  Add 2 feet to
either of the calculations for tying to the insulators and trimming
and cur the wire exactly in half.  Strip 1/2 inch of the insulation
off of one end of each of these wires.

4. Pass the stripped ends of the two wires through the holes you
drilled in the PVC pipe.  Tie the wires to the center insulator
leaving the bare copper of each wire hanging from the insulator about
an inch. It's OK the have 1/2 inch or so of the insulated part of the
wire protruding from the exit side of the insulator.

5. If you already have some 50 ohm coax, strip the outer insulation
off of one end of the coax.  You are going to solder the braid of the
coax to one of the wires and the center of the coax to the other.

6. Put a yellow insulator on each empty end of each wire.

7. If you have two trees far enough apart to support the antenna hang
it up as a dipole by hanging it from each tree with a rope passed
through each end insulator.

8.  If you have only one tree or post, then support the antenna from
the center insulator by hanging a rope over a limb of the tree or some
other support.  Tie the other two ends to the fence on each side of
the yard or in some other manner.  Try to keep the angle at the apex
of the Vee between 90 and 120 degrees if you can.

To add another band just make another two wires cut to the right
length and solder the stripped ends of those wires to the same points
at the center insulator.  It is easier to do this with an inverted vee
than a dipole, but the idea is the same.  No switches needed, no coils
needed the wires that are cut for the band you are transmitting on
will radiate the others won't.

You now have an antenna that will get you on the air while you
investigate other wire antennas you might want to make.

I didn't go into how you trim the antenna to get it to perfect
resonance, but if you have the tuner in the K3 you will be able to
match the antenna without any trouble.

Building and testing wire antennas is one of the most fun parts of
hobby.  If you enjoyed building the first one and want to learn more
about antennas of all kinds you can order the ARRL Antenna Book from
Elecraft or just about any place that sells books.

73,

Tom, N5GE

[hidden email]
K3 #806 with SUB RX, K3 #1055, PR6,
XV144, XV432, KRC2,
W1, 2 W2's and other small kits

1 K144XV on order

http://www.n5ge.com
http://www.swotrc.net

 

 

>2) Battery based power: From speaking with the fellow from customer support
>from elecraft, a 100 Amp-Hr battery is what is required to operate at 100W.
>What type of battery do I use? Is sealed-lead acid acceptable? What size
>fuses do I want on the line running from the radio to the battery?
>
>I recognize that this radio has orders of magnitude of capability that I
>don't understand yet. I also recognize that reading the manual will be of a
>help here. If you have further resources and/or suggestions, please advise.
>
>73,
>
>KC2VNI.

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