[Elecraft] Paddling Up River?

[Ron D'Eau Claire]

Don gave you excellent advice. 

Keep in mind that you can "hear" with a mis-matched antenna far better than
you can transmit. Indeed, a random length of wire stuck in the antenna jack
will make an good receive antenna as long as the antenna isn't close to
sources of RF noise (like computers and other electric/electronic stuff we
have in our homes these days

Attic antennas aren't as good as an outdoor antenna, but I've used them
running QRP at two QTHs with satisfying results. Mine were in an attic above
the second floor - 66 feet long and fed at the center with "open wire line"
made up from two small white hookup wires that came down through two small
holes in the ceiling about 2" apart right above the wall and my operating
desk, and were stapled directly to the drywall down to the tuner. They were
virtually invisible unless they were pointed out. 

At one QTH where the roof and siding were wood it worked great, but at the
second it was rather mediocre by comparison, although I still worked all
over the USA on 40/30/20 meters and plenty of short skip on 80.

I finally traced it to the concrete tile roofing material. Found a chunk and
put it in my microwave and it got smoking hot in a minute (alongside a glass
of water to protect the Maggie). That was a strong indication it was not
very "transparent" at RF, and the attenuation likely went up with the
frequency. 

But, in any case, getting RF to the radiating wire efficiently is paramount.
That's why Don asked about your feed point. A 1/2 wave antenna (66 feet on
40 meters) will offer a pretty good match to 50 ohm line and even a workable
match on 15 meters but on any other band it'll show a very high SWR that
will cost you much of your RF before it even gets to the radiator. Open wire
line, having a higher impedance (typically a few hundred ohms) will show a
much lower SWR and so much lower losses. You can use a balun at the rig or
simply connect one side to the center pin on the coax connector and the
other side of the feeder to the ground lug on the rig. If the rig seems
'hot' with RF (tuning changes when you touch the rig, etc.) a balun will
offer more isolation.

If you opt for traps, you'll need to adjust things for lowest SWR on the
feeder on each band. It's fussier to set up and you're limited only to those
bands where the antenna shows a low SWR, but it allows you to use coaxial
line efficiently. 

If you're in a single story building, you'll find low band operation is not
as good because the antenna isn't high enough. But even at 15 feet above the
ground, you'll put out a fairly good short-skip signal (your main lobe will
be straight up). 

In almost any environment you'll make contacts with an attic antenna. Then
it's a matter of thinking about how to make it better. If you need to bend
the antenna to fit the attic, put the bends out near the ends, keeping the
center section as straight as possible.

It doesn't matter whether your antenna is indoors or outdoors: every Ham who
tinkers with antennas wonders what might be changed to make it better,
whether it's a simple wire or huge beam on top of a 90 foot tower. 

Ron AC7AC



-----Original Message-----


Looking for some advice. I am a new ham running a K3/10 with 66 feet
of stranded copper in the attic using RG213 as a feedline. Using
Fldigi, I hear and de-code CW, PSK, Olivia and Hell very well and from
all over the world. When I call CQ I see it on the waterfall, hear
sidetone and see 4 ALC bars on the K3.............but never an answer.
Is it because I am using 5 watts from an attic location or maybe
antenna problems? I don't believe it is the DATA A issue since I
downloaded the most recent version of the K3 software. Any ideas?
Thanks.

-- 
Frank KD8FIP
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