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Download the S9v 31' Installation Guide
The S9v 31' is a tough, yet ultra-lightweight vertical designed for Amateur Radio use from 40
through 6 meters. Optional 80 Meter coverage is also available.
The S9v 31' is constructed of rugged tapered fiberglass, weighs just 4 pounds and is double
insulated for the safety of your family and neighbors. Be sure to check-out our matching
radial plate and portable mount for the S9v 31'. The S9v 31' is also available in kit form!
The S9v 31' can be mounted on the ground or on your roof.
- Permanent ground-mount installations require a 40-inch long, 1-1/4” (1-5/8” OD
MAXIMUM) galvanized steel pipe. The S9v 31' base tube simply slips over the pipe for a
simple and elegant deployment. (A mechanical connection from the antenna base tube
to the pipe is neither required nor desired.) The optional S9v 31' pipe mount clamp,
shown below, lets you raise the S9v 31' base off of the ground.
S9v 31' Pipe Mount Clamp
- For portable operations and DXpeditions, use the optional Portable Mount, shown
below. The Portable Mount is a heavy-duty mount with an integral stake that makes
mounting the S9v 31' in permanent or temporary field locations a fast and easy process.
S9v 31' Portable Mount
- Because the S9v 31' is so light, you can roof-mount the antenna using a simple 3' tripod
normally used for TV antennas. In this configuration, the S9v 31' functions as a ground
plane (GP) antenna and only 4 radials, each ¼ wavelength at 7 MHz (33 feet, 5 inches
long) are required.
When used with a god RF ground, the S9v 31' is a serious 40 meter DX antenna. The natural
resonant frequency of the antenna is just above the top of the 40 meter band - around 7.4 Mhz
and it is extremely broad banded. Depending on your ground system and proximity to nearby
objects, the S9v 31' may exhibit an SWR well below 2:1 in the upper, SSB portion of the 40
meter band without an antenna tuner.
So, if you primarily operate SSB on 40, you may be able to use the S9v 31' on 40 meters
without an antenna tuner. In this configuration, the coax feed line can be directly connected to
the antenna. Radials and a 1:1 current choke balun are recommended. There are several
commercially-available 1:1 choke baluns available (Balun Designs being one of the best) or
you can create a simple choke balun using your coax feed line.
If you want to use the S9v 31' over the entire 40 meter band without an antenna tuner,
consider our optional 40 meter monoband conversion kit.
Internal rig tuners will easily tune the S9v 31' anywhere on 40 meters. But if you want to use
the S9v 31' as a multi-band antenna, you will need a quality antenna tuner in your shack or
remotely located at the antenna feed point. (Internal rig tuners do not have adequate range to
match the higher impedances presented by the antenna on bands above 40 meters.)
For multi-band use, we recommend the LDG Electronics series of auto tuners. LDG tuners
easily handle the wide-range of impedances presented by the S9v 31' over the higher HF
frequencies.
For multi-band use, a 4:1 unun is recommended at the antenna feedpoint for coax runs over
50 feet long. A 4:1 unun lowers the higher impedances presented by the antenna on
frequencies above 40 meters. Balun Designs manufactures two 4:1 ununs specifically for the
S9v. You have two choices, depending on the amount of power you expect to run with the S9v:
If you are using a quality antenna tuner and have a coax run under 50 feet, a 1:1 current
choke balun from Balun Designs will suffice.
Finally, In lieu of an antenna tuner in your shack, you can use a weatherproofed, remote
antenna tuner at the S9v 31' feed point for absolute lowest loss and best over-all multi-band
performance. There are several remote antenna tuners on the market. Some of these remote
tuners include u-bolts allowing them to be mounted directly onto the antenna base tube. When
a remote tuner is used at the antenna feedpoint, a 4:1 unun is not required. However, a 1:1
current choke balun may be needed between the tuner and your transmitter if you experience
RF current in your shack. (Burying your coax cable also helps minimize RF current from
flowing back into your shack.)
For optimum performance, a ground-mounted S9v 31' should be used with at least 16 radials
(32 preferred), with each radial at least 26 feet, 9 inches long (0.2 wavelength at 7 MHz).
Actually, there is no precise formula to calculate ground-mounted radial length because
everyone has different soil and soil tends to change the electrical length of the radials.
However, a general rule of thumb for radials is: “longer” and “more” is better. If you have the
time and resources, 32 or more radials each at least 26 feet, 9 inches in length (or longer)
should be considered to ensure top performance. It is highly recommend that you use the
optional S9 Radial Plate (or, our PRO Plate) to connect and organize your ground radials.
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- Our Best Seller - Fully
Assembled - Kit Available for $74.95
- Tapered Telescoping
Fiberglass with Stainless
Steel Set Screws - Self-Supporting - No Guys
- No Expensive Mount to Buy
- No Lossy Traps or Coils
- Ultra-Light and Super-Slim;
Weighs 4 lbs - Perfect for Home or Portable
Use - Deploys in 15 Minutes or Less
- Collapses to 45"
- Unique Double Insulated
Design - Safe for Children
and Pets - No Corrosion; Weather-Proof
- No Hose Clamps or Messy
Joint Chemicals - "Neighbor-Friendly" Forest
S9v 31' Multiband Vertical
for 40 - 6 Meters
for 40 - 6 Meters
(Click for full-size image)
