The S9 V31 31' NOS uses supplied stainless screws for assembly instead of the polymer rings. A few extra minutes of assembly time saves you money over the standard version.
PLEASE NOTE: This model is NOT compatible with the ring hardware supplied with the standard S9V31. Using the polymer rings in the assembly of this antenna will result in damage to the antenna and void any warranty.
The S9v 31' Mk II is a tough, yet ultra-lightweight vertical designed for Amateur Radio use from 40 through 6 meters.
The antenna is constructed of rugged tapered fiberglass, weighs just 4 pounds and is double insulated for the safety of your family and neighbors.
The S9v 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 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.)
Because the S9v is so light, you can roof-mount the antenna using a simple 3' tripod normally used for TV antennas. In this configuration, the S9v functions as a ground plane (GP) antenna and four, ¼ wavelength radials are required for each band of operation.
When used with a good RF ground, the S9v 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 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 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.
Internal rig tuners will easily tune the S9v anywhere on 40 meters. But if you want to use the S9v 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 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:
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 Plateto connect and organize your ground radials.
As with all S9 antennas you will receive your choice of a free Unun or Balun from LDG. A rebate form with instructions is included with each antenna.