If it is a true quarter wave, and not one that is shortened by loading coils, read on. shortened antennas are more complex, so the formula below applies only to a standard quarter wave length antenna. It also does not apply to a 5/8 wave antenna, or to a Ringo type antenna. Most of the installation notes, however will apply to them. you can get the length for a quarter wave from the equation 234 divided by the frequency. Since most of the activity on 10 meter SSB is between 28.3 and 28.5, especially during marginal conditions, and since a full size quarter wave has a fairly broad band width, I would use 28.400 as the center frequency of the antenna. This calculates to a length for the vertical radiator of 8.2 feet. That would be 8 feet, 2.4 inches. If I were doing the measuring, I would scrap the .4 inches, and just set the length at 8 feet, 2 inches. Set the length of the radials a bit longer. I would probably start with something like 8 feet, 6 inches on the radials. If you have a General or above license, but have absolutely no interest in working CW, you can use 28.500, or 28.600 and cover most of the phone band. Now, let's be sure that a few other things are in their correct places. There was a time when I didn't know some of this stuff myself. So, not knowing how much you know about antennas, and at the risk of sounding as though I'm talking down to somebody when that is *not my intention, here goes. First, disconnect the feed line from everything on both ends, and check it for shorts. If you don't have an Ohm meter, or a continuity checker that you can use to do that, find a local ham who has one, and ask for help. While the feed line is disconnected, also check for a short between the vertical element and the radials. *You do not want to find a short here. The radials themselves will be shorted together, but they *must not be shorted to the vertical radiator. This statement may not be true for some 5/8 wave models because of their matching arrangement. Once you know things are okay in the shorts department, you are ready to try again. Let's look at your installation location options. For 10 meters, I highly discourage ground mounting. Get the feed point of the antenna as high in the air as possible. About 15 to 20 feet or higher is ideal, but 5 or 10 feet will beat the heck out of ground mounting. If you are in a second floor apartment or higher, try the balcony railing. If that railing is metal, use it as all or part of the radial system. If there is a roof above your railing, simply tilt the vertical outward enough to clear the overhang. Having operated 10 meters from just such a location for a number of years during the 1990s, believe me when I say the antenna will still work very well if it is not absolutely vertical. A ground floor apartment may be a bit more challenging in the "higher the better" department, but you do the best you can with your circumstances. In this situation, try to mount the antenna on a patio fence, yard fence, etc. If you have a metal patio or parking pad cover, try to use that cover as the ground plane. In the absence of such a fence, get hold of the April, 2011 issue of QST, and read the article about the Florida ham who used tent stakes and a 5 foot mast, plus radials made from speaker cable to get on the air with a collection of Ham Stick type moble antennas. In his case, the radials also served as support cables for the mast. Keep working on it, and you will get the antenna going on 10 meters. Once you start having fun, all that work will be worth the effort. Mike Duke, K5XU American Council of Blind Radio Amateurs