V-Quad better know as Delta antenna, swr procedure. These are 14 db gain horizontal beam antennas. They can be configured to do both horizontal and vertical simultaneously, but 4 db gain is lost. Start with obtaining the lowest swr by adjusting the capacitor, sliding it in and out. Second adjust the slider arm mount. Start 4" from the end and fine adjust. The object here is to obtain the lowest swr within the band. Do not get worry about what specific frequency you have obtained the lowest swr on.
If you want the resonant frequency to be higher in the band, shorten all three drive elements. Starting in half inch increments. Do the inverse to go lower in the band, lengthen the elements. It should be noted that being behind the drive element and in from of the reflector has zero effect on swr. I stood on a aluminium ladder in the middle of the antenna while adjusting swr with zero effects. The attached pictures show shifting the lowest swr up in frequency.