A word on the antenna here; the JTB4 is a tri-band vertical covering the 6-meter, 2-meter, and 70cm bands. It is a fiberglass vertical about 9 ft. tall with two short radials and one long loaded radial (see the photo below). The antenna is mounted on a push-up pole that has been moved closer to the radios, eliminating most of the feedline run that was present with the 2-meter hamstick I was using. The push up pole slides down into a piece of 2 inch PVC pipe that was dropped into a post hole with the post hole filled with concrete around the pipe.
On Saturday afternoon, we attempted to dig the post hole and put in the pipe and concrete to support and anchor it. After digging half of the post hole, one of the post hole digger handles broke off; the result was a quick trip to Home Depot to get a new post hole digger. After fighting some thick, strong roots, the hole was finally finished. Some stone was dropped into the bottom followed by the PVC pipe. Quickrete was poured around the pipe and the pipe was plumbed to ensure the mast was straight. The whole thing was left overnight to set up.
On Sunday afternoon, it was time to take down the old hamstick and put up the new antenna. Taking down the hamstick was easy, as was relocating the coax. The comedy of errors really began when it was time to mount the JTB4 onto the push up pole. The diameter of the top section of the pole was too small for the antenna mount. The only choice at that point was to remove the top section of the pole and mount it on the next section (albeit with the loss of elevation). Things continued to go wrong when the PL-259 connector wouldn't fit onto the existing run of RG-213 after the excess cable was cut off. No amount of rigging could get it to fit on. The RG-213, with regret, replaced with RG-8 in hopes that the shorter length of coax would balance out using the RG-8 as far as loss goes.
Eventually everything got put together properly and the antenna was tested. I received a good signal check on the 146.745 Springfield repeater and the 146.715 Whitehall repeater. The Springfield repeater is now received at S8 as opposed to S3 with the hamstick. Interestingly, there is no change in S-meter reading with the Whitehall repeater; it read S1 with the hamstick and still reads S1 with the JTB4. Taking a look at the SWR readings using the 897's SWR meter, it appears that the JTB4 is tuned for the lower end of each band. The high end of 2-meters and 70cm doesn't have an SWR problem, but the SWR seems to be fairly high at the top of 6-meters. The antenna has instructions for tuning it to center at 52 MHz; at some point I imagine that I will make the tuning change.
All in all, things seem to be going pretty well with the JTB4. I'll comment more on the antenna's performance after I use it more.
Mac McCormick, KF4LMT
