| Index | Thread | Archive | Apr-2000 | Archive | Send |
 |
  |
 |
   |
|
  |
|
substituting our new "N" element for our standard EF140 series element. The advantage of doing this would be the enjoyment of the greater bandwidth (2:1.) Doing the swap for antennas such as the C36XR, C51XR, C4XL and others turns out to be a most significant re-engineering task. The first model we are working on is the C36XR. To do this redesign, we must solve significant mechanical issues as the N element weighs more than what we now use and this subsequent weight increase means balance changes and the boom must be strengthened considerably. We must keep the opening for the tower (for side mount installation) where it is and the driven cell can't be moved, so this is just one of the problems. Given enough time and resources, we will solve the variuos issues and offer several models with the "N" series elements. I'm pushing and working to have this done by fall, but no promises yet. W2OX asked about using our antennas with 72 ohm CATV coax and I scratched my head and said why not. An easy solution available to match the antenna to 72 ohm rather than 50 ohms, would be: 1/ Any of our antennas that use a hairpin across the feed point can be matched to 72 ohms by simply adding 2 or three turns to the hairpin coil. You simply need a bit more "L" to increase the impedence to 72 ohms from the presentation impedance. 2/ Use a balanced to unbalanced ferrite balun to do the impedence transformation at the antenna and the same may then be needed at the other end of the coax to get from 72 ohms to 50 ohms IF your radios and amps don't like the 72 ohm impedance. I've no idea what modern output circuits can handle. 3/ Unless you are running an amp that wants to see a very low VSWR at all times, just connect it all up and go operate. Review the charts to see what the VSWR would be using 72 ohm coax and then review the actual loss. Anyone using 72 ohm CATV hardline successfully? Thanks, Natan W6XR Force12 East Ithaca, NY FN12sk -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact force12@qth.com |
This Thread
|
This Author (Apr-2000) |