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I apologize if the post is somewhat hard to follow.. First the original antenna was a KT-34XA at 102'. I used it in the early 1990's and still have it stored in the C-51XR shipping crate (or coffin as my wife put it (Hi)) from Force 12. I then installed the C-4XL/D and had it up for two plus years (even adding a stacked C-3E below it - heights were 102' & 74'). I would say, in general, the C-4XL was better on all bands except 10 meters. The stacked antennas helped even more, but I still wanted more gain.. I had a local ham wanting to buy a C-4XL like mine, so I decided to sell it to him and buy the C-51XR and a C-31XR. I did quite a bit of modeling with AO and NEC. I then talked with Tom N6BT, Jay WX0B, and Jim VE1JF about stacking. Each gave me more in-site to push on and try and find the best combination I could. It was apparent after my own modeling and seeing Tom's numbers that 40' separation was the best (for my situation). The C-51XR was put at 102' and the C-31XR was put at 62'. I had the C-3E and figured I could use it as a multiplier antenna in the contests. I started running the numbers and had to get John, K9UWA, involved when my ham version of AO started choking! He has a AO-Pro version and started cranking. I finally put the bottom antenna at 38' and I think the spacing was best for my tower height (as the C-3E spacing increased it became closer to the ground). In a previous post I quoted some of the numbers, but the top two antennas have about 3 dB over the top antenna and the additional C-3E would gain only .5 - .9 dB. My reason for using the C-3E was, I had it and the switching advantage in the contests made it work for me. Would I use it as a stacking choice (with the C-51XR & C-31XR) if I were to buy it, NO. Things to look out for when stacking different kinds of antennas (just to name a few) are: SWR curves, feedpoint positions, heights, band gain, boom length, etc. I had a problem that did not occur to me until Jim, VE1JF, brought it to my attention and that was the C-31XR and C-51XR feeding. Both of these antennas use the same elements and spacing on 20-10 mtrs. I should be able to use the same length coax right? WRONG! The horizontal spacing of the driven elements on 20-10 meters are around 10 feet. When modeled it shows some difference on 20 meters, but 10 meters is completely screwed up (assuming I don't make the phasing adjustments). The reason for picking the C-31XR to stack with the C-51XR is the fact that they are identical on 20-10 meters. The 2 el. 40 mtr is located behind the C-31XR to make the C-51XR... I would agree with Natan that you generally don't want to have different antennas when stacking. To say to cannot is incorrect, just keep your modeling program fired up! In comparison of the C-51XR, C-31XR, & C-3E to what I had last year, there is no comparison! These antennas will perform much better.. The local ham has the C-4XL at 90' and when comparing it to either of the C-31XR or C-51XR antennas, I am still louder (this has only been random testing - not scientific). As for the possibility of using a monster quad, I am not up for the ice problems seen here in the midwest. I know a few people who swear by them and have had great success in the Indiana area. I have just heard the horror stories about wind and ice... Maybe someone can report on the 6 band monster quad?? The AB-105 tower, from my limited knowledge, is an old military type tower and is very heavy, but durable. The big negative is guying (for me). See you in the pile-ups!! 73's, Kevin --> WN9O "Tommy Tow" <WD4K@Bellsouth.Net> wrote: Hi Kevin, Was wondering about a couple of things after reading your post. At what height do you have your original C31 and where did you locate the second and the C3E?? Did you model this arrangement? After reading W4AN opinions on towers on hilltops, (I am 800'up, in the clear with a 300' d rop and horizon in all directions) I decided to not put up a 100'+ tower. I have a C31 at 74' now and planned on adding another at 37' and have bee n talking to Natan. His advice was not to mix different boom lengths withi n the stack-have you seen any negatives by mixing the two C31's and the shorter boom C3E?? I will have a second tower but just trying to get thi s one correctly configured for the present. Thanks, Tommy WD4K Get free email and a permanent address at http://www.netaddress.com/?N= 1 -------------------------------------------- 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 |