Subj: Antenna & Tower Recommendatios Date: Mon, Apr 24, 1995 1:45 AM CDT From: markg@iserver.starlight.com To: ka9fox@aol.com Scott, Wanted to make sure you got a copy. Thanks to everyone who responded to my questions concerning the antenna & tower configuration I am planning. I decided to go ahead with the Tri-Ex LM-470 tower (I received no specific comments good or bad on the US Tower) and Force-12 520/240 and 4BA antennas. Some requested I post reponses, so here are the relevant portions. I have added my comments with an "*". ------------------------------------------------------------- Here's my tower recommendation: TriEx LM470. I've just put up my second, and the new design is very nice...extra bracing, well made limit switches, heavy duty base design. In my opinion you can't go wrong. As for antennas, have you also looked at M2 (M Squared) by Mike Stahl? Mike is manufacturing a very nice line of HF beams and logs. I have my doubts about putting that second antenna at 50 feet, seems somehow self defeating. I'm using a heavy duty mast, about 12 feet out of the tower with the 20 at the top and lp right at the tower top. . Have fun, and don't ask the XYL to dig the hole for the base!! * I wouldn't dare. 73, Jim W9WU ------------------------------------------------------------- Congrats on your plan to graduate to better antennas. Couple of comments: 1. Is the reason you want the 2nd antenna on a TIC ring rotor is so you can point the antennas in different directions and switch between them or use 2 radios ? If not, I'd save the money and rotate the antennas on a single mast where you can get the same separation (15 ft). * My main reasons were to make sevicing easier since the top antenna would not be 10-15' above the top of the tower, reduce the height when down (for the neighbors)(although it will probably make the system unusable when down since the antennas will on be few feet apart). A small portion of the cost is offset by not having to have an expensive mast to hold a large antenna high above the tower (I want the 520/240 on top so the 40M antenna will nearly a 1/2 wavelength up). 2. I assume by the antennas you've mentioned that you want to cover the usual HF contest bands and the WARC bands for DXing. As an owner of a DXE LP-17 that is mounted 7.5 feet below a DXE 4-el 20m monobander, which is 7.5 feet below a DXE 6-el 15m monobander, I can tell you that the log periodic is not "happy" with the other yagis near it. I've done a fair amount of modeling of my configuration and discovered that the LP is about 1.0 dB over a dipole at the same height on 17m, instead of the 5.5 dB you would get if the LP was at the same height without other antennas around it. Things get better as the frequency increases. Since I have the 15m monobander, I only use the LP-17 in contests for 10-meters. I don't have any experience with the F-12 4BA, but would be careful of interaction issues. 3. 15 feet of separation is not going to do much for you for stacking 20m antennas. To really experience this advantage you need at least 30 feet of separation, and the two antennas should be identical (driven elements at the same x,y location). 4. Something you might consider is stacking a pair of any of the following antennas 30-35 feet apart: Hygain TH-7, TH-11, Force 12 C3, C3XL, 5BA. This would give the TIC ring rotor something useful to do. Good luck with your project. 73 de Bruce, WA7BNM (bhorn@netcom.com) ---------------------------------------------------------------- I have all FORCE 12 antennas now. I have the 4BA you mention amd the MAGNUM 20-30-40. The 20-30-40 is a vey BIG antenna. It has a 36' boom and 7 elements. How big is the 20/40 job? The 4BA looks like a TV antenna up above it! * The 520/240 is also 36'. They have a 620/340 that 44' but its to big for the space. Can you use a ring rotor on on of those crankup towers? * TIC says they have an adapter that fits in the top of legs of the lower sections. I am concerned about the cables from the top section tangling or damaging the lower antenna when the tower is being cranked down. Anyone solved this? A friend of mine has the 5BA and likes it very much. Bruce/WA1G ---------------------------------------------------------------- I don't think putting a second antenna lower down would add significantly to it, but will clutter it up some, mostly mechanically, for you. If the lower antenna is a mate to the higher one and if you have sufficient stacking distance (like 3/4 wavelength) then it might be worthwhile. Otherwise, the biggest yagis for 40/20/15/10 at the top would probably work well -- that is the biggest yagis you can. * True but I want the most I can get on 20 and 40 plus coverage on 10/12/17. 80 still a problem of course, no room for radials, so using the tower as a vertical may not work well. (Rich Boyd KE3Q) ------------------------------------------------------------- I think your ideas are good .... I think either tower is fine. I would use the two Force-12 antennas per your comments. Would not fool with a LP or 5-band antenna, unless you were really going to be able to stack at some reasonable spacing (30'or more) to get decent added performance on 20 and maybe 15. If you were going to stack, I would use 2 or 3 of the Force-12 C3 types ..... they are small and you would get real good results from a stack of them. But, for what you said your basic goals are, I would go with the crank-up tower and the two Force-12 antennas. Put a nice dual-band 2M/70cm antenna on top (one of the Comet or Diamond 8' models). Make sure you ground your tower well and also ground the coax shields at base of tower, etc. Sit back and enjoy your station. By the way, the Force-12 4BA uses two feedlines. 73, * I've decided not to try the stacking, just not enough distance. Good grounding is is definitely part of the plan. The 520/240 also uses 2 feedlines so I will be using a DX Engineering remote box to switch feedlines (with only one radio no point to running all the lines inside for now). Wes ... N5WA -------------------------------------------------------------- Hope to get the new antennas up this summer.. 73, Mark AB6WD markg@starlight.com