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A Tennadyne T10 is on a 24ft boom which, if properly designed should give something in the region of 6.3dBi (or about 4.15dBd). On page 10-14 of the ARRL Antenna Book (19th edition) it shows a design for a 12 element log on a 26ft boom giving gain in the 6.6-6.9dBi (4.45-4.75dBd) region across its range. I have no reason to doubt these figures. On the L.B. Cebik W4RNL webpage (http://www.cebik.com/3lpda.html) he shows a nine element log on a 21ft boom giving gain in the region of 5.63-6.33dBi (3.48-4.18dBd) across its range. Again I have no reason to doubt these figures. The T10 should therefore fit somewhere in between these figures, which would suggest gain in the 6.0-6.6dBi (3.85-4.45dBd) region across its range, as opposed to the totally outrageous 8.24dBi quoted on the Tennadyne webpage (http://www.tennadyne.com/specs&prices.htm). Force12 quote the C31XR as having 8.15-9.55dBi (6.0-7.4dBd) gain across 10/15/20M, or about 2.5db (on average) above the T10. This is a substantial difference. The N1217 is quoted as having 8.15-8.25dBi (6.0-6.1dBd) across its bands which equates to about 2dB over the T10, again a substantial difference. The other thing to take into account is the amount of boom and number of elements you will be happy to try to keep in the air. Going the Tennadyne route results in 10 elements, 24ft of boom and 10.1 sq ft of windload whereas the F12 route results in 21 elements, 49ft of boom and 15.7 sq ft of windload. Really, the decision you have to make is to consider whatever you would be happy keeping in the air and what compromise you want to make on gain. Andrew Williamson GI0NWG / AC6WI Homepage = http://www.gi0nwg.freeserve.co.uk/ One of the ZL9CI gang http://www.qsl.net/zl9ci/ In message <E19CWEV-0000bo-OA.2003-05-05-04-02-30@imailg1.svr.pol.co.uk> , KEN SILVERMAN <k2kw@prodigy.net> writes >A WELL designed log often has no more than 3 dB of gain per band, sometimes >less. F/B performance is also not the same as a monoband Yagi. If you are >interested in busting pileups easier, creating your own pileups, or looking >to improve contest scores, go with the C31 XR and 12/17 Yagis. LPs are >simply not equal to the performance of well designed monoband Yagis, which >is what you are getting with the latter. If you want an LP (I personally >cannot think of why someone would ever consider an LP unless you do serious >MARS or out of band RXing), buy a Force 12 LP! > >Kenny K2KW > > >----- Original Message ----- >From: "Law Offices of J D Lambright, PLLC" <JDLambright@the-law-offices.com> >To: <Force12Talk@qth.com> >Sent: Sunday, May 04, 2003 9:17 AM >Subject: [Force 12 Talk] Force 12 vs. Tennadyne > > >> I would like to hear your comments and recommendations regarding my >antenna >> choices. I have recently acquired the following antennas second-hand: >> >> A. Tennadyne T-10 log periodic (10 elements on a 24 foot boom) >> >> B. Force 12 C-31-XR with 14 elements on a 31 foot boom for 10, 15, and 20 >> meters - (wide-spaced 3 element 20 meter Yagi, wide-spaced 4 element 15 >> meter Yagi, and a 7 element 10 meter Yagi). >> >> C. Force 12 N1217 with 7 elements on an 18 foot boom for 12 and 17 meters. >> >> D. Force 12 EF-706 with 7 elements on an 18 foot boom for 6 meters. >> >> For HF coverage, I'm trying to decide whether to install the T-10 or, >> alternatively, the two Force 12's. (I think they are all great antennas, >so >> perhaps I should find a way to install all three!) My towers are a Rohn >100' >> SSV freestanding commercial-type tower and a Wilson 61' crank-up pole >tower. >> >> I would most appreciate hearing your comments on the pros / cons of these >> antennas and your suggestions on how best to install them. I am located >near >> Houston, Texas, so things like ice are not a problem. >> >> J D Lambright -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com |