Skip's /K6DGW is totally correct .... 73!
K0PP On Sun, Aug 13, 2017 at 1:36 PM, Fred Jensen <k6...@foothill.net> wrote: > Ummm ... let's be truthful here. The B&W folded dipole can be found in > radio catalogs from the 50's. We all knew [I was a kid with a new license > then and even I knew] that the doohicky at the center of the top wire was a > 400 or so ohm non-inductive resistor, and half the power [3 dB] heated it > up. There was no subterfuge and B&W wasn't "conning" anyone, it was very > clear in the specification sheet. 300 ohms at the feed point, hams often > fed them with 300 ohm TV twinlead of the day to a balanced link coupled to > the final tank circuit. A 4:1 transformer netted 75 ohms which nicely > matched that twinlead too. > > Nor did the Nat'l Guard get conned, they had a specific need for an MF/HF > antenna that was light, easy for a couple of troops to erect, and very > broadband ... their operating frequencies are [were] sort of day/night > separated, rarely if ever harmonically related, and required ranges were in > the several hundred miles or so miles. It was a great antenna for a > specific purpose which is why you see [or saw] them at many military > installations, some of which were Nat'l Guard Armories. > > For 10 months in high school, I worked coastal marine from So California. > Very large V-Beams on 200 ft towers with two terminating resistors at the > ends. Moderately broad patterns into the Pacific, very little off the > backs [not many ships back there]. 5 KW from the TX, 2.5 KW into the > resistors, 2.5 KW to all the ships at sea. Great antenna for the purpose. > > As with all things in Engineering, antenna choice is a basket of > trade-offs. The Nat'l Guard rarely tries to work DX. Broadband however > was near the top of their list. > > Incidentally, the "T2FD" [TTFD] acronym arose from the "Tilted Terminated > Folded Dipole" developed by the US Navy during WW2, designed to have one > end hoisted on a ship's mast and the other anchored near the deck. Lowered > the elevation angle of the main lobe, something important to them. Hams > associated it with someone's call which I can't remember at this point. > > 73, > > Fred ("Skip") K6DGW > Sparks NV USA > Washoe County DM09dn > > On 8/13/2017 10:28 AM, Ken G Kopp wrote: > >> The antenna Jim's is referring to (below) is ... I believe ... better >> known >> as >> a "T2FD". In a case of conning the unknowing B & W ... and maybe even >> themselves ... sold hundreds of them to the Army National Guard. You see >> them hanging above every armory here in MT. >> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to kengk...@gmail.com > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com