[Elecraft] B&W Folded Dipole over an Armory

[Fred Jensen]

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.
>