[Elecraft] B&W Folded Dipole over an Armory

[Ken G Kopp]

Skip's /K6DGW is totally correct ....

73!

K0PP

On Sun, Aug 13, 2017 at 1:36 PM, Fred Jensen <k6dgw at 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.
>>
>>
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