Franklin Antennas for MW Broadcasting

AM Radio discussion. Directional arrays are FUN!
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Shane
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Re: Franklin Antennas for MW Broadcasting

Post by Shane »

Present-day photo from Google Maps looks pretty much like the original except for Google Maps' bifocals making it appear the top half of the tower is dancing atop the bottom half.
image.jpg
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jammerdave
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Re: Franklin Antennas for MW Broadcasting

Post by jammerdave »

Yes, KFBK still has the Franklin's, but I retired the 2nd aux amplifuzz this year. Those antennas sitting on a ground conductivity of 30 really honk.

dave

BigRed wrote:KFBK-AM in Sack-O-Tomatoes, CA (Sacramento, CA) had a two-tower DA that consisted of Franklin radiators at one time, maybe they still do? (Do they need a 4-tower phasor for that ? ? ? Never mind . . . )

http://www.fybush.com/sites/2005/site-051028.html

They also had a 50-kW Amplifuzz transmitter. What could go wrong with THAT set-up? :D

They had an advantage in that they are at the upper end of the dial. If you want to build one down around 700-kHz go for it. Just let me know before you start ordering towers as I want to shift some of my investments into steel.
W2XJ
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Re: Franklin Antennas for MW Broadcasting

Post by W2XJ »

I suggest you read and analyze the original Franklin Patent.
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Re: Franklin Antennas for MW Broadcasting

Post by R. Fry »

W2XJ wrote:I suggest you read and analyze the original Franklin Patent.
To whom do you address your suggestion?
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Re: Franklin Antennas for MW Broadcasting

Post by W2XJ »

Kelly
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Re: Franklin Antennas for MW Broadcasting

Post by Kelly »

W2XJ wrote:I suggest you read and analyze the original Franklin Patent.
Don't need to. My uncle Andy Alford, plus the former Chief Engineer at KNBC, said it was a Franklin Antenna design. They explained to me how the Franklin antenna at KNBC and others functioned, as compared with a standard vertical. For obvious reasons, I believe my uncle. That, and he just happened to be one of the most accomplished antenna designers of the 20th century.
Skype:kellyalford Twitter: @KellyAlford
W2XJ
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Re: Franklin Antennas for MW Broadcasting

Post by W2XJ »

Your Uncle is wrong. Read the patent. A Franklin can only be 180 over 180. BTW his expertise was far greater outside of broadcast.
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Re: Franklin Antennas for MW Broadcasting

Post by jammerdave »

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BroadcastDoc
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Re: Franklin Antennas for MW Broadcasting

Post by BroadcastDoc »

W2XJ wrote:Your Uncle is wrong. Read the patent. A Franklin can only be 180 over 180. BTW his expertise was far greater outside of broadcast.
You know, sometimes it's better to be polite than to prove you're right.
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W2XJ
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Re: Franklin Antennas for MW Broadcasting

Post by W2XJ »

I don't see anything impolite in my comment. Dr Alford is virtually the father of aeronautic radio navigation, developed radio direction finding techniques and is the inventor of the radio localizer system all of which insure life and safety for millions of people daily. His company did indeed manufacture the first master FM antennas developed by Frank Kear. Mr. Kear eventually was th recipient of the engineering achievement award for that while Dr. Alford was inducted into the national inventors hall of fame for his invention of the Localizer Antenna System. So I pose the question, what's more significant - keeping aircraft safe or blasting the hits into the either?
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Re: Franklin Antennas for MW Broadcasting

Post by R. Fry »

From an exchange of posts on another website asking me what the
dipole pattern would look like if it had 120 ground radials ...
______

I went back to my Franklin NEC model, deleted all of the above-ground
conductors and replaced them with the center-fed, 1-wave dipole
elevated 1 meter above the common point of the 120 x 1/4-wave buried
radials. Frequency and earth conductivity were as in the original
studies (1 MHz and 5 mS/m, d.c. 13).

At first glance the dipole patterns look the same with or without
the buried radials. With a more careful look, when using the buried
radials the peak field increased by 0.7%, and the sidelobe field
decreased by 1.1%.

A center-fed dipole is a balanced antenna, and radiates nearly
100% of the Z-matched r-f power at its feedpoint with no need
or use of an r-f ground plane to do so.

But this is a far different effect than would exist if the configura-
tion in the Franklin patent, which is an unbalanced, base-driven,
monopole antenna system, had no connection to a good r-f
ground plane.
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