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Practical FM Antenna Seminar

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Kennelly Heaviside
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Joined: Fri Jun 11, 2021 12:06 am

Practical FM Antenna Seminar

Post by Kennelly Heaviside » Sun Sep 12, 2021 11:57 am

Didn't know they had seminars for FM DXers. This one has information on simple FM Antennas.

The man in the video is a retired automotive engineer from Michigan. He also has a First Phone and worked at various FM stations in the past.

He kind of glosses over how good Yagis, even with Armstrong Rotors, can be. He must live in a town that restricts antennas. They should have a much better antenna that can be raised and lowered remotely on the roof like the flagpole on Hogan's Heroes, to get around home owner neighborhood associations and neighborhood "antenna scorn".

Since he apparently is from Metro Detroit, I would have to say this is mainly information from the time there were no Canadian drop ins, translators, LPFM, and especially IBOC sidebands that obliterate first adjacents from neighboring markets, even on an MR-80.

https://www.youtube.com/watch?v=JOEQ5uRn38I


Kennelly Heaviside. The best Technical Consultant no money can buy.

Rich F.
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Location: Illinois USA
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Re: Practical FM Antenna Seminar

Post by Rich F. » Sun Sep 12, 2021 1:25 pm

Interesting how in one part of that talk he pushes the need to have an omnidirectional pattern for the receive antenna, then a few minutes later he holds up a pair of crossed, folded dipoles having an omni pattern and points out how it can receive co-channel interference from stations in different directions ‐‐ which he then says is a problem. Other such disconnects also in that talk.



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SolarMax
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Re: Practical FM Antenna Seminar

Post by SolarMax » Sun Sep 12, 2021 1:34 pm

I worked with Bob K. many years ago. Brilliant guy. His normal conversational tone was pretty much like this lecture. He was active in the Detroit AES Chapter, so this may have been from one of their meetings, not a seminar presented as a public event, like at a library. Looks like oldest comment is 4 years old.



Kennelly Heaviside
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Re: Practical FM Antenna Seminar

Post by Kennelly Heaviside » Sun Sep 12, 2021 2:33 pm

I built a simple interferometer with two Antennacraft/Archer FM-10s I had at one time. I used an old Rembrandt Antenna Switch, without the rabbit ears connected, which introduces phase shifts and atennuation to one antenna, since it was handy, and I didn't have a fancy phasor. I could get cochannels clearly by just changing the switch on the Rembrandt.

This is the Rembrandt Antenna Switch I used as a primitive phasor. Unhook the rabbit ears with identical antennas, to use as an interferometer. Some of the newer models had knobs, which may have allowed more continuous adjustments of phase and attenuation.

Image

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Kennelly Heaviside. The best Technical Consultant no money can buy.

k8jd
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Location: Commerce, MI

Re: Practical FM Antenna Seminar

Post by k8jd » Sun Sep 12, 2021 9:14 pm

I had a nice 5 element "3 Meter Band" Yagi up for a while. Had 2 driven elements, one for the lower half and one for the upper half. a few inches different length.
I used a 4:1 balun to use coax to the 300 Ohm feedpoint. My FM tuner input was converted to a 75 Ohm F connector I mounted on the back panel. It was an old Fisher with great adj Ch rejection. Was a great ear with sensitivity for 20 dB quieting just below 1 Microvolt. (measured with test gear at the work place)..
Well... During a storm a flying branch hit the antenna breaking the feedpoint insulation, and it seems to be made of "UnGluable " plastic. !
This is the setup that I used when I heard WMBI in Chicago , from Redford (MI).



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