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Jerrold FM antenna

Scifi

Scifi

Super Member
I've been interested in getting better reception from WMUC, the University of Maryland radio station which is about 3.5 miles away from my house and broadcasts with 10 watts of power. With a rabbit ear antenna and my Dyna FM-3, stereo was noisy so I put the FM-3 in mono when listening to this station. Later, I got a Jerrold FM antenna and put it on my roof, with a preamp.

The preamp system I used is shown here: http://support.radioshack.com/support_video/doc62/62029.pdf

I had a cable going to the top bedroom already so I rerouted it to go to the antenna on the roof. Now I can listen to the Dyna FM-3 in stereo. I put the antenna on a pole held to the furnace chimney with channel (sometimes called Kindorf), allthread and tubing clamps (see first pages of http://www.google.com/patents?id=YF...urce=gbs_overview_r&cad=0#v=onepage&q&f=false
and http://www.google.com/patents?id=YK...urce=gbs_overview_r&cad=0#v=onepage&q&f=false

I didn't include the rotator, but might put that up later. The antenna is pointed at WMUC and seems to work OK. The antenna can be folded up and is the first folding Yagi-like antenna I've ever seen. See pics below.
 

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I bought it used from an Ebay seller. He said it was a Jerrold FM antenna. It looks a lot like a QFM-9.
 
A downside of using a chimney for an antenna mount is that soot and such from the oil or gas burner can degrade the insulation on the driven antenna elements.
 
On the photos, I don’t see if lightning guard / protection is well organized for your antenna. With a lightning rod as high as possible and well grounded! It’s very important.
 
I know you might not want to hear this, but mounting a antenna to a chimney will over time crack it. The winds will really move it around, and it only takes a little to crack bricks and mortar.


Placed my antennas in the attic and ran the wires through the walls.










Barney
 
Scifi said:
What keeps the winds from not cracking the chimney when there is no antenna on it?
Click to expand...

The antenna acts like a sail in the wind. Watch it in the next storm, you will see what I'm talking about.

The TV shop I worked at would always tell the home owner about this when we showed up. Most would go with the cheapest install. This was back before cable TV when people all needed to have a antenna.


Barney
 
I found some links about cracked brick chimneys and antennas. Looks like it isn't a good idea to put an antenna on a brick chimney. What I have is all metal. I'll keep an eye on it. It could be braced in case its needed. I had a CB antenna and later an HBO antenna on the metal chimney for years before and its still in one piece.
 
These things are all over the place. Saturday night my son, grandson, went with me to see a bluegrass band playing in the back yard of a sort of antebellum house. First owned by a local MD, later by a lawyer etc etc.

I was looking at the TV tower - 3 tube type with the biggest VHS antenna I ever saw. Below it there were two vhf/uhf antenna's. I'm sure they haven't been used since cable TV came to town in the mid-80's.

A shame, really because I'm sure they'd be free to anyone who take them down.
 
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