AM/FM antenna mast height

[sixt9x33rs]

I own a 12C 69 convertible am/fm with a antenna mast height of 23 17/32 inches tall. I recently owned a 4D 69 Convertible am/fm car with a taller mast height. Not by much but slightly taller. The reason I know this is because I had to take the mast off the 4D car to get under my lift. The 12C cars fits with the mast on the car. Both masts appear to be original. Was there a antenna mast height change from the earlier cars to the mid production cars?

Thanks

Lawrence

[bertfam]

As far as I know, all 67-69 Camaro AM/FM antennas had a mast height of 30" (actually, 30.125" measured from the bottom of the retaining nut to the top of the ball).

Post some pictures of the bottom where it screws into the body from both cars.

Ed

[sixt9x33rs]

12C car's antenna.

[sixt9x33rs]

Base

[sixt9x33rs]

04D Car antenna base

[bertfam]

Yep, those look correct. What's the diameter of the ball?

Ed

[WorkinProgress]

Lawrence, are the ends that go into the radio straight, or right angles?

                                                         - Warren

[sixt9x33rs]

Right angles on both cars.

[vtfb68]

Are the cars the same height?
   VT

[sixt9x33rs]

 The height difference in the antenna is too great to be made up in ride height in the cars. I don't own the blue car anymore though.

[Steve Shauger]

Ride height is not a factor. If I remember correctly (my antenna theory occured 35+ years ago) the fixed height antenna is 1/4 wave configuration, 30 inches was chosen for best overall reception because its tuned for the midway point on the FM dial. If you shorten the antenna three inches it increase the sensitivity for stations on the low end of the dial, and if you lengthen it will 3 inches it will increase the sensitivity for station on the high end of scale. Not sure why your antenna is 23 inches.

[bertfam]

I agree with Steve. The only reason I can think of is that someone has removed part of the antenna to receive lower stations.

Ed

[sixt9x33rs]

Hmmm.....could be....

[lakeholme]

So, Lawrence, are you the original owner?  In other words, did a previous owner like the "stubby" antenna look?
If you type "shorten car antenna" in a search engine, you'll get close to a million hits.  A few years ago, we saw quite a bit of that on the show field.
BTW, many of those sites have some interesting, non-scientific suggestions as to how it won't hurt reception....   

[sixt9x33rs]

Wish I was the original owner, but no. I guess someone did shorten the antenna. If they only came in one height. The blue car antenna was definitely taller, and hit the lift when I parked it under the other car. Would the antenna been cut from the bottom or top? I would like to see if I can see a jagged saw cut or evidence of a snip. I will let you know if I find anything.

Thanks