tin roof & base antenna questions

[Rick330man]

I've got a galvalume roof.

My 30 year old 1/2 wave Radio Shack Archer fiberglass "Crossbow" (Shakespeare Big Stick made for Radio Shack) antenna is on a mast on the NE side of the house. These are well built antennas, but they are not great talkers. Because of antenna height limits set by my HOA regulations, only about 9' of my 18' antenna clears the roof. SWRs run from about 1.27 on 40 to just about flat on channel 1. Using the stock 4 watts, my longest local AM contacts have been about 44 miles.

For a while, I took a Solarcon magnetic mount base with a spring and a 102" stainless steel whip and stuck it on the roof. Performance was comparable to what I'm getting now.

 

[Heavy Metal]

2 102 and 2 108 as a rotating dipole

 

[Mike Hannahs MH261]

I put me up a a99 I have it beside my house with a tin roof, my ground plane is one foot away from the roof unfortunately and I think it's causing problems with my swr, I have low SWR of 1.5 on ch 40 but higher SWR of 2.5 on ch 1, I lowered my tuning rings all the way down that made my SWR almost non existent on ch 40 and under 1.5 on 1 but I noticed my finals getting hot quick so I put the rings back, I'm using a cb radio on this antenna so I figured it needs to be tuned back to factory where it is supposed to run at, I'm planning on raising that antenna up, I'm going to buy a tower when money allows me to and it will be 40 foot I think I'm currently using a 20 foot pole attached to my house by clamps and it's fastened up good it talks good to I'm just happy with my SWR, hope this helps someone, my take is the tin messes with my SWR for now

 

[Sonar]

It will affect the tuning of that antenna, you may have to adjust that tuning a bit to get thing 'right'. But then, you'd probably have to do that sort of thing no matter where you mounted it.
- 'Doc

I don't thing that's true. On the contrary it very rare the a99 has to be adjusted via the swr rings. I believe the a99 to be an install and go antenna. There will of course always be an exception but in general those Rings need not be touched after the antenna is in the air.

 

[Mike Hannahs MH261]

I don't thing that's true. On the contrary it very rare the a99 has to be adjusted via the swr rings. I believe the a99 to be an install and go antenna. There will of course always be an exception but in general those Rings need not be touched after the antenna is in the air.

I believe you are spot on there I hope moving it up away from the roof helps me in surenit will do so since it's set in a good spot

 

[Randall barton]

I'm running a Imax 2k here over top a tin roof.....the antenna is 9ft above the roof line and have no reflect or any swr problems, hope this helps...

Oatmeal that's just like mine, and my SWR is at 1.1-1, but I also put a ground on the mast at the bottom with a muffer clamp and a rebar drove 4 ft in the ground and a battery cable to ground it

 

[kopcicle]

First I threw away the A99. Religious beliefs, leave me alone...
Then I threw away the well past due date coax. It went crunch in the hand and closely followed the A99 to the sacrificial pile.
I got out the tin snips and cut a couple 5' stove pipe sections down to 8'5" .
I guyed the false chimney in the middle of the tin roof and set it on an upside down dinner plate .
I screwed the new coax center to the pipe and the shield to the roof and slathered it all with the ritual cold tar roof patch.
At this point as in all projects, came the realization that putting a hat on the chimney before erecting would have been easier. Comedy ensued, however no animals were harmed in the installation of the hat .

VSWR was about 1.2:1 from 26 to 28 .
I have no idea as to resonance or the effect on the ozone layer .

YMMV

 

[HomerBB]

First I threw away the A99. Religious beliefs, leave me alone...
Then I threw away the well past due date coax. It went crunch in the hand and closely followed the A99 to the sacrificial pile.
I got out the tin snips and cut a couple 5' stove pipe sections down to 8'5" .
I guyed the false chimney in the middle of the tin roof and set it on an upside down dinner plate .
I screwed the new coax center to the pipe and the shield to the roof and slathered it all with the ritual cold tar roof patch.
At this point as in all projects, came the realization that putting a hat on the chimney before erecting would have been easier. Comedy ensued, however no animals were harmed in the installation of the hat .

VSWR was about 1.2:1 from 26 to 28 .
I have no idea as to resonance or the effect on the ozone layer .

YMMV