Tilt Feature of MCM 30-2475 & 30-2476

[newmguy]

Hi Guys,

I just got a 30-2476 the other day.

The position of the mounting clamp does not seem right to me.

Shouldn't the clamp be mounted closer to the middle of the antenna?

If so, would it affect the signal on some channels?

Or maybe add a diagonal brace from the mast to the antenna ?

Any thoughts?

[rabbit73]

The clamp should be mounted at the center of gravity.

[newmguy]

Originally Posted by rabbit73

The clamp should be mounted at the center of gravity.

Ok where is that?

The picture shows the clamp beside the coax connector.

[rabbit73]

Between the 1st and 2nd director as shown in the 3rd photo in post #7.




Is that where it is located on your antenna?

A diagonal brace should not be needed if the assembly was done correctly.

[newmguy]

Seems like it should be closer to the center of the antenna (due to the length of the antenna)

I don't have time to install it for another couple of days, just wondering.

[newmguy]

Originally Posted by rabbit73

Is that where it is located on your antenna?

yes thank you

[rabbit73]

The position of the mounting clamp does not seem right to me.

Shouldn't the clamp be mounted closer to the middle of the antenna?

I think you are right.

Good catch!

http://www.mcmelectronics.com/conten...ls/30-2476.pdf

The 30-2476 has the clamp location in the catalog image that is not the same as the clamp location in the instructions diagram.





The optimum point is at the center of gravity which has the same WEIGHT on each side, not the same LENGTH, like a seesaw.

When the clamp is at the center of gravity, there is less chance of the angle adjustment changing, because the rotational torque is equal in both directions.

https://en.wikipedia.org/wiki/Seesaw

Since the clamp fastens around the boom instead of through the boom, it should be possible to move it forward or backward to the balance point.

[bobsgarage]

Originally Posted by newmguy

Seems like it should be closer to the center of the antenna (due to the length of the antenna)

I don't have time to install it for another couple of days, just wondering.

Hi Newmguy,

As Rabbit told you, the center of gravity is the best mounting point for balance of weight.

In the case of the 30-2476, the reflector is fairly large an adds weight to the rear of the antenna, forcing the designers to move the clamp rearward to obtain balance.

Let us know how your 30-2476 works.

Thanks, Bob

[Nascarken]

We'll Bob thanks again ,for your time and the posting of the picturers, that has HELP ME out big time and I have to say ,that the stellar Labs high VHF ANTENNA is one HE'LL OF an antenna I have one hooked up with a channel master 7777amp at 40,Ft high I receive 17channels with it,well everyone have a good day,and,73rabbit

[rabbit73]

Originally Posted by newmguy

Or maybe add a diagonal brace from the mast to the antenna ?

That might be a good idea if the tilt adjustment notch doesn't rest on the upper bolt. It would keep the tilt at the same angle in a windy location.

[Nascarken]

Hi everyone ,We'll I have to say about that is my ,STELLAR LABS antennas A G L is at 30,and the wind that comes off of the ocean at 50, Miles per hour ,does not bother the antenna or it's performeits,

[Nascarken]

How come tv fool does not do a FOOL fest,I think it would have a big impact on TV and on how they work,and how to use them,and I think it would slow down the Fcc from what they are doing to the tv antenna world,and I think it would up antenna sales,and fun for the hole family and members of the FOOL REPORT team,

[bobsgarage]

Originally Posted by rabbit73

I think you are right.

Good catch!

The 30-2476 has the clamp location in the catalog image that is not the same as the clamp location in the instructions diagram.

The optimum point is at the center of gravity which has the same WEIGHT on each side, not the same LENGTH, like a seesaw.

When the clamp is at the center of gravity, there is less chance of the angle adjustment changing, because the rotational torque is equal in both directions.

Since the clamp fastens around the boom instead of through the boom, it should be possible to move it forward or backward to the balance point.

Good catch, both of you!

I have to say, that the images do differ in the location of the clamp.

Mine seemed pretty solid, so I didn't question it.

Rabbit, how much influence can the mast have on reception?

[bobsgarage]

Originally Posted by Nascarken

We'll Bob thanks again ,for your time and the posting of the picturers, that has HELP ME out big time and I have to say ,that the stellar Labs high VHF ANTENNA is one HE'LL OF an antenna I have one hooked up with a channel master 7777amp at 40,Ft high I receive 17channels with it,well everyone have a good day,and,73rabbit

Hey Ken,

If it weren't for Rabbit, I'd never have know how to post the pics so that they show in the forum.

Are you able to post those antenna pics now?

[Nascarken]

No picturers a z z OF yet I HAVE NOT decided yet if I stagger stack them vertical or horizontally stacked to match the 91XG,HORIZONTAL .or use a ANTENNACRAFT MXV 5100,with the 91XG,and THANK YOU again for your pictures,and yes Rabbit 73,is a s m ,

[rabbit73]

Originally Posted by bobsgarage

Rabbit, how much influence can the mast have on reception?

Very little; not enough to worry about. The antenna has horizontal polarization to match the transmitted signal, but the mast is vertical. Also, the mast is located near the center of the elements where the signal voltage is at a minimum which reduces the influence of the mast.

The ends of the elements, where the signal voltage (E) is highest, are more sensitive to touch and nearby objects. The current (I) is highest at the center.

https://en.wikipedia.org/wiki/Dipole_antenna