Antenna radial insulator blocks?

[zonian149]

Does anyone have a source for the plastic insulator blocks similar to the green one in this photo? I want to build a yagi for 162mhz and really need something like this. I could use wood, but I would prefer to use plastic.

 

[mmckenna]

https://www.tapplastics.com/product/plastics/cut_to_size_plastic

Delrin is a good option. Often you can find blocks of the stuff on e-Bay for a reasonable price.
Other option is to go to a grocery store and buy the plastic cutting boards and machining your own out of that stuff. I used one of my wife's old ones for some insulator material.

 

[iMONITOR]

How about using PVC pipe in place the the aluminum?

 

[zonian149]

I just happened to have a 4' piece of aluminum tubing laying around and was just going to use what I have.

 

[k9wkj]

the only element that must be insulated on a yagi is the driven (and not even that if its fed in such a way)
the rest can be mounted directly to/through the boom
youll have to cut them a bit different

 

[zonian149]

Do you have a link to any information about installing the driven element through the boom. I have been googling and couldn't find anything about that. Thanks--Gary

 

[jwt873]

In this link --> 6 Meter Antenna Projects by N2KBK 3 Element Beam and 6 Meter Halo Antenna

Scroll down to the part where it explains the gamma match. If you search more for gamma match construction on Google, you'll get more info.

 

[majoco]

I just happened to have a 4' piece of aluminum tubing

Ideal - I have scrounged/salvaged old low and mid band TV antennas now that all our FTA TV is on UHF. They have all the boom and driven element insulators you could wish for and often come with a small terminal box for the balun.

 

[zonian149]

Thanks for the link jwt873. Martin, I had an old TV antenna 5 years ago, and I got tired of storing it in my garage, so I put it on the curb, and I am now mad at myself, never throw anything away!!!!!!

 

[k9wkj]

a yagi is just a array of dipoles
and dipoles are at a RF 0 in the middle
sometimes through/on the boom element mounting can be used to simplify construction and sometimes it doesnt help (depending on the parts and size your working with)
but they work either way
TV antennas are almost never yagi antennas (except for mono channel jobs) as they hardly have the bandwidth for 1 TV channel (6Mhz)
TV antennas are typically Log Periodic Arrays (LPA/LPDA) and are often several arrays combined to cover the huge frequency spread
but dont use all of your old TV antennas for parts as we here in the US are getting lowband TV channels back! weeee

 

[iMONITOR]

Some related info:

Why are the lengths of the reflector and director different to the dipole in a Yagi antenna
https://www.quora.com/Why-are-the-l...tor-different-to-the-dipole-in-a-Yagi-antenna

 

[barrylewis1234]

YOu dont need to insulate this from the boom arm, just drill through the boom arm and push your ally tube through, then stick a self tapper or rivit in from the top to secure it.

You do need to insulate the driven dipole elements though