Topband: High voltage insulator

donovanf at donovanf at
Wed Jan 31 21:31:52 EST 2018

Hi Ray, 

Suggest you use two porcelain insulators in series. I have some 
long porcelain insulators that might be a better long term solution. 


----- Original Message -----

From: "Raymond Benny" <rayn6vr at> 
To: "160" <topband at> 
Sent: Thursday, February 1, 2018 2:20:24 AM 
Subject: Topband: High voltage insulator 

I need the experience and wisdom of this group. 

I have am 80m vertical hanging off the side of my 160m vertical and share 
the common radial system. The 160m vertical is 4" and 3" irrigation pipe, 
72 ft tall with 4 - 30ft top hat wires and a loading coil at the base. The 
80m vertical is up 68 ft and hangs from a 14" side arms and has its own 
coax and loading coil. I have to short the 160m vertical to ground to 
operate 80m. I run near 1500w output. 

The problem is that the 80m insulator at the top shorts and arcs out over 
time. I understand there is perhaps 6 - 10 KV at the top of the 1/4 wave 
80m vertical. I can see it now arcing at night and my swr is jumping 
between 1.5 to 2.0. My original insulator what just a small, abt 1" x 2" 
white porcelain wire insulator that lasted for 2 - 3 years before it 
cracked and shorted due to mechanical strains. My second was some sort of 
composite insulate about 1" x 4" long that lasted abt a month before it 
melted. My last insulator that is arcing, I think it is some sort of 
porcelain insulator. Maybe its cracked too. 

I am tilting down the vertical tmw to replace the insulator and want to get 
some ideas as what to replace it with. I have both white and brown guy wire 
insulators, about 1 - 1/2" dia by 3" long, or I'm wondering if a synthetic 
material type might work the best. I have three pieces of synthetic rods, 
about 3/4 to 1" dia. One is from the center insulator of a yagi driven 
insulator from my junk box and about 1" dia by 8" long. I think its 
fiberglass, but not sure. I also have from my junk box, one round stock 
that might be Delron another and other might be Teflon or some other 
synthetic material. I just placed the 3 pieces in the microwave with a cup 
of water. After 2 minutes, all three were slightly warm. After a second 2 
minutes hit, two of the synthetic types were very hot. The yagi dipole 
center insulator which I think is fiberglass was still only slight hot. 

So, what conclusions can I deduce? Which one might be best for my use? I'm 
tending towards using one of the porcelain insulators. 

Any thought or experiences? Are there more tests I can do on the synthetic 
material rods? 

Tnx for your thoughts and recommendations. 

Near Prescott, AZ 

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