Topband: High voltage insulator

[Stan Stockton]

Ray,

I have a very similar setup here on Cayman Brac.  The main difference is that my quarter wave vertical for 80 comes off my 160m vertical at about 50 feet or so and slopes down at a steeper than 45 degree angle and then back to the base of the 160m vertical.  So it looks like a short left legged V that has been turned 90 degrees CCW.  I don't have to short out the 160m antenna to make both work.  Both just have hairpin coils to bump up the R.

The top of the 80m wire is attached to the vertical via a short rope and then a few feet of polyethylene tubing which is about 1.5 inches in diameter wrapped around the vertical.  I put it in a microwave oven and it didn't change temperature.  It's very strong going around the vertical with four wall thicknesses drilled through for the short rope.

I had very significant problems due to salt spray, high voltage, etc. but have had no problems since using this material.

I didn't seek out this material but after my previous insulators failed, ropes burned in two and antenna fell to the ground I was lucky to have spotted a new 50 foot roll of it in my neighbor's garbage while driving to go eat breakfast. :-)

73... Stan, ZF9CW

> On Jan 31, 2018, at 9:31 PM, donovanf at starpower.net wrote:
> 
> Hi Ray, 
> 
> 
> Suggest you use two porcelain insulators in series. I have some 
> long porcelain insulators that might be a better long term solution. 
> 
> 
> 73 
> Frank 
> W3LPL 
> 
> ----- Original Message -----
> 
> From: "Raymond Benny" <rayn6vr at gmail.com> 
> To: "160" <topband at contesting.com> 
> 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. 
> 
> Ray, 
> N6VR 
> Near Prescott, AZ 
> 
> 
> -- 
> Ray, 
> N6VR 
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