Re: 80 meter loop

[Ronald Johnson]

On Sunday, January 3, 2016 at 9:25:49 PM UTC-5, Ronald Johnson wrote:

My 80 meter loop is 270 ft, 25 ft off the ground. Feed line 450 ohm ladder line 35 ft length with 25 ft of coax into the shack then into MFJ-969 tunerthrough a 1:1 current balum to my FT-450D transceiver. Its the best ant I have ever used.

[John Dennison]

What if any lightning protection?

[George Riedel]

At the base where the both antenna wires come together

I use a DX Engineering "T"  and tie into the 300ohm L.L..

Its on a pulley up at 60 foot, I release that the rope on a cleat attached to a pole

at ground level and lower the T with both ends of the antenna wire, I have a 8 foot

grounding rod at base of a pole.

I disconnect both wires from the T and put both ends to the 10awg wire on the grounding Rod.

I roll up the T and L.L. and place on the back porch. Now all the equipment, A 200 T tuner balun

and equipment in shack is protected because it is all disconnected from the antenna wire.

I live on a hill and we get normal storms with strikes adjacent the house

and I have never had a problem with both ends of the antenna wire hooked

to my grounding rod.

On 8/26/19 7:48 AM, John Dennison wrote:

What if any lightning protection?

[John Dennison]

George and KC,

Your idea sounds good to me for those times I am on travel.  It makes the antenna the only thing at risk.

During the build I will arrange the pulley system to allow lowering of the feed point so it can be grounded.

I have decided to also take KC's advice and forget the post directly under the loop feed point. I will put a rod there

for the times I need to travel and ground the antenna.

Luck is with me that it is easy to keep the window line at 90 degrees coming away from the side of the loop that the feed point is on.

KC's approach eliminates several design flaws I had in my original plans with a down back up type of path. By stringing the window line directly

to the eve. Connecting it directly to the 1:1 current balun, out of the balun to a coax ICE type arrestor, out of the arrestor into the shack.

Grounding the box, balun, arrestor and coax all to a #4 wire going down the outside of the building to a dedicated rod that's part of the perimeter ground system.

This makes the antenna, window line, box, balun, arrestor, and #4 wire the most likely direct path. This path grounds the coax shield to the balun ground rod,

but even  though the coax comes into the shack, I plan to let it float from the shack ground rod ground. When it is storming, disconnect the coax and let it float.

I don't believe I will have a ground loop problem when operating as the balun ground and the shack ground are both tied to the perimeter which is also tied to the service ground.

A strike gets the balun box, balun, and arrestor with a good path to ground rather than coming into the shack.  I have tried to also eliminate high RFI voltages from a

strike by installing a metal ground grid on the floor of the loft with the shack bench and floor all going down a separate #4 path eight feed from the balun rod and 

closer to the service box.

I really have benefited from both of your suggestions, hope to be on the air soon.  73

John Dennison KW4OI

865-333-2243 CELL 

[John Dennison]