[Elecraft] Parallel line lightning arrestors

[Ron D'Eau Claire]

I haven't used that "arrester" but looking at the specs I see that it's
designed for an impedance range of 300 to 600 ohms. That is, a typical open
wire line working at a low SWR. That is NOT the case with a "Cerbik"
doublet. Your Cerbik doublet will show impedances at various points along
the feeders way outside of that range on most bands - from a few ohms to
thousands of ohms. 

The Cerbik doublet is just a center fed wire similar to what hams have been
using since the 1930's. The distinctive feature that Cerbik developed was to
limit the length to prevent the formation of a vertical radiation lobe on 10
meters. There's nothing critical about that antenna at all. I've used
variation most of my hamming "career" over the past half century. The Cerbik
42 foot length does exact a penalty of a couple of dB if you try to load it
on 80 meters. Center fed antennas lose efficiency very fast when the overall
radiator length drops below 1/4 wavelength (1/8 wavelength each side of the
feed point). 

What the Cerbik antenna needs is a rig or good ATU capable of matching to
the very wide range of impedances it will present to the transmitter. The
Elecraft ATU's will do this in most cases. You may or may not use a balun.
That depends upon whether you care if the feeders radiate. Sometimes the
vertical radiation from an unbalanced feed line helps with DX if the antenna
isn't up at least 1/2 wavelength on the band you want to use for DX
contacts. 

I'd be very suspicious of putting anything on the feedline for "protection"
that wasn't designed to deal with thousands of volts of RF (if you're
running more than QRP) or the impedance extremes such an antenna will
present to it.

The best lightening protection is to disconnect the feeders when there are
storms in the area and, if possible, have them disconnected outside of the
house. That's true of any kind of feedline. 

Ron AC7AC

 

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

In a painfully slow, round-about way, I'm getting a Cebik 44' doublet 
put up.  I'm curious if anyone is familiar with the ICE brand of 
lightning arrestors 
(http://www.arraysolutions.com/Products/ice/impulse1.html#2)?

I'm familiar with PolyPhaser products, too, but the ICE equipment sounds 
well-built & good for the job, too.
-- 
73,
Mike Boice, KW1ND
Karns, TN