I have done this, and can testify that it works very well. If you wind,
say, 3 turns around the mast and attach the ends such that it is loose
when at the mid-point of travel, then a half-turn in either direction
results in very little deformation of the cable, much less than that of
a traditional rotator loop hanging off to one side.
73, Pete N4ZR
The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
spots at telnet.reversebeacon.net, port 7000
On 3/29/2011 8:12 PM, Robert Harmon wrote:
> I have some LMR 600 ultra flex that I will need to do a turning loop
> arrangemet with.
> I am wondering if it is possible to do a 3 or 4 turn coil that is in a spiral
> around the mast, then there would be little abrasion Just thinking.........
> On Mar 29, 2011, at 3:41 PM, K8RI on TT wrote:
>> On 3/29/2011 4:33 PM, Paul Saville wrote:
>>> I have tried various configurations for a rotator coax loop, ranging
>>> from a 10ft length of coax hanging in a single loop from the boom, to
>>> rg58 wound fairly tight around the mast. It seems the optimum would be
>>> to drop the coax as close in to the mast as possible to reduce the
>>> turning radius, but far enough out to avoid snagging. Does anyone have
>>> any hints or clever suggestions?
>> I use a 3 turn coil of Davis BuryFlex(TM) about 16" to 18" in diameter
>> to get a "large" turning radius laying on the flat top of the 45G . The
>> large diameter puts less bending moment on the coax. The coax needs a
>> flat surface on which it can skid. Even a second rotatorshelf/acessory
>> shelf anywhere between the rotator and top of the tower will work for
>> the shelf supporting the loop. with the outside end of the loop going
>> down one of the tower legs.
>> With the 18" diameter I can actually get by using regular LMR-400. I've
>> not tried it with LMR-600, but I assume it'd work.
>> The coil expands and contracts with rotation rather than bending in the
>> normal manner so it takes a bit if calculating, or experimentation to
>> get the right length to keep the coil on the flat plate.
>> If using any of the UF versions such as LMR400 or 600UF the flat plate
>> needs to be *smooth* and I have to emphasize the smooth, as the jacket
>> of the UF cables is not only sensitive to UV it is easily abraded. This
>> is where the BuryFlex shines as it has a very tough jacket that is
>> strongly resistant to abrasion, plus it has about the same loss as LMR-400.
>> Roger (K8RI)
>>> 73 Paul ZL3IN
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