Hi Tom,
Just as an example, let me describe my installation of my Cobra
Senior which received the blessing from Joe,
K1JEC,
Which by the way at the time, suggested not to cut the ladder line
unless absolutely necessary and then suggested some lengths are more
preferable than others. SO if you do have to cut it, call him first and
get his recommendation.
Fortunately I have a tower so I hang it from there at 50 feet as an
inverted V with the ends at only about 5 feet from the ground. I pull
the ladder line out from the apex at about a 45 degree angle away from
the tower and down to the roof of the house about 25 feet away. I ran
two parallel lengths of light strong rope from that point back over to
the tower which are about 2 feet apart and 5 feet above the roof. So at
this point I have about 65 extra feet of ladder line I need to do
something with. So I coil the line around the two parallel ropes back
towards the tower, wrapping the ladder line around the ropes and
securing with zip ties which ends up looking like concertina wire. Or
picture a slinky stretched out wrapping around and supported by the
parallel ropes. This keeps the ladder line off the ground (or roof in my
case) and gives plenty of spacing around the line so none of it comes
close to anything including itself. Looks pretty cool too. The end goes
through a PVC standoff around the edge of the roof and terminates into a
balun under the eves where coax then runs into the house. I use it on
160 through 40 without problems and works reasonably well.
So if you have some horizontal space, consider stretching out your
excess ladder line like a slinky supported by two parallel ropes.
The long length of your ground wire is a concern to me as well. Just
as an experiment, I'd disconnect it from the shack end and see if that
effects the tuning.
Good luck,
Rob K6DQ
On 8/18/2015 6:57 AM, Tom Behler wrote:
> John:
>
> I had thought of that when we originally installed the antennas and
> grounding system, but didn't know of any other good alternatives at the
> time, since my shack is on the second floor.
>
> Overall, things seem to work relatively well, except for the Cobra on 40
> through 10 meters, so I am thinking the Cobra is more of the culprit here
> than anything else. I think my problem may be related either to the
> instalation itself, or more likely, to the excess ladder line.
>
> This is not to say that my RF grounding can't be improved. It probably can,
> and is something I need to think about more as well.
>
> Tom Behler: KB8TYJ
>
>
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of John Miller
> Sent: Tuesday, August 18, 2015 8:52 AM
> To: [log in to unmask]
> Subject: Re: Question About Cobra Ultralite Senior Antenna
>
> If that ground runs all the way to the second floor of your house, that's
> probably causing more problem than it's preventing.
>
> -----Original Message-----
> From: Tom Behler
> Sent: Tuesday, August 18, 2015 8:18 AM
> To: [log in to unmask]
> Subject: Re: Question About Cobra Ultralite Senior Antenna
>
> Tom:
>
> At this point, my grounding system consists of one 8-foot ground rod that is
> connected to the main ground of the house electrical system with ten-gauge
> stranded copper ground wire. I then have a stranded copper ground wire
> running from the main ground connection up to the main ground lug on an MFJ
> window feed through panel in my shack, which is on the second floor of my
> house. All antennas are connected to that feed through panel. And, each
> piece of equipment (i.e. radio, amp, and tuner) are connected to the main
> ground lug on the feed through panel with 12-gauge copper ground wire. As
> far as I can tell, all ground connections are good.
>
> Tom Behler: KB8TYJ
>
>
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Tom Fowle
> Sent: Monday, August 17, 2015 10:58 PM
> To: [log in to unmask]
> Subject: Re: Question About Cobra Ultralite Senior Antenna
>
> Tom,
> first thoughts are about grounding.
> Though not familiar with the antenna, I assume it is basically a loaded
> dipole and that the manufacturer claims it's matchable on all bands.
>
> What is your R.F. grounding system like? is all the gear, particularly the
> xcvr, amp and tuner, well grounded together and to a good heavy lead to at
> least one ground rod?
>
> Tom Fowle WA6IVG
>
> On Mon, Aug 17, 2015 at 10:13:49AM -0400, Tom Behler wrote:
>> Hello, everyone.
>>
>>
>>
>> I guess this question is best directed to those who are familiar with
>> the Cobra Ultralite Senior antenna made by K1JEC, but I'll take
>> thoughts from anyone who is interested in replying.
>>
>>
>>
>> Several years ago, I purchased a Cobra Ultralite Senior antenna from
>> K1JEC, or Granite State Antenna in New Hampshire. My main reason for
>> making the purchase was to have operating capability on 80 and 160
>> meters. The antenna itself is up about 35 to 40 feet, and is strung
>> between trees on my property, and on a neighbor's property.
>>
>>
>>
>> The antenna works well on 80 meters, and much of 160 meters, when
>> tuned with my MFJ 998 auto-tuner.
>>
>>
>>
>> However, I have never been able to get it to tune on 40 meters. In
>> addition, the tuning and performance are questionable at best on 20,
>> 15, and
>> 10 meters. In fact, one problem I have noticed recently is that when
>> tuning it on 20 meters, using my MFJ998 auto-tuner and my ALS600, I
>> actually get RF coming through the PTT switch on my Heil gold line
>> mic. This, of course, is not good.
>>
>>
>>
>> All of this is prompting me to try to correct the situation.
>>
>>
>>
>> Several months ago, I contacted Joe at Granite State Antenna in New
>> Hampshire, and he suggested that I make sure the excess ladder line is
>> coiled in several loops, and is off the ground. I just double-checked
>> this, and it is what we did when we installed the antenna.
>>
>>
>>
>> A ham friend of mine has suggested that I cut off the excess
>> ladderline, and see if that helps.
>>
>>
>>
>> I am reluctant to do this, because the instructions say not to do so,
>> and it is one of those steps that will be difficult to reverse.
>>
>>
>>
>> I am thinking of purchasing some RF chokes to help with the issue,
>> bbut I still think there is a basic problem with my instalation.
>>
>>
>>
>> Fortunately, my Alpha Delta DXCC tunes well on40 through 10 meters,
>> but it would be nice if I could get the Cobra to do the same.
>>
>>
>>
>> Any thoughts on this would be appreciated.
>>
>>
>>
>> Tom Behler: KB8TYJ
>>
>>
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