[Antennas] CushCraft R-7 problems

Wed Dec 30 22:19:53 EST 2015

It may be time to take that antenna back to where you bought it and ask for a replacement or refund.
On 2015年12月31日 02:16:28 +0000
Robert G Strickland <rcrgs at verizon.net> wrote:
> All comments much appreciated. Some data...
>> The antenna is an R8 [not R7, my mistake]. It is brand new. With the 
> several take-downs, it probably hasn't been "up" for more than a month 
> or so, total. SWR readings were taken with the MFJ 256B at the antenna 
> [2ft connecting cable], not at the shack end of a long piece of coax. 
> That said, readings in the shack generally followed those taken at the 
> antenna. Readings at a friend's house w/ the same antenna taken with my 
> 256B generally follow the curves at the back of the antenna assembly 
> manual [under 2:1 and centered in the various bands]. Thus, there's 
> something uniquely wrong with this particular antenna itself. I'm 
> beginning to suspect that one or both of the traps may be bad/loose/etc. 
> That would explain both the generally bad swr readings as well as the 
> wide/wild fluctuations in readings that are observed with the wind 
> blowing. I'm ready to take it down for the third time pending weather 
> [snow and ice at this moment]. I haven't contacted CC after the latest 
> go-around as I wanted to complete swr measurements under all possible 
> conditions and compare with those at my friend's shack. Again, thanks 
> for all comments and suggestions.
>> ...robert
>> On 12/30/2015 22:43, K3SV wrote:
> > Identical thing happened to me. The fracture is hard to see but needed to be repaired. I changed the guying points and have not had a problem.
> > 73 Bill K3SV
> >
> > Sent from my iPad
> >
> >> On Dec 30, 2015, at 2:49 PM, Bob Nielsen <n7xy at n7xy.net> wrote:
> >>
> >> I have a Hy-Gain AV-640, which is similar to the Cushcraft R8 and after several years the aluminum bracket which connects the matching network to the antenna fractured from the stress caused by the weather. This was hard to see except from up close but the SWR and signal levels were all over the place. Since the R7 matching unit is practically identical I would look there for a possible cause. I made a replacement bracket from a piece of aluminum of the same width but greater thickness which I found at my local Ace Hardware and hopefully it will hold up better.
> >>
> >> Bob, N7XY
> >>
> >>> On 12/27/15 3:42 PM, Robert G Strickland wrote:
> >>> The house has aluminum siding. The antenna sits up on the roof, maybe 10ft above the siding and maybe 20ft away from it; the roof mounting spot is around 20ft above ground. I think the problem is with the antenna itself, not the installation context/environment. I had a SkyHawk beam, and the SWR never varied on that antenna, regardless of the wind/weather. So, the wide/wild fluctuations of the SWR when measuring it in a very slight breeze is suspicious of something mechanical.
> >>>
> >>> ...robert
> >>>
> >>>> On 12/27/2015 22:56, JK wrote:
> >>>> How far away from ur house? Have aluminum siding. Any towers nearby? Any
> >>>> vertical wires or metallic objects near the antenna?
> >>>>
> >>>>
> >>>> Check continuity w/ohmmeter?
> >>>>
> >>>>
> >>>> Jay...NE2Q
> >>>>
> >>>>
> >>>>> On Sun, Dec 27, 2015 at 05:29 PM, Robert G Strickland wrote:
> >>>>>
> >>>>> Hi, Jay...
> >>>>>
> >>>>> Brand new!
> >>>>>
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>> -- 
> Robert G Strickland, PhD ABPH - KE2WY
> rcrgs at verizon.net.usa
> Syracuse, New York, USA
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-- 
73, Frank