[Antennas] CushCraft R-7 problems

[Bob Nielsen]

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!
>>>
>>> ...robert
>>>
>>> On 12/27/2015 21:01, JK wrote:
>>>> Is this a new and unused antenna??? Maybe a bad trap/coil
>>>>
>>>>
>>>> Jay....NE2Q
>>>>
>>>>
>>>> On Sun, Dec 27, 2015 at 01:29 PM, Robert G Strickland wrote:
>>>>
>>>>> I have put up a CC R7 and can't get it to "work." CC has replaced the
>>>>> match box. Twice, I have taken it down, cleaned all connecting
>>>>> surfaces and put it back up. I have a lot of mechanical experience,
>>>>> and I'm generally satisfied that I assembled it correctly. Using an
>>>>> MFJ256B at the antenna, there is no resonant frequency dip on 30m,
>>>>> 17m, 15m and 12m; on these bands the SWR is generally flat in the 2.5
>>>>> to 7.5 range. On 40m there is a distinct dip at 7.05 MHz with SWR
>>>>> 2.5:1. On 20m there is a distinct dip at 13.850 MHz with SWR 
>>>>> 2.5:1. On
>>>>> 10m there is a dip at 27.500 MHz with SWR 2.3:1 . Also, when taking
>>>>> these readings there was a slight breeze and the SWR measurements 
>>>>> were
>>>>> extremely unstable even though the vertical is guyed just below the
>>>>> traps. Aside from the usual comments about verticals and CC in
>>>>> particular, these results seem way out of line to me. A local ham has
>>>>> one, and using the 256B shows results that generally agree with those
>>>>> in the back of the assembly instructions. Any suggestions much
>>>>> appreciated. Happy New Year to all.
>>>>>
>>>>> ...robert
>>>>> -- 
>>>>> Robert G Strickland, PhD ABPH - KE2WY
>>>>> rcrgs at verizon.net.usa
>>>>> Syracuse, New York, USA
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>>>>
>>>
>>> -- 
>>> Robert G Strickland, PhD ABPH - KE2WY
>>> rcrgs at verizon.net.usa
>>> Syracuse, New York, USA
>>>
>>
>