Hello Tom:
I had a similar problem with an R-7000 .. I set up the antenna and it tuned
just like the book said .. After
running about 200-300 watts on 20M RTTY the 20/30/40 meters were not tunable ..
Cushcraft reps told me the
problem was installation .. This is installed on a mash fastened to a chimney
and was 15+ feet above the roof
and chimney.
Cushcraft sent me a replacement trap .. I installed the new trap and it acted
new. This worked fine until I
run about 300 watts on RTTY .. The problem returned .. I did not want to bother
with the antenna any more
because I heard many others with the same problem .. I believe N1SIX at
Cushcraft may be able to help ..
I have several R-7 antennas installed in three station locations. These have
been run at 1 kW without problem.
GL Charley
Tim Billings wrote:
> -----Original Message-----
> From: Tim Billings [SMTP:billings@nbnet.nb.ca]
> Sent: June 7, 1998 1:38 PM
> To: 'antennas@qth.net'
> Subject: FW: R7000 VSWR Problems
>
> -----Original Message-----
> From: Tim Billings [SMTP:billings@nbnet.nb.ca]
> Sent: June 3, 1998 8:24 PM
> To: 'techsup@cushcraft.com'
> Subject: R7000 VSWR Problems
>
> HI.....I am an owner of a R7000 Vertical and I have been having problems in
> trying to
> lower the SWR on this antenna. The 10M, 15M and 17M band VSWR is fine...But I
> have been unable to
> lower the VSWR on 20M and 40M.
>
> I have tried the following...
> * Tested antenna at both feedpoint and at transmitter with no noticeable
> change in VSWR
> * Changed out coax feedline in an attempt to find problem in coax.
> * Tested VSWR with 3 meters (Autek, radio, tuner)
> * Relocated antenna
> * Varied height above ground.
> * Adjusted the lengths of the antenna sections in question.
> * Checked the VSWR readings with another MN7000.... No change
> * Cleaned all contacts and joints
> All the above resulted in no changes in the high (6 to 9) VSWR.
>
> HOWEVER.... I did disassemble the top two traps and cleaned the contact
> points. When I reassembled
> the traps and reinstalled the antenna with the dimensions as per the
> manual... the VSWR was low...1.2 to 2
> on the two bands in question..BUT..as power (80 to 100 watts) was applied the
> VSWR climbed again to
> 6 to 9 on the 20M and 40M bands.
>
> I am looking for solutions to correct the problem....Can you help ???
>
> Thanks
> 73 de Tim VE9XA
>
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