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cushcraft r7 issues

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KC2KWR, Jul 20, 2013.

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  1. KC2KWR

    KC2KWR Ham Member QRZ Page

    does anyone know how to tell which way is up on the traps. there was one time arrows showing you but there gone. ive been looking for months! there's no picture of a r7 traps with a arrow on it. also is it true that there was only 2 manuals made for this antenna? 1991 and 1993 is the only ones you can get. i know these antennas were made in the 80's! i guess they didnt give one back then. my r7 is a 1992 but the capacitors on the coils are different.
     
  2. K8JD

    K8JD Ham Member QRZ Page

    If they have little drain holes, put them so the rain water and melting ice drains out.
     
  3. W9GB

    W9GB Ham Member QRZ Page

    The Cushcraft R-7 are fairly straight forward to assemble, and identify.
    Remember that the R-4, R-5, and R-7 share many of the lower vertical parts.

    The TRAPS for 15-17 meters were changed in R-5 and R-7 in early 1990s,
    after the 17-meter band was opened for USA radio amateur usage in 1989.

    Cushcraft R-7, September 1991 Owner's Assembly Manual
    http://www.angelfire.com/planet/als_space/ham/Old_Version_Cushcraft_R7.pdf

    Cushcraft R-7, July 1993 Owner's Assembly Manual
    http://www.mrhamradio.com/manuals/pdf/cushcraft_r7.pdf

    VISUALLY find the end cap (originally white) on the coaxial capacitor assemblies.

    W7MOT repairs
    http://w7mot.org/index.php?option=com_docman&task=doc_download&gid=381

    Troubleshootong Cushcraft Traps
    http://www.iol.ie/~bravo/Troubleshooting Traps.htm
     
    Last edited: Jul 20, 2013
  4. KC2KWR

    KC2KWR Ham Member QRZ Page

    thanx for the reply but that's the first thing that comes up when searching for the manual like i stated! thanx again though!! although as straight foward the anglefire manual and the 1993 manual claim to be they still dont tell you which way is up . it says thats very important to watch out for!!!!!!! hopefully someone out there can answer the impossible.
     
    Last edited: Jul 20, 2013
  5. KC2KWR

    KC2KWR Ham Member QRZ Page

    no drain holes in these traps! i wish they were cuz that would be a dead give away!
     
  6. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Did you get this picture?

    r7trap.jpg

    Maybe it'll help.
    Have fun
    73
    Gary
     
  7. W9GB

    W9GB Ham Member QRZ Page

    I have a Cushcraft R7 and R5 in the garage, and have repaired and restored a number of these 1/2-wave verticals over the past 15 years (since Laird/Cushcraft ended support).
    http://pa0fri.home.xs4all.nl/Ant/R5/onhr5eng.htm

    I have found many new local amateurs (Chicago area) struggle with these antennas -- due to lack of practical mechanical skills (high school shop) OR an understanding how a multi-band vertical 1/2-wave works.

    I don't live in NJ, so I can't run over to your house (on-site Elmering, teaching) --
    BUT you can take pictures and post them here on QRZ ... SO that you can be walked through the steps.

    Your postings are frustrating -- you are searching for a UP arrow, that does NOT exist.
    It is possible that you have an incomplete antenna OR another Cushcraft antenna (like the AP8).

    The manuals do show measurements and orientations (traps vertically and rotationally about the vertical element).
    Take an INVENTORY of your antenna parts. There are ONLY two orientations (UP or DOWN, using your terms) the pre-assembled traps can be oriented.

    The Cushcraft R-5 (parts inventory in first photo) at 17 feet shares ALL same parts for 10,12,15, and 17 meter traps ! The R-7 adds 2 traps higher up on that antenna, for 20 and 30 meters.
     

    Attached Files:

    Last edited: Jul 20, 2013
  8. KC2KWR

    KC2KWR Ham Member QRZ Page

    ok heres a pic of the traps. 10 meters from the top to 30 meters on the bottom. i have every part for this antenna and i put it together exactly according to the picture of the 1991 r7 manual. the arrow thing im talking about is "NOTE THAT THE ARROWS ON THE TRAPS MUST POINT UP WHEN ASSEMBLED" when i got this antenna i completely stripped it down. so im just following directions. all the parts measurements are correct according to my manual but the picture does not show my dual 30 meter capacitor. DSC04439.JPG
     
  9. W9GB

    W9GB Ham Member QRZ Page

    The orientation of the traps, in your Photo, are CORRECT -- UP on the Right and DOWN on the Left.

    Regarding the Dual coaxial capacitor for 30 meters, as you noted, it is not shown on the April 1991 manual.
    HOWEVER, this 30-meter trap (using a dual coaxial capacitor) is shown in the last revision, JULY 1993.

    The early 1990s saw a number of production revisions to the R-5/R-7 design to fine tune WARC band performance (especially 17 and 30 meters).

    Cushcraft/MFJ R-7 Vertical Antenna Manual, July 1993 revision.
    http://www.cushcraftamateur.com/pdffiles/r7.pdf

    NOTE: You will notice that the 20-meter trap (staggered), shown in the July 1993 manual, is not like your trap.
    Your 20-meter trap (in photo) is like the EARLIER production version (April 1991).

    As I stated earlier, your lower sections (and traps) are little changed R-5/R-7.
    You will have to play a bit with the 20-meter / 30-meter traps (dimensions between traps) using an Antenna Analyzer -- as a starting point with dimensions from manual.
     
    Last edited: Jul 21, 2013
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