Rivets in Force 12 DXpeditioning antennas; 160M antennas

Robert A. Wilson n6tv at vnet.ibm.com
Sun Dec 13 20:32:57 EST 1992


Sorry to take so long to reply.  I fell behind in my CQ-CONTEST reading.

There are two kinds of rivets used by Force 12:

            Closed-End                         Open-End
           ------------                      ------------
    | <--Steel mandrel is pulled up.  It pulls
    |    aluminum up and breaks off.
    |                                       (mandrel removed)
  -----      -----                           -----      -----
   | |        | |                             | |        | |
   | |       |   |  <---solid aluminum,       | |        | |
   | |        \_/       fills hole.  Doesn't  | |       /---\
   +-+                  elongate.             +-+

 Before      After                           Before     After

Normally, the closed-end rivets are used for permanent installations
(they can easily be drilled out when you need to disassemble the
antenna).  Rivets don't cost much (about 8 cents each for the big ones).

For temporary installations like the CE0Y DXpedition, the plan was
just to use uncrimped open-end rivets, held in place with heavy tape.
No good for a permanent installation, but OK for a weekend-long
contest.  Each element taper gets three rivets.

I do not know if they actually did it this way (I wasn't there) but
that was the plan.  Nice thing about this technique:  no tools of
any kind required to assemble the elements, not even a pliers!  All
holes are pre-drilled, so you don't need a tape measure either.

For those viewing the above drawings on funny terminals:
  "|" is a vertical bar
  "/" is a slash
  "\" is a backwards slash (backslash)
160 meter antennas on small lots.
I live on a small suburban lot.  I shunt-feed my 89' crank-up at the
base.  Tower is grounded with four 8' ground rods and some heavy braid,
but no radials.  I seem to get out really well.  Ground conductivity
is very good here in Silicon Valley -- must be all the silicon! ;)

Receive antennas are a big problem, because I have no room for a
beverage.  I use a small indoor 4-turn receiving loop from July, 1977
QST, page 30, with an Industrial Communications Engineers 20 dB 160m
pre-amp.  With the loop I can null-out the heavy line noise that
is being re-radiated by my tower.  The loop has a bit better S/N
ratio than receiving on the tower, but even with the pre-amp most
signals barely move the S-meter.  Guess I may have been an alligator
(all mouth and no ears) to some, but hopefully not to too many.

Finished with 409 x 66 = 53,988 (slept through the JA runs both
mornings; big mistake).

Bob, N6TV

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