This was a discussion from a long time ago. The information is still very useful.
https://groups.google.com/forum/#!msg/r ... 7NoptB1p0J
The problem with all tensiometers that I have seen offered is that
they measure across the spoke so part of the reading is spoke
thickness and none of these instruments allows zeroing the gauge on
the spoke, tare, so to speak. Besides, Hozan in particular and others
I've seen use too large a test load, one that will affect tension of
the spoke being measured.
For this reason I designed a precision gauge that measures from the
support side and uses a dial micrometer so that small deflections can
be used. It also zeroes on the spoke and, because it uses such a
small deflection, bending stiffness over a 100mm span is small enough
to make the difference between 1.6 and 2.0mm diameter spokes
insignificant. The instrument is shown in "the Bicycle Wheel" and was
in production at Avocet but shops were unwilling to pay $300 for this
precision calibrated gauge. 100 of them were subsequently sold by DT
in Europe.
Jobst Brandt
