[Test-Equipment] M.C. Jones Model 711N MicroMatch

[k4pf at juno.com]

> Richard Knoppow  <1oldlens1 at ix.netcom.com> wrote
The original article describing the Micromatch is in 
QST for April 1947. There is a description of an upgraded 
version from the March 1955 edition of QST at: 
http://www.cqham.ru/zm.htm
This may be pretty close to the commercial version you have.

Hi, Richard

Thank you very much for the research, but this 711N is quite a bit
different from the original Micromatch design, which used a series
resistor in the coax center conductor to sample rf current.
The series resistor was about 1 Ohm, made up of something
like 10 small carbon resistors in parallel.
That design was subject to burnout at high power and/or high SWR.

This model Micromatch 711N apparently has no current sense resistor,
as determined by an Ohmmeter check across the two coax connector's
center pins.

The new design sampling unit is quite compact, whereas the previous
Micromatch pickup was physically large to allow air to circulate around
the current sense resistor.

73,
Ed Knobloch