Broadcast Technical Consulting and Sales
AM Antenna Current
Built by M. W. Persons and Associates, Inc.
|October 27, 2014: It is amazing
how customers come up with ideas for custom panels to solve needs that
manufacturers ignore. This one is is for AM antenna current
calibration. It goes between a current sample, such as a Delta TCA
ammeter, and a remote control system. The goal is to get exact
calibrations of antenna current from five power levels on a single
channel of the remote control. Linearity of the sample is the
problem. Calibrating at high power and then changing to low power
could give a sample that is way off and unusable for accurate
determination of power. A jeweler's screwdriver is used to
set each sample level. A rolled steel 19 inch wide rack panel has
excellent rigidity for the task.
|The panel has a DC
amplifier on the left that boosts the incoming DC sample by a factor of
five. So, a 0.5 volt sample becomes 2.5 VDC. Five relays, on
the right, select which of the five 10-turn calibration controls is in
use at the time. This panel was constructed to automatically use
"status" indications on a Broadcast Electronics 5000 watt transmitter to
select the appropriate calibration control in five steps from 5000 watts
down to as little as 25 watts..
Close attention to detail is important.
Wiring is run in such a way as to be easily serviceable or changed in the future.
Custom panels like this are built here often.
Questions? Email Mark Persons: firstname.lastname@example.org
page last edited 02/22/2016