Just another day in the RI Office - Ian Walker ZL1BFB
|In the early 1960's the Radio Inspectors tested not only for radio interference but also when applications for radio transmitter licenses were received, including CB sets.|
This photo was taken at the Regional Engineers Building in Federal St (Reid House) on the first floor where tests were carried out. This room was used for testing all appliances etc., for type approval to the BS800 interference specifications and the NZ Radio Regulations.
|The photo shows the tool shadow rack on the wall
designed and painted by myself and mounted on the wall above the
test bench where transmitters and tools etc. were tested for
|No prizes for guessing the identity of the fine
young clean shaven, well groomed person in the photo. I am
testing a CB set for type approval at the time of issuing a licence.
|Starting from the left of the photo we have the
shadow board, arranged by myself so that the tools required were
easily accessible. These had previously been located in desk drawers
or on shelves in a clutter***
|On the far left is the paint brush used to clean
the working components or graphite from within the equipment to be
tested. A lot of interference could be caused by tracking
within the appliance from soft carbon brush material. Many of the
electrical tools or pieces of equipment that came in for testing had
been given a had life and found to be electrically noisy, so
cleaning out the residue of the soft carbon brushes was a priority.
|The SKILL battery drill was used on the many
screws or sets that were holding appliances together and had the
advantage of not to rely on mains power other than for charging.
Allan keys were also used to open appliances. To the left of the
scissors is a second chuck for the drill and above this is the
socket set and drive adaptors for the battery drill.
|On the top shelf is an AM/FM modulation meter,
and to the right of this the two tone audio generator which was
applied to hand microphones. Next is the 50 watt dummy antenna
load, mainly used on MF Radio equipment; this had an output terminal
for the counter etc.
|For testing the accuracy of frequency measurement
we used the Marconi digital frequency counter. This
incorporated a down converter that would extend the counter range to
10 GHz. Again to the right is the 12 volt regulated power
supply which was coupled to the CB set being measured. This
was set at 13.5 volts and could handle up to 7 amps. It was
purpose built by the NZPO Radio Workshop in Galatos St.
|Like all the best radio workshops, we couldn't be
without the AVO 8 Volt/Ohm meter.
|Below the counter is the 3 watt / 10 watt Marconi
dummy load with direct readout of the power of the set under test.
The CB set under test is being tested into this and the read out can
been seen (on the original photo) as 26.499770 Hz. although the watt
meter reading is hard to read. Also on the main bench is a
hand held CB which was waiting to go through the same process.
|At the bottom far left is our oscilloscope, used
for harmonic checks and distortion on signals etc. generated by
appliances when operated from the mains. The equipment was
also able to be used in the field on a battery supply (although not
|The RI 2 measured frequencies from 35 MHz to 220
MHz with three RF amplifiers into one common IF amplifier unit.
There was a mains isolation head which acted as the artificial
antenna pick up.
|This was normally used in the office for
measurements of electrical noise from appliances using the mains.
The measurements were at + / - 3db at the frequency after
calibration, whereas the frequency of the RI 1 was for LF (beacon
band) to 30 MHz, and had to be recalibrated after each frequency
shift. It was accurate to also + / - 3db. Both measurement
receivers could be used in the filed by using lead acid batteries
and power supplies. Both units had similar types of artificial
antenna pick up for measurement in this case. When used out in
field testing they used calibrated antennas. All equipment at
the office was operated on isolation for the protection of staff.
|In order to prevent damage any equipment being
tested or the testing equipment itself, the bench top was covered
with a padded insulating material. From memory this was the
same as that used for appliance testing - a ¼ inch, rubber, non
*** No comment!!!!!! - ZL1TRH Back