Hi all,
This discussion brings up a couple of points, both fairly off the
Ten-Tec topic, however they are certainly on the topic of two way radio
and since the subject line has already been labeled "OT", it should be
alright.
First, retrofitting an older fluorescent fixture, which originally
had a plain iron core transformer style ballast, with a new "electronic
ballast" could possibly make more noise than the electronic ballast
would have made in a fixture designed for a electronic ballast. This is
because the fixture may have different shielding of all the wires, and
different spacing between the metal frame and the fluorescent tubes, and
therefore different capacitive loading of the switching devices in the
ballast. I understand the motivation to change from T12 tubes to T8
tubes and considering the cost of labor I wonder if it makes sense the
change the ballasts in old fixtures to accomplish this, compared to
changing the entire fixtures?
Second, the story of the building design department and the
wireless communications team not necessarily working together until
after it is too late, reminds me of a snafu at a former place of employment.
I worked for a county government two way radio shop. We contracted
service to municipalities in our county, including the city fire
department. We had been servicing the base station VHF FM radios in the
city's fire station for years. The department outgrew their old station
and got funding for a brand new state of the art fire station. They
wanted new radio equipment (They were using some very old yet reliable
equipment) and our shop advised them what radio gear they should budget
for. We included transceivers, antennas and transmission lines. We
calculated the length of transmission line needed, based on the location
of the room they had specified as the radio equipment room and the
location of rooftop antenna mounts they had specified. Based on the
needed length, we specified the transmission line and connectors. They
city fire department was looking forward to a top notch fire station and
radio system, and they were sure they would get it because the
architecture firm contracted to design the building was reputed to be
experts at designing fire stations. We asked them for details along the
way, and were always assured that everything would be just fine, because
the designers of the building were fire station experts.
The radio gear was all ordered and delivered waiting for the day we
would install it. We expected a straight forward job, mounting a few
antennas and running some heliax through conduits. We had already
programmed the radios to their channel plan, and made up the cabling for
power supplies and tone encoders and whatever else was required. Then
came the day we were supposed to install the radio system. We brought
all of the gear to the shiny new fire station. We were shown the
designated radio equipment room and the designated location of the
antenna mounts. We were surprised to find that the fire station design
expert architects did not realize that fire stations used two way radio
systems. There were no provisions for mounting the antennas where the
fire department wanted them mounted or anywhere else on the building,
and there were no conduits run from the radio equipment room to the
roof. I guess they figured it is wireless, so who needs conduits?
DE N6KB
Jim,
I've been retired for six years and do not have the NEC and FCC manual sets nor the ballast information available... It seems like this class of device was industrial / commercial use only and was not considered part 15. As previously stated the electronic ballasts were generating a lot of VHF - UHF energy which was strong enough to QRM standard one way pagers that were carried into the building. We ran a spectrum analyzer and the ballasts were within manufacture's specifications and in compliance with FCC regs but we could not use the slide projectors when the ballasts were energized. We got what was specified by our building design department (no coordination with my unit which was the company's "wireless communications team" http://www.csm-gh.com/ECS-2000.htm ) and the manufacture was not liable but replaced the A/V equipment anyway.
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