AJ wrote:
We've been given the opportunity to setup a remote receiver at the end
of local local cable television provider's plant on the hill to help
with coverage. Powering is the only issue we're running in to -
currently the only power available within 6 pole spans is the 90 V AC
plant power across the CATV coax. They've offered to cut in a power
inserter at this location to feed up to 4 amps of 90 VAC to us
(roughly 85 VAC at that point in the plant) - what is out there for a
reasonable cost effective solution to convert this to 12 VDC?
This stub of plant does not have RF across it, nor will it any time
soon (RF removed when fiber backbone was overlashed on the same pole
line). Our first concern was leakage but that shouldn't be an issue.
Build new coax plant as close to the desired location as possible. Have
the CATV company feed this coax with the power inserter. The power
inserter will allow the extraction of power without upsetting the RF if
it is ever re-activated. Have the lineman cut in an old CATV amplifier
housing with a mating power pack at the end of the coax line. Use the
power supply module (power pack) inside the amplifier to convert the
available AC to 24 volts DC. Then, use a regulator to cut the 24 down
to 12. Obtain a few spares of the power pack so when lightning does its
thing, you can get it back up and going.
Another option to continuing the coax plant is to have them cut in the
power inserter and then run some kind of power line (duplex cable) and
use this line to feed a CATV power pack housed in a weather proof box.
You can make the AC go much farther then the DC.
I had a ham remote receiver location work for many years using this
principal. The power availability wasn't nearly as substantial as what
you have. I was at the end of the line in a 60 volt plant. Nearest
power supply was 2 miles away and it fed the microwave receive site on
the same tower I was on. I had to be careful not to drag the AC down
too far or the receive site would go out. Available AC was about 45
volts and I used it to supply a CATV amplifier switching power pack (24
VDC out). The 24 volts fed a home brew charging circuit to trickle
charge a 12 volt SLA battery. Since the duty cycle was relatively low,
there was plenty of time to recharge the battery after use. The
charging circuit was limited so even if the battery was stone dead, it
wouldn't load the line too much that it outened the CATV microwave site.
Kevin
