Kris Kirby wrote:
> So what's the consensus opinion on how best to rack radios, duplexers and
> amps? I've got a 5' rack I'm putting everything into and my amps are
> continuous duty rated and accordingly have forced air cooling. What I'm
> looking at is that I have two 3RU shelves of duplexers, a 4RU amp, a 3RU
> power supply and then the radios themselves. I'd like to keep everything
> so the jumpers are as short as possible, and I don't want the repeater to
> overheat come summer.
There are plenty of amps out there rated for continuous duty in various
power levels that don't require forced air cooling. ;-)
Anyway...
> Most installations I've seen place the power supply near the floor. I'm
> also a bit torn when it comes to how to space things out to prevent any
> interference to the recievers if at all possible. By and large, it seems
> that to conserve rack space, I'll have to use two radios per shelf, which
> means the RX and TX will be on the same shelf. I do have a small quanitity
> of hardline I'm looking to wire the TX side with.
Sometimes common sense takes over. Where's your power at the site? In
an overhead rail configuration, or coming from the floor. Will your
cabinet be grounded/bonded to the ground system? Are you going to set
it on the concrete or isolate it from the floor as a possible ground
potential at lightning voltages?
There's some "practical" questions about the real site that you have to
answer before answering the "where to put stuff in the cabinet" question.
> Now, another question is that with 25MHz spacing, can I expect the 100W
> duplexers to survive in an enviroment with 150W going up on a different
> frequency (f+25MHz) using the same antenna?
Someone else will have to answer this part - I tend to say "use things
at their rated power levels or not at all..." but someone here may have
more useful comments.
> So far I've been playing with this idea:
>
> Duplexers
> Amp
> Radios
> controller
> power supply
>
> But an alternative that came to mind is:
> power supply
> amp
> duplexers
> controller
> etc.
Also don't forget depth -- many repeaters are designed to have the
radios in front and the PA in the back, in the same rack-space, vertically.
Our configuration in one cabinet is this, if it helps:
PC sized AC UPS/Ethernet/Telephone gear on a shelf
PC on a shelf
Gap in front and back
S-Com 7K Controller
VHF Repeater w/PA mounted behind (MASTR II Station/Repeater)
Gap in front, terminal barrier strip in back for various connections
Controller
UHF linking repeater w/PA mountd behind (MASTR II again)
Monster Astron Power Supply for all of the above
(We might be changing this a bit and switching to GE MASTR II power
supplies if the Astron ever dies... then each repeater would have its
own power source.)
Duplexers are not in this cabinet, they're mounted to a shelf behind the
cabinets about 2' below the ceiling. All cabling to them runs from the
polyphaser panel to them and then down into the tops of the cabinets.
If we can, we use good quality N-bulkhead connectors to do pass-throughs
from the outside of the cabinet to inside, avoiding putting a cable
through a possibly sharp-edged hole in the top of the cabinet. (Also
gives a convenient test point, and we've never seen a good quality
N-bulkhead passthrough connector cause us any trouble (yet... knock on
wood).
Cabinet is grounded/bonded to tower lightning protection system and all
three cabinets are side-by-side and bolted together. Cabinets are
raised off the concrete floor of the building by placing them on
custom-built "Trex" decking material platforms. This way the old
"everything rises and falls together" rule of lightning protection is
accomplished.
> Please, oh great gurus, impart me with wisdom. :)
No guru here, learned from others.
Nate WY0X
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