I just got some SMA:UHF adapters from L-com, and they had their catalog in the
box, which I browsed through desultorily, prompting the interesting
observations...
Fiber optic cabling is getting pretty commodity and inexpensive. A 20 meter
dual fiber patch cable is about $35 (the pricing looks like about $20-25 for
the connectors and assembly, plus a length dependent addition for raw cable).
Couplers to join two cables are in the $3-$5 range.
Ethernet to Fiber converters are about $75-200 depending on environmental needs
(waterproof ruggedized ones cost more)
The mouser catalog has Amphenol fiber assemblies for about $13 for a 20m long
dual cable with LC connectors.
I haven't browsed through the Mouser or Digikey catalogs for this, but it seems
that there must be analog transmitter/receiver components that are fairly
inexpensive for HF thru UHF use (I know there are microwave links for fiber
from Ortel, etc., but they arent' cheap)
I wonder what it would take to build a HF preselector/amplifier/fiber
transmitter and corresponding receiver. You could put the widget up the tower,
and completely eliminate the whole "feedline as a radiator" or "feedline
carrying lightning" issue. This is a receive kind of application.. It's
probably a bit bold to suggest putting your kilowatt linear up the tower, but
the idea is there..
Or, for relay/tuner controls...
A complete link is still in the $200 range (2 ends+cabling) but that's not
totally unreasonable. For instance, if you had to string several hundred feet
of multiconductor rotator or SteppIR controller cable.. copper prices are rising
For instance, 10 conductor AWG22 cable runs about $1/ft these days (Mouser
catalog page 904), so a 300 ft run is going to be $300. Compare that to a
couple 75 dollar boxes on the ends and a cable at $20-30.. Browsing page 2075
in the catalog, it looks like the low end cables are about $0.03/ft....Single
mode (higher data rate) runs about $21 for a 20m cable and $16 for a 10m cable
($5/10m or $0.15/ft for the cable)
I've also started to see this kind of thing showing up used/surplus (when they
refurbish a business/commercial property, and pull the existing cabling
infrastructure out).
Maybe we need to start pushing the mfrs to build rotators, relay boxes, and
stuff with fiber interconnects.
Has anyone seen something like a "fiber to relay contacts" box? (sounds like a
good QST project).
(for short range.. the TOSlink plastic optical fibers like are used on audio
gear are really cheap.. the LED and/or detectors are about $1 each... Cable is
about a buck a meter in small quantities.)
Jim, W6RMK
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