Ed,
Thanks for putting a clarification of these devices on the reflector. There
are many other consumer devices on the market which use the 433.92 MHz and
the 902-928 MHz amateur bands under Part 15. The integrated circuit RF
devices available on the market for OEM's (from RF Monolithics, Linx and
others) are designed to be compliant with Part 15 for remote indicators and
remote control (garage door openers, TV remotes, etc).
N4UAU wrote a series of articles on remote control system(s) in the amateur
band (and for legal amateur purposes) using the Linx LC series of T/R
devices at 433.92 in the Jul/Aug, Sep/Oct and Nov/Dec 2000 QEX Magazines.
See http://www.linxtechnologies.com/ for data sheets and application notes
for 433.92 devices.
My own testing of these (Linx) devices at 433.92 using coded data streams
and decoders indicates I can reliabily achieve 500' - 1000' ranges using
simple 1/4-wave antennas in virtually any surrounding. This could be very
handy for remote control of a HF station, etc., and adding a simple
transistor RF amp. (it would be legal to do so by amateurs in the amateur
bands provided the appropiate Part 97 identification rules are followed)
could easily extend the range and reliability.
Such (simple and economical) T/R devices would be useful to control an
amateur HF transmitter from the location of a 'neighbor' experiencing
RFI/TVI/CATVI, telephone RFI, HiFi interference, etc., to facilitate rapid
and efficient testing and demonstrate the effectiveness of filter
application to consumer equipment in 'real-time', and without the necessity
of having another ham of the appropiate license class operate your
transmitter upon command/request via telephone or VHF/UHF links.
There is a growing concern over the proliferation and concentration of Part
15 devices which operate in the amateur bands and their collective
(cumulative) source of energy affects upon amateur communications (and any
shared services). [See January 2002 QST, "DC Currents", page 15]. The
effects of these retail devices will certainly be more noticeable in areas
of urban/suburban (concentrated) population, but neverless, it is a serious
matter to be dealt with by the amateur community.
73, Dave, K1FK
Fort Kent, ME
|