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AOR AR3000A "PLUS" Modifications
Introduction
The following modifications were originally developed by AOR (UK) Ltd as a result of popular requests by
enthusiasts. They are described individually and can be carried out on that basis but when all modifications
are done together they are collectively known as the "AR3000A PLUS" modifications.
The degree of difficulty in carrying out the modifications varies considerably. The discriminator modification
simply involves the addition of one wire whereas the narrow AM filter uses very delicate surface mount
components, fine wiring and the drilling of a hole in the main PCB. We therefore recommend that the instruc-
tion are read very carefully and tool kits inspected for suitability before attempting any modification. No test
equipment should be needed for carrying out the modifications but a basic DVM is useful for fault finding. All
modifications can be checked using off air signals and where applicable the SDU5000.
It is assumed before starting a modification that the AR3000 / AR3000A is in full working order and that no
previous modifications have been carried out. All description are based on the fact that the IF board has been
removed from the set; this however is not necessary for some of the simpler modifications and partial removal
is recommended by removing the five coaxial connectors on the front of the board and hinging the board on
it's remaining wiring loom over the back of the set.
In all the descriptions it is assumed that the front panel is facing towards you and is known as the "front" and
the rear panel away from you and known as the "rear". Where colour of additional wires is given it is simply
for clarity of description and is based on our original development of the modification. Components described
are again based on those used in our original development and in most cases can be substituted; we have
therefore only given recommended suppliers where the component is of a more specialised nature.
"Limited" support is offered by our technical department, time being valuable!
Written communication is discouraged in respect of these modifications due to the complexity of the
subject matter. For answers to quick questions, phone 01773 880788. AOR (UK) LTD, 4E East Mill,
Bridgefoot, Belper, Derbyshire DE56 2UA. England. Thank you.
WEFAX SATELLITE narrower switchable filter (1-3000)
The WEFAX custom modification has been designed to optimise the receiver's passband
for reception of orbital weather satellites operating in the VHF band around 137.500 MHz
and geostationary satellites operating in the UHF band around 1691 MHz. Ideally an IF
bandwidth of 30-50 kHz is required for reasonable results, unmodified the AR3000 /
3000A is too narrow on NFM and too wide on WFM.
A small PCB is mounted on the IF PCB and holds both the original WFM filter for BAND2
& TV sound reception plus a new filter offering approximately 50 kHz bandwidth. The
WFM filters are switched using an IC via a rear panel mounted slide switch (UP is narrow
and DOWN is standard). A small component change is also carried out to ensure the
squelch operates with the bandwidth switch in either position.
Of course you still require some form of data encoder such as the AOR WX2000 decoder/
printer (no longer available as new) or a computer hardware/software package. For VHF
reception a crossed dipole is quite adequate but a dish or yagi is required for UHF along
with a LNA (low noise amplifier). The slide switch may be easily reached from the front of
the set. The bandwidth is of course NOT selectable via computer control.
AOR AR3000/3000A receiver modifications.