AR3000A

AOR ar3000a User Manual

5 (1)

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 instruction 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. © AOR (UK) LTD 1994 - 1999 - Page 1

No responsibility is accepted for damage caused by customers carrying out these modifications.

Using the accompanying diagrams and photographs build the small WEFAX PCB, the parts list being as follows

1 x Blank PCB 30.5 mm x 15.5 mm 1 x SMD 4066 IC quad switch 2 x SMD 10k resistors 1 x Murata SFE 10.7 MF filter, bandwidth 55 kHz Bonex part no 080125 1 x 300 mm green wire 1 x 300 mm blue wire 1 x 300 mm yellow wire 3 x 30 mm tinned wire leads 2 x wire links

WEFAX PCB

"artwork" negati ve

Very carefully remove the existing WFM filter XF1 from the IF board and solder it to the new WEFAX PCB. Our experience tells us this is quite a fragile filter.

Add a 30 mm red supply feed wire to the hole in the IF PCB

AOR AR3000/3000A receiver modifications. © AOR (UK) LTD 1994 - 1999 - Page 2

No responsibility is accepted for damage caused by customers carrying out these modifications.

alongside the XF1 position (see photograph). Fit new WEFAX PCB to the IF board where the WFM filter XF1 was removed from.

The board should lean backwards with the filters towards the rear of the set (see photograph).

Solder the 3 wires to the IF board and the left hand edge of the new board to L7 transformer alongside.

Trim and solder the red supply wire to pin 14 of the 4066 IC on the new WEFAX board.

Locate and remove R57 4k7 resistor from the IF Board (see photograph) and replace with a 1k0 resistor.

Refit the IF board, twist the blue, yellow and green wires together and run them down the right hand edge of the IF board with the main loom. Follow the main loom towards the position of the new slide switch.

Using a sharp knife cut out the hole in the rear panel escutcheon next to the antenna socket to allow the fitting of a miniature DPDT slide switch. Drill out the mounting holes and fix the switch using 2 x M2x4 screws.

Trim and solder the blue, yellow and green twisted wires to one set of switch contacts connecting the yellow to the top connection, the blue to the middle connection and the green to the bottom connection.

The new switch now selects the standard WFM filter in the down position and the new narrower WEFAX filter in the up position. As a non technical test, tune to a WFM broadcast signal and switch in the narrower filter. You should hear slightly distorted reception as the incoming signal is deviated more than the filter bandwidth.

Refit the case halves and the modification is complete.

NARROW AM switchable filter (2-3000)

The narrow AM filter custom modification has been designed to optimise the receiver’s passband for reception of short wave AM broadcast transmissions. Generally speaking on long and medium wave a 9 kHz channel spacing is used (in Europe) and a 5 kHz channel spacing for short wave. The standard AR3000A AM filter is 12 kHz as this permits reception of “offset” civil airband transmissions, the same filter is also used for NFM.

The modification adds a rear panel switchable narrow AM filter (the same switch as used for WEFAX switching - both are switched at the same time if both options are fitted), the filter specification bandwidth is 4.0 kHz but when fitted “in circuit” is actually wider than this. There is still a very worthwhile improvement which helps reduce BLOCKING when listening close-in to a strong transmission, heterodynes may also be reduced or removed

AOR AR3000/3000A receiver modifications. © AOR (UK) LTD 1994 - 1999 - Page 3

No responsibility is accepted for damage caused by customers carrying out these modifications.

when listening to many transmissions. There is also a small increase in sensitivity over the standard filter by a few dB.

The additional narrow AM filter is fitted to the IF PCB with the data lines used to select the filter by diode switching in conjunction with the rear panel switch. The reception of NFM is still routed through the standard filter even when the narrow AM filter is selected.

When the narrow AM filter is selected the squelch closing position is affected. Instead of closing around 11 o’clock, it closes around 2 o’clock. This is not a problem as the

squelch is usually left “open” when monitoring short wave broadcast transmissions.

The squelch characteristic is normal and unaffected when in the standard filter position. The bandwidth is of course NOT selectable via computer control.

The filter used is a CFW455IT, Bonex part no 080079. The filter sits on a blob of hot melt between L29 and the existing

AM filter and is prepared in such a way that of it’s three connections the input and output legs are extended and pass through holes in the PCB and the earth connection sticks out of the side of the hot melt and solders to the earth plane on the top side of the board.

Move the grey loop of wire on the underside of the IF board as far to the right of the PCB as possible and drill a hole 0.8 mm ( through the board next to L29 on the IF PCB and suck the solder from the second hole if filled (see photograph).

Cut the input and output leg of the filter short and solder a 50 mm length of kynar wire vertically to each. Cut the middle leg of the three earth connections short and bend and cut the outer two to meet it. Solder all three together and add a 50 mm kynar earth wire

to exit horizontally to the filter towards the front of the set. The overall effect is that the filter should be able to sit low in it’s blob of hot melt with its top level with the muRata SSB filter CFJ455K, it’s two vertical wires through the prepared holes and the earth connection available to be soldered as close as possible to the earth land on the top of the PCB.

On the underside of the board add 2 x 1SS268 SMD diodes piggy backed onto 2 existing

AOR AR3000/3000A receiver modifications. © AOR (UK) LTD 1994 - 1999 - Page 4

No responsibility is accepted for damage caused by customers carrying out these modifications.

diodes D15 and D17. The 1SS268 is a double diode package but only one diode in each is used. Solder the front pins only.

Add a 22k SMD resistor to the front anode of the diode above D15 and a 5k6 SMD resistor to the rear anode of the diode above D17

Connect the non diode ends of the resistors together with a

piece of tinned wire and connect a 0.01uF SMD capacitor between this tinned wire and an earth plane (see photograph)

Connect a 300 mm length of yellow wire to aforementioned tinned wire and connect the kynar wires that are protruding through the board from the filter to the diode ends of the resistors, one to each.

Cut track to pin 6 of IC4 and connect a 300 mm blue wire to the now isolated pin. Connect a 300 mm green wire to the right hand anode of D19. Insulate the delicate surface mount work with hot melt Refit the IF board, twist the blue, yellow and green wires together and run them down the

right hand edge of the IF board with the main loom. Follow the main loom towards the position of the new slide switch.

No responsibility is accepted for damage caused by customers carrying out these modifications.

To test the unit tune to a broadcast AM station and switch the narrower filter in. You should hear a narrowing of tonal quality and a reduction in adjacent channel interference.

Refit the case halves and the modification is complete.

SDU5000 spectrum display compatibility (3-3000)

The SDU5000 is a new spectrum display unit designed to compliment the AR3000A (and other receivers). In order to provide compatibility, a custom modification has to be carried out to ensure the AR3000A will plug in and go!

Note: The AR3000 does not provide microprocessor compatibility with the SDU5000 so only basic facilities are available.

The modification to the AR3000A/3000 adds a rear panel BNC socket providing the required 10.7 MHz IF signal. The bandwidth is 10 MHz and gain is about 10dB compared to aerial input. A rear panel toggle switch provides AGC / mute for the SDU, normal is UP and active is down... the normal position being used most of the time. Of course the switch is NOT selectable via computer control.

Summary of SDU5000: The SDU5000 Spectrum Display Unit adds a variety of features to extend a receiver’s capabilities, such as visually identifying new active frequencies and taking measurements. The SDU5000 may be used with a number of receivers which have a 10.7 MHz IF output and produces a bandwidth up to ± 5 MHz in 1 kHz increments with a resolution of 5 kHz or 30 kHz.

The SDU5000 remains compact due to the use of an internal 3.1" HQM simple matrix 16 colour LCD 192 dot x 210 dot. An external home colour television with video input may also been connected (PAL or NTSC).

In particular the AR3000A has been designed to provide best compatibility by communicating directly via the receiver’s CPU via the RS232 port / SDU5000 COM1 ensuring the full potential of the SDU may be exploited.

Operation is extremely simple as the SDU5000 utilises an on screen menu system. The AR3000A frequency, mode & attenuator may be controlled from the SDU so that a displayed frequency may be easily monitored. When using the AR3000A, the cursor frequency is equal to the receiving frequency of the AR3000A, by using the cursor in the SDU, frequency and signal level can be read directly. This enables the SDU5000 to be used as a wide coverage spectrum monitor between 100 kHz to 2036 MHz with DDS providing an accuracy of 100ppm. Dynamic range is 50 dB with an acceptable input level between -10dBm to -90dBm with selectable gain control. The SDU-5000 has a multiple

No responsibility is accepted for damage caused by customers carrying out these modifications.

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