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ICOM IC-R9000
Modifications - under construction

This page gives a detailed account of the modifications that were made to the ICOM IC-R9000 receivers that were used by the Dutch Radio Monitoring Service (RCD, now: AT), when the device was used in combination with the PAN-2000 intercept system. As the RCD/AT used many of its devices in a mobile environment, it was important to reduce the weight and power consumption.

It is estimated that approx. 20 complete PAN-2000 systems were ever made. After they were decomissioned – sometime between 2005 and 2007 – they were sold as government surplus, but in many cases the ICOM IC-R9000 got separated from the main PAN-2000 set, as it was a desired professional (amateur) receiver.

When we obtained our PAN-2000 set (mid-2018), it came with an unmodified IC-R9000, as the original one had disappeared. Although an unmodifed one will work with the PAN-2000, it will have a reduced accuracy and performance.
  
ICOM IC-R9000 communications receiver

As we wanted to restore our PAN-2000 to its original operating conditions, we decided to modify our IC-R9000, so that it would have the best performance when used in combination with the PAN-2000 panoramic FFT unit. This involves altering the AGC circuits, using a different 10.7 MHz IF path, changing the characteristics of some filters, and adding new connectors at the rear. All this would not have been possible without the wonderful assistence from several parties [1][2].

Interior - top side Interior - bottom side Demodulator unit IF unit
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Interior - top side
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Interior - bottom side
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Demodulator unit
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IF unit

Modifications
Rear panel modified
All connections of the receiver are located at the rear panel. A row of sockets along the bottom edge of the case, provides room for expansion. Some of the connections are brought out on poor quality CINCH (RCA) sockets (e.g. IF output), whilst others are missing completely (e.g. CENTER).

For use with the PAN-2000, some CINCH sockets were replaced by BNC sockets and a new (BNC) socket was added for the discriminator meter (CENTER). It was decided to remove the sockets for DC OUTPUT, EXT SP (external speaker), REC / REMOTE and REMOTE, and use the vacated space to fit 3 BNC sockets for IF, TUNING and REMOTE.

For this, the connection board was modified, which involved removal of some of its parts, and cutting away a section to accomodate the new BNC sockets. In the new setup, the sockets for DC OUTPUT and REC / REMOTE were dropped.
  
Modified connection board and new BNC sockets, seen from inside the receiver

The REMOTE connection was made available on one of the BNC sockets, as it was found to be more robust than the existing 3.5 mm jack. For connection to the ICOM REMOTE socket on the PAN-2000, a simple BNC-BNC cable can now be used. Another socket was reserved for the IF output, which was previously present on a CINCH socket at the other end of the rear panel (on most receivers the IF signal was fed out over a fixed coaxial cable. The third socket was reserved for the signal from the discriminator meter, here known as the CENTER meter (or: CM OUTPUT).

Audio output and REMOTE socket Power connection board at the rear of the bottom side Removing components from the connection board Modified connection board Loop wire at the bottom to restore speaker connection New BNC sockets mounted in the rear panel Modified connection board and new BNC sockets, seen from inside the receiver New BNC sockets at the rear (note that the order may differ between receivers)
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Audio output and REMOTE socket
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Power connection board at the rear of the bottom side
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Removing components from the connection board
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Modified connection board
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Loop wire at the bottom to restore speaker connection
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New BNC sockets mounted in the rear panel
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Modified connection board and new BNC sockets, seen from inside the receiver
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New BNC sockets at the rear (note that the order may differ between receivers)

Mains power supply removed
As the IC-R9000 was commonly used in a mobile environment, the internal mains PSU was not used. As it is rather heavy — the PSU is built around a conventional transformer — is was often removed in order to reduce weight. Note that this was not the case for the receivers that were used in a (semi) stationary setup, such as the ones that were used in fixed monitoring stations.

The image on the right shows the conventional transformer of the IC-R9000. It is fitted in the lower section of the case, at the rear right.

In our case, we decided to leave it intact, as it allows the unit to be powered from the mains during demonstrations. Note that, when the receiver is powered from the PAN-2000 FFT unit, the jumper connector at the rear of the receiver has to be removed, as the socket is needed for the 15V DC power supply from the PAN-2000. Do not lose the jumper plug, as you might need it when powering the receiver from the mains.
  
Mains transformer

Note that the receiver requires a minimum DC voltage of 13.5V for a proper operation. It will not work well with a lower voltage. In the case of the PAN-2000 system, it was powered by the 15V DC output of the FFT Processor. Suitable connectors for the DC INPUT of the IC-R9000 can be difficult to find, but it is possible to modify an old harddisc power connector for this purpose.

Mains transformer
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Mains transformer

Timer disabled
The receiver has a timer switch at the top left of the front panel, just below the power switch. If this switch is pressed accidentally, the device can not be turned on by supplying power and switching it ON. As in such cases, the PAN-2000 will be completely dead, it might be wise to disable the timer switch altogether.

Monitor disabled
At the center of the front panel of the IC-R9000 is a monitor, or display, which is built around an amber cathode ray tube (CRT). A CRT requires a high voltage and usually consumes a significant amount of energy. Although it is possible to turn the display OFF by pressing the DISPLAY button at the front panel, this switch only interrupts the video signal and not the power supply. As the display was not needed — the PAN-2000 has its own display — it was decided to cut the power supply to the monitor, as this would reduce the total power consumption of the system by 1A.

This was done by cutting the brown wire from the connector at the back of the display casing, and bringing it to the back of the radio, were it was soldered to the outer pins of the (modified) 5-pin DIN DATA socket. When for some reason the display was needed, e.g. when servicing the radio, the display could be enabled by installing a shorting plug in the former DATA socket.

When the modified Dutch IC-R9000 receivers were decommissioned, many of the new owners reverted this modification by soldering the wires back together, in order to restore the display.
  
Monitor power switch added to the options board

We decided to take a different approach, by adding a switch to the options board (below the small removable panel at the top of the receiver). This allows the monitor to be enabled/disabled easily for demonstration and testing purposes. This solution is shown in the image above. For this modification, only the brown wire from the connector should be interrupted by the switch.

Accessory compartment at the top Monitor power switch added to the options board Wiring of the monitor power switch Monitor power switch wiring
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Accessory compartment at the top
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Monitor power switch added to the options board
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Wiring of the monitor power switch
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Monitor power switch wiring

Discriminator output added   TUNING
In order to be able to tune-in more precisely to a station, the IC-R9000 has a discriminator meter (shared with the S-meter). In case of the PAN-2000 however, the receiver is controlled remotely and the discriminator signal is not available externally, so it is necessary to add an output for it.

To accomodate a BNC socket for this additional output, the narrow connection board (at the bottom side of the receiver, near the mains fuse) will have to be modified (as described above).

The new discriminiator output is made by taking the discriminator signal at pin 1 of IC14 on the demodulator board (also available at the top of R221), and bringing it out via a 10K resistor that is placed in series with a coaxial cable that leads to the new BNC socket at the rear. The shield of the coax is connected to the ground side of R224 (the pin nearest to the edge of the PCB).
  
Modification - discriminator output added

The new (modified) situation is shown in the image above. On the IC-R9000 receivers used by the RCD, the discriminator output was labelled CM OUTPUT (center meter output). It should be connected the TUNING socket at the rear of the PAN-2000 FFT Unit, using a BNC-BNC cable.

 View circuit diagram and PCB (PDF)

Power connection board at the rear of the bottom side Area where discriminator output should be added Modification - discriminator output added
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Power connection board at the rear of the bottom side
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Area where discriminator output should be added
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Modification - discriminator output added

New IF output
At the rear of the receiver, a socket is available with the 10.7 MHz IF output. This signal is needed by the PAN-2000 in order to be able to create a panorama display. In practice however, there are several problems with the existing IF output, as a result of which modifications are necessary.

In the default situation, the IF signal is available on a CINCH socket at the rear, close to the ACC accessory socket. This is a bad choice, as CINCH sockets are intended for low-frequency signals only. Furthermore, the place that is chosen for the socket is not a very good one, as it appears to be picking up spurious signals and noise.

For this reason, a new 10.7 MHz IF output has been created in the vacated space near the connection board (see above). The IF signal can be made available on a new BNC socket, or via a fixed cable to the IF input of the PAN-2000.
  
New IF output connection on the IF unit

In our case, we decided to add a BNC socket, so that the receiver does not have any fixed wiring. To accomodate the new socket, the connection board behind the rear panel has to be modified. This is described above. The existing (grey) coaxial cable is removed (cut-off) and replaced by a better quality teflon one, that is soldered directly to the pins of the removed socket on the IF unit.

New IF output connection New IF output connection on the IF unit Old IF output connection removed (cut-off) New BNC sockets mounted in the rear panel Modified connection board and new BNC sockets, seen from inside the receiver New BNC sockets at the rear (note that the order may differ between receivers)
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New IF output connection
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New IF output connection on the IF unit
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Old IF output connection removed (cut-off)
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New BNC sockets mounted in the rear panel
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Modified connection board and new BNC sockets, seen from inside the receiver
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New BNC sockets at the rear (note that the order may differ between receivers)

Documentation
  1. IC-R9000, Instruction Manual
    Icom Inc. 1989.

  2. IC-R9000L, Instruction Manual
    Icom Inc. 1999.

  3. IC-R9000L, Service Manual
    Icom Inc. 1989.

  4. Modification - new discriminator output
    2 pages [1].
References
  1. AT/RCD technician, Personal correspondence
    April 2018 — August 2018.

  2. Nico van Dongen (PA3ESA), PAN-2000 and system description
    Crypto Museum, July 2018.
Further information
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Crypto Museum. Created: Sunday 26 August 2018. Last changed: Sunday, 02 September 2018 - 21:17 CET.
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