iCOM PCR-1000

Details

Date of Manufacture:1997 - 200?

Manuals and schematics :

Download Here

Tube and Semiconductor Complement:

T.B.A

Model Notes

(To Be Completed)

The iCOM IC-PCR1000 was a conventional double/triple superheterodyne radio receiver produced in 1997. It was one of the first radios to be controlled entirely through software mounted on a personal computer. The only mechanical part of the set was the on/off switch.

This is not a "software defined radio" or SDR in the true sense, since the signal is processed by conventional analogue circuitry. 

Design

The receiver covers 10kHz to 1300MHz in tuning stes of 1Hz (minimum). In practice, the lowest frequency covered is 200kHz.  In all modes except wide-band FM, the set is a triple superhet with a first IF of 266.7 MHz, a second IF of 10.7 MHz and a final IF of 450 kHz. Selectivity may set to 2.8kHz, 6kHz, 15kHz, 50kHz and 250kHz for wideband FM (WFM). The two sharpest settings work with SSB/CW and the remaining settings work with AM and FM. On 50kHz, you can select FM or WFM - I can't say what the difference is, but there must be one, because weather satellites could not be resolved with WFM. 

The set is very sensitive - less than 0.5uV. This, coupled with the almost complete lack of front-end selectivity causes a severe problem if you attempt to attach a high gain (or even a long-wire) antenna to the receiver. Although the set has a 20db attenuator, it may still not be enough to stifle the impression that you are tuned to the entire SW band all at once. The only way to make the radio usable, is to attach it to an iCom discone, or similar low-gain antenna. On the shortwave bands below 50MHz, the radio uses fixed combinations of low and high - pass filters feeding a single RF stage. Above 50MHz, tracking filters are used feed in different RF amplifiers depending on the received frequency.

Direct digital synthesis is used to generate local oscillator frequencies. 

All receiver operation is controlled by an HD6433334Y04F CPU. Alignment settings are stored in a 24C01 EEPROM . 

Controls

These include: 

IF shift
Squelch
AF Gain
Buttons to enter a frequency into memory
Memory Write
Memory Clear
Tuning
Tuning step select
Band Select
Channel Select
Noise Blanker
AVC/Fast or Slow (NOT on or off!)
Voice Scan Control
Atteunuator 20db
AFC in FM Mode
Functions for programable scanning
DTMF functions for using the receiver to control the computer from a remote tx
Mode Selection - bandwidth get automatically selected by default
Selectivity - you can override the above
Muting

- And probably many that have been omitted.

With the the optional UT106 digital signal processing (DSP) unit, you get an automatic notch filter and a noise reduction control.

The set does not have synchronous AM or SSB demodulation.

There is a large tuning display (all those numbers), which can be programmed to show station names, as well as an 'S' meter and a large bandscope. 

Using the Receiver

Although the set has a built-in loudspeaker, most people will connect the output to a computer sound card. The set has an RS-232 cable for connecting to a a computer. To avoid disappointment, use the best sound card you can afford. I wasn't able to get satisfactory results using a laptop computer's built-in card. Nowadays, you will be lucky to find a computer having an RS-232 connector, so a good quality USB to RS-232 convertor will be required. The final step is to load the iCOM software (or other, if preferred). You might have to edit the receivers .ini file to tell it you are using COM port 11 (or whatever), since the software only allows up to COM port 4.

The previous paragraph really explains why this radio is unacceptable to the large number of people who are not computer experts, and have no desire to be. 

The remaining users of this set love it or hate it. There is no middle ground. The set's poor intermodulation performance (described above) coupled with iCOM's sometimes buggy sotware and receiver firmware has created disgruntled users. iCOM's refusal to publish the software commands for the radio created further unhappiness (in spite of the fact they were all hacked within a month or two). The happy users include the many who can only use simple antennas on HF and, of course those who don't use it for HF listening anyway. Plus of course the many who either used someone else's control software, or for whom the iCOM software gave no trouble. One of the nastiest things this set can do, is to lose its EEPROM settings (see later).

Those who rated the set highly found it could do most of the things they wanted and couldn't do before, such as capture satellite images from the NOAA satellites on 136MHz, decode teletype messages, display WEFAX, decode CW and Hellschrieber, SSTV and so on. For broadcast listeners, it could resolve SSB from AFN, receive MW and FM as well as TV sound. Even with a halfway decent antenna, the 20db attenuator can be switched in, giving at least a respectable performance.

The AFC used to be handy for satellites, because the radio would track the satellite frequency as it changed due to Doppler effect. (There are still some transmissions in the 136-138 band). The image on the right comes from a PCR-1000 and companion discone antenna.

Many radios of the period used "real" controls, as opposed to the virtual controls of the PCR-1000. The SONY SW-100, for example uses push-buttons exclusively, and the Drake R8 series has similar up/down controls plus a tuning knob that is connected to a digital encoder. In other words - the sets give the illusion of physical controls. They have no gears or dial cords. The buttons in these sets also connect to a CPU inside the radio.

The techniques used in the PCR-1000 are no longer used much in computer controlled radios.  It is hard to imagine that this set was brought to the market some 17 years ago. 

Service Note

Most problems with this radio are to do with software. It seems there are or were timing issues in establishing communications with the receiver and the host computer.

The receiver settings are all contained in EEPROM - the set has to be aligned using conventional equipment, but the adjustments are carried out via a computer program called EX2099.EXE, rather than a set of trimming tools.

It is probably best to have the set unplugged and the antenna removed when not in use. The receiver is powered from a small external power supply, which in this location got damaged (along with several other transformers) by a mains surge. Static from nearby thunderstorms can damage the RF amplifiers.

References

iCOM IC-PCR1000 Service Manual, 1997, iCOM Inc.