The Realistic PRO-2022 certainly is a look-alike for the all-time popular, but now-discontinued, PRO-2005. But is the similarity only cosmetic? What tricks can be done to increase the utility of the lower-cost 2022, now available from Radio Shack and Grove Enterprises? Of the greatest interest, can cellular phone coverage, censored at the factory, be restored? Yes!

After removing the two upper back screws and the top lid, locate the black cable just behind the front panel. Adjacent to the cable are four diodes locations: D42, D43, D44 and D45.

D42
is not present; installed, it adds the 68-88 Mhz European mid band (which includes the US 76-82 MHz mid band), removing the US 30-54 MHz low band.
Even if a switch were installed to allow the diode to be selected, additional components and realignment are necessary for that higher frequency coverage. Don't do it!

D43
is present, allowing the 800 MHz band to be received; the diode may be deleted so that the same microprocessor may be used in scanner models which don't have that 800 MHz capability. Don't touch it!

D44
is present, deleting the cellular mobile and base frequencies. If one lead is cut, total 806-960 frequency is restored, including 30 kHz steps in the cellular band. Keep in mind, however, that mobile telephone eavesdropping is prohibited by the Electronic Communications Privacy Act!

This modification may void your warranty it is best to cut the lead carefully, gently separating the gap slightly so that it may be resoldered in case the radio needs warranty repair later.

D45
is not present; installed, it makes the cellular 30 kHz increments change to 12.5 kHz. A small SPST switch connected in series with one lead of a 1N914 or 1N4148 could allow selection of the 25 kHz step interval in those areas which utilize that channel spacing.

Mods for the discriminator:
There is a growing interest in tapping the discriminator audio out of various scanners for decoding a variety of signals, (in my case (pocsag) including:CTCSS, POCSAG, DTMF tones, RTTY, FAX, ETC. By and large, such signals *cannot* be taken from TAPE REC jacks, headphone jacks and EXT SPEAKER jacks because of the voice-band filtering that is done between the signal source and these output jacks. So, not a good thing.

Therefore, it is necessary to tap directly to the output of the discriminator chip in your scanner.
For the Realistic Pro-2022 it is pin 9 on the MC3361(x).

Hints and Tips

Improving Squelch:
Replace resistor R91(33K) with a 220K type, chip, 1/10W, 5%, to improve the squelch sensitivity. MFR's Part No. RCM224J55