Minitor I

These units are not synthesized. They use crystals for the RF frequency and use Vibrasponder reeds for tone selection. There is nothing programmable about it.

Inside the case they all have in common two boards, the RF board, and the audio board. Obviously the RF boards are band specific, and come in low band, highband, and UHF models.

Generally speaking you can move these radios throughout their entire band although you may need to remove the ferrites and replace them with brass set screws if you are moving them upward in frequency past their design limits.

The audio boards come in four flavors; carier squelch only, PL only (RARE),four tone and carrier (EXTREMELY RARE), and two tone and carrier. The latter is by far the most common.

The Vibrasonder reeds can have their decode frequency changed by adding a bit of solder to lower the frequency and shave off a bit to raise the frequency. With a 'scope on one of the three pins of the reed (not sure which one it is) inject the tone you wish to decode into the receiver and tune the reed for max output.

In 2 tone mode, they can decode 2 sequences with one common tone. Jumpers can be strapped to select which fequency is used in alert mode (there is a 3 pos switch, mon 1, mon 2, alert).

The Minitor I pager also comes in a 2-tone model that does not have the selector switch for monitor/alert. Just a "bare bones" two-tone alert. The rubber gasket that covers the top of the pager under the metal frame has a hole for the switch, but underneath it is just a transistor and a few jumpers in the area of where the switch is supposed to be. The model number for this type of Minitor is CAO3EAC24688, and they seem to be fairly common with the fire dept's in Ontario since many FD's use shared channels.

Minitor II

These units are not synthesized. They use crystals for the RF frequency and a Perma-Code active filter for the decode frequency.

They have the option for a second channel, and the signalling is programmable (at least in later models). There is no option to do a PL squelch.

Table 1 gives the jumper arrangement for the standard model, and Table 2 for the different options. The jumper connections referred to in the tables are located on the Decoder and Squelch Circuit Board, unless noted with an asterisk (*).

*Located on RF Circuit Board.

Here are the Jumper and Test Point locations for the Minitor II.

Minitor IISV are the Stored Voice pagers. The quanity and length of the message are determined my SMT jumpers. Take a look at this chart to see how to set it up.

Table 1 lists the alert-mode tone-code sets available. The standard monitor is supplied with tone-code set 4 (A-B interrupt alert). The other tone-code sets are options.

Monitors equipped with the On-Duty/Off-Duty option use a tone-code set that includes tone C: Set 1, 2, 3, 5, 7, 8, or 9. In the On-Duty mode, the monitor responds to all the tone codes in the selected tone set. In the Off-Duty mode, the monitor does not respond to any code that contains a C tone, but does respond to all other codes in the selected set.

Tables 2 through 4 list the jumper connections for the tone code sets and for the standard and optional features.

*Require jumper cuts to remove.

*Located on RF Circuit Board.

Here are the Jumper locations for the Minitor IISV.

The pinout of the connector on the bottom of the Minitor II is as follows. The contacts are numbered with #1 being closest to the battery.

1) Charge input. It is connected to '+' battery tip through a 47 ohm resistor

2) Ground

3) 50 ohm antenna input

4) Audio disable. When this contact is grounded the internal audio amp is muted, used for charger amp application

5) Audio out. This is not speaker level audio, it is used as audio feed to charger amp. Normally at 0 volts ac / 0 volts dc, switches to .7 volts p-p ac/ .7 volts dc when pager is active. This output is not affected by the volume control and is not active during pagers power up or alert beeps. Not affected by 'audio disable' contact.

6) Alert out. This contact switches 'high' ( 2.5 volts dc ) when the pager is alerting. Stays high as long as pager is beeping. Does not switch high on power up beep. Used for charger "alert" lamp.

For reference that set of connections is referred to as J401, and Pin 1 is located directly under the screw.

If you are looking for a scan adapter for these pagers, contact:

They make a unit which uses very little power and offers a wide variety of scanning options, including scanning one or both channels for your paging call only. They also manufacture a "voicebox" module for the Maxtrac that installs inside the radio, and offers "radio voicemail" and simplex repeater functions.

Minitor III

These are fully synthesized and programmable for frequency and two tone signaling. But, as with the II, it has no option for PL. They also have options for scan, multiple codes, and vibrate. Supposedly the III has a worse receiver than that of the II.

You need a Universal Programming Interface NLN3548A (see the schematics for this box elsewhere on the site).

You also need NYN8358A which is a programming stand that plugs into the UPI. Comes with the RSS (rather poorly written software).

Looking at the back of the programming base, the RJ-11 style plug has the contacts on the top of the jack. Label these contacts from left to right a,b,c,d. Inside the programming base 3 pins of 6 are used (they are labeled 1-6). a->3, b->1, c->5.

There are no out of band modifications for the RSS, yet.

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