Tech Flashback: Gold Apollo AL-924-T Synthesized POCSAG Pagers

Just recently, I posted about my Motorola Advisor pagers, which got me interested in acquiring a more modern style of pager – namely one with a frequency synthesizer so that I don’t have to worry about ordering custom cut crystals for each frequency I intended to operate on and doing the necessary surgery. A bit of trawling on the internet didn’t leave me many options, mainly because the pagers from overseas were mostly UHF band (in the 900Mhz band), quite a few were Flex. It seems pagers are very much hard to get.

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That was, until I came across two auction listings from an Australian seller for a refurbished Gold Apollo AL-924-T pager. The starting price was quite high for what was essentially a novelty to me, but I was prepared to pay to make sure I had some examples of synthesized pagers. Buying a single custom-cut crystal would have been half the asking price. The best part? These were also mostly hand-programmable, so no more programming cable needed for basic changes. In the end, I was the only bidder, and I ended up with the two units seen above – one formerly rebadged as Xacom Novelle which was somewhat beaten-up, and the other Apollo branded and still very much “as new”.

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Being a much more modern pager, it’s volume is about half that of the Motorola Advisor I reviewed earlier. In order for it to achieve its compact size, it sacrifices a number of keys, resulting in only three buttons which make operation a little more tedious. Another thing it sacrifices is the size of the screen, which can make for difficulty in reading pages, hence the “zoom” functionality. The plastic protection in front of the screen is a slightly “gummy” type of plastic which takes certain knocks and self-heals. It isn’t particularly hard, so accidentally gouging it could be a possibility.

As for its vintage, I am unsure, but the online manual shows a date of 1998 in its example images, and its metadata points to 2002. When the pager is powered up, its default date is 2003, but it may also have been firmware upgraded. Very similar units are still sold today for customers of Vodafone Messaging.

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Its design is similar to the Motorola in the sense that it comes with a belt clip slide-in holster, which allows for you to belt-mount your pager and easily remove it for reading. The plastic is translucent, and the clip is designed for the pager to be inserted in one way, although forcing it in the wrong way is possible and results in a poor fit.

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The Gold Apollo also supports 2400bps POCSAG, and its frequency synthesizer can run from 130-180Mhz on the VHF models, regardless of what is printed on the back. One disadvantage is that the unit seems to have marginally lower sensitivity specs compared to the Motorola, likely because of its smaller size and synthesized nature. This unit came from WiPath, which is one of the companies supplying Apollo pagers in Australia. The cap-code information is missing, but is programmable, so it’s no big deal. Three contacts are provided for computer programming, and a barcode serial number label for inventory management.

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Gold contacts are used for the battery inside, which is one single AAA battery as with the Motorola, and the battery door slides in on rails with a tang that “clips” into place to hold it.

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There is a notch for threading a lanyard to wear the pager around your neck.

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It was also supplied with this chain and clip which is another alternative way of wearing the pager.

Hand Programming

Hand programming is very easy provided the pagers are “unlocked”, meaning that they use the default password of 0000. If they are not, and you do not know the actual password, then you must use the computer programming method instead. The instructions are freely available online and involve pressing the leftmost button while inserting the battery.

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With the limited number of buttons, data entry is done with the left-most key normally being the advance value key, the middle key being the move cursor key and the right most key being the enter-data key. During programming, as each step is entered with the enter-data key, you cannot go back to correct mistakes. Your options are either to finish the programming and then immediately re-enter programming mode and correct the mistake, or remove the battery and re-enter programming mode and start fresh.

In this case, the pager is unlocked so we can accept this and move to the next step.

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The previously programmed values in this unit show up in programming mode, and it seems that this unit can have its frequency and its deviation changed, where WB stands for wideband and presumably, it is also capable of NB narrowband.

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A total of up to six capcodes can be configured into the pager. The first toggle setting is whether a given slot is on or off. The next section is the capcode itself, followed by the four function code types. In most cases, this can be set to A for alphanumeric paging. There are other options, including – for unused, N for numeric, P for PRC numeric (as far as I can tell), I for international character-set (as far as I can tell) and T for tone only. Choosing the wrong type will result in either missed message data, pages being stored as personal messages, or garbled text.

Unlike the Motorola pager, the capcodes can be configured with no POCSAG framing limitations in play. However, the last two capcodes appear only usable for Mail Drop purposes by default, or personal message if computer-programmed.

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After the six capcodes are configured, the baud rate must be programmed. Choices include 512bps, 1200bps and 2400bps. Only one baud rate is supported at a time.

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The password can be changed to prevent others from reprogramming the pager, however, it is not recommended you do this unless you are sure you won’t forget your new password.

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The last step is to adjust contrast of the LCD screen, with 5 as the default. Increasing it over the default seemed to produce a stripey display, so I didn’t change this. After this step is completed, the pager will beep and pass! will show on the display to indicate it has been programmed. The pager will reboot (or you can cycle the battery) to run with the new settings.

Computer Programming

In stark contrast to others, it seems that computer programming software for the pagers is also very much openly available. As far as I can tell, they seem a little bit confused as their older programming software is labelled LPT1 which indicates the use of a parallel port, but the connection looks to be serial. There is a later version of the software for their USB programmer which has a Prolific USB to Serial chipset, so it seems that using a USB to TTL serial adapter with the right pin-order is what is necessary to use the software.

I did not actually try to link the software with the pager, as I was satisfied with hand-programming, but it’s good to take a look around to see what other features are available.

about-softwareOnce installed, the software will ask you for the password. The password is AC5678 (as listed on several sites and verified by myself).

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The software looks pretty horrid in full-screen by default, but once restored to normal size, it begins to make sense. The first page configures all the paging system parameters.

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The second page configures the alerts and other functions of the pager, and can configure date format and power up logo text.

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The final page configures the pager’s text prompts for localization purposes.

Powered Up

Owing to the fact that this post is relatively image heavy, and the full manual is pretty easy to get, there isn’t many images of the pager “in action” as some of the other images are much more interesting.

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When idle, the screen is blanked and a small target appears in the top to let you know the unit is powered up and receiving. Once awoken, we get the battery status, and time/date displayed in double-sized font. The display is a matrix display normally run with four lines of text unless in zoom mode where only two lines are displayed.

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The unit has a very orange coloured backlight with a textured screen at the back. The backlight is activated by pressing and holding the rightmost button for three seconds, and stays on until the pager goes back to idle. The evenness of the backlight is nowhere near as good as the Motorola’s EL backlight, and its orange colour suggests it’s an incandescent backlight as well – not an LED!

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Trying to review pages using the buttons results in a stern reminder that I haven’t received any yet. It seems that even though this unit is claimed to be refurbished, its internal back-up must have failed as replacing the battery even for a short period results in the loss of time, date and all received messages.

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The menu itself is very Motorola-esque, with more options. From left to right, you can change the alerts, you can turn off the pager, set up a do-not-disturb period known as “sleep”, set up to five alarms, set the time, set-up auto-scroll, toggle the zoom mode and switch between mail drop, private and regular messages.

Torn Down

It would always be nice to take a look inside – and even though I paid more than I had wanted to, I still wanted to take it apart. The unit itself is held together by two screws – one is visible in the corner, and the other is inside the battery compartment area. Once the screws are removed, prying on the shell releases the two halves.

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The unit itself is similar to the Motorola in the sense it has two boards – the top board is responsible for the air interface and notifications, with the bottom board responsible for the LCD, memory, time, buttons etc.

The radio board appears to have three adjustment pots or caps on the rear. The programming contacts are also visible and somewhat dirty from solder flux – it appears the rightmost contact is ground, with the left two either RX and TX or TX and RX (I did not determine).

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The antenna is a ferrite rod with band as with the Motorola, and a few crystals with silicone sleeve coverings are visible. The vibration motor and beeper are also placed on this board.

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The bottom motherboard itself is mostly bare, with their own ASIC marked AL-A25_6 running the show. It seems very likely that most of their pagers are based around the same IC with a different shell. A Microchip branded serial flash can be seen to store configuration.

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The front is adorned with the LCD and the incandescent backlighting (one underneath, the other visible to the right). The front panel buttons are soldered down switches.

Compared with the Motorola Advisor, it is much more modern technology with no ceramic packages in sight. The number of components is markedly reduced, and the whole unit is approaching a “system on a chip”.

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The errant memory back-up seems to be an ELNA 3.3v 0.22F supercapacitor. There is no outward signs of problems, but it probably deserves to be replaced seeing as the unit will not hold time nor messages across a battery replacement.

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We end our teardown with an image of the empty front shell and LCD window.

Conclusion

This unit is quite a modern pager and has many desirable features, not least its hand programming facility, ease of getting the programming software, synthesized frequency and support for multiple capcodes without frame restrictions. Even though it cost me a little more than I expected to get it, and its small size leads to some frustrations when using it, it’s quite likeable mainly because it has many possibilities.

When I ever get the time, I would like to implement a 2m band amateur radio POCSAG paging system for fun maybe on a simplex channel at low power just to see it can be done. Others have formerly done it with TNCs such as the Kantronics KPC-9612+ which is insanely overpriced in my opinion, but with SDR technologies and GNU Radio, it should be possible to get it done using gr-mixalot and an SDR with transmitting functionality. At least with these units, I shouldn’t need to worry about ever cutting a custom crystal or tuning it up.

However, it seems that these units have seen some time, as its internal back-up super-capacitor is probably not functioning. At this stage, I’ve got a few on order, ready for surgery.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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One Response to Tech Flashback: Gold Apollo AL-924-T Synthesized POCSAG Pagers

  1. Jason Brown says:

    Hi Gough. I thoroughly enjoyed this article and also your article about the Motorola Advisor pager. I have an Apollo AL-924 pager. I discovered something interesting about it. If you hold down the far right button while you insert a battery that will make the pager go into a self test mode.

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