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Beide Seiten der vorigen Revision Vorhergehende Überarbeitung Nächste Überarbeitung | Vorhergehende Überarbeitung Nächste Überarbeitung Beide Seiten der Revision | ||
skyperdescription [2018/09/06 23:30] df2et |
skyperdescription [2019/04/16 16:45] oe7bsh |
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These units support automatic time synchronisation to the DAPNET transmitter/core and rubric messages. The latter need an activation which can be sent out from the hampager portal (See "rubrics"). The rubrics abonnement is apparently lost if the battery dies. | These units support automatic time synchronisation to the DAPNET transmitter/core and rubric messages. The latter need an activation which can be sent out from the hampager portal (See "rubrics"). The rubrics abonnement is apparently lost if the battery dies. | ||
- | === RIC programming === | + | ===== Modification for UHF ham band use ===== |
+ | |||
+ | The old German POCSAG network used 465.310MHz as broadcast frequency. Fortunately the units can be modified to work in UHF ham band range. In Germany there is a centrally coordinated frequency used for POCSAG broadcasting: 439.9875MHz. To make Skypers work on this QRG you need to change the crystal, remove a frontend filter and probably add two capacitors to the replaced crystal. After that it is necessary to re-align the RF components. | ||
+ | |||
+ | ==== Removing the frontend filter ==== | ||
+ | |||
+ | First thing to do is removing the frontend filter because it is designed for the 468MHz range and rather deaf on UHF hamradio band. It has four pins. the outer two are in- and ouput. You can easily remove it by removing solder with solder wick on the outer pins. The inner two are GND and rather hard to get warmed up. Warm those both up at the same time by adding some more solder and then gently pulling the component from the other side. | ||
+ | |||
+ | {{ :skyper:skyper_removed_saw.jpg?direct&600 | Removed SAW filter}} | ||
+ | |||
+ | In order to make it work again you can simply add a little piece of silver wire to reconnect in- and output. A good source is the shortened ands of the crystal which is also exchanged. Of course this is just an easy hack and obviously reduces sensitivity. | ||
+ | When re-adding the piece of wire be sure that it is not shortened to GND. It is recommended to add some heat shring tube to isolate. | ||
+ | |||
+ | {{ :skyper:skyper_short_saw.jpg?direct&600 | Reconnected in- and output of removed SAW filter}} | ||
+ | ==== Exchanging the crystal ==== | ||
+ | |||
+ | Next is to exchange the crystal to get the LO to the correct frequency. You will need a crystal with 69.764583MHz to get the Skyper working on the (German) centralized DAPNET frequency of 439.9875 MHz. To remove the old crystal you can remove solder with a desoldering pump. Be sure not to loose the little SMD resistor between the two pads while heating. It s a 1k2 one just in case you lost it :-) | ||
+ | |||
+ | The new crystal (from [[https://shop.funk24.net/weiteres.../skyper/286/quarz-fuer-skyper-zum-umbau-auf-amateurfunk|funk24.net]] for example) should be soldered to the two small holes. | ||
+ | |||
+ | {{ :skyper:skyper_new_crystal.jpg?direct&600 |New crystal}} | ||
+ | |||
+ | ==== Mounting additional capacitors ==== | ||
+ | |||
+ | To improve the LO you can add two capacitors (15pF and 18pF). The 18pF cap needs to be added on the solder side (bottom) in parallel to a component labelled with "33". The 15pF capacitor goes to the top side in parallel to the component labelled "R22J". | ||
+ | |||
+ | There are two ways. You can add standard components which are easier to solder but harder to fit into the case. | ||
+ | |||
+ | {{:skyper:skyper_18pf_standard.jpg?direct&400|18pF on the bottom}} {{:skyper:skyper_15pf_standard.jpg?direct&400|15pF on top}} | ||
+ | |||
+ | An alternative is to use SMD components (for a set see [[https://shop.funk24.net/weiteres.../skyper/287/quarz-fuer-skyper-mit-smd-kondensatoren|funk24.net]]). Those are easier to fit into the case but a little more challenging to solder. But there are nice tricks :-) | ||
+ | |||
+ | The 18pF SMD capacitor on the bottom can be added to two SMD pads which are actually not in use. Those can be found between the "33" labelled component and a 560R SMD resistor. On the top there are no unused pads apparently. But you can put the 15pf capactor upright between the "R22J" component and a SMD capacitor next to it. Then solder the two pads to those of the already existing SMD capacitor. | ||
+ | |||
+ | {{:skyper:skyper_18pf_smd.jpg?direct&400|18pF SMD on the bottom}} {{:skyper:skyper_15pf_smd.jpg?direct&400|15pF SMD on top}} | ||
+ | ==== Re-aligning the RF components ==== | ||
+ | |||
+ | After changing the hardware the Skyper needs a realignment to make it work on the new frequency. First step is to realign the LO with the new crystal. You need a transmitter on the new working frequency (439.9875 MHz) transmitting a 600Hz tone to trigger the Skyper. An easy way is to use the test function of UniPager (connected to a RasPager board). This is an overview of pins and trimmers used for alignment: | ||
+ | |||
+ | {{ :skyper:skyper_alignment_points.jpg?direct&600 | Alignment pins and trimmers }} | ||
+ | |||
+ | Then you have to dig onto pin 16 of the receiver IC with a scope. You should see a more or less symmetrical signal. The goal is to align it to be symmetrical calibrating it with trimmer CT2. It should look like this when finished: | ||
+ | |||
+ | {{ :skyper:skyper_align_lo.png?direct&600 | Aligned LO }} | ||
+ | |||
+ | When this is finished you can improve reception by tuning the antenna circuit to maximum signal strength. Therefore conncect your scope to pin 12 and tune to maximum signal by turning trimmer CT1 carefully. | ||
+ | |||
+ | If all is done your Skyper should receive messages from DAPNET network. You can test that using the "Send Message" function of UniPager which circumvents the DAPNET connection and sends out POCSAG calls directly. | ||
+ | ===== RIC programming ===== | ||
+ | |||
+ | Although Skypers come with pre-programmed RIC these can be modified. You will need a hardware interface for RS-232 port and the corresponding (DOS) software. | ||
+ | |||
+ | ==== Hardware ==== | ||
+ | |||
+ | You need an interface that supplies 3v0 to the pager to activate its programming mode. A small SMD PCB that fits into a DB9 connector case is described here: https://github.com/dk4pa/SKYPER_PROGRAMMER. Power is drawn from a USB port and converted to 3v0. A small amount of PCBs is available at cost from the authors. Please contact DK4PA or DF2ET. The Skyper has a programming interface which is located inside the battery compartment. It requires the wiring of GND, 3v0 as well as RX/TX lines. All experiments to build some sort of plug failed so far. Thus we normally solder the 4 wires to the pads after opening the case. | ||
+ | |||
+ | {{ :skyper:skyper_prog.jpg?direct&600 | Skyper Programmer }} | ||
+ | |||
+ | The connection between programming interface mentioned above and Skyper are as follows: | ||
+ | |||
+ | {{ :skyper:skyper_progger_connection.jpg?direct&600 | Connection of progammer and Skyper }} | ||
+ | ==== Software ==== | ||
+ | |||
+ | There is a DOS software that is able to read/program Skypers model 1 and 2. The software to use can be found on the internet from various Russian? sources. It refers to the pager as NEC21a which is probably some vode or development name for the units. You will need an (old) MS-DOS machine with a physical serial RS232 interface to run the application. Tests with VMs failed so far. | ||
+ | |||
+ | After starting the software you have to load a .ROM file before you can read the pager configuration. There a different ones corresponding to the Skyper versions 1 and 2. After you have successfully read the pager configuration you can identify its RIC (if the label is lost for example) or even change it to a different value. You will also find the RIC that is used for group calls and rubrics. | ||
+ | |||
+ | {{ :skyper:upgrom.jpg?direct&600 |}} | ||
+ | |||
+ | ==== Removing the display from the PCB ==== | ||
+ | |||
+ | lorem ipsum | ||
- | There is a DOS software that is able to read/program Skypers model 1 and 2. You need an interface that supplies 3v0 to the pager to activate its programming mode. A small SMD PCB that fits into a DB9 connector case it described here: https://github.com/dk4pa/SKYPER_PROGRAMMER | ||
- | A small amount of PCBs is available at cost from the authors. Please contact DK4PA or DF2ET. |