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Alinco DJ-X2000 :: вывод дискриминатора (англ.яз.)
Начало » Alinco
Разместил: Qwerty_Alex 4.5
Источник информации
Необходимые детали, приборы, инструменты Чип конденсатор 0,1-3,3 мкФ,
провод сечением не больше 0,4 мм,
Паяльник, отвертка
Текст статьи:

Discriminator tap instructions for DJ-X2000

Hi all,

I finally got brave enough to open the X2000 to install a discriminator tap. Here's how its done.

First, lay a soft cloth on the table to prevent scratches to your radio. Remove the battery, and pull off the rubber bung that covers the clone & earphone jacks. Pull off the top mounted dial knob (you may need a thin, broad flat blade of some sort to lever it off, protect the plastic from the sharp edge by using a thin soft cloth like a handkerchief) and take off it's rubber collar.

Remove the four screws in the back of the radio, and the two halves hinge open. Carefull: the hinge is only a few thing flexi-tracks which are easy to damage, so go gently.

Once open, the IF board is immediately visible on the front 'half' of the X2000, you will need to remove the two screws that hold the bottom of this board in.

The IF board is now held in by an inter-board connector underneath - using a slow see-sawing motion, the IF board can come free.

On the underside of the IF board, you will find near the inter-board connector (at the top of the connector marked with a white '50' on the PCB) a solder land with a track leading to the clone port. It turns out that the 'tip' of the clone port is unused by the radio - it simply goes to this solder land that I have just identified - almost as if Alinco had planned it for a modification such as this!

Anyway, put a little bit of solder on this land, and then search for a suitable capacitor. The capacitor you need to find (not out of the X2000!) needs to be small, and low in profile, a value of 0.1 uF is OK, but if you can find larger up to say 3.3 uF that would be even better.

for use are a 0.1 uF surface mount cap, or a small monolithic multilayer type, or maybe a very physically small tantalum type. Install one leg of the cap to the solder land, making sure it's orientation does not foul other things when the PCBs go back together, and that the legs are short as possible.

If using a polarised cap like the tantalum, then solder the positive side to the solder land, but this isn't critical.

Next, take some really fine enamalled copper wire and solder to the free leg of the cap you just installed, and cover the solder join with a piece of very small insulation spaghetti or similar. The enamalled wire I speak of shoud be self-fluxing (ie the enamel easily melts away with the application of heat from a soldering iron) and should be around the 0.4mm or less diameter.

Take the other end of the wire, route it to the other side (top side) of the IF board via the small square notch in the side of the IF PCB, and identify the discriminator IC, IC301, a TK10931.

This is where the other end of the wire is to solder onto. Cut the wire to the correct length.

The TK10931 is a tiny IC, about half the size of your little finger fingernail, with 24 legs in all. You are soldering the wire onto pin 12 - look carefully for the tiny circle/dot that identifies pin 1, and pin 12 is on the same side as the dot, but at the other end.

Solder the wire directly to pin 12.

Need I say that you will need to have:

a good awareness of anti-static handling proceedures for PCBs and ICs.

a really fine soldering iron tip and fine solder

steady hands

good eyesight and lighting, maybe a magnifying lens

near perfect soldering skills.
That is pretty much the mod complete. Now re-assemble the radio - carefully plug the IF PCB back into the microprocessor PCB (joined by that inter-board connector I spoke of earlier), install the two screws that hold the IF board in place, make sure the rubber cap for the external power port is in place properly at the side, carefully align the two case halves together and finally put the four screws back in and tighten (not too tight, though!)

Put the rubber bungs back on/in and finally the dial knob.

That's it.

When using the discriminator tap, use the tip and sleeve of a STEREO 2.5mm audio connector. Using a mono connector will short the 'clone' pin (the 'ring' of the connector if you like) to earth - probably not good for the radio!

I have found that the tap works well in AM and FM modes, and works from everything from 512 bps POCSAG pagers to 9600 bps EDACS control channel info. I have not been able to test it on any higher data rates due to a lack of such signals here locally. I have also not tested it for CTCSS tone decoding - since this is built into the radio already!

Just be aware that inserting or removing the audio connector while the radio is on may not be the healthiest thing, so when ever you insert your cable to the clone port, be it for PC operation for the X2000 or for discriminator tapping, then turn off the X2000, and turn it on once the connector is plugged in.

Well done Alinco - the more I think about it, the more I think Alinco specially left the tip of the 2.5mm clone port free and bought that connection out to a nice free PCB land pad for exactly such a modification.

I suppose there is nothing stopping anyone using this land pad for other taps instead of the discriminator - 10.7 MHz wideband output, maybe?

Ta - Jason

This article has been read 5936 times.

Комментарии к статье
Автор Комментарий
15 Сен 2009 23:20:29

Сделал себе выход с дискриминатора, немного изменил действия по переделке.
Посчитал что подпаиваться к выводу микросхемы не самый лучший вариант, да и нашел по сервис мануалу деталь висящуюю на 12-й ноге микросхемы (R334) со стороны пайки разделительного конденсатора, конденсатор поставил 2,2 мкФ чиповый.
Провод использовал МГТФ относительно толстый.
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Файл создан: 21 Апр 2008 22:52:33, посл. исправление: 23 Апр 2008 12:42:09
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