Pro-2006: PRO 2006 Mod?

[W8WCA]

Just purchased a PRO 2006 and it seems to have a mod in it.

See attached anyone know what it is?

I am not sure - but I do not recall this being stock board - but it has been at least 20 years since I had one.

Other than need to clean the Volume Pot. - it seems to be good.

 

[KevinC]

Just purchased a PRO 2006 and it seems to have a mod in it.

See attached anyone know what it is?

I am not sure - but I do not recall this being stock board - but it has been at least 20 years since I had one.

Other than need to clean the Volume Pot. - it seems to be good.

Maybe the data squelch option board?

 

[Ubbe]

It shows an audio amplifier, taking the signal somewhere from the discriminator area, that then has diodes and capacitors to detect audio at a certain level set by the potentiometer.

As the scanner already has a sound squelch it has to be the opposite like Kevin suggests, a data squelch to block high modulated data signals. I would have thought that it also required a second pot, to adjust how quick it should react to not false trigger from loud voices.

/Ubbe

 

[W8WCA]

It shows an audio amplifier, taking the signal somewhere from the discriminator area, that then has diodes and capacitors to detect audio at a certain level set by the potentiometer.

As the scanner already has a sound squelch it has to be the opposite like Kevin suggests, a data squelch to block high modulated data signals. I would have thought that it also required a second pot, to adjust how quick it should react to not false trigger from loud voices.

/Ubbe

It looks like there is a small pot on the board above and right of the LM339

 

[Ubbe]

That's the gain pot for the modulation level, at what level it will trigger. But I guess the filter tantalum capacitors value have been selected to give a 1/2 sec delay before it close squelch or continues the scan function at a data signal. It also needs to somehow quickly drain the capacitor to not affect the next channel in scan.

/Ubbe

 

[jrl44430]

Data slicer for computer software?

 

[Ubbe]

No. Its a diode rectifier and a smoothing capacitor to produce a DC signal that follows the modulation level.
I have looked at Bill Cheeks modification books, they don't cost much from the internet book stores but the shipping cost to me are astronomical. It probably explains in one of those books how it is supposed to work and how it is done to not false trigger on the next channel in scan and skip it.

/Ubbe

 

[wtp]

are there any leds or other hookups, even an RCA jack that is not original ?

 

[W8WCA]

are there any leds or other hookups, even an RCA jack that is not original ?

No external 'add-ons' LEDs - jacks etc.

 

[rgchristy]

You might be able to identify it in one of these documents. Worth a shot.

If you don't find it in these two, I have a bunch for the PRO 2005, which should be the same.

 

[ande5]

No. Its a diode rectifier and a smoothing capacitor to produce a DC signal that follows the modulation level.
I have looked at Bill Cheeks modification books, they don't cost much from the internet book stores but the shipping cost to me are astronomical. It probably explains in one of those books how it is supposed to work and how it is done to not false trigger on the next channel in scan and skip it.

/Ubbe

You right, that's was a mod made by Bill Cheeks. I've the 3 books in my shell as a reference. Great days...

 

[ande5]

You right, that's was a mod made by Bill Cheeks. I've the 3 books in my shell as a reference. Great days...

(Bookshelf)

 

[W8WCA]

There is a NAND Gate IC and a Comparator IC on the board but still not sure about it

 

[markclark]

That board looks like the GE EDACSs mod to filter out the jingle at the end of transmissions.

 

[Ubbe]

There's no frequency dependent components on the board, so all strong modulated sounds over a certain time length will trigger the circuit and either mute and/or continue scan.

/Ubbe

 

[W8WCA]

A side note: My PRO-2006 has a bit of a Buzz in earphone jack - and not from the internal speaker

 

[Ubbe]

It's the same signal as the speaker but the sleeve of the headphone connector does not go directly to ground, there's 270 ohm resistor there to reduce the level. To test make a ground connection to the sleeve, like people used to do to some portable scanner to make the headphone louder. If the hum increases then it's probably the headphone that are too sensitive.

I use an extension cord with a volume control on it, and a stereo-mono switch, and when using head or ear phones I turn a scanners volume control fully down and then adjust the cords volume until I hear no background hum. Many earphones are just too sensitive and picks up background noise too easily.

/Ubbe