Tapping the RS Pro-2050

[mkewman]

Has anyone tapped the 2050?

i have one lying around and i'm interested in putting a tap on it. i've never done a descriminator tap, so detailed guides would be great! thankies!

mk

 

[fmon]

Pin 9 of IC-2 which is chip MC3361CDR2 The bottom 16 pin chip in this illustration is IC-2
http://ph.groups.yahoo.com/group/pro2052owners/photos/view/f503?b=3

Remove the board and turn it upside down with the display towards your belly. IC-2 is the 16 pin chip on the left. Pin 9 is the closest pin to you on the right lower side of the chip. Solder to the pad next to pin 9 (you can see the trace running to both). Find any ground point to solder the ground wire to. BNC ground would be fine.

I use a 1k resistor as illustrated in this 2052 tap. http://ph.groups.yahoo.com/group/pro2052owners/photos/browse/9c72
I have not tapped the 2050 however, so do not have a picture for illustration.

 

[ab3ai]

I used a pad almost in the center of the board labeled "DS". I'm not 100% on the label, it was a while ago when i did it. But I got 100% using Unitrunker (line in on soundcard). I ran a wire from that point to a jack on the back of the radio with a 0.1uf cap inline with the tip and ran the ground of the jack to the board. I don't have the radio anymore, but I know who does. If you want, I can give him a call to get the pad label.

 

[mkewman]

where on the board would one ground it. a screw? i'm not used to unlabeled boards.

 

[jellotor]

You could ground it at the same location a headphone output is grounded but you may not have to ground it at all. Depending on the configuration of the connector you use (presuming you use the "ring" portion of a phono-style connector as ground) and if the ground area on the connector contacts the metal chassis of the scanner, you've already grounded it without soldering anything. I have a BC760, BC560, BC890 and BC895 that are all grounded to the chassis and I didn't solder a separate ground wire.

Some may chide me for laziness or other reasons...but if the same ground is good enough for the headphone output then I don't see the problem with using it for the discriminator output, either.

 

[mkewman]

well,

i did everything but it's not working. 1k resistor, etc. hooked it up, no signal. what could go wrong?

 

[SCPD]

i did everything but it's not working. 1k resistor, etc. hooked it up, no signal. what could go wrong?

Hi Mark - what are you doing with the signal? Are you using a slicer or direct sound input?

Some things to check:

Turn the radio ON.
Tune to a know control channel.

1. when you plug the discriminator into your computer, does the speaker volume drop? If so, you may need more isolation (replace the 1k resistor with a 10k, 47k, or 100k). That resistor is wired in series, right?

2. for sound input; run an oscilloscope program to display the waveform of the audio
a. is the signal flat - too weak?
b. is the signal clipped (vertical lines extending the full range of the display)?

3. for a data slicer; does it work with another known good disc. tapped radio?

-rick

 

[mkewman]

what do you mean "in series"?

(excuse my ignorance)

 

[SCPD]

what do you mean "in series"?

Here's an example:
http://www.csupomona.edu/~apfelzer/demos/resistor/ser-par/10-ser.html

Consider "Vs" to be your discriminator audio signal. Consider "R2" to represent the load on the discriminator signal caused by the computer's sound input (or the input to your slicer).

Resistor "R1" is wired in series - the current must pass through R1 to get to R2.

-rick

 

[ab3ai]

Hi Mark,
I used a mono 1/8 jack on the back of the radio. Being a plastic cabinet, I ran a ground wire to a screw that holds the antenna jack to the chassis. I ran a .1uf cap in series with the tip. On thing to try, I couldn't get a signal with Unitrunker until I invertered the data. Once I didi that, 100%.
Chris

 

[digilink]

Hi Mark,
I used a mono 1/8 jack on the back of the radio. Being a plastic cabinet, I ran a ground wire to a screw that holds the antenna jack to the chassis. I ran a .1uf cap in series with the tip. On thing to try, I couldn't get a signal with Unitrunker until I invertered the data. Once I didi that, 100%.
Chris

How did you go about "inverting" the data? And what kind of cap did you use(electrolytic, ceramic, etc)?

Mark, I have a Pro-2050 myself and I am looking to do the same thing, I believe the tap point is labeled TP DS on the top of the board. If someone could validate, that would be great....

How wide of a signal comes out of the discriminator? I am looking to try using this scanner as a WX sattelite image receiver as well.....

 

[mkewman]

i know that TP DS - IS the one...

but i'm hearing two different things. Use a Cap, and use a Resister.

i'm lost. lol.

 

[SCPD]

How did you go about "inverting" the data?

It's a software option.

And what kind of cap did you use(electrolytic, ceramic, etc)?

Electrolytic - a 2.2uF works for me. Make sure the voltage rating is 16 volts or more.

How wide of a signal comes out of the discriminator? I am looking to try using this scanner as a WX sattelite image receiver as well.....

Read the specs on your radio. Most consumer receivers run about 15 khz wide on the filter just before the discriminator. I think WX sat requires 30khz wide.

but i'm hearing two different things. Use a Cap, and use a Resister.

Either will work. The cap is probably safer. For the most part, it's "six for one, half a dozen for the other."

-rick

 

[ab3ai]

Hey digilink,
Under the options menu, hit the "I" key. That wil invert the data.
I used a .1uf ceramic disk cap.
Chris

 

[digilink]

Hey digilink,
Under the options menu, hit the "I" key. That wil invert the data.
I used a .1uf ceramic disk cap.
Chris

Thanks for the tip I will hopefully get this done today, I'll post my results.....

btw, 73's from a fellow ham, N1VLV/4