BCD996P2: How Come BCD996P2 Doesn't Always Show The PL/DCS During Custom Search?

Status
Not open for further replies.
Joined
Feb 14, 2008
Messages
2,105
I have the tone code search setting set to CTCSS/DCS in the menu settings. But when doing a custom search, the scanner often doesn't automatically display the PL or DPL on analog conventional channels that I know have a PL or DPL. This is a great feature that works awesome on the BCT15X everytime, but not the BCD996P2. Why?
 
Joined
Feb 14, 2008
Messages
2,105
Well, I went ahead and did a complete reset on the scanner and re-programmed it and got it working right. But then it quit working again. It will not display the PL or DCS.

And there's another problem I'm noticing. Conventional frequencies that I have programmed with a PL or DCS. When the frequency becomes active, the scanner just keeps scanning and never stops on it. If I manually stop scanning and navigate to the frequency and hold on it, there's no signal at all. Even though I have another radio on that frequency receiving a transmission.
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
12,011
Location
VA
When the frequency becomes active, the scanner just keeps scanning and never stops on it. If I manually stop scanning and navigate to the frequency and hold on it, there's no signal at all. Even though I have another radio on that frequency receiving a transmission.
That is exactly what is supposed to happen if the broadcast PL/DPL doesn't match what you programmed in the channel settings.

Have you double-checked your settings?
 
Joined
Feb 14, 2008
Messages
2,105
I have it on Display Mode 2 and know that I 've got the right PL tones programmed. Even if you had a wrong PL, you'd still see signal strength bars, but no audio. But I don't even see any signal bars. But on a custom search, I receieve the transission and can hear the audio. Just no PL / DPL showing up.
 

Eng74

Member
Joined
Dec 19, 2002
Messages
1,757
Location
Kern County, CA
I haven't used Proscan, but if it is like ARC-XT or FreeScan they have a tone lockout tab next to the tone tab. Are sure it is off. If it is on then it will pick up everyone but the one you have programmed.
 
Joined
Feb 14, 2008
Messages
2,105
It's just weird the way this scanner is behaving with PLs. The only other thing I can think of is the discriminator tap mod I did on it last week. I'm wondering if there's anything I did that messed it up somehow. Like maybe it went haywire and blew a transistor or something.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
4,875
Location
Stockholm, Sweden
If the tap loads the discriminator audio too much to loose the sub audio decoding you should have noticed that if the speaker volume got much lower. But perhaps you have AGC working and will mask it.

The tap is done using a capacitor and a resistor at a suitable tap point? The resistor have to be 1k or larger to not load the discriminator too much.

/Ubbe
 
Joined
Feb 14, 2008
Messages
2,105
The speaker volume is the same (this radio has very good audio with an external speaker) and I used a [FONT=&quot]10k ohm resister in series with a 10 uF tantalum capacitor. For the ground, I used [FONT=&quot]one of the[/FONT] ground screws on the board.
[/FONT]
 
Joined
Feb 14, 2008
Messages
2,105
A little more experimenting and I'm noticing a pattern now. If I unplug the stereo cable from the discriminator jack that I added, power off the scanner, and power it back on again, the CTCSS / DCS works properly. Plug the stereo cord back in turn the scanner off and then back on, and now the CTCSS / DCS doesn't work right. There must be something about the discriminator mod that makes the radio not decode PLs for some reason.
 

byndhlptom

Member
Joined
Nov 1, 2005
Messages
376
Location
JoCo, KS (SoDak native)
996TP2 CTCSS

The resistor/cap on the discriminator tap may be attenuating the low frequencies just enough to affect the CTCSS decode.

You may want to experiment with different r/c values......

$.02
 
Joined
Feb 14, 2008
Messages
2,105
I've actually done the same mod on a BCT15X with the same components and the BCT15X never had a problem.
 

byndhlptom

Member
Joined
Nov 1, 2005
Messages
376
Location
JoCo, KS (SoDak native)
996tP2 discriminator tap

The two circuits may not be identical, they were released at least 5 years apart.

That's a long time in the IC world anymore, odds are one or more chips are different.

$.02
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
12,011
Location
VA
You need to increase the resistor value on the discriminator tap. I'd suggest a 10KΩ or 100KΩ between the tap pad on the scanner board and the capacitor, and a 100KΩ or 1MΩ shunting the output side of the capacitor to ground (the shunt resistor value should be about 10X the series resistor value).

Higher resistor values will load the scanner less, and pass more low frequencies to the output device.
 
Joined
Feb 14, 2008
Messages
2,105
I used a 10k ohm resister already, so I guess I need 100k? Hopefully that won't weaken the signal too much going to the sound card.

And I'm not following what "shunting" is. Is that a whole nother 2nd resister I need? Where should I solder it?

I am not very good at soldering and this could be a mess.
 
Status
Not open for further replies.
Top