BC895 xlt discriminator tap

[dbrown2]

I have connected a wire to the discriminator tap of the unit (based http://www.radioreference.com/digital/dig/bc895-tap.jpg). I put a 1k ohm inline from the tap to a 274-0246 on pin 2 (with pins 2 and 5 shorted and 3 and 4 shorted) and a ground wire from pin 1 to ground of the unit.

I have mtrunker working (have not tried wtrunker yet), the unit is in trunk search mode. When it locks on a group ID trunker reports no signal. If you listen to the line feed it has sound coming out of the 1/8 plug as long as the unit is searching, but when it locks on a group id the sound stops. Then when it un-locks from the group id the sounds start back. That is why trunker reports no signal I would think.

Is this right? Should the sound stop when the unit locks on a talk group id?

 

[ka3jjz]

What is 274-0246??

If you're putting this signal onto the 5 pin connector in the back, it won't work - it's not meant for that. You're mixing apples and oranges, I'm afraid, if that's the case.

Depending on the utility you're using you need to feed that input into a data slicer (Mtrunker, I think, would need one) or directly into the soundcard input of your PC (UniTrunker). You would see the data, along with talkgroups and other information, on your PC.

We have a Wiki page on Data Slicers, and at the bottom of the page, where you can buy pre built ones are listed.

http://wiki.radioreference.com/index.php/Data_Slicers

73s Mike

 

[dbrown2]

274-0246 is a part number from Radio Shack sorry about that. And yes it's a 5 pin 1/8 plug. So I need a 3 pin 1/8 plug then right?

MTrunker32 v3.8.3b1 build 1 does work with this plug although the sound does stop whenever the radio locks on a talkgroup ID. You don't need a dataslicer (or the docs say you don't with mtrunker) I have not tried uniTrunker yet, I did sign up for yahoo group trunker, but have not agot approved yet.

So you think that chaning the plug will stop the current "feature" of not hearing sound when the radio locks on a talk group?

 

[ka3jjz]

I don't know why you couldn't just use a simple phono jack - there's tons of room for one on the back. Just feed the audio to the hot side, and firmly ground the jack at some convienient point. No cross over wiring of any kind should be required. AFAIK the sound should not ever stop when it locks on an ID - in fact, you don't need to be trunking at all. Just lock the scanner on the control channel and let MTrunker read it.

73s Mike

[edit] Now that I'm rereading things here, I think you are assuming MTrunker can control the 895 while in trunking mode. I don't think so - if the docs say it can, what you would need is a RS232 connection from your PC to the 5 pin port that's already on the back. You will need a 2nd tapped radio to get the control channel signal, along with a 2nd serial port or connection to the soundcard.(if it's set up to work that way). Tapping the discriminator does not provide any RS232 control at all - it simply is the unfiltered audio that exists before it's reshaped and filtered by the audio circuits. Now I'm sure you're crossing apples and oranges.

The cable that mates to that 5 pin connector uses a jack like that found on an audio output of a CD Rom drive. In addition, I think Scan Control and Scancat both sell compatible cables.

If you are looking for a program that will capture talkgroups and so forth using the 895 in trunking mode, the 895 wiki already has several of these. MTrunker and programs like this would be useful for tracking other trunking formats that the 895 cannot handle. 73s Mike

 

[SCPD]

So you think that chaning the plug will stop the current "feature" of not hearing sound when the radio locks on a talk group?

You'll have to clarify what you mean by "locks on a talkgroup". Is the radio in trunking mode or do you have it in manual mode? Is the radio also in remote mode with a serial cable connected for computer control?

Normally with trunker and derivatives - to hear voice you must run two radios - one with a discriminator tap; the other with computer control to follow voice calls.

-rick

 

[dbrown2]

To clarify what I mean by locks on talk group...
First I thought that the scanner had to be in trunk mode with the trunk control channel(s) programmed in. I put the scanner in trunk mode and then had it search (not scan) so it would display -- --- until displayed a talk group ID. When it "locks" or "displays" the talk group id it then begins to give you audio like it would normally and you can hear dispatch of whatever is on the talk group. At that point the audio that is coming out of the discriminator tap stops and you can hear the voice of the person talking. At the same time mtrunker and unitrunker (now tried it) stops getting a signal. When the person stops talking and the scanner (still in trunk mode) begins it's search again mturnker begins again. I fixed this by not programming any talk groups into the scanner and putting the scanner in trunk mode and in scan mode (not search mode) since there are no talk groups programmed in it never "locks" or "finds" a talk group and mtrunker works. I have not tried the manual idea where you don't put the scanner in trunk mode. But will try it.

No I do not think that mtrunker or unitrunker would be able to control the scanner with nothing other then a audio cable. I do think that a 3 pin 1/8 plug would have worked better now. I made a mistake when bought the plug and got the wrong one; I now see that. I just want to know if I need to take it apart again and replace the plug with a 3 pin or can I leave the one I have. I think what I hear is the scanner should not be in trunk mode only manually set to the control channel.

While we are on the topic on what to expect. Other then getting the talk groups ids, radio ids (what is a control channel or not) what also can I do with mtrunker?

 

[SCPD]

I have not tried the manual idea where you don't put the scanner in trunk mode. But will try it.

You can also scan the control channels as if they were conventional channels. That way the radio follows the control channel when it changes - but turn the volume down!

I just want to know if I need to take it apart again and replace the plug with a 3 pin or can I leave the one I have.

A 2 or 3 pin is fine. I use a 2 pin mono. Some folks don't like mixing mono & stereo plugs - understandable. OTOH, if it ain't broke ...

I think what I hear is the scanner should not be in trunk mode only manually set to the control channel.

Yes - although what you've done is useful for folks who want to listen but don't have a second radio. They can still see activity in between calls - provided there aren't too many active calls matching your ID list.

While we are on the topic on what to expect. Other then getting the talk groups ids, radio ids (what is a control channel or not) what also can I do with mtrunker?

Patches, affiliations, and neighbor site info. There are a number of techniques to figure out the purpose of a new talkgroup. Being able to correlate users between known group ids and a new unknown group ID helps. Identifying radio ids used by dispatchers is very helpful in this area. With affiliations you can see who's listening in - though they may never speak. Patches are often used (1) during tactical situations or (2) when dispatchers are working multiple areas at once - usually late at night when there's not much going on (one person at 3am covering a set of talkgroups normally handled by 3 or 4 persons during the day).

All of this combined provides cues and clues as to what's going on.

If you add a second radio for voice - then you also have true priority scanning - something that an ordinary scanner can't do. Because one radio is dedicated to watching the control channel - it can pre-empt a lower priority voice call with a talkgroup you've marked as more important.

-rick

 

[dbrown2]

Yes, I have BCD996T that I would like to be the voice scanner controlled by the 895xlt, but as of yet the unitrunker does not support the radio and it does not support control of another scanner yet. Now that I know what I am doing I may put a tap in the BCD996T and control 895xlt when the feature is added to unitrunker. As soon as I get access to the trunker group I will download and try wtrunker to see how it compares.

Thank you again for your help. The next tap I use I will use a 2 pin plug.

 

[ka3jjz]

Unnecessary to get a new radio like that to tap it. Get something like a 780, 785 or 796 - if memory serves, tapping those radios is quite easy, and I've seen 780s for USD175-220 or so. Much less than a nearly USD600 for a 996. In addition, I don't know if anyone has snooped around to find the tap point in the 996 yet (altho I'm willing to bet some folks are looking for it).

73s Mike

 

[dbrown2]

I already spent the money for the new BC 996, I bought the 895 just for tapping until I saw now that you can't control the 996 with trunker software yet. Maybe I should just wait for someone to add it.