MTR2000 TTN5067C wireline board

[RF_Burns]

I have a number of MTR2000 repeaters with TTN5067C wireline boards that I need to connect to a 4 wire E&M Mux.

I know the E&M connections are best done with the Aux I/O board, but I'm looking on the TTN5067 and there are 4 opto-isolators.

My question is, are these Opto-isolators used in the COR/PL out and PTT in lines? If so I should be about to use them to isolate the -48V on the E&M from the radio ground and not need $6000.00 I/O cards.

Thanks

[Bill_G]

B3/C3 are the two sides of the RDSTAT relay on the 4 wire board which is the equivalent of COR. B21/C2 is the OCO of RDSTAT at TTL levels (5v = unsq). C10 is the ext PTT at TTL levels - normal 5V, ground C10 for PTT. If you use ext PTT, you can use line 1 in for tx audio, but you need to change the PTT route in the station programming.

This is all discussed in the installation manual. Hope this helps.

[RF_Burns]

Thanks Bill,
But I'm thinking the relay for B3/C3 is on the Aux I/O card as I don't see an actual relay on the TTN5067C 4 wire card. There are 4 opto isolators on the card, but if B3/C3 was an opto isolator, I'm thinking it should show me which (B3 or C3) is the emitter connection and which is the collector.

I'm thinking I'll need to build some small circuit boards with a couple opto-isolators to accomplish the voltage level change from E&M to TTL.

[Bill_G]

I've never had a station with the aux i/o card, but have always had the rdstat output available. You should check your stations to see what they do upon carrier det. RDSTAT goes high on carrier det / PL decode which may be inverted from what you want for your application.

As for PTT, you simply need a diode for isolation (if isolation is required). You should check your E&M cards. E lead usually requires a dry closure, and M lead produces one. ie: a closure on the E lead at the near end causes a closure of the M lead at the far end. So, an open collector to return (ground) on the near E lead will close the far M lead, and vice versa. The cards may be in a chassis run on a -48v supply, but voltages on the E lead are current limited. There should be no voltage on the M lead unless there are jumper settings on the E&M card that bias a line for user preference. If there are jumpers, they should be discussed in the manual, or may even be silk screened on the board.

[RF_Burns]

The C2 works fine as far as COS/PL Detect. Nothing at all from B3/C3 in any measurable form.

[Bill_G]

Sorry for the confusion. B3/C3 are the two sides of a relay - a dry contact closure. RDSTAT causes a closure. So, put your ohmmeter across those, not your voltmeter.

Do you have the installation and op book? The system plug is described in depth towards the back. Super handy.

[RF_Burns]

Yes I ohmmetered across B3/C3 and got nothing, and tried 3 stations incase there was a fault in the circuit but still nothing. I have the installation and field service manual.

I have one station with the Aux I/O card, so I'm going to test it with and without the I/O card tomorrow.. err today. I'll post what I find.

[RF_Burns]

B3/C3 works with the Aux I/O board installed.

Guess I'll be making up an opto-isolator circuit and using C2.

[Bill_G]

Look at the manual. C2/B21 is an optoisolator already.

[RF_Burns]

Bill,
You must have a better manual than my Field Service Manual, it only labels C2 & B21 as a Open Collector Output, Which would be great if I was pulling a positive to ground, but I need to pull a negative voltage to ground in this case. An OCO NPN opto transistor won't do that unless I can connect it's collector to ground and use the emitter as my output. I don't see anywhere I can do that, but then my manual says its a CLN1203 wireline board, but shows a picture of a board clearly marked TNN5067C like mine.