MTR3000 and SNV-12

[celltech25]

ANyone have much experience with a SNV-12 Voter tied to a MTR3000?

Have one thats been in service for about 15 months was moved about 7 months ago from one Tower site to a water tank about 2 miles down the road since it was moved we are having issues with the SNV-12 just locking up or stopping working. It will still receive and vote the best signal but it only keys the transmitter for about 1 second then the TX will drop it has no fault's present on front and power and everything on that looks good. To correct the issue we can simply power down the SNV-12 and power it backup and it will go through its self test and start working correctly and might work for a month before it does it again but its getting annoying have to cycle the power.

It doesnt seem to be consistent as to when it does it as it might do it mid day or like last night it was around midnight so its not during a certain time frame.

Some Have asked about hte AC since its at a water tank we have monitored the AC with a line monitor from the electric comapny and it has ahd very little flucuation and stays around 121 volts ac it had one dip in 2 weeks of monitoring to 119 and one spike to 123.8 V

The tank is a stand pipe without a pump so its not like a water pump is starting and causing it jsut trying to figure out whats going on. I have called and tried to speak with raytheon but they must not have alot of techs as so far i have got no one on the phone.

Is there any kind of diagnostic software for the SNV-12 to see if it has internal Faults?? that dont show up on the front panel or that when its in its failed state you could see anything internally?

[FMROB]

When you say that the SNV keys the transmitter for about one second than drops out, does the SNV still indicate that it is transmitting, or is it that the MTR is only transmitting for one second than dropping out.

If the SNV is still indicating a transmit condition, I would start looking into yuor linking medium and tone levels. I would assume the use of phone lines, which if not operating properly or if your levels are not adjusted propely could easily cause the condition you speak of.

When you changed sites did you also change phone circuits. Did anyone do an end to end test of the new phone line to ensure proper response and levels?

Rob

[Bill_G]

Yes. The SNV-12 has diagnostic software. Depending on the vintage it will either be through the front panel on the ethernet port, or through the back on the serial port. You web in to look at the stored faults (if someone enabled them), or you use a terminal program (like Hyperterm) to interrogate it through the serial port. Download a manual, if you don't have one, so you know how to drive it, how to log in, what commands to use, etc.

That said, like FMROB asked, if you are certain it is the voter, and not the station, reseat all the cards in the frame. You may even want to clean the board edge connectors carefully. I've had individual cards flake out, do weird things, and the resolution was pull and seat the card.

[FMROB]

Ah, I misread his post. Good advice on re seating the cards.

[Bill_G]

Ah, I misread his post. Good advice on re seating the cards.

Yeah. If the product had a soft belly, it is it's vulnerability to card edge connector problems. I've had SVM cards report line faults that were, in fact, card seating problems, not lines dropping out. Chased my tail for a while. Alcohol swabs and WD40 on a brush can fix a lot of stuff. Since the OP picked this up and moved it to a new location, it probably got a little rock-n-roll in the process. Mighta shook something loose. I won't be surprised if the fix is that easy - just to pull everything, clean it, and shove it back in.

[celltech25]

the snv-12 does drops the keying the links are done via RF and pilot tone and they are not dropping you can locally key the mtr3000 until the time out timer kicks in and it has no issues

i spoked with raytheon earlier and they advised to reseat the cim-2a card next time without power cycling and see if it comes back

[Bill_G]

So, I got it you use pilot tone over an rf link for the receivers returning to the voter, but do you use tone control or E&M keying over that rf link back the the MTR?

Glad to hear that JPS Raytheon and I are on the same page about reseating the cards. Kind of a known problem.

[celltech25]

when the pilot tone drops it generates a ground on the PTT line on the back of the mtr3000 so i guess that would be e&M

[Bill_G]

Well, that answers something - you get a hard PTT from the voter that is then applied to the MTR. If that PTT goes through an rf link to reach the MTR, it might be E&M. If it goes a couple feet by wire to the MTR, that would be called local control.

Back in the olden days when telephone lines and microwave links were king, there had to be a way to get hardware signals from one end to the other. The Telco invented E&M signalling (ear and mouth). If you placed a closure on the E lead at one end, it showed up as a closure on the M lead at the other end. You could use them for a lot of things. In radio world, we used them to send PTT from the control point to the base station, and to send carrier detect (CD or COR) from the base station back to the control point. Anything that could be done with a relay or a switch could be sent over E&M .... if you only needed one thing done in each direction. It has it's limitations, but it still gets used.