Minitor III, IV on narrowband

[pfish]

Our county will be switching to a narrowband VHF channel eventually (they say soon). We were going to buy a few Minitor V's to replace the few 3s and 4s we have issued, but one of the radio shops sent an email to the chiefs saying he did a bench test and got the Minitor 2s, 3s, and 4s working on a narrowband frequency.

I initially had concerns about this, because audio/reception on our system is already horrible, and a lot of times the signal is barely enough to trigger an alert on the pagers. Can anyone tell me, if we did have the 3s and 4s re-programmed for narrowband operations, what the side effects will be?

Here's what was said:

In wideband the pager receives at least a 1 KHZ signal
In narrowband the pager will receive a .5 KHZ signal, about half the size

I did a bench test and toned out a M2,3,4 and a 5

At .5khz all pagers worked without error. Actually all the pagers worked without error down to a .3KHZ signal. At a .2KHZ signal the M2 did not work at all and the test worked about 90% if the time.

My unsolicited opinion is that you will find that most all pagers will work in a narrowband system.

[pfish]

Can anyone confirm if the M5's are truly narrowband?

And to add to my last post, would having a narrowband frequency on the older pagers open it to possible interference? I also seem to understand that reception can reduce by a small percentage? Can someone with some experience chime in?

Thanks

[tvsjr]

The M5 can either be ALL narrowband or ALL wideband, if you're using a two-channel model. No mixing. But yes, they are designed to operate properly on a 2.5KHz deviation channel, normal or splinter. We have two departments in my county being toned out on their own narrowband repeaters with no problems.

Using a wideband pager like the M3/4 on a narrowband channel is asking for trouble. The received audio is going to be much lower, as the deviation is cut in half. The possibility to miss tones is there (you could drive the deviation way up on the repeater side and fix that, but that's not a good solution). And, what happens when someone takes up residence on the next narrow channel up or down? You stand a good chance of missing pages due to interference from them.

Sounds to me like someone's trying to be cheap and avoid paying for the new pagers (not you - you're doing your homework...)

Cough up the bucks and buy the proper M5s. If you're not a governmental entity (say, a VFD, which operates as its own private corporation), list the 2/3/4s up on eBay and recoup some of your funds.

You will also discover the M5s are significantly more sensitive than the M4s.

[pfish]

Thanks, tvsjr. I searched quite a bit but didn't get all the info I wanted until now. Your response had all the info I was looking for. Again, thank you!

[tvsjr]

Thanks, tvsjr. I searched quite a bit but didn't get all the info I wanted until now. Your response had all the info I was looking for. Again, thank you!

No problem, that's why the board is here. Good luck with your narrowband migration... feel free to throw another post out if you need more help.