Radio Question/problem

[EMT111 149]

So I've found a small problem with the radio/radio system my VAC uses, the second we step inside a building, our portables become completely broken and no one can copy us. However, our local PD, who uses the same system and dispatchers but different portables doesn't have this issue and can be heard fine. This leads me to believe that it's a issue with our portables rather than anything else. We use Motorola HT750s and the PD is using Kenwood portables. Anyone have any ideas on how to fix this issue?

[Bnechis 3,961]

Call your radio vendor

[v85 212]

This is what I got from radio reference:

Well for starters, the PD is licensed for 50w (70w ERP) vs EMS at 25w (25w ERP). Also, the PD's antenna is mounted 20 feet higher on the tower than the EMS antenna.

The PD antenna could be a higher gain model than the EMS antenna. The PD's repeater could also be a different brand/model than the EMS repeater, and/or maintained better. The antennas could be mounted on different sides of the tower, which would give them different characteristics even while standing in the same spot in the middle of the town, depending on any nulls that are introduced.

From this thread: http://forums.radioreference.com/industry-discussion/274735-building-portable-coverage.html

Edited September 23, 2013 by v85

[sueg 77]

Also, is there s frequency difference, high band versus low band? That and the wattage and tower position mentioned earlier could affect radio wave penetration, etc.

[velcroMedic1987 330]

The wattage of the portables may make a difference too. Check that out.

[everybodygoes 331]

gain on an antenna only works one way, and that is transmitting. 20 feet is a big difference. Can you talk to PD from your radio? Perhaps they use vehicle extenders as opposed to speaking directly to the repeater site. Give us some more info on where you work. And calling your vendor will just equal money. Do the prelim stuff on your own.

[Bnechis 3,961]

And calling your vendor will just equal money. Do the prelim stuff on your own.

That all depends on what you already paid them for. If you paid for a system that works and it does not, they need to figure out why.

[wcr20 17]

It's not clear from your original post - but are the VAC radios on the same frequencies as the PD? Can you talk directly with the PD cars/portables, and they with you, or does a dispatcher need to relay between 2 rados or frequencies? If a PO is standing next to you - and he can talk to the same dispatcher on the same frequencies and same base radios (and/or repeaters) that you are using and you cannot- then you have a problem with the portable radios - could be misprogrammed etc. If you cant HEAR the same dispatcher on the same frequency that the cop standing net to you can hear, then that is also indicative of a portable problem, but a different symptom. That could be programming, tuning and sensitivity, choice of antenna, etc. All of those should be discussed with your radio vendor.

No - If you are NOT on the same frequency/system as the PD, but talking to the same dispatcher on a different radio in thier console - then thats a whole different problem.

I think the original response from Capt. Barry is right - call your vendor right away. No one here is going to be able to solve this for you without tons of more specific info, and probably a lot of expensive hardare

[bronxfireradio 45]

Good points on this post. I'd check out the transmit power on the portables as a starting point. If PD radios can be heard by dispatch, but EMS's cannot, it may be a power level issue (if all else is equal - frequency, PLs, etc.). Portables usually can be programmed to transmit from 1 to 5 watts. Is there a problem receiving on the portables, or is it just on transmit?

[firerescuecapt 20]

No matter what, let us know what you find out from the vendor. I'd be interested in hearing what they have to say.

[res6cue 67]

This is what I got from radio reference:

Well for starters, the PD is licensed for 50w (70w ERP) vs EMS at 25w (25w ERP). Also, the PD's antenna is mounted 20 feet higher on the tower than the EMS antenna.

The PD antenna could be a higher gain model than the EMS antenna. The PD's repeater could also be a different brand/model than the EMS repeater, and/or maintained better. The antennas could be mounted on different sides of the tower, which would give them different characteristics even while standing in the same spot in the middle of the town, depending on any nulls that are introduced.

Gee, I wonder who posted that over there? Oh wait...it was me.

Next time do the right thing and post a link back to the thread on RR, instead of picking our brains over there then coming back here and posting a few select quotes. Bad form, bro.

http://forums.radioreference.com/industry-discussion/274735-building-portable-coverage.html