maratrac VHF-Hi questions

benrussellpa · Post by **benrussellpa** » Mon Dec 17, 2001 8:19 pm

Hi all,

Let me start by saying that I am not a radio tech. I use a Maratrac VHF-Hi radio for work and am trying to figure some things out.

The radio I have is programmed with PL tones on both Tx/Rx for most channels. On several of these channels, I get other user interference even when the Monitor button is not activated. I confirmed with a scanner that the other users are NOT using the same PL that is supposed to be in my radio.

This is not a major problem most of the time. The most common occurance is on 151.490, which is used by the PA State Police as a tactical car-car channel. It is supposed to be programmed with a tone of 186.2Hz. However, I constantly receive traffic from two septic hauling services (both using different tones). This becomes so annoying, I remove the channel from the scan plan. Unfortunately, this would be the channel to use if I wanted to contact PSP.

Other times, my radio will be smacked by intermod on a channel that has a PL. This, as most people will probably agree, is a horrible thing to have to listen to. I hate all those beeps and whistles and burbles.

The second problem I have with this radio is an occasional lack of transmit ability. At seemingly random times, the radio will transmit at very low power. So little, that another mobile can only hear me within a few hundred feet. This makes hitting repeaters impossible. The problem only began in September this year. I have been using the radio since April.

I had the truck shopped in October at our contracted Motorola radio tech. They replaced the external antenna with a Maxrad and supposedly rewired the electrical hook-up, which they said was a mess.

Unfortunately, the lack of transmit ability still pops up sporadically. It does (and did) go away when the radio is turned off and then back on.

Also, when I asked the tech about the PL problem to upon picking the vehicle up he told me it was because I had the Monitor button acvitaed. I explained to him that I knew what the Monitor button did and that I had only had it activated upon drop-off because I was fiddling with it on the way up. Needless to say, they didn't bother looking at the programming to check the PL's because they thought it was user error.

Too bad I work for government, I can't go get a second opinion. Any ideas on what might be wrong with this radio?

PETNRDX · Post by **PETNRDX** » Mon Dec 17, 2001 8:42 pm

Wrong mic (without the hangup connected), un grounded mic hangar, or incorrect programming would be my first things to check. The bad TX is likely poor connections (bad grounds mostly) in the radio itself. Usually opening the radio, loosen then re-tighten all the circuit board screws most often fixes them. After that look for bad solder joints.

PETNRDX · Post by **PETNRDX** » Mon Dec 17, 2001 10:00 pm

I forgot to mention that you also need the special little plug in the back of the control head on the "advanced" head for decode to work. Either that or a jumper...

kens · Post by **kens** » Thu Dec 20, 2001 1:21 pm

Low tx power in the Maratrac is often found when the control head power is taken from a different point that the radio itself(large red lead). I was told that when there is a difference in voltage between these two lines, the radio thinks there is an antenna mismatch and will shutoff the amp section. Our fire department has changed wiring so both leads take power from the same place and it seems to have fixed our power problem.

benrussellpa · Post by **benrussellpa** » Sat Dec 22, 2001 4:56 pm

Thanks for the replies. I'll try to mention these things to the radio shop when I go to get the radio serviced, *again*.

Ben

radiofreak · Post by **radiofreak** » Sat Dec 22, 2001 8:49 pm

The maratrac was produced with 2 different mic hang up arrangements. The first type will have a button on the back of the mic that when pressed will hang up the PL. If you have this type of mic it may not be making the connection to ground when depressed into the clip. The other type has no button on the back, only the round peice that fits into the hung up clip. In order to put the radio into PL mode this round peice must be grounded. This is done through the clip but only if the clip itself is grounded, either through a metal dash or a ground lead. If you have this type of mic you can verify this by jumping a ground lead from the frame and touch it to the rear of the mic. Make sure you do this while recieving traffic not on your PL. If the unit mutes the non PL traffic just connect a ground lead from your vehicle frame to one of the screws on your mic clip.

Hope this helps

evans1733 · Post by **evans1733** » Sun Dec 23, 2001 9:29 am

You might want to have the programming checked to make sure the carrier scan option is not on, this will require a pl to open the radio. My department had the same scan problem and this fixed it.