Motorola PM400 Antenna Question, Need Help

My son’s fire department gave me a Motorola PM400 radio to listen to fire calls. I want to set the radio up inside my home. I have a A/C to D/C convertor and have everything set up and working. I need help with finding a antenna that I can it on the floor and get decent reception. I now have a magnet mount antenn sitting on the floor hooked to the radio, but the recepiton is poor, it’s a cheap small antenna. The connector on the radio for the antenna looks like on that’s on my TV to hook my cable to. I am new to radios as you can tell. What Antenna would be Best for using inside the home? Thanks

Those are very good radios, and they can be programmed for either VHF or UHF channels. You don’t really need to know what those terms mean, but basically before anyone can give you advice, we will need to know the frequency that the fire department is using. It will be a number, followed by MHz. If the numbers are between 136 and 174 MHz, it is a VHF radio. If it is between 400 to 470 MHz, it is UHF.

The antenna must be matched to the frequency range, and this is why we will need to know the frequency they are broadcasting on.

Even if the department don’t know the frequency, there are comprehensive databases of scanner frequencies that you can look up the name of the department and find it quite quickly. Or if you want to tell us your location, someone on here can maybe look up the frequency for you.

The company that hosts this forum can help guide you to the proper antenna once they know the frequency. One thing to consider is that two-way radios are line-of-sight transmissions so the higher the antenna, the better.

By the way, that radio is designed to transmit and receive. (I am sure they warned you not to use it for transmitting!) It is basically designed to be mounted on fire trucks, and interestingly enough, antennas work best when mounted on top of flat metal surfaces such as the roof of a fire truck. They will not be optimized for use in a home.

One of the complicating factors to using this radio to monitor transmissions is that most public services are moving to a new radio system entirely. Some are going to a “trunked” system, which means a lot of agencies can share frequencies, or more likely to digital radios. One of the most common digital formats for fire and police departments is statewide transition to a P25 (APCO Project 25) digital radios, so agencies can all talk to each other when needed. I suspect this is why they gave you that older radio.

If the fire department is moving to new technology such as P25, they will also transmit on the old analog frequencies, but it is more of just a ‘spillover’ effect and cannot be counted on. Fire departments especially like to keep the analog frequencies at the same time as digital, just to test out their system and be a backup until they know for certain the transition to digital is going to work. What this means to you is that you will not hear all the calls, and in a few months or years, you will not hear any calls.

(Interestingly, why fire departments still run analog VHF frequencies as backup is because in the early days of digital radios and P25 adoption, some makes of digital radios would fall apart into just digital noise if they were used beside very loud machinery … such as a working pumper truck. Those problems have been mostly solved now, but many fire departments are a bit ‘gunshy’ so to speak, because of problems for the early adopters of digital radios.)

So, basically, if you want to monitor fire calls, I would suggest not spending a whole lot of money right now. That radio may be obsolete in your area soon. Save your money and look at getting a scanner that can monitor trunked radio plus P25 digital radios. (Right now, they are VERY expensive, but give it a year and the market will respond with more models at more affordable prices.)

The Frequency is 151.58000 , my son told me they are analog and have no plans going digital anytime in the near future. All the fire departments, police, EMS around me are all Analog. Can you tell me which antenna would be best by the list? Also, what antenna cable fitting is used to plug into the back of my radio? I have an old antenna on it now and used a cable tv fitting to hook it to the radio. Sorry for the probably dumb questions, but I have no clue about radios, just like to listen to them. I took the Mic off the radio so I wouldn’t accidently hit the talk button. Thanks for the help.

I will leave it up to the antenna experts for specific recommendations, but you are basically looking for a VHF antenna with a mini-UHF connector to the radio.

The best solution is a scanner antenna mounted to the roof of your house.

If this is not possible, you can mount an antenna directly to the back of the radio. It will not give you as much range, but it may be all you need if they are close to you. It is called a “back of set” antenna, and mounts directly into the antenna connector. If you have trouble finding a back of set antenna with a mini-UHF connector, you can find someone who can sell you an antenna with a more common connector such as one called a BNC connector, plus an adapter to go from BNC to mini-UHF.

Antennas designed for vehicles may not work as well as a simple scanner antenna because you will not get the same ground-plane effect as an antenna mounted on the roof of a metal truck. When you are talking to some antenna experts, tell them it is for receive-only and not for a vehicle.

There are some mobile antennas designed for off vehicle use, sometimes called no ground plane antennas. You may need to buy the antenna and the cable separately. I am not an expert so I will leave it up to others to say if this is a good option for you.

One other suggestion for you is that if all the public service agencies in your area are staying with analog for now, why not get a scanner. This is designed to quickly scan from channel to channel and you can listen to police, fire, aircraft etc. It can also be a very interesting hobby.

You can get good quality scanners for not much more than the price of an antenna for your mobile radio.

I have a scanner now and it just doesn’t pick up all the channels this radio does. On my old scanner for some reason I couldn’t pick up the fire department, police or EMS in my area. I had it programmed to the correct frequency by the list on, but they wouldn’t work? When I got the scanner and couldn’t pick up the channels, someone told me I needed a Trunked Radio? I don’t know what a trunked radio is, but the Motorola PM400 I have will pick up all the channels, I just want a better antenna for better reception. Again, I am NEW to the radio world, so if anyone has a antenna recommendation please let me know the brand and model number I can order from. Thanks again.

Would this Antenna be a good choice?

With Mini UHF male connector installed

Manufacturer Tram
Model #1100
Product Description
136-174 Magnet Mount
Frequency (MHz) 136-174 MHz (Tunable)
Product Narrative Includes 12’ of coax and PL-259 (UHF) connector installed
Usable Bandwidth 5 MHz
Gain (dB)
Maximum Power (Watts)75
Whip Length (In.) 20.5" (At 136 MHz)
Whip Material Stainless Steel - Chrome
Mount Type Magnet
Cable 12’ RG58/U


Yes, you are correct. An older scanner will not pick up trunked radios. Some newer ones have the capability, although in your case, I would use what you have now and enjoy hearing the calls.

That Tram antenna will work. It is designed to be mounted on a roof or trunk but should work okay in your house if you can get some metal underneath it to act as a ground plane. The best solution is to get it up as high as possible in your home. (Height is everything with VHF/UHF.)

I have heard of people getting good results placing that antenna on top of a metal filing cabinet. If you have no convenient metal filing cabinets, simply get a plate of steel or galvanized steel about the same size as the top of a metal filing cabinet. Paint it, place it flat somewhere to get it as high in your house as you can, and stick the antenna to the middle of it.

Good luck and be sure to check back with us to let us know how it works.