Review on 🔔 Dakota Alert MURS Alert Transmitter (MAT) - Battery Operated PIR Motion Sensor with Telescopic Antenna - Enhancing Multi Use Radio Service by Russ Charmin

First of all, I'm a retired radio and aerospace engineer with a lot of RF experience. As many have said, previous units had many water/moisture issues. I've spoken to the engineers at Dakota Alert a lot and while they try to be extremely helpful, they aren't engineers! Priority number 1: use high quality ALKALINE or LITHIUM batteries! During transmission, these devices require a lot of power from the power supply. A limited current due to bad batteries will result in reduced performance! The BNC antenna connector used in previous versions should never have been used for such an outdoor device. The telescopic antenna was also a VERY bad idea for a number of reasons. This is primarily due to the weather, since water can penetrate between the antenna connections and get into the housing through the BNC socket! As serious as water damage is, operating it with an unmounted or incompletely extended antenna is even more detrimental to the transmitter. This can destroy the HF output transistor. This alone can cause irreversible damage much faster than water damage. The manual warns against using the device without an antenna, but says nothing about fully extending the antenna. The newer model with SMA connector and rubber duck antenna has some advantages over the BNC model, but also has some problems. The SMA bulkhead fitting used at the top of the case must be well O-ringed on the inside and not just resting on a rubber grommet on the outside. You cannot ensure a good seal on the threads of an SMA gland. There was an issue with the rubber washer added to the first generation SMA models preventing the antenna from being screwed in deep enough to make contact. This has since been fixed, but large numbers were being sent. The transmitter on them can be damaged due to a lack of proper contact with the antenna. In itself, the rubber ducky is a poor choice for the antenna. While it is less obtrusive than a telescoping antenna and less prone to water ingress, the effective radiated power (ERP) of this small antenna has been measured to be approximately 25% that of a full 1/4 wave whip antenna such as a telescoping antenna when fully extended is. This means that the transmission power is reduced to about 1/4 of the previous power with the same battery power. The rest of this energy is wasted in the antenna. Dakota Alert should have used a thin, flexible 1/4-shaft whip instead. It is less conspicuous than telescopic and rubber duck antennas and still offers full transmission power. Now for the sex change. Indeed, the female voice is too quiet to be heard well unless the volume is turned up higher than necessary. This is very annoying if, like us, you also use Dakota Alert and/or HT base stations for homestead communications. There is a small knob on the top of the transmitter board to set this. The transmitted sound increases counter-clockwise. Please note that these are narrowband (+/- 2.5kHz) certified transmitters for MURS channels 1-3 and increasing the transmitted audio too much may result in exceeding the FCC approved bandwidth. MURS channels 4 and 5 are wideband channels (+/- 5 kHz) and are not subject to the same restrictions. I have personally tried several motion alert systems and found the Dakota Alert MURS system to be the best for my application. . I observe remote properties and property lines through many trees, often in inclement weather. The VHF range of these MURS Warning Beacons penetrates wet film much better than the more common and less expensive UHF systems. However, I've encountered some of the design/implementation issues mentioned above, as well as a few others not mentioned above. For a VHF system like this, every transmitter must have a ground transmitter or ground plane. HF tends to penetrate transmitted audio and cause buzzing or beeping in some installations. This can be virtually eliminated by using a 1/2 wave antenna on the transmitters. Even if half of this amount were placed in the internal or external load coil at the base of the 1/4 wave whip antenna, adequate performance could be maintained. I have replaced the antenna on all my paging transmitters with 1/2 wave prongs with 37" .039" diameter stainless steel music wire. I hope this review helps someone.