Of the many and varied differences between LMR licenses and where LMR operationally differs from ‘Ham Radio’ can be initially summarised as -
a) LMR equipment is mandatory Type Approved, with various degrees of additional compliancy requirements in use over valid TA compliancy and certification. In some LMR categories, you have very restrictive conditions governing antennas and use of additional RF equipment - especially in the license-free or license-exempt categories of use and destined equipment use as certified.
B) With LMR usage, you have defined bands and channelised frequency allocations and usage outside the license mandated parameters is outside of the central governing broad permitted usage of radio equipment as well as a criminal offense in many countries - without certified license exemptions or temporary permit which gives you limited use of additional defined frequencies. Where licensed usage exists (and still includes L-F and L-E provisions), you can apply for a specific limited exemption, or what we call in the UK a ‘variation’ - however, and whilst it’ll vary region to region and by governing PTT, generally NOV’s (using the UK terminology there) are few and legit qualifying reasons within those few instances are even rarer.
In fact, unless your variation need and application ties into mandatory necessity to have means to assist officially with emergency services as a relay operator (to narrow the variations into one recognisable type) or the LMR service you use requires addional permits/variation permits for you to maintain/service/certify, the typically spread of LMR variation permission qualifying criteria is pretty much bordering on nil. Where they do exist, don’t even think about being creative with the truth, as a falsified application can also be a criminal offense, a cause for future licensing to be issued/permitted under much discretionary terms or both, and even where you’re officially black-marked, don’t expect to get full provisions on any kind of operator license.
C) With LMR, it’s pretty universal (either for TA compliancy, or simply down to legislation) that your radio is a sealed ‘black box’ and where you are permitted to alter it, it’s by permitted types of ancillary equipment. The ‘black box’ is not to be tampered with under any circumstances, by a non-authorised personnel (ie you need to be certified, unless it’s part of LE or government investigation where they (law enforcers or government investigators) have certain rights over the norm).
In some regions, and by simple logic it’s actually fair, leaving ancillary test equipment (RF) attached out of actual testing can be a license breach. SWR/Reflectometer and Power meters, used the RF output side as ancillaries, are actual sources of stray RF harmonics (especially cheapo stuff which is barely fit for purpose anyway). Under such conditions, and under most responsible usage (in any license category or grade), a LPF or BPF is usually permissible as (where they actually function properly) they are added efforts to reduce any stray harmonic levels ‘out of band’. Equally, attenuators are often permissible for attenuation of overly strong local signals in high congestion areas or if you are near a high field density generating transmitter site. But you usually can’t (under LMR licenses) use an attenuator to bring a high power compatible transceiver into line with your licensed max ERP limits. Region variations exist, but that’s pretty universal to one extreme or another.
C) The fact you solely have your commercial or leisure LMR license does not permit you to have functioning unlicensed or non-licensable equipment in any kind of use. Some regions will permit Rx use of such equipment, but in most cases, that doesn’t cover transmit inhibited Transceivers for use soley as receivers. Where the equipment is not licensable, it usually can be exempt if it’s not in any kind of working condition - we are talking here, stuff you can gut for parts and hardware, but not with intent to repair and make functional.
Note :- that last section about unlicensed transceivers is pretty universal valid unless you’re a licensed Ham Radio operator as well.
D) In conjunction with restricted band and channelised frequency use, with LMR services, if you do import equipment that’s allegedly TA certified, if it’s capable of operating using modes and or emission classes or has ‘extra’ stuff like sending position data/GPS ranging data/very high level encryption, even if it’s truely interoperable (how a lot of Chinese cheapo PDTS/PDS market stuff gets marketed as Tier 1/2 DMR/PMR and suchlike) it’s generally not legal to use even if you are capable of reprogramming it for the right modes and frequencies.
Ham Radio - where ham radio operators get to bypass most of that, and worst case, get a lot of latitude instead of a freedom, they get it because they qualified as Technical Grade operators and are recognised as being competent to experiment and modify/ convert equipment or scratch build or even hybrid equipment as part of their legally permitted research and investigation into radio communication and the physics and other science factors such a propagation, provided they use it within their allocated frequencies on allocated bands. They are licensed to use radios in fully tunable mode (VFO), use a very wide variety of operational transmission modes and emmision classes required by the transmission modes.
They can test equipment ‘off frequency’ to evaluate it’s functional state, but under sink condition where a non-resonating load is put into the antenna connection. Some test gear has it’s own ‘dummy load’ so acting as a non-resonating load as well as for measurement. But once it’s adjusted to be correctly in band and frequency allocation, they are permitted to go actual on-air as some parts of testing and adjustment requires free air testing. It’s here they measure, analyse and assess what’s necessary to suppress out of band emissions and whether it’s emissions are a valid type for licensed use. Another aspect is they also have a lot of freedom to import/purchase or otherwise legally obtain equipment in any state provided it’s decommissioned (where it was a restricted item) and certified as and not under any standing total prohibition making it illegal own/possess by civilians. So, that means the limits to what’s obtainable and legally importable is pretty ■■■■■■ wide ranging. They are also not required to have TA’s on equipment used for Ham Radio use (multi use, say Commercial LMR and Ham usage under separate programmed setups, still requires TA to be there in as much as the Commercial use would require it under such use).
So that’s a pretty comprehensive summary of differences in practice between LMR users and Ham Radio operators as end users.
E) Emission classes and modes are two sides of a common coin. A mode refers to how voice and telegraphy is used modulation wise and bandwidths etc. For reference, every kind of transmission can be defined as voice or telegraphy transmission. Digital Voice modes are just voice converted to data and sent telegraphically. So in DV, voice refers to the content, digital refers to how it’s delivered over telegraphic transmission and resolved as to restore on reception.
Emission classes refers to types and sub-types of the actual way and shape the carrier is modified. For example, FM has at least three different e.c.'s, depending it’s content and how it’s frequency shift modulated. Pure FM, has limiter governed frequency shifting inserted very early in the transmission chain, often pre to final centre frequency has been multiplied to it’s final frequency. Delta modulation refers to frequency shift where you apply the modulation as a difference or small shift the final empty carrier or pretty much in the later frequency generation stages.
Most FM transceivers use delta modulation to achieve their FM mode, but high end stuff drifts towards true FM.
So whilst emission classes and modes are intertwined at one level, they are two entirely separate things.
I hope that’s shed some light on some question commonly asked or pointed towards in radio licensing and restrictions and a few more technical things you may come across when choosing and sourcing.
Note, licensing and usage is very subject to local andvregional variation, so check what applies to you and why and use that to assess advice and pointers towards your enquiries and subsequent usage.