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Just started changing my mobiles (CDM 1250) and portables (HT1250) over to narrow band using CPS. Just changing 25 to 12.5 in the settings. Am I missing anything else??? I am not happy with the radio transmit strength and audio. There is a noticable difference. Anyone have any suggestions

Changing the radio over to 12.5 khz is the main and only setting you must change. If you go to the advanced tab and change the expansion setting to Low-level expansion and make sure you have de-emphasis and pre-emphasis selected for the emphasis selection it will help. You can also go into the tuner and increase the transmit deviation to the full 2.5 khz allowed, typically the max deviation from the factory is 2.1 to 2.2khz. Other than that, join the crowd, narrowbanding just sucks compared to wideband.

I have used narrowband for years.
When you are accustomed to the sound of a wideband carrier to a narrowband one, you do hear the difference.
Range is a little reduced, but in the real world, not so much.
One can do the theoretical and plot the effects of the two in operation, and possibly hear the differences at range limits from one another as well. Most people have no clue
the system/s they use are narrow or wide.

Properly designed radios, repeaters and sites in the real world, rarely provide mediocre service areas as there are far too many Fresnel zones within the coverage area to actually hear the changes. Tower shadowing plays a huge role in coverage areas when any site is on a shared tower. Elevation, cable type and loss plays a big [art, as does receiver sensitivity, modulation acceptance bandwidth, usable modulation range, receiver dynamic range and of course, duplexer losses. Every site is different, and terrain plays just as important a role, as does transmitter power.

Multipath in urban locations wreaks havoc on any system, and this also has a detrimental effect at a repeater site, so does site congestion, a single site can cause receiver degradation within the operational band (2A X B) Strong in-band interference, close spacing of systems at the same site, inverted systems, such as two UHF systems, one using standardized I/O frequencies, and one using non standard. This can create a feedback loop on the affected system, PL/DPL falsing and more.

Even on highband, I use nothing but narrowband, and have never been sorry either.
Tune your cans to the extreme, take the time to squeeze every dB you can before placing them into service, and you should never have to worry.
I make use of the notch feature, and spend the time to wrangle the best response from my cans, the more in a system, the better, but 4 usually work fine, as long as they are 4" cavities or larger.

As fr the CDM/HT1250, there is little you can do, aside from the service side of the radios, and fine tuning these for optimal use on the frequency range yo are using, not just broad tuning that is done by the factory. You can make the front end filters respond far better when you fine tune each item on its own.
I have a CT450 that opens on DPL at -137dBm.
My HT1250 opens with DPL at -128 dBm, but these radios are notorious for poor performing front ends. Bench tuning works best when coupled with actual usage tests so you have a mapping for radio performance that can be used with known results, known drop-off points, interference areas, as well as shadows (hills, valleys Etc..).
The bench can never tell you about poor service areas, only a real-time drive test can do this.

ard099 wrote:Changing the radio over to 12.5 khz is the main and only setting you must change. If you go to the advanced tab and change the expansion setting to Low-level expansion and make sure you have de-emphasis and pre-emphasis selected for the emphasis selection it will help. You can also go into the tuner and increase the transmit deviation to the full 2.5 khz allowed, typically the max deviation from the factory is 2.1 to 2.2khz. Other than that, join the crowd, narrowbanding just sucks compared to wideband.

You should never set the deviation to the full 2.5 K on the display!
If you are deviating to the 2.5 Khz. limit, the actual deviation WILL go outside the allowed limit as your modulation acceptance bandwidth WILL be outside the FCC limits, which means you might be causing IMD to another service.

Steady note deviation is less than peak deviation, so you should never go above 2.3x limits to prevent interference to other services.
You can test the process by listening to a narrowband signal on a service monitor and listen to where the receiver cuts off as the deviation level increases. This is NOT to be used to actually set the deviation, but it does give you a real-time observation of the effects.

Also, if you have the CDM radios as control stations in certain cases full compression will help with the audio delivered to the console or remote, it seems to help clean it up a little but I typically don't use it on a radio to radio basis. And AEC, could explain to me why I'm not allowed to set my radios for maximum 2.5khz deviation that would be great. The maximum deviation allowed is 2.5khz for 11K0F3E emission designator and according to the formula for calculating occupied bandwidth you don't exceed that occupied bandwidth. 2*(3+2.5)=11.