Bandwidth and Mic Gain Question

[OLLIE]

I was messing with my FT-8800 (2M/440) the other day and came across the setting for Mic Gain and Band Width. The two setting are Narrow and Wide. Wide is the default setting. As I read the instruction book it said that in some circumstances Narrow would give me better TX/RX abilities. Do I assume correctly in saying that simplex would be that circumstance for better TX/RX since you are locking into one frequency???

[ki6kui]

Narrow bandwidth is used in other regions that do not allow as much bandwidth as we are allowed here. Be careful with the mic gain. Too much and you will over deviate. Your signal will be clipped to stay within the allocated bandwidth.

[OLLIE]

Narrow bandwidth is used in other regions that do not allow as much bandwidth as we are allowed here. Be careful with the mic gain. Too much and you will over deviate. Your signal will be clipped to stay within the allocated bandwidth.

So would that be a "no" to the question above?

[sdnative]

That's a good question. I was wondering the same thing myself.

In any case, I believe both ends have to be setup the same.

[cruiserlarry]

Narrow bandwidth is used in other regions that do not allow as much bandwidth as we are allowed here. Be careful with the mic gain. Too much and you will over deviate. Your signal will be clipped to stay within the allocated bandwidth.

The mike gain usually refers to the dynamic range and sensitivity of the mike amplifier output. I don't think it can cause the transmitted signal to deviate in bandwidth. But, when using a narrower bandwidth, it is easier to overload the dynamic range of the transmitted signal and create a distorted output. The wider the bandwidth, the more room you have for dynamic variation. So you want to adjust the mike gain to the highest level with which you can still present an undistorted output to the receiving station.

As far as setting the bandwidth, you would pick the setting for the allocation of that particular radio service in your area...

[ki6kui]

I have a VX-170. From the manual, it states "In many areas of the world, channel congestion has required that operating channels be closely spaced. In such operating environments, it often is required that operators use reduced deviation levels, so as to reduce the potential for interference to users on adjacent channels." The primary reason to use narrow bandwidth is because the band is crowded. In some other countries, narrow bandwidth is required on VHF/UHF.

In the United States, we do not have that requirement. You can use narrow bandwidth, and it should still work because you are reducing the bandwidth you are using. You are not changing the characteristics of the signal, so a receiver set to receive the wide bandwith would still receive the signal. However, as Larry stated, you are diminishing your dynamic range by cutting the bandwidth in half. Your signal will probably sound different because it will need to compress your dynamic range to fit the bandwith.

With the mic gain, since it increases the dynamic range, over deviating may cause the parts outside of the dynamic range of the signal to be cut off. It depends on how selective the receiver is. If it rejects frequencies outside of the allocated bandwidth, the audio portion is muted during the times of over deviation. For more information on bandwidth, see this article at Repeater Builder http://www.repeater-builder.com/tech-in ... ctrum.html.

[OLLIE]

Thanks guys... I'm starting to understand it now. It's not crystal clear but mud clear. I really need to get my General soon.

[cruiserlarry]

Thanks guys... I'm starting to understand it now. It's not crystal clear but mud clear. I really need to get my General soon.

...Maybe you need to turn down the "brain gain"...

[OLLIE]

Thanks guys... I'm starting to understand it now. It's not crystal clear but mud clear. I really need to get my General soon.

...Maybe you need to turn down the "brain gain"...

OUCH!!!!