Transmitter audio freq response

[Marc]

Has anybody found away to increase the transmit audio freq response on the newer radios.
I noticed most are 300-2500 Hz. I would like to get it to 200-5000 if possible.

Marc

[Tombstone (R.I.P.)]

I'll just make a couple of suggestions and I know what you want to do so I'll try. I don't know if going to a different audio transformer or changing the values of related parts would help or not. You could try coming off of the external speaker jack and using a little larger speaker with a wider response. Using an equalizer with that should help too?? Good luck.

Tombstone

[Marc]

What I am trying to do is , open the audio response of the Mic amp circuit from the standard 300-2500 Hz to 200 - 3500Hz
or higher if possible.

I saw that the 2985DX was 400- 5000 on am what is the mobile version of this radio?

[Tombstone (R.I.P.)]

Sorry, I misunderstood. I don't know what the mobile version of that radio is but maybe a mic with a wider frequency range will help.

Tombstone

[Sandbagger]

Feb 6, 2009 15:48:51 GMT -5 Marc said:

What I am trying to do is , open the audio response of the Mic amp circuit from the standard 300-2500 Hz to 200 - 3500Hz
or higher if possible.

I saw that the 2985DX was 400- 5000 on am what is the mobile version of this radio?

Expandng the microphone frequency response is usually just a matter of changing the element. But bear in mind that changing the response of the microphone will usually not be enough to expand the response of the whole radio. Depending on the radio, there will be audio low pass filters and other cap values to be changed, something best tested with a variable frequency audio generator.

[Tombstone (R.I.P.)]

Thanks for jumping in there, Sandbagger! I was more or less baffled when offering suggestions to the question. I thought that there would be a way to change the response inside the radio but I've never had a request for that and have not even given it a thought.

Tombstone

[Sandbagger]

Feb 7, 2009 15:05:39 GMT -5 Tombstone (R.I.P.) said:

Thanks for jumping in there, Sandbagger! I was more or less baffled when offering suggestions to the question. I thought that there would be a way to change the response inside the radio but I've never had a request for that and have not even given it a thought.

Tombstone

In order to keep CB radio transmissions within a 10 Khz channel, and allow for frequency errors and provide a guard band, the audio frequency is limited to 6 khz (+/- 3 Khz). Typically what they call "communications quality audio" falls between 300 and 3500 hz. Most CB radios are designed to pass this range.

Some radios are a little wider than others and a bunch of people are into "hi fi" expanded frequency audio and they modify their radios to increase the audio frequency range. Of course, the other thing to remember is that most receivers are also limited to 6 khz and any audio above that frequency will get rolled off by the receiver and wasted, unless modifications are also done to the receiver. But widening the receiver's passband will allow in more adjacent channel bleedover and will reduce the signal:noise sensitivity somewhat. But if done right, it sure sounds good. Just like a broadcast station.

[Night Ranger]

Feb 7, 2009 18:06:18 GMT -5 Sandbagger said:

Feb 7, 2009 15:05:39 GMT -5 Tombstone (R.I.P.) said:

Thanks for jumping in there, Sandbagger! I was more or less baffled when offering suggestions to the question. I thought that there would be a way to change the response inside the radio but I've never had a request for that and have not even given it a thought.

Tombstone

In order to keep CB radio transmissions within a 10 Khz channel, and allow for frequency errors and provide a guard band, the audio frequency is limited to 6 khz (+/- 3 Khz). Typically what they call "communications quality audio" falls between 300 and 3500 hz. Most CB radios are designed to pass this range.

Some radios are a little wider than others and a bunch of people are into "hi fi" expanded frequency audio and they modify their radios to increase the audio frequency range. Of course, the other thing to remember is that most receivers are also limited to 6 khz and any audio above that frequency will get rolled off by the receiver and wasted, unless modifications are also done to the receiver. But widening the receiver's passband will allow in more adjacent channel bleedover and will reduce the signal:noise sensitivity somewhat. But if done right, it sure sounds good. Just like a broadcast station.

I think the whole wide band audio hi-fi ssb stuff is non-sense. Generally when I hear someone try that it usually sounds terrible over a stock receiver, and since 99% of all CB and ham receivers will be stock that means sounding terrible for 99% of the people that hear you. Some of those guys have the bass cranked up so high it reminds me of the teenage cars that have nothing but bass in the sound system. They ruin the music just to make the trunk vibrate. One of the locals in Spartanburg, SC has so much bass you cannot understand what he says. All you hear is some unintelligible low boom on the channel when he keys up.

You can add alot of nice pleasant audio tone to a CB or ham radio simply by increasing the value of two of three coupling capacitors in the mic amp circuit. After that it just becomes a waste of money and bandwidth to make a radio sound bad.

You use to hear radio tech savvy people on ham radio discussing the science of radio communications, but now about the only thing most of them can comprehend is adjusting their microphone equalizer. It speaks sadly for the current state of ham radio. In the United States we shipped the know how over seas along with the manufacturing plants.

[Sniper..Unit 305]

I know that I hear alot of fellas on the ham bands with the expensive eq's and mics and they sound to me like they are talking with a mouth full of marbles. If thats high fidelity, then they can keep it. Sniper

[Sandbagger]

Feb 9, 2009 0:02:18 GMT -5 Night Ranger said:

Feb 7, 2009 18:06:18 GMT -5 Sandbagger said:

In order to keep CB radio transmissions within a 10 Khz channel, and allow for frequency errors and provide a guard band, the audio frequency is limited to 6 khz (+/- 3 Khz). Typically what they call "communications quality audio" falls between 300 and 3500 hz. Most CB radios are designed to pass this range.

Some radios are a little wider than others and a bunch of people are into "hi fi" expanded frequency audio and they modify their radios to increase the audio frequency range. Of course, the other thing to remember is that most receivers are also limited to 6 khz and any audio above that frequency will get rolled off by the receiver and wasted, unless modifications are also done to the receiver. But widening the receiver's passband will allow in more adjacent channel bleedover and will reduce the signal:noise sensitivity somewhat. But if done right, it sure sounds good. Just like a broadcast station.

I think the whole wide band audio hi-fi ssb stuff is non-sense. Generally when I hear someone try that it usually sounds terrible over a stock receiver, and since 99% of all CB and ham receivers will be stock that means sounding terrible for 99% of the people that hear you. Some of those guys have the bass cranked up so high it reminds me of the teenage cars that have nothing but bass in the sound system. They ruin the music just to make the trunk vibrate. One of the locals in Spartanburg, SC has so much bass you cannot understand what he says. All you hear is some unintelligible low boom on the channel when he keys up.

You can add alot of nice pleasant audio tone to a CB or ham radio simply by increasing the value of two of three coupling capacitors in the mic amp circuit. After that it just becomes a waste of money and bandwidth to make a radio sound bad.

You use to hear radio tech savvy people on ham radio discussing the science of radio communications, but now about the only thing most of them can comprehend is adjusting their microphone equalizer. It speaks sadly for the current state of ham radio. In the United States we shipped the know how over seas along with the manufacturing plants.

Well, hi-fidelity audio will not get out any better, and unnecessarily wastes bandwidth with audio frequencies that are not neccesary for voice communications.

But it does sound nice when done properly. I like hearing those guys who sound like broadcast stations. But I haven't done anything to my receivers to get that sound, so it is possible to get that "broadcast sound" without going totally nuts with audio bandwidth expansion. Much of the "warmth" that you hear comes from the low frequency area. The nice thing is that expanding the low end does not require increasing your receiver bandwidth, but you have to be careful to not overdo it. Just like echo, where a little bit will add depth, many CB'ers use way too much, and the same can hold true with a graphic equalizer....

[Marc]

Thanks for the input . That is what I looking for .

Marc

[BladeRunner now OLD FLASH!!!!!]

I had and old equlizer from the mid 80's, I connected it to my mark III and have it connectd it to an inexpensive set of jenson Computer Speakers. The improvement over the radio speaker is dramatic. I at the age where I'm haveing a small problem hearing voices and this change has mad such an improvementment I can hardly believe it. I'm going to find a better set of speakers and see if that helps any more.....I'm glad someone suggested that...Thanks