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internal CB preamps

Red Ranger

Active Member
Aug 16, 2008
150
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I wonder why don't they build the Preamps into base station radios? I know there are internal preamp kits you can buy and modify your radio to an internal preamp.


Would a internal preamp using your CB's internal front end of the receive work better than say an external preamp in a linear that just amplifies the noise?
 

Why look for a noisy external preamp - when you can get more out of your radio's preamp?

Some radios can be modified with Shottky diodes along with a better quality transistor in the first IF stage. This mod can be done with Cobra, Uniden, Ranger, Galaxy, and a few other radios. I've done these mods on several Cobras with great success. This info is available on this site if you look for it. These parts can also be purchased in a kit on eBay; that is where I discovered it for the first time. The results are xlnt and well worth the $5 and the 30 minutes to install. Check it out on eBay.
 
Most radios don't need a pre-amp, they are as sensitive as the need to be. In fact, if you take a look at some of the better receivers, they have an 'AIP' or advanced intercept point selector, which is basically a way of making that receiver less sensitive, an attenuate.
- 'Doc
 
I wonder why don't they build the Preamps into base station radios? I know there are internal preamp kits you can buy and modify your radio to an internal preamp.


Would a internal preamp using your CB's internal front end of the receive work better than say an external preamp in a linear that just amplifies the noise?


All preamps increase noise and are worthless. If you can't hear someone without a preamp then the problem is clearly on their end and they need to deal with it.
 
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In a Base station, I'm talking about that distant station on a quiet night, where you can barely make them out. I can see a preamp built in being useful.
 
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In a Base station, I'm talking about that distant station on a quiet night, where you can barely make them out. I can see a preamp built in being useful.


The way I look at it.....if someone wants to be a mudduck then let them talk to people who are close. Tell the duck to go to the pumphouse!
 
Most radios don't need a pre-amp, they are as sensitive as the need to be. In fact, if you take a look at some of the better receivers, they have an 'AIP' or advanced intercept point selector, which is basically a way of making that receiver less sensitive, an attenuate.
- 'Doc

fancy name for an attenuator,

much the same as the radios that have AIP also generally have a preamp that isn't a preamp but nothing more than an attenuator off switch (not quite as glamourous), ironically the preamp off switch is actually an attenuator on switch and the attenuator on/AIP is nothing more than a deep deep undercover serious attenuator.

reminds me of the cobra dynamike, a fancy name for mike gain, or what is really a mike attenuator (how many people would see that as a useful function if it was labelled mike attenuator?). its amazing how a few carefully chosen words can give the impression your getting more than you actually are, and the respective manufacturers obviously see cb'ers and hams in exactly the same light, as they con both equally and view both as equally gullible.
 
In a Base station, I'm talking about that distant station on a quiet night, where you can barely make them out. I can see a preamp built in being useful.

Let's say that both you and a distant station are using the same radio. If you can barely hear him; what chance does he have to hear you unless he has a preamp and an amp to make up the difference?

Even Ham rigs have preamps in them, and aren't so useful. Why? Because preamps end up amplifying noise for the most part. Even in some of the better models. If you want to receive better; then consider a better antenna if you must.

Dedicated receive preamps aren't a 'hot seller'. Why? Because they just don't work like you imagine they would. The could work better if they use expensive parts - but they don't. The receive amp in a Texas Star amp works well; but even then - it still amplifies a LOT of noise vs signal.

If the radio you have is one of those I mentioned on my earlier post; then you would do well to get the receive kit that I mentioned. You will like the results, as I have liked all of the radios that I've modded with these kits. That is your best bet - IMO.
 
Probably the best thing you can do to improve your receiver's performance is to have it aligned by a good tech. A receiver can be "peaked and tweaked" just like a transmitter with good improvement in performance. Adding the schottky diode/transistor upgrade that Robb mentioned will help a lot too.

The big problem with adding a preamp (besides the fact that it amplifies the noise) is that the boosted signal usually overloads the receiver's mixer stage and actually degrades performance.

- 399
 
It's all about signal to noise ratio.

A cheap preamp will not improve SNR.

It will also screw up most noise blankers.


External ones are not within the receiver's AGC loop so they cause gain compression on moderate to strong signals. They can make the receiver much more prone to pick up unwanted off frequency stuff.

Preamps are useful on VHF and UHF where coax has thermal noise.
 
Probably the best thing you can do to improve your receiver's performance is to have it aligned by a good tech. A receiver can be "peaked and tweaked" just like a transmitter with good improvement in performance. Adding the schottky diode/transistor upgrade that Robb mentioned will help a lot too.

The big problem with adding a preamp (besides the fact that it amplifies the noise) is that the boosted signal usually overloads the receiver's mixer stage and actually degrades performance.

- 399

Or he could go up another 10 ft with the antenna.
 
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Or he could go up another 10 ft with the antenna.

a far better solution,

not only will it benefit rx but it will benefit tx too, in ways a preamp could never achieve. although in saying that its not always practical to raise the antenna higher. an alternative better route would be to buy a better antenna and/or better quality coax .

a combination of all three, better antenna, coax and more height would be by far the most rewarding solution of all in the long run, although it does call for an initial greater investment, but when you take into the account the initial cost V the long term improvement its probably the cheapest of all routes when weighed out over time.


skimping to begin with only leads to more financial outlay later on as disappointment inevitably drives you to seek out better gear. it kills me the amount of people who spend many hundreds or even thousands on a radio yet skimp on the most important parts of their whole setup, the coax,the antenna and the height the antenna is mounted at.

a thousand dollar/pound radio on a 50 dollar/pound antenna system will always fare worse than a 100 dollar/pound radio on a 300 dollar/pound antenna setup. all the bells and whistles in the world won't achieve anything if the basics are flawed.
 
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all the bells and whistles in the world won't achieve anything if the basics are flawed.

Jazzsinger... you are absolutely right.

First,I make certain that everything is properly grounded. Improper grounding can wreak havoc on receive noise pickup. Then check the coax, connectors, and antenna. The antenna height should be AT LEAST one wavelength. Then have the radio aligned (xmit and recv) by a good tech. Good techs don't brag, they let their work speak for itself, and they charge a fair price. The SCREWDRIVER JOCKEYS always BS you and tell you how great they are, then screw up your radio and charge you a fortune.

After you have the basics covered then you can try other signal boosting/ noise reduction techniques.

- 399
 

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