How much power can be safely coaxed out of a standard CB radio now days?

[kc0bus]

Hi,
How much power output (in watts) can be safely had, without destroying the final, from a new or vintage standard mobile CB radio after a "peak and tune" job or a "tune up" job? And where would I take my radio to have such a job done?
Thanks

 

[jonwienke]

That varies widely depending on the brand/model of CB, and to a lesser degree the individual unit. You'd probably be better off with something that doesn't need a "golden screwdriver" job, like the Stryker 955. It will output more power without having to overmodulate and splatter 10 channels in each direction.

 

[RFI-EMI-GUY]

Hi,
How much power output (in watts) can be safely had, without destroying the final, from a new or vintage standard mobile CB radio after a "peak and tune" job or a "tune up" job? And where would I take my radio to have such a job done?
Thanks

I think you will find your answer in the FCC part 95 rules. The FCC has a limitation on the exact dissipation and power handling of the final transistor. You won't get much more than 4 watts AM / 12 W SSB.

A "peak and tune job" is a hack. Don't waste your money. The radio will sound like crap. If you want overmodulation, splatter and distortion, go for it. I wouldnt.





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[ridgescan]

Are you talking about a base? If so, I'd put up a high-gain directional beam antenna and put that 4 watts to work. Better than violating the inside of the radio.

 

[DaveJacobsen]

Safely...

it depends on the unit. "vintage" means a lot, and there used to be a LOT of radios back then in "vintage" times.

Some could be tweaked to put out 5 watts, maybe 6 or 7. The gain you get isn't really worth the added strain on the finals (which shorten the life).

If you want to put out more than 5watt power, which, if in the USA, is illegal, I would suggest something like a KL203 which can be found in a kit form and fit inside your radio. unlike the RX75, the KL can be turned on/off as needed.

Personally, I would run an external amp. But now that you've started down the road, "it depends" on how much power you want.. More power means: Bigger power wires, Better ground, & a better antenna. Usually, an SWR of 1.5 is the maximum you want to have to not wear out your amps.

I have used the "internal" amp; which is nice but then requires an external speaker. So I prefer using a KL203P external amp (if that power is in your range) as then you get a pre-amp too (and get to keep your internal speaker). My current mobile rig uses a KL503P, and base uses a midnight-special 400; both are "entry level" amp and require filters to keep from splattering to your neighbors' TV...

That's a long way to say "it depends on a lot more than just the radio, it depends on what you want to do"

BUT: Modifying your radio to put out more than 4 watts is illegal (aligning/tuning your radio is not); using an amp on a CB is also illegal. The FCC occasionally goes after CBers that piss off people who complain enough.

 

[krokus]

I have seen some CBs that could put out 7 to 10-ish Watts AM.The FCC certification was maintained by altering the bias on the final, with the bias resistor determined on a unit-by-unit basis.

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[K5MPH]

it depends on the unit. "vintage" means a lot, and there used to be a LOT of radios back then in "vintage" times.

Some could be tweaked to put out 5 watts, maybe 6 or 7. The gain you get isn't really worth the added strain on the finals (which shorten the life).

If you want to put out more than 5watt power, which, if in the USA, is illegal, I would suggest something like a KL203 which can be found in a kit form and fit inside your radio. unlike the RX75, the KL can be turned on/off as needed.

Personally, I would run an external amp. But now that you've started down the road, "it depends" on how much power you want.. More power means: Bigger power wires, Better ground, & a better antenna. Usually, an SWR of 1.5 is the maximum you want to have to not wear out your amps.

I have used the "internal" amp; which is nice but then requires an external speaker. So I prefer using a KL203P external amp (if that power is in your range) as then you get a pre-amp too (and get to keep your internal speaker). My current mobile rig uses a KL503P, and base uses a midnight-special 400; both are "entry level" amp and require filters to keep from splattering to your neighbors' TV...

That's a long way to say "it depends on a lot more than just the radio, it depends on what you want to do"

BUT: Modifying your radio to put out more than 4 watts is illegal (aligning/tuning your radio is not); using an amp on a CB is also illegal. The FCC occasionally goes after CBers that piss off people who complain enough.

You could also use the PCN-60 internal amp with out removing the speaker,but it only put out up to 50 watts I do agree using a amp would be better than hacking the radio not saying it cant be done.....

 

[prcguy]

If the radio dead keys more than 4W carrier, its no longer type accepted under any circumstances. A properly adjusted 4W AM transmitter will produce 16W peak power at 100% modulation, the FCC knows and expects that. Most radios will not quite get to 16W peak due to the modulation limiter settings from the factory, but every CB should be capable of that. To measure peak power you must use a peak reading wattmeter or oscilloscope, most wattmeters will not show it.

I have seen some CBs that could put out 7 to 10-ish Watts AM.The FCC certification was maintained by altering the bias on the final, with the bias resistor determined on a unit-by-unit basis.

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[FiveFilter]

Like DaveJ, I too like the KL203P external amp. For about 70 bucks, it will put your RF signal out there with much longer legs.

The best part is, you don't risk your radio to a tech who might mess it up more than pep it up. And you don't force the radio to do more than the manufacturer designed it for.

In my case, a little Uniden 520 radio puts around two watts into the 203P, which then amplifies the signal to about 60 or so watts dead key. I use this combo in car, and it talks and listens very well via a 56-inch Wilson 500 mag mount antenna on the roof.

This is just my approach. Beefing up a radio is another approach. It's nice to have choices.

 

[TheSpaceMann]

Many die hard CBers prefer keeping their actual output wattage down, so they can feed external power amplifiers. You can see some of those amplifiers here: DaveMade Amps

 

[RFI-EMI-GUY]

Like DaveJ, I too like the KL203P external amp. For about 70 bucks, it will put your RF signal out there with much longer legs.

The best part is, you don't risk your radio to a tech who might mess it up more than pep it up. And you don't force the radio to do more than the manufacturer designed it for.

In my case, a little Uniden 520 radio puts around two watts into the 203P, which then amplifies the signal to about 60 or so watts dead key. I use this combo in car, and it talks and listens very well via a 56-inch Wilson 500 mag mount antenna on the roof.

This is just my approach. Beefing up a radio is another approach. It's nice to have choices.

There are a couple companies selling nice 27 MHz bandpass filters that would compliment the KL203P in both transmit amp and receiver preamp modes. It would suppress harmonics and prevent your "handle" blasting through the local ATC tower.

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[FiveFilter]

RfiEmiGuy, thanks for the tip! I'll certainly keep that in mind. However, this little amp seems to be quite controlled. I don't remember reading of anyone reporting harmonics problems with it, and to my knowledge mine doesn't. If I ever do get an indication of any problems I'll certainly look into those filters.

One thing I'm careful to do is to keep the feed power to about two amps or less. I know that if any amp is fed too much power, it can cause unwanted consequences. So far, my set-up seems to be doing well.

 

[RFI-EMI-GUY]

RfiEmiGuy, thanks for the tip! I'll certainly keep that in mind. However, this little amp seems to be quite controlled. I don't remember reading of anyone reporting harmonics problems with it, and to my knowledge mine doesn't. If I ever do get an indication of any problems I'll certainly look into those filters.

One thing I'm careful to do is to keep the feed power to about two amps or less. I know that if any amp is fed too much power, it can cause unwanted consequences. So far, my set-up seems to be doing well.

I looked into it because I found that some of those amps had a nifty preamplifier, but it has no bandpass filter which is just stupid. So you can buy a high power bandpass filter and improve the receiver and at same time the FCC won't be getting a call about TVI or interference to aircraft due to your amplifier.

Model 411CB CB Band $38.00

https://www.iceradioproducts.com/filtersrf.html

https://www.iceradioproducts.com/images/ICEBPFdatasheet.pdf

This is just one of about 3 companies making HF bandpass filters for ham and CB. A 10M filter wont work, it must be 11 meter or a 10/11 meter model.

More here:

http://www.kitsandparts.com/W3NQN_May_June_1998_QST.pdf

 

[FiveFilter]

Thanks for the references. Hope I don't need them, but I now know what and where they are if I ever do.

One advantage I have is that I only use my little amp while in my vehicle on the highways, and then only if I'm struggling while barefoot. So, if I get on anybody's nerves, it likely won't for long. I don't talk a lot anyway.

I have found the KL203P's preamp works really well. Even though it does bring in some background noise like they all do, it's proven to be very useful and usable when trying to enhance weak signals.