Maximum Swing Power?

[wa373]

I am in the market for a new base station and am considering a Galaxy-2547 because it fits my budget and has very good reviews. I currently own a Galaxy DX-959 and I know that the innards of the 2547 and 959 are the same but the 2547 has better ergonomics for me.When looking at various websites that sell the 959 those sites claim 30 watts of "swing" after being "specially tuned". I also saw a Lincoln 2 which was rated by the factory at 28 watts but with a "special tune" are claimed to put out close to 50 watts. Really? Is it possible that those radios could put out that much power PEP with a "special" tune?

 

[binrat]

The whole swing thing to me is overrated. Trying to get every last watt can lead to failure and money into the techs hand.
For the receiving radio to see another S unit you 4x the power.
I have had both radios, alignment to ensure on frequency and a good mic is all you need, along with a sound antenna system
Just my humble opinion.

 

[543_Dallas]

The special tunes are used to take advantage of the ignorant customer. These guys are only concerned with making the watt meter swing higher because the customer doesn't know any better and it's easy money.

The Lincoln is an export radio so it does not have to be limited to 4 watts. The engineer that designed it didn't call it a 50 watt radio for a reason.

The 959 is a CB and has to comply with the 4 watts carrier and 12 watts pep rule. The engineer didn't spec it with the components to be a 30 watt radio.

 

[kopcicle]

The difference between 2.5w audio output and 6w output is .05% THD for 2.5w and nearly 10% for 6w!

2SC1969 specs can be a little less obvious. Although 16 volts will get you 28 watts out, this easily overwhelms the thermal dissipation of the TO220 package let alone the 2SC1969 die. On the other hand output power, collector efficiency vs input power crosses at 2.5 watts. Okay, so we know 2.5 watts is go and 28 watts is blow, so what does this mean in real world practice?

The easy route is to ask @unit_399 . Jim wrote extensively on the virtues and vices of the 2SC1969 some years ago and I have little to add. The readers digest condensed version is a 4 watt dead key and a corresponding 16 watts AM @ 100% modulation just works. You aren't stressing the 2SC1969 and the audio supplied is well within livable distortion limits. I've had reasonable success with 14.2 volts and 5 watts but the stress is on the power supply in "most" radios. This edges up on the audio requirement and leads to the questions , can you really tell the difference between .5% THD and 5% THD , and what is the difference in reliability between 4 & 16 and 5 & 20 watts?

I've included the datasheets for the 2SC1969 and TA7222AP so you can see for yourself.

 

[kaos513]

I have a dx2547 my self all stock works perfect, heck I haven't even aligned it my self

 

[wa373]

Does "swing" even matter or is average power a better indicator of the radio's transmit capabilities?

 

[Tallman]

Does "swing" even matter or is average power a better indicator of the radio's transmit capabilities?

The swing is what gets you heard.

 

[binrat]

A 1:4 ratio of swing works very well in my books.

 

[blasphemy000]

I'd just stick with a standard 4:1 PEP to Carrier ratio and leave it at that. Good clear audio, clean RF, and a good antenna system will easily get you heard. There are some specific reasons to use a different ratio but unless you have one of those reasons, I'd stick to the normal. Any standard receiver can hear a 4:1 without issue as well. Higher ratios can cause some receivers to distort badly for various reasons. One very important bit is to make sure you're not pinching the carrier off or flat-topping, both will cause adjacent channel splatter, reduce your range, and make you sound terrible. Don't get sweet talked out of your money by some tech that claims they can make your radio do miraculous amounts of power.

 

[Mustang 131]

A lot of swang watts are just harmonics. But lets assume it's not, are you really louder. Yes, no, maybe. Just buy an amp for the desired ouput and be done with it.

 

[543_Dallas]

I heard a guy on the air last night that is a prime example of this BS. He bought a new to him galaxy base a few years ago and it sounded very good. Within a few weeks his good friend and cb expert had him down to the cb shop getting it hacked up. Now they both sound equally shitty. Years of listening to trashed out radios has damaged their brains and they think all the distortion sounds powerful. It's a sad situation.

 

[Captain Kilowatt]

The swing is what gets you heard.

And yet high power international shortwave broadcasters use massive carrier and 85-90% modulation to be heard around the world under the most adverse conditions.

 

[Captain Kilowatt]

A 1:4 ratio of swing works very well in my books.

Agreed. I never did see the sense in going from double sideband full carrier AM to double sideband reduced carrier which is basically what this whole swing thingis doing. The guys on 80m with big iron run a 1:4 ratio and they sound GREAT.

 

[2NC995]

I heard a guy on the air last night that is a prime example of this BS. He bought a new to him galaxy base a few years ago and it sounded very good. Within a few weeks his good friend and cb expert had him down to the cb shop getting it hacked up.

Turned my mobile on this morning while headed to the store. S9 bleedover on all 40, all modes. Completely wiped out my receive.

I backed off the RF gain, and flipped over to AM. Finally found the guy...(wasn’t very easy as he didn’t sound significantly better on the right frequency than he did in bleedover mode).

He was giving radio setup advice to another guy...who couldn’t understand him.

I think the second guy overlooked the obvious...who would take set up advice from someone who is intelligible?

 

[Tallman]

And yet high power international shortwave broadcasters use massive carrier and 85-90% modulation to be heard around the world under the most adverse conditions.

Not many of us could put a installation up for 100's of kilowatts at home or in the mobile.
A good asymmetrical modulation works really well for low power systems.