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QuestionS About CB's and Hams

Find someone who has a calibrated spectrum analyzer (not an oscilloscope). Take a look at the output of the amplifier with the analyzer and see how much of the signal is on the correct frequency and how much of it is scattered around the entire HF/VHF spectrum in the form of harmonics, spurs and IMD, as well as how much is simply overwhelming the output and spilling onto adjacent channels.

Spectrum analyzers are expensive, but there's no other easy way to separate decent amplifiers from those made for CB, which are illegal to begin with and therefore have no industry standards to which the "builders" can be held.
 
I've often wondered why builders/designers of these amps just don't put in 5 or 6 dollars worth of parts and make them cleaner. Focusing the output transistors in throwing out a signal that is on frequency would also mean using all of the transistors ability where it is needed most. Who wants to pay for amping harmonics and IMD anyway? Sure, it might sound louder at the other end (class "c" comes to minde here), but it really squandering the power that is available. Putting the filtering BEFORE the final transistor stage would help insure a cleaner, more accurate and powerful output. Yeah, it would mean changing the board design a bit and cost more for some parts, but the end result would be far better - IMO...

Besides, if they were to make these amps run on track as they should and be a bit more expensive, it would be interesting to see Hams buying/using them. Especially after they have been collectively knocking them for so long. As opposed to those way over priced/underpowered Ham amps which are hyped up. Talk about a racket; just because you can have a license that allows you to use more power and then getting your last dollar for their overpriced gear. What a crock!

Of course, making the radio as clean as possible before it gets to the amp is also a major concern. Putting a scope on the radios output and cleaning up its act BEFORE it gets to the amp is also a critical factor for clean output...
 
To answer that last question, no, we don't know that. We can't tell you which is clean or dirty, or to what extent an amplifier is clean/dirty. To the best of my knowledge no one has ever done a legitimate study like that. Why? Because it is expensive, requires equipment that very few individuals own, and time they don't have. Not to mention getting an anonymous typical example of an amplifier to test. Sure, we all have suspicions of which is which, but no documented facts from an accepted authority on such things.
Do this. Think yourself through the steps of buying any amplifier, specifically, not just a generic step by step thing. Where do you get one, how do you get it, what's it cost, what are you going to tell the seller that you want it for, etc, etc? Be paranoid about each of those steps, you know? Even so, how long before someone 'twigs' to what you're doing and spreads the word? Far fetched? Not as much as you might think. Can you imagine the problems you'd run into after that? There goes your testing.
So does that mean it's impossible? Of course not, just a @#$$ of'a lot more difficult. Know of anyone who'z willing to do that? I don't.
A lot like evaluating the quality of 'street drugs', huh? I ain't going there either! It ain't the same! Oh? Both illegal, no standards, "iffy" dealers, and the Lord knows what other comparisons. Same difference, just a matter of degree.
Ain't this fun?
- 'Doc
 
I imagine that there are probably a few people that have put these amps on Spec Analyzers to test them out, but there aren't any "official" specs. I remember a few years ago looking at a Texas Star on a spec analyzer, but I don't remember the outcome.

You can speculate fairly easily which are the cleanest of the CB amps by looking at how they are constructed. Look for something that has AB biased transistors, thermal bias regulation of some type, and some type of output filtering. Just about the only thing that I've seen that has all of that are some of the Palomar amps. You can also add your own filtering (30Mhz cutoff low pass filter) externally, if you want.

The other thing that's important to understand is that you have to be careful with how hard you drive these amps also. Most (probably all) of the CB type amps don't have any type of input swamping to prevent over-driving the transistors. When you overdrive them, they will show more power output, but at the cost of giving off a lot more harmonics, spurs, IMD, etc. Most CBers will drive the amp as hard as they can until they see no additional power increase, which will guarantee that it gives off lots of trash.
 
thanks, well thats some good info there....

it makes me happy i never "peaked the radio to drive my amps to their fullest.

both amps i own are ab biased, i made sure of that when buying, i wanted best cleanest ssb operation... thats about all i knew...
 
Rob KI6USW said:
Besides, if they were to make these amps run on track as they should and be a bit more expensive, it would be interesting to see Hams buying/using them.
Click to expand...

If they were to make these amplifiers "run on track", they could get them certified by the FCC, just as the manufacturers of amateur radio amplifiers have done for decades. THAT'S why the AR amplifiers are so much more expensive. Certification is an expensive process.
 
Tez if you are debating on wether to take the plunge into ham radio.I would have to say go for it !! And go for at least the general class ticket,that way when you can afford the HF gear you will have the ticket already in hand.You will get a good chunk of all the bands in the HF range as well as the vhf and uhf bands.

There is so much to get into in ham radio.For example not to long ago I was in my truck at work and heard the international space station on 2 meter.... (145.800) simplex loud and clear,I was to surprised to give the iss a call to see if I could make the trip back,but I did hear them/him.

I am also a storm spotter with my local group,this is always interesting and provides an important service to the local area. Here is a link to the skywarn group that I work with MoKan Skywarn MoKan Skywarn of SW Missouri and SE Kansas we have a media player linked with our reapeater so anyone that visits the site can see what we are up to at any time (as long as the link is active of course,and it usually is)

Cant leave out the everyday chatting and running the various bands chasing that rare DX,the nets local and the ones around the world for the HF bands.

VHF gear is fairly inexpencive,and will get your foot in the door.Usually can get a radio and mobil antenna for around 200$ new,or if you decide to set up in your home, you can make an antenna for almost nothing and just buy the radio.I built a 2 meter j pole for under 20$ that works great for the local area repeaters and have 125$ in an icom 2200 h 2 meter radio that I picked up used in the local area,the antenna pole that I have is something that I picked up at work for no cost to me other than a bit of time to get it put together and stood up with the jpole on the top

Hope that helps you out a bit and good luck on the test should you decide to go for your ham ticket
 
I have a Plomar TX-5200 that is actually built pretty good filtered and band selecting included although I have yet to try it out on the other HF bands. Has anyone ran one of these on the HF bands other than 10-11 meters
 
TheTeZ,
A test site should be no problem. There are more than 71 test sites in the state of New York. Those are just the ones through the ARRL, there are probably as many not listed with them. I can't imagine you being very far from a few of them.
Try this, go to;
ARRLWeb: ARRL Home Page
In the top left part of the screen you should find an 'Exams' selection. Go there, select your state and go through the list of sites. If you aren't close to at least one or two of them, I'll be surprised.
- 'Doc
 
moleculo said:
The other thing that's important to understand is that you have to be careful with how hard you drive these amps also. Most (probably all) of the CB type amps don't have any type of input swamping to prevent over-driving the transistors. When you overdrive them, they will show more power output, but at the cost of giving off a lot more harmonics, spurs, IMD, etc. Most CBers will drive the amp as hard as they can until they see no additional power increase, which will guarantee that it gives off lots of trash.
Click to expand...

Many hams will do the same and it seems more and more of them lately too.

Probably the biggest issue, equipment aside, is the obsession with wringing every last watt from the given setup. A carry over from CB myths for sure.

CB gear is dirtier by its nature but there are plenty of horrific ham signals on the bands too as a result of that last watt mentality, running all knobs to the right, doing service menu 'tune-ups' etc etc. It's a shame.

I'm running an SDR for a receiver full time now, one that has a 125MHz sampling rate direct conversion front-end. The pan-adapter and spectrum view is very high resolution. Since starting out with SDR, it's been incredible just how dirty some guys run day in and day out.

I'm tempted to make a hall of shame site and start listing screen shots and recordings with the call signs for credit but most of these ops are just plain dumb....it wouldn't make any difference.

The worst locals are the Spanish guys over in NYC that do the service menu turn up with the TS-2000's to drive them well over 150W and then drive +15db of 100Hz into their audio. They have almost 2k of opposite sideband bleed over and wind up about 8k wide on SSB all told.

The worst SSB signal I've ever seen on the band regularly is on 3.823 with a 3 call guy that sounds like he's on a Uniden with the clipper pulled out. He's an easy 8k wide with a LOT more signal energy in that width too and almost no opposite sideband suppression.

Problem with a lot of this is, these guys are dumb as stumps and just don't care. The FCC can't regulate stupid unfortunately and once an IQ is low enough, no amount of advice will get through.

For the original poster, get your ticket, you will learn a LOT if you are motivated. The amount I've picked up in just the last two years has been stunning and I have played with radio for almost 30yrs. Having the right people and the right information available to guide you can really open your eyes to how this all works. Look for local clubs and attend a few meetings of each one until you find a fit for what you are looking for. There is a lot to be had in the hobby, something for everybody. Trick is finding out all the options.
 
W5LZ said:
TheTeZ,
A test site should be no problem. There are more than 71 test sites in the state of New York. Those are just the ones through the ARRL, there are probably as many not listed with them. I can't imagine you being very far from a few of them.
Try this, go to;
ARRLWeb: ARRL Home Page
In the top left part of the screen you should find an 'Exams' selection. Go there, select your state and go through the list of sites. If you aren't close to at least one or two of them, I'll be surprised.
- 'Doc
Click to expand...

Ha, their are 6 of them that are about 20 miles from me...

I guess ill stat to study, i have a little over the last year, a little at a time.... guess ill step it up a little...
 

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