CB stuff just not acting right

[Tallman]

I grabbed this KL200P because it was the lowest priced one i could find in the US, and it only needed 4W AM input and 10W SSB input. Thats what got me. But i use it, and i've talked 22 miles with it with my Dad, and when i turned it off, he called me and said he lost me completely. What is the class "C" amplifiers?

It get technical real quick. But the short version is if you know what a sinusoidal wave looks like, it only amplifies 1/2 of the waveform.
The distance in miles is not really relevant unless we know what the topography of your area is like. If you were out in an area that was flat with no trees and low noise 20 miles might be considered lacking.

 

[JeepRider]

It get technical real quick. But the short version is if you know what a sinusoidal wave looks like, it only amplifies 1/2 of the waveform.
The distance in miles is not really relevant unless we know what the topography of your area is like. If you were out in an area that was flat with no trees and low noise 20 miles might be considered lacking.

Lots of trees, hills, bridges in the way of where i talked to. Maine...heavy wooded areas and hills. And i'll have to find out what a sinusoidal wave looks like. I think i've heard of it, but not seen it.

 

[Tallman]

Lots of trees, hills, bridges in the way of where i talked to. Maine...heavy wooded areas and hills. And i'll have to find out what a sinusoidal wave looks like. I think i've heard of it, but not seen it.

It is the Ac wave form.

 

[Tallman]

Lots of trees, hills, bridges in the way of where i talked to. Maine...heavy wooded areas and hills. And i'll have to find out what a sinusoidal wave looks like. I think i've heard of it, but not seen it.

 

[codeman]

Different amplifier altogether. The KL-203 is an AB biased push/pull. The KL-200 is a class c amplifier. I have 4 or 5 of the 200's I won't even waste a pill to fix it.
The 203's I can buy new all day long for $30.00. They sound good though.

Sorry, my mistake. I need to read things a little closer. I do like my 203, it makes dx contacts a lot easier. I think I paid $60 for mine, but still a good little amp for the money. A 100 watts is plenty for me on sideband.

 

[222DBFL]

Might be a good idea maybe to ask for a KL203P for Christmas!! This is what you need for SSB operation. It's an AB biased amp vs. the class C KL200. I'll let one of the amp gurus explain the differences, but if the amp you are using on SSB is a class c amp it may sound okay if there is an SSB delay, but it won't be as clean as an AB biased amp. And this is also where the Low Pass Filter is a good thing to have as well. It keeps unwanted spurious emissions from getting into your neighbors electronics and yours as well. Look at the RF Limited DF3000. At least one of these after your amp will help. 2 is even better. Price for the ones I listed are roughly $40-$-45. And all handle way more power than you'll be using. And they do work. I've 2 dipoles and use one and have never had a complaint out of any of the neighbors. They do work. Some are better than others. But for the price the one I listed is a good deal IMO.

 

[Tallman]

It's not all watts for DX. I have talked to Russia with only 25 Watts. A good antenna is a must.

 

[JeepRider]

Might be a good idea maybe to ask for a KL203P for Christmas!! This is what you need for SSB operation. It's an AB biased amp vs. the class C KL200. I'll let one of the amp gurus explain the differences, but if the amp you are using on SSB is a class c amp it may sound okay if there is an SSB delay, but it won't be as clean as an AB biased amp. And this is also where the Low Pass Filter is a good thing to have as well. It keeps unwanted spurious emissions from getting into your neighbors electronics and yours as well. Look at the RF Limited DF3000. At least one of these after your amp will help. 2 is even better. Price for the ones I listed are roughly $40-$-45. And all handle way more power than you'll be using. And they do work. I've 2 dipoles and use one and have never had a complaint out of any of the neighbors. They do work. Some are better than others. But for the price the one I listed is a good deal IMO.

But the 203 needs 10 watts input for 100 out. I couldn't ask for it because my christmas money was given to me early so i could get a decent bycicle. Anyways, my Dad told me i might of had the deadkey too high, so i turned DK to about 2 watts. Now when i talk, it doesn't swing backwards nearly as much, but still does. With the amp hooked up, i deadkey 40 and swing down to around 35. Should be getting at least above 70 am. Also, on SSB, i only get 38 out, even if i talk real loud. Should be getting more than 150. And this amp does have an SSB delay. Just ordered a dummy load on ebay. Sorry if i'm annoying you guys, but i don't have THAT much kmowledge on this stuff, but i have some. Thank you all for staying with me on this. I appreciate it. :-D

 

[222DBFL]

You may have blown the amp with too much dead key. The input of 4 watts is the modulated pep wattage not the dead key wattage you need. Those amps take about .25-2 watts max dead key input and a pep of 4-6 watts. SSB 12 watts is fine. With this said, you may have burnt one or more of the Mosfets by over driving the amp. By what you are describing it seems you may have an issue with the amp. JMHO. With the dummy load you'll know for sure.

 

[JeepRider]

You may have blown the amp with too much dead key. The input of 4 watts is the modulated pep wattage not the dead key wattage you need. Those amps take about .25-2 watts max dead key input and a pep of 4-6 watts. SSB 12 watts is fine. With this said, you may have burnt one or more of the Mosfets by over driving the amp. By what you are describing it seems you may have an issue with the amp. JMHO. With the dummy load you'll know for sure.

I don't think it is, i have had the cover off of it and checked for any cold cracked soldering joints because the pre-amp doesn't work correctly unless the amp is physically warm. (Usually above 50 oF and it works properly.) I didn't see anything that was burnt or discolored. But i'll check again. I lowered AM deadkey to 2 watts, and if my meter is correct, it still swings down a little bit, but not as much. So if i adjust RT203, labeled AM POWER pot, by the looks of it, it lowers the total power and not the deadkey. So, what the heck is going on? I have been at this radio for a good 4 months now and got nowhere.

 

[222DBFL]

Yes it will lower the total output power but it should not be enough to make a difference to the receiving station. It's a bit more than just looking for cold solder joints and cracks when trouble snoring a MOSFET. I'll let the amp gurus step in here and take over.

 

[JeepRider]

Yes it will lower the total output power but it should not be enough to make a difference to the receiving station. It's a bit more than just looking for cold solder joints and cracks when trouble snoring a MOSFET. I'll let the amp gurus step in here and take over.

is mosfet the little black 3 legged squares? This has a white circular thing soldered on 4 different points. Looks like a advil pill. White and circular. Nothing looks burnt. Oh, the reason i was looking for cracked soldering joints is because my preamp doesnt work correctly until it gets warmer in the Jeep. If its cold, it turns on and makes my receive almost silent. When it warms up, it gives me an extra 2 signal bars. So i was told the amp could have a cold cracked soldering joint somewhere.

 

[Tallman]

If its cold, it turns on and makes my receive almost silent. When it warms up, it gives me an extra 2 signal bars.

Sounds like the relay.

 

[222DBFL]

Tallman, can you read a few of the posts here and give some input as to why the amp he has is only putting out about 1/2 the power it should. Or Seems that way from the posters description. And to the poster those numbers by RM Italy are PEP numbers and are over rated. Those amps don't require much drive to get them the to the output they actually put out without being over driven. A god rule of thumb is to set the amp up to dead key about 1/4 of the total output. So if the amp is rated at 100 watts, a 25 watt carrier is what you want. This may take anywhere from .25-2 or more watts. From all I've seen with these small amps, they like the dead key at 2 watts max, and pep wattage of 6-8 watts. On SSB 10-12 watts should be fine. Anymore and the amp is being over driven and can or may have already sustained damage from having your dead key set too high. You won't be able to tell if the transistors are burnt or not. Looking at the spec sheet for this amp, it appears it needs 5 watts input on AM and 10 watts max on SSB. These are the pep numbers. So your radio only needs to put out 5 watts pep into the amp and 10 watts pep on SSB. Read up on what pep vs dead key power and also average vs pep power as if sounds as if your swr/watt meter is reading average and thus the reason for you seeing back swing, tnis is just a thought and might not be correct, but it appears that way. Look at this pic below and you'll see the power needed for your amp, and remeber these are PEP input. And the output is over rated. If the fuse is 12 amps. The amp is capable of maybe 60-100 watts max. I wouldn't believe the 200 watts on SSB either. But hey I could be all wrong here. Any input from some of the users of these amps would be appreciated for the sake of helping the young man here get his things in order. Thanks for all replies and thoughts gents.

 

[Tallman]

Sure thing. Just give me the website and I'll check it out.
I noticed that most of the text was in Spanish.
The drive into the KL (RM Italy) is a ticklish area.
90% of those amps I repaired were over driven. But there were other problems as well which I will not go into in a public forum. The KL-203 will never put out 200 watts.

The amp listed in the attachment at the maximum current draw of 11 amps at 13.8 volts = 151.8 watts.
Unless I missed something 100 watts out means there is a lot loss going up in heat.