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Need of new am
- Thread starter Johnboat
- Start date
I'm so tired of this class ab vs c crap. I have both class boxes and talked am and ssb on both. Clean signal in, clean signal out. I have a ms700 and it talks fine on ssb. I also have a TS667 which does great on am too. Don't forget this is cb, not your local broadcast radio station.
It doesn't matter what the input signal is, if less than half of that signal is being transmitted it'll sound chopping on SSB.
Audio quality is just a tiny part of it. Put that class C box on a spectrum analyzer or scan the different bands and you will see how bad it really is. The problem with most class C box users is that they tend to think that if the guy they are talking too says they sound fine then that is all there is too it.They have no idea how much junk is being broadcast on other bands.You cannot hear harmonics or IMD when listening directly to your signal. The second part to that is that some of them do in fact know but just don't give a damn as long as they can stomp over the other guy. You can run a clean signal into a class C box but I can guarantee it will not be clean coming out especially on SSB because class C is not linear meaning that the output is not an exact reproduction of the input.
The lower the class (towards class A) the more linear the amplifier and the lower the distortion and byproducts.An amplitude modulated signal (which includes SSB which really is a form of amplitude modulation) requires at least class B and preferably class ab2 or better for decent spurious byproduct rejection. Whether or not it's just CB is irrelevant when that dirty CB amp starts showing signals on the commercial business band or even worse public safety frequencies. Fire or EMS dispatch may not think the guy calling for skipland is too funny.
Really the difference in power out from a class ab box and a class C box with the same number of pills really won't be noticed on the air signal strength wise but it will be noticed interference and IMD wise so why not run a clean amp? Too many people get caught up in meter readings and whether or not they can stomp on someone else. In the end it's usually just a numbers game and who can make the meter swing higher. Unfortunately its a game where there are more losers that winners.
Yes it is CB but the laws of physics and TX harmonics apply just as equally to CB as they do amateur radio.
The third harmonic is in the FM broadcast band, 81MHz and the fifth in the aircraft band but I guess you don't give a shit about transmitting in those bands? You can be sure the FCC does.
At least if you insist on using those godawful things please fit a 30MHz low pass filter after it?
Are you talking AM or ssb or both? Are you saying a class c amp on am will be transmitting on other fm bands?
I really don't care if my equipment bleeds a few channels, that just means the audio is blaring loud.......as long as it sounds impressive. SSB is a complete different story, class C amps just don't cut it. You can make your SSB signal sound acceptable using a class C amp by cutting the drive way down, but it won't sound good enough to be proud of.....been there tried that.
If its bleeding a few channels on 11m you can be damned sure it'll be giving the broadcast and aircraft bands a good hammering. And no it doesn't mean your audio is blaring loud, rather that it just sounds like a pile of distorted crap.
Your signature is appropriate..
I think I asked a valid question. Why would you want to spatter over several freqs? By the way this is not a put down on cbers as there are plenty of Hams that overdrive the piss out of their amps to be the "loudest".
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