Another interesting thing is that 250 watts PEP output sounds like a lot for the 2SC2879 but in reality that's only asking and 8 pill amplifier to hold 500 watts average AM on the Bird 43. The 500 watt carrier will still only show about 500 watts average on the Bird 43 when it's 100% modulated. But those audio peaks should be at 2 KW PEP output when you switch on the peak kit on the meter. Those 2 KW peaks are easy to reach on 18 volts without flat topping either.
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Booty, if more people ran their equipment like you intend, there would be much less bleed over on 11 meters. Please don't think I'm telling everyone to overdrive their amp, I'm just pointing out what is possible to achieve from the 2SC2879 and there are ways to do it reliably.
B
BOOTY MONSTER
Guest
no problem here shockwave . it was obvious to to me you were discussing the peak capability of the pill , not the proper use of it 
BTW, I am not taking sides here but I suggest anyone that follows the thread on QRZ about this to pay attention to what Tom, W8JI has to say. For those of you who do not know, Tom is the chief DESIGNER of amplifiers for Ameritron both solidstate and tube types. I believe he also designed and built very high powered amps for the ISM business. Again, I'm not taking sides but offering a credible outside source to pay attention too.
The Thread will not get locked as long a serious debate is adhered to with no name calling. Let the discussion continue, slow down and look at the possibly.
And there is the same kind of debate going on at the ...uhm ..other forum as well...if you look at the last post over there...OK here
This Topic was started for what ever reason, and has progressed to what Can a 2879 do at its extreme limits, If we want the discussion to continue, just remain civil to each other.
73
Jeff
(on edit, Captain Kilo and me were replying at the same time, and I copied the reply he was talking about)
And there is the same kind of debate going on at the ...uhm ..other forum as well...if you look at the last post over there...OK here
Seems that Shockwave is not alone in his statements. Now I am sure he will agree that for the Average operator, this would not be a desirable condition to run the stated device at on a daily basis. But can the device do it? I will side with Shockwave...would I build an Amp and expect this kind of output? No... but what he is saying is the 2879 can do the output, NOT at 12 volts ... it would be running on the edge, but based on experience with the 2879 that i have it IS possible ...desirable? No , not in my opinion..
This Topic was started for what ever reason, and has progressed to what Can a 2879 do at its extreme limits, If we want the discussion to continue, just remain civil to each other.
73
Jeff
(on edit, Captain Kilo and me were replying at the same time, and I copied the reply he was talking about)
Last edited:
B
BOOTY MONSTER
Guest
things that make you go hmmmmmm..................
"3.) Just because a CB'er or anyone else runs SSB, that does not mean they use a linear amp. Linear is a transfer function issue, NOT amplifier class. Anyone running a 2SC2879 at more than 80-100 watts PEP per device probably has an unacceptable signal for SSB or AM. Let's not pretend that running a certain mode means the equipment is good."
so he is the "chief DESIGNER of amplifiers for Ameritron both solidstate and tube types" and made the statement above , but his company sells a amp using four 2879's and advertises it as a 500 watt amp . which is 25-45 watts more per device than his comment above says they can cleanly do .
Ameritron
wassupwitdat ??????
"3.) Just because a CB'er or anyone else runs SSB, that does not mean they use a linear amp. Linear is a transfer function issue, NOT amplifier class. Anyone running a 2SC2879 at more than 80-100 watts PEP per device probably has an unacceptable signal for SSB or AM. Let's not pretend that running a certain mode means the equipment is good."
so he is the "chief DESIGNER of amplifiers for Ameritron both solidstate and tube types" and made the statement above , but his company sells a amp using four 2879's and advertises it as a 500 watt amp . which is 25-45 watts more per device than his comment above says they can cleanly do .
Ameritron
wassupwitdat ??????
Come on out of the closet Richard and show yourself and explain to us all how much more superior you feel now.
FCC Callsign Lookup from QTH.com
Don't be shy, I am sure the 2 gentlemen having this discussion would welcome your views and expertise on the subject in question.
Heck who knows, you might even be able to educate some of us.
FCC Callsign Lookup from QTH.com
Don't be shy, I am sure the 2 gentlemen having this discussion would welcome your views and expertise on the subject in question.
Heck who knows, you might even be able to educate some of us.
It was refreshing to read what W8JI had to say in the other forum based on his extensive experience. I already knew the most I've ever been able to get out of one 2SC2879 was 291 watts each in class C. I wasn't going to reveal that fact because it seemed so unlikely anyone would believe me. With Tom's calculations showing it's possible to reach 337 watts output deep in class C without exceeding the dissipation rating, can we put the 250 watt output debate to rest now?
B
BOOTY MONSTER
Guest
i wonder how that 291-337 watts from a single 2879 would sound ?
10-8 ? top shelf ? wall to wall and tree top tall ? walking the dog and kicking the cat ? hehehehe
sorry , couldnt keep from trying to inject a little humor .
so it seems the 2879 can indeed do the 300 watts class c builders claim when highly volted but at the expense of severely compromising the signals fidelity and creating multiple strong harmonics .
10-8 ? top shelf ? wall to wall and tree top tall ? walking the dog and kicking the cat ? hehehehe
sorry , couldnt keep from trying to inject a little humor .
so it seems the 2879 can indeed do the 300 watts class c builders claim when highly volted but at the expense of severely compromising the signals fidelity and creating multiple strong harmonics .
In all honesty Booty, it doesn't sound as bad as one might think on AM. However, slide up or down 10 KHz. and it will become apparent how dirty the signal is as a result of the IMD. If you keep the carrier and modulation level at a sensible point, some even think they sound good. I'm often amazed at how much distortion can actually be on a signal before it seems objectionable to the average listener. I run an HF rig on 11 meters with a spectrum analyzer (pan adaptor) on the receivers wide band IF. Sometimes the IMD contained in the sidebands is absolutely horrendous. Yet the operator asks for a radio check and he's told "sounds great"!
One last thought, while I was able to get 291 watts off a 2SC2879 and W8JI has pointed out that in theory you could reach 337 watts output before exceeding the dissipation, 250 watts PEP is about the practical limit if you don't want to replace transistors all the time.
I am guessing the reason is that the specs for the 2879 are at 12 volts. In a mobile environment where the ALS-500 would be, the Vcc would be at least 13.8 volts and since each device would be called upon to provide only 125 watts pep that it is still operating within acceptable FCC IMD limits. Obviously it is because it is certified.Clean operation is relative. there is clean, acceptable, and then down right dirty.
op:By all means, im not hiding, Just cutting grass, I dont live on here like most.
And yes I did start the thread on QRZ to get some outside information from people unaffiliated with this thread. Because shockwave did get me thinking. But Like what was said, it would need an efficiency rating that is astronomical and unfeasible for our purposes. And just like I said, even the engineers agree that pulse is about all your gonna get, NOT sustained work.
And PRO151, my callsign is already on here in a few places.....Im not exactly hiding. As I already said, whoever wants to try this, be my guest. I have no desire to "RELIABLY" get this power because I keep my station and my amplifiers clean.
But I am man enough to stand up and say if I am arguing on the wrong side, and It seems in this case I am. But I still stand behind the fact that the harmonics have an adverse affect on watts meters, and more than 6.6%!!
To the moderators, I will apologize for the name calling.
And yes I did start the thread on QRZ to get some outside information from people unaffiliated with this thread. Because shockwave did get me thinking. But Like what was said, it would need an efficiency rating that is astronomical and unfeasible for our purposes. And just like I said, even the engineers agree that pulse is about all your gonna get, NOT sustained work.
And PRO151, my callsign is already on here in a few places.....Im not exactly hiding. As I already said, whoever wants to try this, be my guest. I have no desire to "RELIABLY" get this power because I keep my station and my amplifiers clean.
But I am man enough to stand up and say if I am arguing on the wrong side, and It seems in this case I am. But I still stand behind the fact that the harmonics have an adverse affect on watts meters, and more than 6.6%!!
To the moderators, I will apologize for the name calling.
The big problem is that most people have no idea what distortion is or sounds like and think that because it is LOUDER! then it's working just great. I have a back ground in commercial broadcasting and my standards of what sounds good are completely different than most people's. I have sat back and shook my head when I have heard someone tell another that their gear sounds good while I can hear the raspy buzziness of the distortion. Some people think that because they can hear you splatter 5 or 6 channels away then you must have a great station. I have heard stations on the bowl via DX and when listening on ch.7 I could still make out every word they said even tho the signal on ch 6 was only about S-9 so I knew they were not creaming my RX frontend.Whenever I make audio adjustments to my gear and look for signal/quality reports I usually look for one of the regional crowd here that are current/former b'cast engineers like myself to get valued and accurate opinions of what I sound like.A bunch of us get together every Sunday on 80m AM for a round table.
By all means, im not hiding, Just cutting grass, I dont live on here like some.
And yes I did start the thread on QRZ to get some outside information from people unaffiliated with this thread. Because shockwave did get me thinking. But Like what was said, it would need an efficiency rating that is astronomical and unfeasible for our purposes. And just like I said, even the engineers agree that pulse is about all your gonna get, NOT sustained work. BUT he is right, you can get 250 and more.
And PRO151, my callsign is already on here in a few places.....Im not exactly hiding. As I already said, whoever wants to try this, be my guest. I have no desire to "RELIABLY" get this power because I keep my station and my amplifiers clean.
But I am man enough to stand up and say if I am arguing on the wrong side, and It seems in this case I am. But I still stand behind the fact that the harmonics have an adverse affect on watts meters, and more than 6.6%!!
To the moderators, I will apologize for the name calling.
And yes I did start the thread on QRZ to get some outside information from people unaffiliated with this thread. Because shockwave did get me thinking. But Like what was said, it would need an efficiency rating that is astronomical and unfeasible for our purposes. And just like I said, even the engineers agree that pulse is about all your gonna get, NOT sustained work. BUT he is right, you can get 250 and more.
And PRO151, my callsign is already on here in a few places.....Im not exactly hiding. As I already said, whoever wants to try this, be my guest. I have no desire to "RELIABLY" get this power because I keep my station and my amplifiers clean.
But I am man enough to stand up and say if I am arguing on the wrong side, and It seems in this case I am. But I still stand behind the fact that the harmonics have an adverse affect on watts meters, and more than 6.6%!!
To the moderators, I will apologize for the name calling.