hundreds of watts per 2879 ???????????????????????

[dxhound]

Wow, I said 50%????where? I said it would drop the output. If I would put a percentage on it I would say 15% maybe 20%.

I did see that, and the way it read to me was that the test will show you why your getting the erroneous readings, And this will help solve your problems

 

[W5LZ]

Bird watt meter 'slugs' are frequency sensitive?
- 'Doc

 

[Shockwave]

Wow, I said 50%????where? I said it would drop the output. If I would put a percentage on it I would say 15% maybe 20%.

I did see that, and the way it read to me was that the test will show you why your getting the erroneous readings, And this will help solve your problems

Well you didn't say 50% but that's about how much the inaccuracy would have to be off to see any real difference in signal. Even 15% to 20% loss in power from adding the filter is quite high. That's saying 20 watts out of every 100 is going out on the second harmonic. Before you started thinking so hard you told us your 2 pill had 4 watts on the second harmonic as confirmed by your spectrum analyzer. According to you that thing was such an extreme case you could talk 5 miles on the second harmonic. If that amp could only make 100 watts output, that's still only 4% at the harmonic and closer to being what you would see as loss on the meter from adding the filter.

 

[BOOTY MONSTER]

the palstar always gets good comments . the thing that doesnt work for me on them is that they dont measure on a scale less than 300 watts so they wouldnt be good for measuring deadkey and pep power on a typical cb radio , at least not for my eyes .

 

[dxhound]

Well you didn't say 50% but that's about how much the inaccuracy would have to be off to see any real difference in signal. Even 15% to 20% loss in power from adding the filter is quite high. That's saying 20 watts out of every 100 is going out on the second harmonic. Before you started thinking so hard you told us your 2 pill had 4 watts on the second harmonic as confirmed by your spectrum analyzer. According to you that thing was such an extreme case you could talk 5 miles on the second harmonic. If that amp could only make 100 watts output, that's still only 4% at the harmonic and closer to being what you would see as loss on the meter from adding the filter.

Trust me, Im not thinking very hard......this isnt exactly a battle of wits, your not exactly challenging me....just annoying, as my patience is low.

And no the amp was not producing 100 watts, we were intentionally overdriving it to get these results. It produced somewhere in the neighborhood of 350 watts on 27mhz to achieve that harmonic. and this was driving the amp ridiculously hard. By the time you look at the other harmonics involved, and their power levels, the TOTAL power output was around 375 or so, when combing the power levels of the harmonics. Then for kicks we put a directional coupler inline with the load and hooked it to a resonant 6 meter antenna. Yes the coupler was a band pass device to allow only 35-70 mhz to pass. Are we learning yet?

So that comes out to be around 11% or so
You can preach me your top honor roll valedictorian status all you want. In the end, the test equipment and results will not lie!

If you are so confident of your 250 watt on 27mhz 2879 lasting more than a few seconds using standard cooling practices, build a jig and show us on a spec an. Do it and I wont argue thing more!

 

[Shockwave]

Trust me, Im not thinking very hard......this isnt exactly a battle of wits, your not exactly challenging me....just annoying, as my patience is low.

And no the amp was not producing 100 watts, we were intentionally overdriving it to get these results. It produced somewhere in the neighborhood of 350 watts on 27mhz to achieve that harmonic. and this was driving the amp ridiculously hard. By the time you look at the other harmonics involved, and their power levels, the TOTAL power output was around 375 or so, when combing the power levels of the harmonics. Then for kicks we put a directional coupler inline with the load and hooked it to a resonant 6 meter antenna. Yes the coupler was a band pass device to allow only 35-70 mhz to pass. Are we learning yet?

So that comes out to be around 11% or so
You can preach me your top honor roll valedictorian status all you want. In the end, the test equipment and results will not lie!

If you are so confident of your 250 watt on 27mhz 2879 lasting more than a few seconds using standard cooling practices, build a jig and show us on a spec an. Do it and I wont argue thing more!

This is almost amusing because any power the 2 pill amplifier produced in excess of 100 watts just lowers the percentage of total output the 4 watt second harmonic was at even further! Four watts is only 1.06 % of the total 375 watts you claim.

You now say you have 350 watts on the fundamental and 375 total output. The difference is 25 watts and 25 is only 6.6% of 375. Not even close to your 11%. You do know math is very important in electronics right? How'd you get so far? When you say there was another 21 watts of harmonics on frequencies other then the 4 watt second order harmonic it tells me you're one of those guys that never even operated a spectrum analyzer before.

What was I suppose to learn about your directional coupler and 35 to 70 MHz bandpass filter? The fact you may be truly clueless here because as described you just left the 350 watts on 27 MHz with no load to go into? Maybe you just used a zener diode to separate the harmonics to the analyzer and fundamental to a dummy load? LOL. It takes more then a spectrum analyzer, directional coupler, and bandpass filter to do the test you described properly. Tell me the bandpass device had a reject output port on it?

Exactly what do you think is going to blow up the 2SC2879 in a few seconds when it would only be running at 108 watts of dissipation? Did you forget the part we are talking about is rated for 250 watts of continuous dissipation and how much lighter the duty cycle is in 2 way communications? Or how easy it is to remove the harmonics with a Chebyshev filter? When you show me the picture of that 2 pill on the spectrum analyzer with those 21 watts of harmonics on frequencies other then 54 MHz, I'll build you the one pill test gig that's shown in the datasheets.

 

[Robb]

Hey BootMon:

There has been a thread started on QRZ about your thread here. Some interesting answers too. I thought you might like to see it. You can thank a member here for going to QRZ trying to make it an object of ridicule.

Actually, I think it was a fair question - considering that some amp mfr claim such large, unqualified numbers for their amps. it appears that these transistors CAN do that many watts; but not for continuous duty cycle C-class amps. Only for short bursts...

Read:
http://forums.qrz.com/showthread.php?t=248732

 

[dxhound]

This is almost amusing because any power the 2 pill amplifier produced in excess of 100 watts just lowers the percentage of total output the 4 watt second harmonic was at even further! Four watts is only 1.06 % of the total 375 watts you claim.

You now say you have 350 watts on the fundamental and 375 total output. The difference is 25 watts and 25 is only 6.6% of 375. Not even close to your 11%. You do know math is very important in electronics right? How'd you get so far? When you say there was another 21 watts of harmonics on frequencies other then the 4 watt second order harmonic it tells me you're one of those guys that never even operated a spectrum analyzer before.


What was I suppose to learn about your directional coupler and 35 to 70 MHz bandpass filter? The fact you may be truly clueless here because as described you just left the 350 watts on 27 MHz with no load to go into? Maybe you just used a zener diode to separate the harmonics to the analyzer and fundamental to a dummy load? LOL. It takes more then a spectrum analyzer, directional coupler, and bandpass filter to do the test you described properly. Tell me the bandpass device had a reject output port on it?

Exactly what do you think is going to blow up the 2SC2879 in a few seconds when it would only be running at 108 watts of dissipation? Did you forget the part we are talking about is rated for 250 watts of continuous dissipation and how much lighter the duty cycle is in 2 way communications? Or how easy it is to remove the harmonics with a Chebyshev filter? When you show me the picture of that 2 pill on the spectrum analyzer with those 21 watts of harmonics on frequencies other then 54 MHz, I'll build you the one pill test gig that's shown in the datasheets.

Are you Retarded?????? Seriously, You have no reading comprehension at ALL!!!!!!!!!! You know that is a basic requirement for life right. where in the hell are you getting 108 watts???? You have a math issues!!!

The amplifier made around 350 watts on 27mhz! Thats 350/2 = 175 per device on the fundamental freq. With the Harmonics the total accumulative power output was in the vicinity of 375. That leaves 25 watts in just harmonics.......4 of which were on the second harmonic. and guess what, the harmonics reached well into 800Mhz!!! and yes, 11% was a typo, I must of hit the calc button wrong. congrats you have some math skill!

Also my test had a dummy load, again reading comprehension..not your strong suit.

I am actually sitting infront of my equipment at the moment, you know the stuff you say I dont know how to use. Do you even know what a SNA is?? or a DICMU???? And believe me, I wish I had videotaped the test!!!

But back to the original BS about 250 watts sustained out of a 2879. The only feasible way for the device to produce this would be in a direct on off pulse situation. And we are talking very short bursts of peak energy lacking any use in sustained RF communications. Not to mention avg power would be low.

Again, show me 250 watts continuous....and ill shut up!

 

[Shockwave]

Are you Retarded?????? Seriously, You have no reading comprehension at ALL!!!!!!!!!! You know that is a basic requirement for life right. where in the hell are you getting 108 watts???? You have a math issues!!!

The amplifier made around 350 watts on 27mhz! Thats 350/2 = 175 per device on the fundamental freq. With the Harmonics the total accumulative power output was in the vicinity of 375. That leaves 25 watts in just harmonics.......4 of which were on the second harmonic. and guess what, the harmonics reached well into 800Mhz!!! and yes, 11% was a typo, I must of hit the calc button wrong. congrats you have some math skill!

Also my test had a dummy load, again reading comprehension..not your strong suit.

I am actually sitting infront of my equipment at the moment, you know the stuff you say I dont know how to use. Do you even know what a SNA is?? or a DICMU???? And believe me, I wish I had videotaped the test!!!

But back to the original BS about 250 watts sustained out of a 2879. The only feasible way for the device to produce this would be in a direct on off pulse situation. And we are talking very short bursts of peak energy lacking any use in sustained RF communications. Not to mention avg power would be low.

Again, show me 250 watts continuous....and ill shut up!

Listen, guys like you never shut up even when presented with the facts. When a part has a continuous power dissipation of 250 watts, to say it can only produce this in pulse mode is ridiculous. Had you been reading it would be perfectly clear to you that 108 watts of dissipation is all the part will be handling at 252 watts of output at 70% efficiency in class C. On a decent heat sink the transistor could run 100% duty cycle at this output. When you read the data sheet for the 2SC2879 PLEASE point out what spec it is that will prevent this from happening.

You argue with ohms law, your calculations are off by miles and you debate power outputs from a transistor you've obliviously never worked with long enough to know what it's capabilities are. All this crap about harmonics extending past the 29th order or 800 MHz, doesn't change the fact that by your own admission it has only thrown your meter off by 6.6% and easily corrected by a simple filter. You do realize that most power meters have an accuracy tolerance of more then this right?

You'd do better to shut up and just let people think you don't know what you're talking about rather then to keep debating and remove all doubt. Build your own test jig as outlined in the data sheets and you'll know as much as I do about the 2SC2879. By the way in that circuit with it's tuned L network for input and output, you won't see anywhere near those harmonics.

 

[dxhound]

You know what, have fun getting 250, when you burn it up, Ill fix it for ya.

Have fun in lala land. Guys, please dont try what this yoyo is telling you is ok.....it will cost you!

 

[Shockwave]

Hey BootMon:

There has been a thread started on QRZ about your thread here. Some interesting answers too. I thought you might like to see it. You can thank a member here for going to QRZ trying to make it an object of ridicule.

Actually, I think it was a fair question - considering that some amp mfr claim such large, unqualified numbers for their amps. it appears that these transistors CAN do that many watts; but not for continuous duty cycle C-class amps. Only for short bursts...

Read:
http://forums.qrz.com/showthread.php?t=248732

Yes Robb, there are plenty of people that are getting about 250 watts from a 2SC2879. It's not clean and has lots of IMD. The duty cycle that you can run this power at depends entirely on how large the heatsink is and boxer fans extend it even more. You absolutely need to increase the DC voltage in order to do this otherwise excessive collector current on 12.5 volts will blow it up instantly before you reach that power level. I've put amps like this together countless times before and know how to use a filter to block harmonics from hitting the meter. God forbid I didn't and the harmonics threw my readings off by an entire 6.6%

 

[Shockwave]

You know what, have fun getting 250, when you burn it up, Ill fix it for ya.

Have fun in lala land. Guys, please dont try what this yoyo is telling you is ok.....it will cost you!

Basically what you have here is a guy that has never been successful at getting 250 watts output from a 2SC2879. After spending days trying to convince everyone it can't be done, he's realizing he can't support his claim with even an ounce of sound technical theory. He now asks you all to disregard all of the specifications I've quoted and to believe him based on nothing. The choice is yours

 

[Captain Kilowatt]

Debate is great guys but the personal attacks regarding one's intelligence had better cool down or the thread will be locked. Let's just let each member decide for themselves who has the smarts and who is full of it shall we?

 

[Shockwave]

Debate is great guys but the personal attacks regarding one's intelligence had better cool down or the thread will be locked. Let's just let each member decide for themselves who has the smarts and who is full of it shall we?

Point well taken Captain. I totally agree because the forum is about spreading knowledge and why I came here in the first place. There is some degree of frustration involved when people dispute things you know to be accurate based on lots of past experience working with the 2SC2879. I wouldn't debate a point like this had I not seen these watts out of the transistor on the fundamental frequency every time I put one on 18 volts and limited the current to 20 amps. I've shared my solid state amplifier protection circuit that eliminates any transistor failure when you run the part on AM but they still say it can't be done reliably.

 

[BOOTY MONSTER]

Hey BootMon:

There has been a thread started on QRZ about your thread here. Some interesting answers too. I thought you might like to see it. You can thank a member here for going to QRZ trying to make it an object of ridicule.

Actually, I think it was a fair question - considering that some amp mfr claim such large, unqualified numbers for their amps. it appears that these transistors CAN do that many watts; but not for continuous duty cycle C-class amps. Only for short bursts...

Read:
http://forums.qrz.com/showthread.php?t=248732

thanks robb . i havnt been there in a week or so looking at their threads . i cant post there because i dont have a ham ticket . but i dont have to be a member to see the post , which i think is nice of them to have it that way .

maybe i should have posted this in the meter section or used a different title . i was mainly interested in how the harmonics of the over driven pills/rf transistors affect the meter to show more watts than it is actually producing because of how the meters are made . I HAVE ABSOLUTELY NO PROBLEM WITH ANY OF MY THREADS GOING OFF TOPIC , so admins please DO NOT edit the thread . many times ive seen the peripheral conversations/comments are just as interesting and helpful as those more focused on what started a thread .

i knowa 2879/pill can produce a little more CLEAN power than the pdf toshiba specs it for . i know increasing the voltage can give a little more too . i believe that ammount of headroom and bump from the voltage isnt enough (keeping it fairly clean ) to allow me to make a contact i couldnt make at 12.5 volts without the headroom . they can obviously produce much more watts when over driven , but my goal is to run a clean station .... clean but quality modulation and without adversely affecting other electronics nearby or splattering on folks on adjacent channels . proximity plays a roll in that , but you get the idea .

i thought it interesting that the article explains how someone claiming 400 watts per device are really only getting about half of that and the rest is meter error due to the primary frequency and the pills over driven harmonics together throwing the meter off . the signal is very dirty though .
tit for tat , yin and yang , you dont get something for nothing ...... theres always a tradeoff .

i really hope this thread doesnt get locked .