amplifier power claims -bogus!

I am Mr. CB Linear designer/builder...
My TX-800s would do every bit of 800 watts out. You are quoting "facts" from a data sheet that you are incorrectly interpreting. The Toshiba 2SC2879 will do 200 watts out at 13.8vdc... if you actually had any electronic engineering knowledge you would have been able to understand that... simply by looking at the input/output graphs on the datasheet and some real hands on experience without preconceived "knowledge". Like so many other armchair "engineers" and "technicians" you think you are sharing knowledge but it is nothing more than your own flawed opinion. The best IMD figure is at 60 watts out with 12.5vdc per device... so if you're going to talk about IMD performance then yes the TX-800 is a 240 watt amp... The fact you compare a Bird wattmeter to a Dosy and think they are equal tells me a lot. Had you ever tested a TX-800 correctly, you would have seen that they actually do every bit of what they say on the label. Try driving the amp with a single or double tone in SSB... if your equipment is adequate for the 100 amp draw you will see 800 watt plus output. That does not mean the amp was designed for SSB, or that the amp sounds good pushed to the maximum, just that your AM testing and interpretation of the results is flawed. The TX-800 was designed primarily for AM, the final section is class C, driver is class AB-2... They do perform fairly well on SSB but obviously they are not as clean as a pure Class AB amplifier, the single transistor driver adds some distortion as well. You will not see 800 watts average power when driving the amp with an AM signal... this is a condition of the type of modulation, an AM carrier is not supposed to change when modulated. test the amp in CW or SSB, then comparing the spectrum analyzer and scope displays you will clearly see that the peak envelope power is the same in AM. Yes all amp builders try to get as many watts as possible out of their creations... there was/is little profit to be made making amps and my amps were not overbuilt with unnecessary parts to make them appear larger/better, however they were better than 99% of the amps built then. Better quality components and better quality construction.
The TX-800 performs very well on AM with 125 to 400 watts carrier as headroom must be maintained for modulation, the small heatsink being the limiting factor for FM carrier power, but they will run at 600 watts out FM carrier if the heat is controlled by limiting keydown time. This is why the amps had a Lo/Med/Hi switch. Many TX amps are still functioning fine today decades after I built the last one with the cover still riveted on as original, the failures can mostly be attributed to operator error... too much drive, poor or defective antenna setup, running them too hard and getting them extremely hot and damaging the transistors, output transformers and output tuning caps.
The design was a compromise so that the amps would be compact and they were marketed mainly to truck drivers. No amplifier RF or audio was ever designed to do 100% of maximum power 100% of the time.

 

Check out this transmitter tour..
http://hawkins.pair.com/wor.html

 

You guys gotta check out this documentary on WLW's 500,000 watt transmitter..

 

Wow an old thread that has been indexed on this Internet.

Mr amp designer/builder ... seriously?

Too funny,

Rabbi, I had a gates transmitter out of an am station down in Texas, it is a small 5kw thing, three pieces and I got it up and running a few years back reducing the power to the legal limit, it sounded fantastic. The cost of it, transport and repairs was just under a grand, sold it to make room for my Collins setup. it can be heard today on 80 meters every once in a while when the new owner isn't working.

My point is if you want to be serious about am, there are a lot of these still around, many end up in the scrap pile because no one knows what they are really worth.

 

If you are the same gentleman who some years ago sent me an e-mail about the TX-800, which according to that email you designed, I inserted that as a valuable rebuttal to my comments regarding its usable ratings into my existing web page about 'Transistor Mobile HF Linear Amplifiers' Transistor Mobile HF Linear Amplifiers, then it is good to see that you have posted here.

I can see that you have not accurately read my original post here, before proceeding upon a hysterical personal attack, even reaching so far as to cast aspersions on whatever equipment may be in use, but you may rest assured that it includes not only power supplies capable of >100 Amps, but also spectrum analyzers.

The fact you compare a Bird wattmeter to a Dosy and think they are equal tells me a lot.
Nope. I said: "a Dosy or Workman will read 1.5 to 2 times higher than the power shown on a ham, military, or Bird meter."

Had you ever tested a TX-800 correctly, you would have seen that they actually do every bit of what they say on the label.
I won't dispute your power measurements, but I disagree that driving an amplifier to twice its data sheet recommendations is correctly testing it.

I believe it could have made the stated power for some period of time before incremental damage began in the output devices. This is not unique and is a common failure point in transistor RF power amplifiers. It depends on how hard it's driven, for how long each time, and how hot the tiny structures inside of the transistors get. I'm familiar enough with semiconductor failure mechanisms after 13 years at a semiconductor manufacturer's application lab to believe the attachment in the original post is accurate. That is the reason I opined the usable (safe) operating level for the TX-800. It is, or was, called "Continuous Commercial Service". CCS. It really has little to do specifically with the TX-800 nor an attack upon it, and there are many like it that could have been mentioned (1 driving 4). It just happened to be here for the checkout and was a well made example.

I concede that CB radio is not for continuous use, but everything I build is rated CCS. I don't like having to fix my own stuff and don't like it when my stuff breaks after several years. HORN will not destroy a CCS rated (or operated) amplifier over time.

Because my story here about experiences with CB amplifiers concerns operating the devices within their suggested ratings for the sake of clean signals and long life, especially avoiding pushing higher than manufacturer-recommended drive or output levels, I expect rebuttals about what can be gotten away with. However, I find no merit in personal attacks because they cloud the facts. I did say that "If I take heat off purveyors of such gear, so be it." Well so be it.

Yeah it is an old post - and now even older. It was amusing to be insulted here. Like a gift.

Oddly, I was directed here when searching the internet for 800-1000 watt audio amplifiers, looking for those with real output ratings and robust straight analog designs. Why? It's way off topic but there are high-brand names out there offering things like 2000 watt amps that plug into a 120V 15 amp wall socket. How interesting they claim that the amplifier can actually manufacture electricity, providing 2000 Watts of clean audio, while consuming less than 1800 Watts (max. wall-plug power in homes). Don't get me started on PC speakers fake watts ratings. So, back to that search - but it was necessary to set a few things straight here on the way.

 

I had pretty good luck with RM amps, really gotta make sure that your radio's power is turned down though so you don't burn the amp, but if it says 200 on setting 3 & 500 on 6, that's exactly what you'll get.

As for meters, man, I just keep running into junk. The only dependable one I had was stolen so if I want accurate power, I swap in one, SWR, swap in a another. None of my radios have proper readouts so they're a necessary evil.

The jap one I have from days of old might be good if they didn't make you guess which part of the dial was registering what, but it's a guess which is swr/ref.

I'd like one with four separate dial windows & switches/knobs dedicated to each bay but the kind of money being demanded is far beyond what I consider sane or even reasonable.

 

It's fun to read people expound with authority about the old days, who are too young to have experienced it. As far as amps go, we always knew to figure about half on AM. Example TS 350 HD, about 150 to 175. You could get a little more out of it, but they'd run hot and usually quit on you. Lo drive them and run them about half throttle and they'd reach out there just as good as driving them to their limits, and last a long time. FWIW