How much carrier output?

[groundwire]

Ok just for kicks, i posted the question on my Facebook groups, "for an hg 2879 amplifier, how do you know what output carrier to set the amp for that wont blow up the amp or push it to it's limit? 25w max output per transistor? The 4:1 ratio? Etc". And as expected tons of people had an opinion, all different and most of them the most ridiculous answers you have ever heard. What blows my mind is with any commercial or amateur amplifier, the manufacturer clearly knows and defines what the maximum drive, peak output and carrier levels should be to avoid damage and/or failure. Yet most of the cb people are all over the place with their answers and generally dont know what the hell they are talking about, as usual (sorry but its true). Even the guys that build the amps ALL have a different answer. So with that being said, there has to be a definite and correct answer to the question, "how do you know what the correct carrier output level from an hg2879 amplifier should be"?

 

[dave457]

Whatever the spec sheet calls for, not the builder

 

[groundwire]

Whatever the spec sheet calls for, not the builder

Hg transistors have no spec sheet.

 

[144inBama]

25 watt per transistor in the final stage. 1X4 = 100 max 2X4 = 100 max. The 25 per is the result of many a blown transistor and lifespan at different drive levels. Most every builder that has used Toshibas in builds found out the expensive way. One has gone as far as to run them at X watts, check the Hfe, step up to Y watts, then check Hfe and so on. If they found breakdown at Y, they'd go back to X and run it for awhile and check the Hfe. His findings were somewhere between 23-27 watts @ 14VDC provided the longest lifespan with reasonable output so, "25" is an easy number to remember.
Read this a few years ago so I have no way of providing a link though.

 

[groundwire]

25 watt per transistor in the final stage. 1X4 = 100 max 2X4 = 100 max. The 25 per is the result of many a blown transistor and lifespan at different drive levels. Most every builder that has used Toshibas in builds found out the expensive way. One has gone as far as to run them at X watts, check the Hfe, step up to Y watts, then check Hfe and so on. If they found breakdown at Y, they'd go back to X and run it for awhile and check the Hfe. His findings were somewhere between 23-27 watts @ 14VDC provided the longest lifespan with reasonable output so, "25" is an easy number to remember.
Read this a few years ago so I have no way of providing a link though.

Thats what i do, 25w per device. Never had a problem or overheating issue ever.

 

[144inBama]

What's the name of the group?

 

[groundwire]

What's the name of the group?

Facebook group? Two ch6 super bowl groups and 11m box builders

 

[nomadradio]

Ditto. 25 per 2879.
15 to 18 per 2SC2290.
73

 

[snippits75]

25 watts per Toshiba 2879 is what I have been doing for over 20 years now.

Original Dave Made 1x4 mobile I ran at a 100 watt carrier for round about 8 years in my 18 wheeler. Ended up selling it for more than what I paid for it.

 

[sp5it]

25W for each Toshiba 2879?
Interesting, because manufacturer datasheet says max 10W PEP.
Mike

 

[144inBama]

25W for each Toshiba 2879?
Interesting, because manufacturer datasheet says max 10W PEP.
Mike

Data sheets are the suggested/recommended. The manufacture recommends an oil change every 5K miles, yet people will go 8K or more with no issues. Toshibas were built beautifully which allowed them to be pushed well beyond the spec sheet and survive. For longevity, the data sheet for the Toshibas is what should be followed for HGs to survive.

 

[Shadetree Mechanic]

25W for each Toshiba 2879?
Interesting, because manufacturer datasheet says max 10W PEP.
Mike

I think they are saying 25w output, not input.

 

[144inBama]

I think they are saying 25w output, not input.

Yes sir.
For years I ran 1 pill 2879 box (90 PEP) into 2 pill 2879 box (100 PEP dead key and 500+ PEP out) with no issue, so even them saying 10 PEP in doesn't mean it's going to explode into dust if you exceed it. Toshibas were so underrated on the data sheet it's ridiculous.

 

[groundwire]

Hahaha, so im assuming the reason these makers say like 175w carrier max on a 2pill or 1,100w on a 16pill is so you blow it up and buy another one. Lol

 

[nomadradio]

I think they are saying 25w output, not input.

Yes.

73