Talking about amps ... who are the better ab1 manufactures?

[project]

I have a Texas Star amp Dx 350 HDV with 2 X 2879's running with a RCI 2950 DX on ten meters SSB and if you are not clean on ten they will tell you. Nice amps but I would add a fan to keep it cool and don't max it out for every last watt.Several people I know swear by the 4 X 2879's in the DX 500 HDV and run them with ham radios with good reports on 10 and 11 meters and would run nothing else.

It's been my experience that if you have to add a fan then you are running it too hard. That heat sink is more than enough to dissipate the heat.

 

[The Mad Scientist]

It's been my experience that if you have to add a fan then you are running it too hard. That heat sink is more than enough to dissipate the heat.

This is not nessassarly true. In my experence you should have some type of supplemential cooling.

 

[project]

This is not nessassarly true. In my experence you should have some type of supplemential cooling.

Why is that? You should be able to run that amp all day without over heating problems. There will always be heat generated by the transistors and the heat sink will absorb and dissipate the heat, that's its job. If a TS 350 is running hot enough to need a fan then there are other issues that need addressed. I have parked on a hill and talked for hours with several amps with no cooling fans and never had a single issue. If you want to watch that meter swing and try to get every last watt you can then yes, you will need a fan but that is only a band aid to a problem that only a pill will fix eventually.

 

[Grogan]

I just like to run a good fan. It can't hurt and I ratchet jaw so it does get warm at times. Hot to the tuch no, but very warm. I talket to the guys at Texas Star teck support once about heat and he told me the 2879's are durable and you should be able to heat them up to the point the solder melts???????? WOW?????

 

[The Mad Scientist]

Why is that? You should be able to run that amp all day without over heating problems. There will always be heat generated by the transistors and the heat sink will absorb and dissipate the heat, that's its job. If a TS 350 is running hot enough to need a fan then there are other issues that need addressed. I have parked on a hill and talked for hours with several amps with no cooling fans and never had a single issue. If you want to watch that meter swing and try to get every last watt you can then yes, you will need a fan but that is only a band aid to a problem that only a pill will fix eventually.

Uh ok, I think not. In order to acheave what you are saying you would have to run the amplifier less than 1/2 it's rated output and or full rated output for less than 3 minuites with 20 or so minuites off. I have worked with these amplifiers for a very long time and supplemential cooling IS needed if you intend to use it for moderate periods of time. I have run mine for 12 years with 48 cfm of airflow on the heatsink via a custom setup and I can ragchew for at least 10 minuites in the dead of summer before the heatsink ever reaches 120 degrees checked via laser thermal gun.

 

[The Mad Scientist]

I just like to run a good fan. It can't hurt and I ratchet jaw so it does get warm at times. Hot to the tuch no, but very warm. I talket to the guys at Texas Star teck support once about heat and he told me the 2879's are durable and you should be able to heat them up to the point the solder melts???????? WOW?????

durable? I would have to question that with the new versions of the 2sc2879 transistors. I have seen pictures of an amplifer that this has happened to. That amplifier was totally insulated stuffed behind the back seat of a pickup.

 

[project]

Uh ok, I think not. In order to acheave what you are saying you would have to run the amplifier less than 1/2 it's rated output and or full rated output for less than 3 minuites with 20 or so minuites off. I have worked with these amplifiers for a very long time and supplemential cooling IS needed if you intend to use it for moderate periods of time. I have run mine for 12 years with 48 cfm of airflow on the heatsink via a custom setup and I can ragchew for at least 10 minuites in the dead of summer before the heatsink ever reaches 120 degrees checked via laser thermal gun.

Like I said , If your a meter bater and want to see the needle swing as far to the rite as possible then you will need a fan but I don't fall into that category . I run everything within the design specs of the transistors and it will run that way for years. Just because someone tells you that you can get 200w out of a 2879 doesn't mean you should.

 

[project]

Uh ok, I think not. In order to acheave what you are saying you would have to run the amplifier less than 1/2 it's rated output and or full rated output for less than 3 minuites with 20 or so minuites off. I have worked with these amplifiers for a very long time and supplemential cooling IS needed if you intend to use it for moderate periods of time. I have run mine for 12 years with 48 cfm of airflow on the heatsink via a custom setup and I can ragchew for at least 10 minuites in the dead of summer before the heatsink ever reaches 120 degrees checked via laser thermal gun.

Like I said , If your a meter bater and want to see the needle swing as far to the rite as possible then you will need a fan but I don't fall into that category . I run everything within the design specs of the transistors and it will run that way for years. Just because someone tells you that you can get 200w out of a 2879 doesn't mean you should.

 

[The Mad Scientist]

 

[Captain Kilowatt]

I just like to run a good fan. It can't hurt and I ratchet jaw so it does get warm at times. Hot to the tuch no, but very warm. I talket to the guys at Texas Star teck support once about heat and he told me the 2879's are durable and you should be able to heat them up to the point the solder melts???????? WOW?????

The max junction temperature of the 2SC2879 is 175 degrees C or 347 degrees F. Typical 60/40 solder melts at 370 degrees F. Anyone that would even consider running an amp at those temperatures is not only flirting with catastrophic failure they are also completely lacking in knowledge of how equipment should be run. It matters not if the person that said it was OK to do so was from the manufacturer of the equipment or not. They did not make the components that went into their gear. The real key to heat management is a properly sized heatsink. Most manufacturers use too small of a heatsink to keep costs down and thus the reason to use supplemental cooling in the form of a fan. A properly sized heatsink and properly mounted transistors using thermal heatsink compound will result in an amp that can be run at maximum rated power while maintaining safe temperatures. A heatsink should never burn you if you touch it however it may be what is considered to be hot in which case you should be able to keep your hand on it for several seconds.

 

[The Mad Scientist]

Nice post.

Perhaps you could enlighten us to the differences between the beryllium oxide ceramic insulator and the newer aluminum nitride insulator on the newer devices?

 

[Captain Kilowatt]

Nice post.

Perhaps you could enlighten us to the differences between the beryllium oxide ceramic insulator and the newer aluminum nitride insulator on the newer devices?

Other then they do not contain a hazardous material (beryllium oxide) and that the aluminum nitride has a lower thermal conductivity ( about half that of BeO) I don't know nor care. The temperature of the P-N junction of the device is what matters when it comes to heat tolerence. Keep that junction temp down and all is fine.