Toshiba vs HG

[Shockwave]

Better not open up HF power transistors, they contain berillium oxide very poisonous.

That's only hazardous if the BEO ceramic cracks and you inhale the dust particles. Do not break the cap off, pop it off at the glue seam. The data sheets for many newer transistors no longer contains the old BEO warning because that material had to be substituted for another (with lower thermal conductance), in order to meet the ROHS safety guidelines.

 

[oldtymer]

That's because they spent more time copying the data sheet than they ever did copying the Toshiba part. If the specs were what they say on the datasheet, the part would be the drop in replacement they attempt to deceive people into thinking it is by the fake number.

If the market demand was not high enough to keep the original part in production by Toshiba, there is zero possibility that another manufacturer is going to see anything profitable, other than counterfeiting with a different part. Remember, 11 meters is the ONLY place there is any demand for this part and the Chinese know they can get away with selling anything that says 2SC2879 on it, because they already have.

Some of the older HF radios used them for finals also.

 

[Shockwave]

Some of the older HF radios used them for finals also.

The vast majority of quality 100 watt HF rigs used them at one time or another and that was Toshiba's marketplace. Especially in mobile applications. Some would use the 2SC2290 like the Kenwood TS-430S. That all ended many years ago and all that is left for this market is CB. That does complicate things as far as keeping those older HF rigs on the air if you pop a final but most had good enough protection to prevent that. The only piece of HF gear I'm aware of that is still in production using the 2SC2879 is the Ameritron ALS-500M. Its online reviews took a nose dive the day their Toshiba supply dried up.

 

[Shadetree Mechanic]

What do HF rigs use now days and is that what we should be using to build amps with?

 

[Shockwave]

What do HF rigs use now days and is that what we should be using to build amps with?

If it's powered by 12 volts, today the most common final in the 100 watt HF class is the Mitsubishi RD100HHF1 and it's a MOSFET. We should have been using them a decade ago. The reason you don't see them in use on 11 is because when you place them in the typical 2879 circuit, they make no power because their input impedance is 6 times higher (also, 6 times closer to 50 ohms) and good bias is not an option you can do without.

 

[543_Dallas]

Better not open up HF power transistors, they contain berillium oxide very poisonous.

That was the good stuff. I doubt the Chinese would use it.

 

[AudioShockwav]

The only piece of HF gear I'm aware of that is still in production using the 2SC2879 is the Ameritron ALS-500M. Its online reviews took a nose dive the day their Toshiba supply dried up.

Tom has a facebook page about the AL amps and he has posted some pictutes of the, in my opinion, sloppy work on these amps.
Dirt under the transistors, runny thermal compound and other quality issues with these.
If they would pay attention to the build I think they might not fail so much.

73
Jeff