RFT PP100 transistors vs DEI 2879s

[bassman21]

Hi all,

How have the RFT PP100 "power pill" transistors that Xforce and others have been using been holding up and how much less/more power do they put out vs the Toshiba 2879 and the DEI 2879s? Are they better than the DEI's? I'm asking because I have a 2x8 class C that someone fried and was thinking about putting PP100s in it. How much you think I can expect to get out of it at 15 volts?

 

[543_Dallas]

Need more info. How much you can get out of it depends on how long you want it to last.

 

[bassman21]

Thanks for the reply. I know they probably will not be as durable as Toshiba's. Not looking for a debate on how hard a amp should be pushed. Just asking to compare to DEI's with reference to Toshiba's. I already stated the voltage, the drive will probably be 15 watts. I know a 2X8 competition amp with Toshiba 2879s can do about 1800 to 2200 watts pushing it hard. The 2X8 I had back in the day with Toshiba's did 1500 at 15 volts with no issues. Just like my Dave Made 1x4 will do 800 to 1000 being pushed hard and does 700 pretty easily. My old straight 4 pill Texas Star DX 500 with DEI did 500 with about 20 watts drive. So that is our reference points for the output of the PP100s.

 

[Robb]

Man, I'd be surprised if these pills didn't pop with recommended input voltage and input power.

 

[bassman21]

Man, I'd be surprised if these pills didn't pop with recommended input voltage and input power.

Do you have any experience with them or know anyone that has? BBI did a voltage test on them in one of his videos and they took over 20 volts. Inside they were the same as the hg2879, they out preformed the DEI 2879s. Of course this doesn't mean much as far as long term use, but says something. Apparently gatekeeper has an updated version of the hg2879's that is supposed to be better, of course they all say that theirs is the best.

Bottom line I don't want to spend the money for Toshiba's on this box

 

[Robb]

Not a lick of hands-on. But I've read that there are a bunch of very unhappy people out there that feel as though they expected more and got way less. The days of the 'Great White Pill' are over; welcome to the day of the LDMOS. Which are also fussy but are tough and powerful enough if you treat them right. No more whacking great input power to overdrive them - either.

 

[dave457]

Why not just run it to manufacture specs of the transistors, I'm sure it'll sound better, run cooler and last longer

 

[543_Dallas]

Why not just run it to manufacture specs of the transistors, I'm sure it'll sound better, run cooler and last longer

That's the truth but no one wants to hear it. They need a cheap 8 pill that will perform like a 16 pill and last forever.

 

[nomadradio]

Do you want a daily driver?

Or a weekend racer?

Should it go a whole quarter mile before it blows up? Or maybe two or three quarter-mile runs? Or a 50-lap round-and-round race?

The stresses you put on machinery will dictate the service life. A motor that wins quarter-mile races won't go 150,000 miles between rebuilds.

A machine is a machine is a machine. How hard you stress it dictates the service life.

I will occasionally ask a customer how much "KBK" he wants from his box, explaining that this will dictate the power level he can get.

"KBK", as in Keys Between Kabooms.

The harder you push it, the sooner it breaks. The Toshiba transistors were incredibly tough. The first year or so they were in production, they seemed easier to pop. If you see one with a 'cursive'-looking "Toshiba" on it, that one is really old. Be nice to it. The logo changed to the bold upright block-letter font in the late 80s. For every ten years they made those parts, they just got tougher. Pretty well-accepted rule of manufacturing is that the more of them you make, the higher the quality level tends to be. By the time Toshiba had been making the 2290 and 2879 for 20 years you were getting a part that was radically tougher than the specs would suggest.

And that's what nobody else can sell you now. A part that's been coming out of the cookie cutter for decades.

The sweep tubes used in linears for years exhibited this same problem, Tubes made when the television factories used them by the million were just tougher. Tubes made the last ten years before they stopped altogether were built in smaller production runs. We were seeing a higher and higher rate of new tubes that were "duds" as the size of production runs would shrink smaller and smaller.

If you want mean-azz transistors that will burn rubber and survive, all you need is a time machine. Jump back to about 2002 or so. Just check the dates printed on your cash before you go. Wouldn't want to get locked up for counterfeiting when you hand the guys at RF Parts a Franklin that says "2013" on it.

73

 

[bassman21]

I finally got the pp100s installed in the 2x8. It worked great for about two weeks and now the power is going from 150 swinging to 900 to 50 swinging to 500 or so. It will work right for a little while and then cut the output in half. The box does about 1200 with 15 watts drive, but I was running it light. Reflect is very low. One of the resistors burned up coming off one of the transistors. I replaced the resistor and it is still doing it. Do you think one of the transistors is bad or do you think there is another problem? I was thinking either a bad cap or a bad transistor. Guess these pp100s may be crap.

 

[ExitThirteen]

If it's one of the 10 ohm resistors going between the base and the emitter of the transistor, the transistor is bad. That would be why your output is lower than it was before. I would not recommend using the amp further until you can get that particular pair replaced (never replace just one, they need to be gain matched and while you should replace all 8, you could get away with replacing just the 2) since it can damage the other ones due to a mismatch. The transistors work in push/pull, so you have to replace them as a pair at the bare minimum.


~Cheers~

 

[bassman21]

If it's one of the 10 ohm resistors going between the base and the emitter of the transistor, the transistor is bad. That would be why your output is lower than it was before. I would not recommend using the amp further until you can get that particular pair replaced (never replace just one, they need to be gain matched and while you should replace all 8, you could get away with replacing just the 2) since it can damage the other ones due to a mismatch. The transistors work in push/pull, so you have to replace them as a pair at the bare minimum.


~Cheers~

Great thank you! The good thing is the beta gain is written on the other transistors, so if I can get two pp100s with a beta gain of 66, I should be good. I might just put Toshiba's in it and call it a day or fix it and sell it, my Dave Made 1x4 does almost as much as this did.

 

[543_Dallas]

I finally got the pp100s installed in the 2x8. It worked great for about two weeks and now the power is going from 150 swinging to 900 to 50 swinging to 500 or so. It will work right for a little while and then cut the output in half. The box does about 1200 with 15 watts drive, but I was running it light. Reflect is very low. One of the resistors burned up coming off one of the transistors. I replaced the resistor and it is still doing it. Do you think one of the transistors is bad or do you think there is another problem? I was thinking either a bad cap or a bad transistor. Guess these pp100s may be crap.

A local bought a 6 pill tnt from xforce and had similar results. He bought replacement pp100s from xforce and still isn't happy. He runs it at 500 watts pep because he's afraid of blowing it again.

I wasn't there when it blew and didn't repair it so I don't know anymore than what he's said. He's a friend so I told him I would fix it if he bought a matched set of Toshibas instead of the Chinese pills. He went the cheaper route.

There is another local guy building amps with the HG transistors. They seem to be holding up for him. I've thought about buying a pair of them to test, maybe one day. I have a new xforce 2 pill I won on their forum. I should stress test it and put in some HG pills when it blows.

 

[bassman21]

I think I'm going to drop a matching set of HG2879s with the same gain.

 

[9C1Driver]

Man, I'd be surprised if these pills didn't pop with recommended input voltage and input power.

Looks like you called that one.