Brand New Texas Star Sweet Sixteen DX 1600

[Ranch55]

I have a brand new, out of the box, Texas Star Sweet Sixteen on my bench.
1).... Upgrade power wire, positive and negative, to the board and to the output transformers
2).... Upgrade the 4 filter capacitors from 1000uf 16V to 3300uf 25V
3).... Move the fan thermal switch from the PC board to directly on top of heat sink. There is a spot with room
to do this.

Now then, as found right out of the box.
1).... Guess what, this amplifier came with 8 Toshiba 2SC2879 transistors.
That's right.
But I am fairly sure they are knock-offs ...... But they are damn good knock-offs
They do produce over 1000 watts of power with a very acceptable VSWR
2).... The output transformer balancing/tuning capacitors are large surface mount parts.
First time I've seen this. May be getting hard to get the metal clad capacitors.
3).... The power filter capacitors are 1000uf 16V, lowest value I have seen in a new DX 1600

 

[kc8adu]

16v caps in a mobile amp is unacceptable!
some temp compensated regulators can exceed that in very cold temps.
minimum 25v.
and i have heard of fake 2sc2879 on ebay.
the fakers can copy anything but the performance!

 

[Tallman]

16v caps in a mobile amp is unacceptable!
some temp compensated regulators can exceed that in very cold temps.
minimum 25v.
and i have heard of fake 2sc2879 on ebay.
the fakers can copy anything but the performance!

If a manufacturer can save a penny on a product, you can bet your next paycheck they will. The only places that don't don't do that are the ones that deal with the Military programs. Once they certify they design and release it for manufacture no changes are allowed unless they approve it.
Military design would require those capacitor to be at least 32 Vdc..
I hope the capacitance value changes don't cause you any problems like parasitic oscillations.

 

[2NC995]

If a manufacturer can save a penny on a product, you can bet your next paycheck they will. The only places that don't don't do that are the ones that deal with the Military programs. Once they certify they design and release it for manufacture no changes are allowed unless they approve it.
Military design would require those capacitor to be at least 32 Vdc..
I hope the capacitance value changes don't cause you any problems like parasitic oscillations.

The military would also pay $40,000, if not more for the device. We have a highly dysfunctional procurement system.

 

[Tallman]

You are so correct. One of the reasons that it cost so much is testing. The 1000uf capacitors might have been a three month pissing contest.

 

[Road Squawker]

The military would also pay $40,000, if not more for the device. We have a highly dysfunctional procurement system.

That's just one side effect of being REQUIRED to supply parts for many years in the future,

... what good is a 4 billion dollar plane if you can't get repair parts after (say) 5 years?

 

[2NC995]

Thats just one side effect of being REQUIRED to supply parts for many yearsin the future,

Actually, there’s tons of situations where a part cannot be sourced for current equipment and has to be purchased from outside the system, or obtained from salvaged equipment...aka “scrounged”.

 

[Slowmover]

Because most of the money is stolen.

 

[Ranch55]

I hope the capacitance value changes don't cause you any problems like parasitic oscillations.

I don't really expect any issues with that.
These electrolytic capacitors are really for the dc voltage filtering.
Shouldn't be any issues.
I have seen Texas Star use anywhere from 100uf 50v, up to 4700uf 35v, and also some have had 2200uf 25v, or 3300uf 25v.

 

[Highway Man]

Don't leave us in suspense, where did it come from?

 

[Ranch55]

Well, if these are knock-off Toshiba's, which I think they are, they are pretty good ones.
I have compared them to originals, and the printing on them is identical as far as I can see with my eyes and magnifying glass.
I pulled them all and the hfe gain on them are higher than I have ever found on new HG's.
I upgraded all the power wires and 5 electrolytic capacitors.
Resoldered some joints that looked iffy.
Put it all together. Remounted the thermal switch directly on the heat sink. Yes there is room for that.
Hooked it up today.
Input and output tuning is actually very good. VSWR in and out is 1.2 to 1.4 .....
I'll leave well enough alone.
Power output is excellent. 75 watt PEP input produces 1250~1275 output.
I'm gonna run it for awhile and we'll see how it does.

 

[snippits75]

New Texas Star amps R Made With "Fake" TOSHIBA'S ??

 

[Ranch55]

Yep, I just saw that myself this morning.
I will say that according to what I can see in the video, the 6J coded Toshiba knock-offs are internally more robust and the tabs are connected internally much, much better than the HG transistors.
And the upper & lower ceramic insulators are thick like the genuine Toshiba's whereas the HG's are much thinner and break very easily.
As BBI says, I am not bashing anyone in this case. Just reporting my observations.
This is the same Toshiba 6J code that came in this Sweet Sixteen I have been writing about in this post.

 

[Highway Man]

Said vijao from that other thread

 

[Ranch55]

Don't leave us in suspense, where did it come from?

When I purchased it, it was from Copper Electronics directly.....