I understand that
Anyway diyaudio mod Sangram already confirmed these tests (capacitance, weight etc).Currently i don't have a LC meter
Best Regards.
Find a friend that does. Or buy one. I have a DMM that measures L and C (actually three of them the same). Consider it an investment in infrastructure that you NEED if your sources for transistors are iffy. Buying a $95 meter instead of the cheapest $29 available saves money in the long run if you can use it for parts screening and making crossover inductors instead of paying 3 prices for them.
If you have to ask if they are fakes then you bought from wrong seller.
Only buy from reputable dealer if possible.
The picture indicate authentic component to me. However the proof of the pudding is in the eating.
The best way is to check Die size by break open. If you cannot do this Just test them at load in a prototype circuit with proper circuit protection. In my openion "fake" doesnot matter much to me if they are extremely cheap and sustain at least 75% of rated specification.
Original components are not cheap. How can a seller give any authentic component at a cheaper rate than MRP?. It must be either Fake or the die manufactured by a different manufacturer.
In electronic component sourcing, the reputation of the seller is very important unless you buy it directly from the company distributer. I only trust RS for component sourcing for critical applications even if they are expensive than other sellers for 100% authenticity.
Just to clarify - The posts attributed to me are from quite a while ago, things have changed a bit over the years.
Recently when working on a Class A SE amp I procured a couple tubes which now had the 'Japan' inscription, and matching on a tube are about 5% from top to bottom. From memory, the ones without 'Japan' had identical packaging, were non-magnetic, and stood up excellently to stress testing and long-term reliability. I still don't know if they were official parts or not, as the matching was not so good. I don't remember testing capacitance either, pretty sure I didn't. Those sets are resting, because we shifted to MOSFETs.
About load testing, it's better to put them in a real circuit and check actual performance against the keantoken models used in simulation. You'll get a much better estimate of whether they are genuine, if you're not able to crack one open. Keeping a device under SOA while applying heavy loads requires some experience.
Recently when working on a Class A SE amp I procured a couple tubes which now had the 'Japan' inscription, and matching on a tube are about 5% from top to bottom. From memory, the ones without 'Japan' had identical packaging, were non-magnetic, and stood up excellently to stress testing and long-term reliability. I still don't know if they were official parts or not, as the matching was not so good. I don't remember testing capacitance either, pretty sure I didn't. Those sets are resting, because we shifted to MOSFETs.
About load testing, it's better to put them in a real circuit and check actual performance against the keantoken models used in simulation. You'll get a much better estimate of whether they are genuine, if you're not able to crack one open. Keeping a device under SOA while applying heavy loads requires some experience.
