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No Bureau cards, please!

They trashing my
incoming QSL!

   

It is a pity, because it is known that China has the technologies that are written about in Europe in sci-fi novels describing the distant future. We know that there is a production capable of producing practically anything in record time and in a quality that surpasses even the wildest dreams of a spoiled, demanding European customer. We know that China has the best engineers and scientists. We realize that China is able to take first place in any field, because hundreds of thousands, perhaps millions, of people will work honestly on a given task. Unfortunately the voracious Chinese traders are capable of destroying even such reputation.

One such gluttonous sellers, shameful across the country, is the Alibaba Group, which brings together dozens of smaller groups, such as Aliexpress, Alimama, Alipay, Fliggy, DingTalk, Juhuasuan, Taobao, Tmall and others. These traders ignore the fact that sellers in the European market must offer a guarantee of at least two years, that the customer has the right to return the goods without giving a reason for a certain period (sometimes up to the entire warranty period) and that cases where poor quality goods cause damage to the customer are solved in court and usually the customer wins. These Chinese merchants shamelessly take "advantage" of the high postal costs in Europe, which, if returned, would mean further loss for the customer, who would rather throw away the non-functional goods. These traders should be aware that complaints of socks and electronic components cannot be dealt under the same rules, that photo documentation is often irrelevant, that complaints must be dealt with an expert who is able to understand measured parameters and that a remark like INVALID (see here and here - refund 0 !) is a real insult to the customer. Anyone who wants to avoid all such difficulties should never buy from Aliexpress or any other member of the Alibaba Group!

What happened to me: under the impression of a number of positive reviews, I ordered a kit of an automatic antenna tuner of the N7DDC design - a 100 W version and at the same time a version for 1 kW. I built the kit for 100 Watts without any problems, but before putting it on-air I received a notification from France that fake toroids are used in the kit and the coil with them has Q = 5, which causes losses, so the tuner is not usable for 100 W, but satisfies only for QRP. When I returned to the reviews, I found that the tuner from this kit was actually used exclusively at QRP power level. So I removed one coil from the finished ATU and measured Q on my VNWA 3-E vector analyzer. The result – Q=7 is shown on the picture, next to it is for comparison the measurement of the same coil, wound on a toroid manufactured by Micrometals. The result - Q = 210 leaves no one in doubt that the French colleague who pointed out the problem was right. Unfortunately, the removal of all coils from the printed circuit board resulted in its partial destruction, a poorly designed board is really not intended for repairs. The teared-off connections had to be replaced with a wire, I used a wire with Teflon insulation, so from electrical point of view the repair was successful, but not visually.

Fake toroid T68-2

Fake T68-2 toroid from the kit.

Genuine Micrometals T68-2

Genuine Micrometals T68-2.

I didn't even start building a 1 kW version of the tuner. The kit contained 6 pieces of T200-2 toroidal cores, so I wound 6 threads on one core and measured it. The result can be seen in the picture. The second figure also documents the calculation - the coil on the supplied toroid had, in addition to Q = 10, double the inductance. The material was obviously different, only the same color as the original Micrometals material 2.

Fake T200-2 toroid

 

Measurement of a coil with 6 turns
on a fake T200-2.

Note the inductance which is
more than twice than expected!

Calculation of an inductor on T200-2

A calculation of a coil with
6 turns on T200-2.

Note the inductance
which should be 0.432 μH!

What with this? I completely resigned from the 100 W ATU complaint. $ 26 is not worth it, I did not deal with INVALID offensive remarks. However, $ 156 for 1 kW ATU is a completely different problem - I need a tuner of this size. Therefore, I demanded either the sending of the original T200-2 from the production of Micrometals or at least their payment. I asked for only $ 42, which is barely enough to buy 6 pieces of T200-2 in the US, without postage. In Europe, I actually pay some $ 100 + postage, which I don't want to do, it's too much for an old pensioner with a minimum income. So the question of my kilowatt tuner remains open…