Maybe, maybe not. I have a pair of traces from him that are identical, you can superimpose one on top of the other. The other two are not very close. I paid $358.00 for a matched quad.
just sayin🙄
just sayin🙄
I just bought a curve traced matched quad as well. If it turns out they are not well matched, I will let him know. He is a very reasonable guy to deal with.
I bought a quad of THF-51S. I am eager to see Nelson's design, but would like to work on my own. I am new to the sand, hollow state is usually my interest, so I am learning much here in the Pass Labs forum. Much of single-ended class A tube design translates, which makes the learning curve much more manageable.
I would like to design a choke-loaded common source amplifier. Based on Nelson's measurements, a very low output impedance buffer seems necessary to run the THF-51S in common source. I went searching for a JFET solution, of which there seem to be many! I came across a very good article by Erno Borbely called "JFETS: The New Frontier". After reading in detail, I like his JFET analogue of the White Cathode Follower to drive the THF-51S gate.
Output impedance of the buffer in LTSpice simulation if about 4ohm, measured 2.3ohm using the 2SK170 in Borbely's article. This should yield very good bandwidth with the THF-51S. I have much to learn and this is a draft, details of the power supply are yet to be fleshed out, but this is the general idea of what I would like to do.
Bandwidth is good in simulation using the 2SK180 model as a substitute.
I would like to design a choke-loaded common source amplifier. Based on Nelson's measurements, a very low output impedance buffer seems necessary to run the THF-51S in common source. I went searching for a JFET solution, of which there seem to be many! I came across a very good article by Erno Borbely called "JFETS: The New Frontier". After reading in detail, I like his JFET analogue of the White Cathode Follower to drive the THF-51S gate.
Output impedance of the buffer in LTSpice simulation if about 4ohm, measured 2.3ohm using the 2SK170 in Borbely's article. This should yield very good bandwidth with the THF-51S. I have much to learn and this is a draft, details of the power supply are yet to be fleshed out, but this is the general idea of what I would like to do.
Bandwidth is good in simulation using the 2SK180 model as a substitute.
Very cool. Your circuit is so straightforward I have fooled myself into thinking I understand it! Will be following with interest.
So, I've opened a dispute:
"I've made a purchase based on that picture, it shows almost certainly an original NOS device:
After some day of my purchase, seller changed the picture, it shows a suspicious, uncertain device, what I wouldn't purchase for that price, it is for sure.
My problem is:
I didn't get that device, what I've paid for.
Moreover, the devices what I've got, are two different kinds of.
I don’t want to put anyone in an awkward position, but it simply cost me too much money.
Regards, Gyuri"
Seller's answer was:
"Dear buyer . they are same products . they are same part number . The first photo is old date code . the second is new date code . they are very good quality . I didn't send you wrong products . If you don't accept the items . pls return it to me . Thanks ."
What now?
"I've made a purchase based on that picture, it shows almost certainly an original NOS device:
After some day of my purchase, seller changed the picture, it shows a suspicious, uncertain device, what I wouldn't purchase for that price, it is for sure.
My problem is:
I didn't get that device, what I've paid for.
Moreover, the devices what I've got, are two different kinds of.
I don’t want to put anyone in an awkward position, but it simply cost me too much money.
Regards, Gyuri"
Seller's answer was:
"Dear buyer . they are same products . they are same part number . The first photo is old date code . the second is new date code . they are very good quality . I didn't send you wrong products . If you don't accept the items . pls return it to me . Thanks ."
What now?
I had a similar experience with Ali Express. They did not care that I had a dispute. The loss was my loss.
In your case, I recommend that you have the Vds-Id curves traced for your parts. Find someone in the community on your continent who can do this for you. The curves will look something like the attached.
Attachments
Buyers remorse is a very difficult emotion to overcome. If you are not comfortable with your purchase, and the seller will allow a return, then...
I've curve traced these, so these can be SITs.
But my point is:
He is misinformed me.
I wouldn't have bought his item, if he upload photos, that contains current product, what I've got.
So in this way, the dispute, and the whole case simply wouldn't exist now.
It was not my fault, I think.
But my point is:
He is misinformed me.
I wouldn't have bought his item, if he upload photos, that contains current product, what I've got.
So in this way, the dispute, and the whole case simply wouldn't exist now.
It was not my fault, I think.
100% Agreed, I ordered a bunch of Power Transistors, 4 kinds, from UTSOURCE and I haven't found any indication of being fakes other than one of 4 kinds has the HFE a bit lower than indicated by Toshiba, everything else is fine, still I can't stop thinking they may be fake....
Bottom line, lesson learned, a couple of hundred USD spent, never again.... Only buy from Trusted Sources from now on....
First option is to send goods back, but there is no guarantee as seller may claim he never received them back and it is additional expense.
Second option is to escalate dispute to AliExpress staff. Your purchase is saved as snapshot on AliExpress so you have proof that you didn’t receive what you paid for. Seller hopes that you are a geezer, with no actual knowledge, that will fall to his story.
Seller must be told that you perfectly well understand that there is no “date code” difference between two pictures, rather difference between real and fake product. Stamping the same FAKE code on different used and refurbished products doesn’t make them the same. You must tell him that you understand this is a FRAUD and that you will escalate dispute and that your product review will have all that details. It’s questionable whether he will even bat an eyelash on that but better to try than to leave this as is.
Second option is to escalate dispute to AliExpress staff. Your purchase is saved as snapshot on AliExpress so you have proof that you didn’t receive what you paid for. Seller hopes that you are a geezer, with no actual knowledge, that will fall to his story.
Seller must be told that you perfectly well understand that there is no “date code” difference between two pictures, rather difference between real and fake product. Stamping the same FAKE code on different used and refurbished products doesn’t make them the same. You must tell him that you understand this is a FRAUD and that you will escalate dispute and that your product review will have all that details. It’s questionable whether he will even bat an eyelash on that but better to try than to leave this as is.
This ime is a mistake. Aliexpress allows all goods sold to EU to be returned within 14 days, no reasons required. As long as you ship with registered mail i can foresee no issues. Cost of shipping is just a small fine for your negligence 🙂
Sometimes I have better luck with the Credit Card company I used for paying, not sure if that's an option for you but its worth checking.
I've paid with my credit card associated with Paypal, not direct Bank transfer with that card.
But I don't know, how it can help?
But I don't know, how it can help?
First, PayPal will help you with the transaction, no seller wants to make PayPal mad. Second, your a better customer of the credit card company than the seller, once again, no seller wants to make VISA/MC mad.
Return goods not an option, because of postal fee.
I don't even dare enough to ask how much it could be.
I don't even dare enough to ask how much it could be.
Hello, this is a fake, not a NOS. Believe me, I know what they are. They are refurbished and processed by electroplating. Their original identity is 183, not 182, and not 51. I have rich experience, know They are electroplating.
In China, there are many suppliers who steal my photos. At first they upload my photos, and then they mark cheap prices, attract customers to buy, and actually ship them.
This product is printed with other models For fonts, if they use 183, users who are generally less demanding can use it.
According to my experience, this appearance is only 182, 51, 183, 2SD646, but 182, 51 in the Chinese market is very rare. ,
The supply of 183 still exists, but the Chinese do not like to use 183. They agree with the articles on the forum and like 182, 51
In China, there are many suppliers who steal my photos. At first they upload my photos, and then they mark cheap prices, attract customers to buy, and actually ship them.
This product is printed with other models For fonts, if they use 183, users who are generally less demanding can use it.
According to my experience, this appearance is only 182, 51, 183, 2SD646, but 182, 51 in the Chinese market is very rare. ,
The supply of 183 still exists, but the Chinese do not like to use 183. They agree with the articles on the forum and like 182, 51