More fake units sold on Ebay

Talk about anything else here.
AcidJazz
Posts: 9
Joined: Sat Nov 25, 2017 3:29 pm

Re: More fake units sold on Ebay

Post by AcidJazz » Wed Jan 15, 2020 11:58 am

Username wrote:
Fri Dec 06, 2019 3:22 pm
And Inside?
Inside is visibly here
It's just pcb from blue dongle with additional HF pcb, without 1ppm tcxo, without injector, cooling rubber, etc...
HF pcb, with 99% probability, without LNA and transformer, just 1 transistor like here.

radiolistener
Posts: 60
Joined: Thu Jan 25, 2018 10:48 pm

Re: More fake units sold on Ebay

Post by radiolistener » Thu Jan 16, 2020 3:06 pm

AcidJazz wrote:
Wed Jan 15, 2020 11:04 am
He meant the original filter RTL-SDR.COM, but component values are trade secret, of course.
what is the secret? You can desolder components measure it and solder it back with no problem... :ugeek:

I'm asking what component values are used just to put it into simulator and compare how aliexpress fake item parameters are different from original one. Just interesting :)

AcidJazz
Posts: 9
Joined: Sat Nov 25, 2017 3:29 pm

Re: More fake units sold on Ebay

Post by AcidJazz » Fri Jan 17, 2020 8:45 am

radiolistener wrote:
Thu Jan 16, 2020 3:06 pm
what is the secret? You can desolder components measure it and solder it back with no problem... :ugeek:
Tssss........ Don't tell that to the Chinese. For some reason, they still haven't done it, and selling filters with terrible characteristics.

radiolistener
Posts: 60
Joined: Thu Jan 25, 2018 10:48 pm

Re: More fake units sold on Ebay

Post by radiolistener » Sat Jan 18, 2020 4:06 am

I think they selling filters with terrible characteristics just because they use cheap component that they have instead of what is required. For example they can put a little different inductors just because they don't have inductor which is exactly needed. The same for capacitors. They can use inductors and capacitors with low Q to reduce price, as result the filter have high loss etc. :)

For example in my Chinese filter I see 3 exactly the same inductors. But the middle inductor should be a little different. Also I see different inductors on the input and output, but they needs to be exactly the same...

rtlsdrblog
Site Admin
Posts: 2509
Joined: Mon Nov 19, 2012 11:54 pm

Re: More fake units sold on Ebay

Post by rtlsdrblog » Sun Jan 19, 2020 10:35 am

Sorry i'd rather not release the exact component values because they were hand tuned over many iterations and component brands to get something good. The cloned ones probably didn't spend the time to check the differences in Chinese component "brands". Some of the cloned filters I tested really fail at keeping the out of band insertion loss down, I bet they just measured the values and got the cheapest components they could find.

Timpanogos Slim
Posts: 9
Joined: Mon Feb 10, 2020 1:39 am

Re: More fake units sold on Ebay

Post by Timpanogos Slim » Fri Feb 14, 2020 8:10 am

radiolistener wrote:
Thu Jan 16, 2020 3:06 pm
AcidJazz wrote:
Wed Jan 15, 2020 11:04 am
He meant the original filter RTL-SDR.COM, but component values are trade secret, of course.
what is the secret? You can desolder components measure it and solder it back with no problem... :ugeek:

I'm asking what component values are used just to put it into simulator and compare how aliexpress fake item parameters are different from original one. Just interesting :)
Even 20 years ago there were test harnesses for circuit boards that implemented a foam elastomer with a grid of thin vertical wires to connect to all possible points on the board to measure voltages.

If a counterfeiter sincerely wanted to duplicate the component values on the board, they could without serious inconvenience.

RF reception is a pain in the ass and wide-band RF moreso. It's believable that passive components of very specific specifications perform a little better than others.

Post Reply