Identifying a component on RTL-SDR.com dongle

thewraith2008

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Nov 22, 2016
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On one of my RTL-SDR.com dongles, I can no longer get any reception on the MW band when selecting the Direct sampling (Q branch).

I have traced this down to the following component pointed to with red arrow in following image:
dntgDvQ.jpg


Does anyone know the real part number for this.
From what I can tell, the marking is "LPt" and the package is a SOT-363-6.
Yy95c1c.jpg
uFT2gO9.jpg



More testing detail:
If I probe the signal path starting at the antenna connector, no change in signal is detected.
If I probe the input (pin 6) of the unknown part, no change in signal is detected.
If I probe the output (pin 3) of the unknown part, change in signal is detected an MW is heard.
Also, pin 1 of part has 5v (4.88v - USB +V) on it.

Again, if anyone knows the real part number for this component, I would be grateful.:love:
 

thewraith2008

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Nov 22, 2016
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OK folks, out of the rabbit hole to report the following:

I believe I found the part:
  • Manufacturer: NXP
  • Part number: BGA2867
  • Part description: MMIC wideband amplifier
  • Marking Code: LP* (* = MFG site. Mine was: t = made in Malaysia)
  • Package: SOT363

General description
Silicon Monolithic Microwave Integrated Circuit (MMIC) wideband amplifier with internal
matching circuit in a 6-pin SOT363 plastic SMD package.

The pin description and working voltage matches.

Source information

Now it remains to be seen if this can be purchased.
The usual places show no stock with large lead in delays.:cry:
 

thewraith2008

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Yes it failed, but I'm not sure when this occurred or why.
I wouldn't worry about it unless it fails on yours.

Since it powers directly from the USB port, maybe it got spiked there? (the part has a 7v MAX voltage rating)
The RF path ESD protection is OK so I don't think it got zapped there.
I was just doing some testing and noticed it wasn't working.

I removed it and just put a jumper across pins 6 and 3 and it's working OK. (signal level is weak obviously)
It will do until a replacement is found.
 

thewraith2008

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Nov 22, 2016
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Just a followup with what the MW frequency spectrum looks like when:
  • RTL-SDR.com dongle with wideband amplifier removed and jumper in it's place.
  • RTL-SDR.com dongle with wideband amplifier removed and jumper in it's place with RTL AGC used.
  • RTL-SDR.com dongle with (a working) wideband amplifier in place.

QDRhdjE.png


Rrsfev0.png


jLeotD2.png
 

merlin

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If that is the front end amp, it went the way one of mine did and that was static discharge in an electrical storm. Sadly, my bad vision won't let me work on this micro stuff.
 

thewraith2008

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If that is the front end amp, it went the way one of mine did and that was static discharge in an electrical storm. Sadly, my bad vision won't let me work on this micro stuff.
Maybe, but I don't think it came through the RF path in my case.
None of the so called ESD protection (D12 and the dual signal diode "A7" (clamp)) in the RF path faulted.
The dongle worked as expected when using quadrature sampling.

Yes working on SMD is not without some challenges that's for sure.
More hands are needed to hold the soldering iron, solder, light, tweezers etc...:rolleyes:
 

thewraith2008

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Maybe of interest to list some more components (that could be subject to failure) that are known and unknown.
NOTE: I stand to be corrected with any information below and you should see datasheets for full specs on components listed here.


Some other components of note that can be identified:
Code:
Circuit ID: ?
- Description     : 3.3v LDO Regulator - Used as main B+
- SMD Marking Code: GH12E
- Real part number: AP2114H-3.3TRG1 (from BCD Semiconductor?)
- Package         : SOT223

Circuit ID: ?
- Description     : High-speed switching diode (Dual) - Used as clamping diode for ESD protection?
- SMD Marking Code: A7 or A7W
- Real part number: BAV99 (from Nexperia)
- Package         : SOT23

Circuit ID: ?
- Description     : 4.5v LDO Regulator - Used for BIAS-Tee switching (ON/OFF)
- SMD Marking Code: 4BE0 *
- Real part number: LN1134B (SOT-23-5L)(from NatLinear?)
- Package         : (SOT-23-5L)

* Also seen as: EY-BO4 on newer dongles and will probably be same type of component only manufactured by someone else.

Some other components of note that can't be identified: (Does anyone have an idea about these?)
Code:
Circuit ID: D12
- Description     : Unknown (Zener?) - Used for ESD protection (see image in 1st post that points to this)
- SMD Marking Code: None
- Real part number: ?
- Package         : ?

Circuit ID: ?
- Description     : Resettable fuse (200mA?) (newer dongle versions only)
- SMD Marking Code: T02
- Real part number: ?
- Package         : ?

There is another component used in latest dongles that looks like another LDO over near the USB connector.
Image I've seen of it is not clear enough but I thing it's marking is:
- SMD Marking Code: AABB
This could be a 1.2v external power for the RTL2832U.
Normally the RTL2832U has an internal one but it's said to be noisy.
 

Carter911

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Aug 17, 2021
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Wow, regarding the BGA2867, what an interesting chip!

Mouser says it ought to have 9,000 in stock by the end of August.

Wow, again, this time with emphasis!
It is $0.31 each, (USD).
The last dual op-amp chip I needed, 3 for the board, was $4.50 each, and it was for a low noise audio amp circuit, not an RF circuit!
Given this chip's bandwidth, it is amazing it isn't more costly.
Perhaps it is in the front end of cell phones and therefore massively mass produced?

JC
 
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