[Hackrf-dev] I lost the pre-amp on the HackRF. How to get it back ?

[Ben Z en de rest]

Hi,
I received my HackRF a week ago. Did run some tests on SDRSharp, works
quite OK but a lot of imaging / mirrorred signals.

Switched to SDRConsole, much better, after setting bandwidth from auto to 5
MHz the imaging and mirrorred signals disappeared.
I did turn on the internal amplifier in SDRConsole. That way I was able to
receive meteo sonde signals in the 403 MHz range. Turned it off for 70 cm
signals and on again for some HAB balloon signals. All well so far.

Then I moved the HackRF to the Ubuntu 14.04 box and tried it on gqrx. Only
the most strong signals where readable.

I started playing with the gain setitngs and noticed that the gain setting
at the top ( 0 - 14 dB) should have to be the preamp settings. I did read
in the faq that it would gain about 14 dB so I made the assumption that 0
was preamp off and 14 was preamp on.

After switching the gain to 0 dB I did receive more signals, but at 14 dB
only the strongest local signals appear. So it seemed to me the preamp was
not working anymore.

Tonight I re-connected the HackRF to the Windows laptop and started SDR
console. With the preamp off I do receive signals but with preamp on only
the very strong signals appear.

Is there anyone who can help me to get the preamp working again? I can not
receive weak signals anymore....

Thanks,

Ben - PE2BZ

[scateu]

The preamp is electrostatic sensitive device. It seems to be broken easily.

I had to replace it with soldering iron.

I think the other reason maybe transmitting while antenna port connects nothing, the reflection of RF signal breakdown the MGA-81563 preamp.

Hi,
I received my HackRF a week ago. Did run some tests on SDRSharp, works quite OK but a lot of imaging / mirrorred signals.
Switched to SDRConsole, much better, after setting bandwidth from auto to 5 MHz the imaging and mirrorred signals disappeared.
I did turn on the internal amplifier in SDRConsole. That way I was able to receive meteo sonde signals in the 403 MHz range. Turned it off for 70 cm signals and on again for some HAB balloon signals. All well so far.
Then I moved the HackRF to the Ubuntu 14.04 box and tried it on gqrx. Only the most strong signals where readable.
I started playing with the gain setitngs and noticed that the gain setting at the top ( 0 - 14 dB) should have to be the preamp settings. I did read in the faq that it would gain about 14 dB so I made the assumption that 0 was preamp off and 14 was preamp on.
After switching the gain to 0 dB I did receive more signals, but at 14 dB only the strongest local signals appear. So it seemed to me the preamp was not working anymore.
Tonight I re-connected the HackRF to the Windows laptop and started SDR console. With the preamp off I do receive signals but with preamp on only the very strong signals appear.
Is there anyone who can help me to get the preamp working again? I can not receive weak signals anymore....
Thanks,
Ben - PE2BZ
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[Guan Yang]

Post by scateu
The preamp is electrostatic sensitive device. It seems to be broken easily.
I had to replace it with soldering iron.
I think the other reason maybe transmitting while antenna port connects
nothing, the reflection of RF signal breakdown the MGA-81563 preamp.

My preamp might be broken too. When I check with a broadcast FM station,
it goes from -24dBFS without preamp to -36dBFS with preamp. (Identical
IF and BB gain settings.) I don't have any weak signals I know well to
test with, but my local NOAA broadcast station can be received without
preamp and I can't hear it with preamp.

Are there instructions for replacing it somewhere, including a photo of
where it's located? Is Digi-Key part 516-1586-1-ND the correct part?

I'm not very good at de-soldering. What's the best way? I'm thinking
that maybe I can cut the legs on the existing part, and then de-solder
each leg separately.

[scateu]

You may need something named ‘hot air gun’, (热风枪 in Chinese), which heats the whole component at one time, then you can replace it.

You can find it on the assembly document.

https://github.com/mossmann/hackrf/raw/master/doc/hardware/hackrf-one-assembly.pdf

There are two amplifier, one for TX, one for RX.

TX:

U25;MGA-81563;Avago;MGA-81563-TR1G;0.1-6 GHz 3 V, 14 dBm Amplifier;;;;;

RX:

U13;MGA-81563;Avago;MGA-81563-TR1G;0.1-6 GHz 3 V, 14 dBm Amplifier;;;;;

Post by Guan Yang

Post by scateu
The preamp is electrostatic sensitive device. It seems to be broken easily.
I had to replace it with soldering iron.
I think the other reason maybe transmitting while antenna port connects
nothing, the reflection of RF signal breakdown the MGA-81563 preamp.

My preamp might be broken too. When I check with a broadcast FM station,
it goes from -24dBFS without preamp to -36dBFS with preamp. (Identical
IF and BB gain settings.) I don't have any weak signals I know well to
test with, but my local NOAA broadcast station can be received without
preamp and I can't hear it with preamp.
Are there instructions for replacing it somewhere, including a photo of
where it's located? Is Digi-Key part 516-1586-1-ND the correct part?
I'm not very good at de-soldering. What's the best way? I'm thinking
that maybe I can cut the legs on the existing part, and then de-solder
each leg separately.
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