Please or Register to create posts and topics.

PreAmp Option seems not work ?

Page 1 of 2Next

Hi friends

I Have one amazing problem !
I have  a RX250 spectrum with preAmp option .
now I want say preamplifier can not  amplify my signal . without preamplifier signal amplitude is more then when I turn on the pre amplifier option !! it means that preamplifier option decrease my signal amplitude !
is it need some setting ?

First of all make sure that you are measuring a LOW signal otherwise the preamplifier might get saturated and would be of no use.

If this still is the case with small signals you for sure have blown the preamplifier e.g. by using a signal generator generating a signal with high crest factor.

Please note that the MAX input level is 23dBm (absolut max). Any higher level might kill the preamplifier.

Please contact our service for a repair quote.



David3542 has reacted to this post.

Hi again
yes sure
I know that maximum input signal level should be below 23dbm

but I have to say , I never connect any signal generator to this Spectan, it only received radio signal via an omni antenna , so signal level always was low .

Today when I was measuring the Wi-Fi  signal, for the first time  ( signal level was about -70 dbm )try to check Preamp effect  test  Amp- Pre Amp -None - Both

but the result was amazing , preamp not work correctly and even Both result was not good too, None was better than preamp !!

so I guessed maybe it need some setting


Are you sure you lowered the Ref-Level?

Some screenshots may be helpful to see where the problem might be.

Quote from AdminTC on 19/01/2022, 22:12

Are you sure that you lower the RefLevel?

Some screenshots might help to see where you problem is.

Ok, I will share some screenshot with you.

Thank you for your attention

FM radio signal ( about 90MHz) can be good reference for test and take screenshot ?

No, please use bluetooth ...

Hi again

I did some test

I pair two mobile via Bluetooth and transfer data , and didn't change the position of the mobile and antenna during the test

This was the result  (every time after change the Amp state I cleared the Max Hold  )

Amp Disable and Ref was -20

Amp Disable and Ref was -20


Amp  Enable and Ref was -30

Amp Enable and Ref was -30



PreAmp Enable and Ref was -30

PreAmp Enable and Ref was -30


and finally Both was enable and ref was -30

Both was enable and ref was -30


What do you think now ?

The Amp for sure works, easy to see at the drop from the noise floor and preamp looks damaged, as expected.

But without a real screenshot showing all settings etc. this is of no big help.


which settling is your mean ?

if you need any detail that can help , let me know , I will share it

ALL: The complete layout screenshot

Page 1 of 2Next