[hpsdr] feedback signal level for pure signal

[Gerhard Burian]

Hello,

 

I received my new ANAN100D last week and made first tests with pure signal,
the main reason why I changed from my FLEX5000A to the ANAN100D.

 

Pure signal without external Linear Amplifier works ok, using the  internal
crosstalk.

 

Using an external amplifier and feedback coupler shows following problems:

My setup:

PA with 2 kW (63 dBm).

Feedback coupler: -43 dB (as one with 63 dB didn't work, always in red zone
at S-ATT 0 dB). 

Feedback signal on EXT1 and "ETX1 on TX" checked, S-ATT set to 31 dB,
autocalibrate on.

 

I had to check "Disable BYPASS" to get the green signal with autocalibrate
and S-ATT to 5 dB.  Checking "HPF on TX" doesn't show any change.

Without checking "Disable BYPASS" or when only checking "HPF on TX" showed
red signal at S-ATT at 0 dB.

This tests were done with software Version 25.

IMD of two tone test is more than -53 dB on DUP, IMD on FreeDV signal shows
-62 dB of the sidebands on DUP.

When I changed to version 27, this setting didn't work and I always get a
red signal with S-ATT autoset to 0 dB.

"Disable BYPASS" and "HPFon TX" doesn't show any change, so I am now using
version 25 again.

 

Documents on Wiki say I must not have more than +13 dBm feedback signal on
the RX preamp (with S-ATT at a high level).

If I calculate 63 dBm minus 43 dB minus 5 dB, I get +15 dBm on the RX
preamp. 

Otherwise Wiki is requesting -17 dBm after the step attenuator.

 

Is this correct? Why does version 27 react this way?

 

 

73's

Gerhard OE3GBB 

 

 

 

 

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