no Bias, Driver stages cannot be activated.

[do6ep]

Hi there, i've got one of Huawei WRFUe 2100 with 2 of these Modules in it, is there any way to get them up and running for DATV on QO-100 ?

At the moment i got no Bias, so i need some help to activate the different Driver stages.

[do6ep]

I now found out, that the stages would be controlled and monitored by amc7812 through the following inputs/outputs. For first try (bypassing the amc7812) the bias voltage can applied by the test pads near amc7812. Then in order to activate the stages (used as PTT), on the first pin above the rf-input pin approx. 1.5 - 3.3 V are also required.

STAGES                          |   DACx-OUT    |    CHx IN |    Test-Pad   |
Stage 1 (MW6S004NT1)                    |   0   |   0   |   PA_0    |
Stage 2 right (AT2S15N / AFT20S015N)            |   2   |   2   |   PA_2    |
Stage 2 left (AT2S15N / AFT20S015N)         |   3   |   3   |   PA_3    |
Stage 3 right (AFT21S240-12S)               |   6   |   6   |   PA_6    |
Stage 3 left (AFT21S240-12S)                |   7   |   7   |   PA_7    |

I also found an AVR Driver for AMC7812 from Orthogonal-Systems at Github maybe its useful : https://github.com/Orthogonal-Systems/amc7812

[olgierd]

Hi,

yes, some time ago I drew a simple connection diagram - updated in Readme now.

AMC7812 does not seem to be overly complicated when it comes to just setting DAC, but since I'm not QRV on qo-100 for some time now, I'm not actively trying to run it. Since you found the convenient test points, maybe just building an old-fashioned potentiometer bias board would be good enough? ;-)

[do6ep]

Hello,

yes, building an old fashioned potentiometer bias board should work so far. For a first quick test, I simply bridged all the test points and applied the voltage. From approx. 1.5V the current of the PA starts to rise quickly.

So I was able to get about 20W at 2.2GHz with the handbrake on. Unfortunately, however, I had to find out that the transistor of the first stage no longer generates an output signal from approx. 2.3 GHz (the data sheet already said: up to 2000MHz).

There are now further tests to be carried out directly from the 2nd stage.

[olgierd]

Awesome!

If you would like to share your experiences, I would be happy to include it in this repository to help fellow OPs facing the same problems :-)

Did you leave the output circulator as is?

[do6ep]

No problem, I would like to share my experience.

After the first test, I removed all the isolators such as the output circulator and replaced them with coax cables. However, I didn't have time for a new test afterwards.

In addition, further details can also be viewed on my QRZ.com page (call: DO6EP). But the last photos I took are not updated yet. Maybe I'll get to that in the next few days.

[do6ep]

Hi,

good news, I have a few watts at the output!

It seems removing the isolators and output circulator does the magic. Unfortunately, as expected from Datasheet, the transistor of the 1st stage is no longer suitable for 2.4GHz (locks off from approx. 2.3GHz), so it has to be additionally bridged. With [Adalm Pluto --> SPF5189Z --> SBB5089+SZP2026 --> PA] I was able to get about 52.2dBm (165.96 watts) for DATV at 24 V and about 18 amps.

For the bias I used 2.00 volts for the 2nd stage transistors and 1.90 volts for the 3rd stage transistors from my simple 5x DC-DC bias board. There might be some room for improvement, but for now it works.