Impossible to lower transmission power on HL2

[Christian Dragicevic]

Hello Groups !

I Have problem with my HL2, it remains stuck on a power of 5w, it's impossible for me to lower the transmission power.

I Use Thetis x64 2.9.0.6 HL2

Thanks !

73

F8NDN

[Steve Haynal]

Hi F8NDN,

How are you adjusting the output power, via the drive control? I am not a Thetis user but maybe this new video will help:

https://www.youtube.com/watch?v=LTm6evv3swk

Also, confirm if it is or isn't a problem with your hardware, can you also try Quisk, SparkSDR or SDR Console? There is help on the wiki linked below as well as YouTube videos if you search.

https://github.com/softerhardware/Hermes-Lite2/wiki/Software

You should be able to adjust the power by roughly 7.5dB via the drive control.

73,

Steve

kf7o

[DL1YCF]

Clearly, for a bug-free SDR program the HL2 output power must go to about 1.25 Watt
when the drive slider approaches zero. This is true even if the SDR program
does not know about the HL2 specialities (4-bit „db“ word instead of 8-bit „amplitude“ word)
in drive regulation.

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[F8NDN]

It's ok with SDR Console, Tune 1w, TX 0-4w

With Thetis there is no reaction neither with the drive nor by changing the PA parameters. With Power SDR, same problem.

73

Christian

F8NDN

[F8NDN]

What is surprising is that we had ordered 2, no worries with one.

Same problem on all PCs. On the other hand, I go through a router to connect in ethernet, not directly.

73

["Christoph v. Wüllen"]

If a software can do 0-5 watt on a HL2, then it
scales the IQ amplitudes directly and does not
(solely) rely on the step attenuator.

A while ago I have built this into piHPSDR as
well, but then removed it since it is not
compatible with PURESIGNAL (adaptive predistortion).

The TX step attenuator is at about -1.5 dB when
you produce 5W out, and you can regulate it down
do -7.5 dB then you will get 6 dB less (1.25 Watt).

Nevertheless, if the drive slider goes down to zero,
then the TX step attenuator should be at -7.5 dB
and you should not see max power out. So it seems
that there is also a problem in the SDR software.

Yours,

Christoph

[V85NPV]

Hello, since it looks like your using THETIS and Powersdr i will suggest to reset both database. It it is working with SDR console there is no reason regarding the harwdare to work with THETIS and POWERSDR.

73s Didier

[Steve Haynal]

Hi Christian,

Do I understand correctly that you have two HL2s but the problem of lowering the power only occurs for one?

There are two ways to adjust TX power for the HL2: change the amplitude of the IQ data which is sent from the host to the HL2, or adjust the TX gain on the AD9866 with range of ~7.5dB. Some software has separate controls for each, some software combines how they are used. Maybe others can speak up about other software, but I am most familiar with Quisk. Can you try Quisk?

With Quisk, there is a Spot button in the lower left corner. Right by the Spot button is a small slider button. If you click on that button, a slider window appears. That slider adjusts IQ amplitude. By adjusting it during spot TX you should be able to go from 0 to 5W.

In the Config menu, there are sliders for Tx level and Digital Tx level. This is what adjusts the TX gain on the AD9866. Assuming the spot data is at 1.000, this slider will change the TX from about 5W down to just below 1W, but never to 0W.   

Can you please try both TX adjustments with both radios and report back? This will help us determine if there is a problem with TX AD9866 gain adjustment on one HL2.

73,

Steve

kf7o