Always full RF power with PowerSDR or linhpsdr

[Mathis Schmieder]

Dear group,

I'm sure it's something obvious, but I can't find it. With both PowerSDR and linhpsdr/piHPSDR, I'm always getting full output power, regardless of the set drive level. This happens both with tuning and whistling into the mic on SSB. With SDR-Console, setting the output power works perfectly fine. Can anyone point me to the correct setting?

Thanks a lot,

Mathis, DB9MAT

[Don Solberg]

Mathis,

I can only speak for PowerSDR.  The power setting is done with the drive control on the main screen, left hand side.  This is a relative number, so 50 is about 50% of the maximum power of the HL2.  PowerSDR remembers this setting for each band.  I run a 1KW homebrew solid state amplifier with the HL2 and I have different drive settings for some of the bands.

With PowerSDR you can have the tune power equal the drive power, or you set a different power level for tuning.  This is done on the transmit tab in setup.  I have mine set for 1 watt because I need to have my amplifier in line, but at low power, to provide enough power for my auto tuner to work.

Let me know if this doesn't solve your problem.

73,

Don K9AQ

[Matthew]

I just did a clone from here:

https://github.com/g0orx/linhpsdr

The "Drive Level" button functions as I expect. I am varying the drive using the bottom green bar in the attached and I see on my analogue power meter a varying output.

73 Matthew M5EVT.

[Mathis Schmieder]

Hi Don,

First of all, thanks for your answer. Unfortunately, it doesn't really help. Of course I know the drive slider, but as I said, its setting doesn't really make any difference in my setup. I am running the HL2 with my 100W PA and regardless of the drive control slider, the output is always close to 100W or more. Tune power is set to drive level.

Somehow, I'm guessing it's related to the piHPSDR or PowerSDR PA gain setting. Setting it to 38.8 dB as suggested in Steve's PowerSDR setup video it works fine with a "bare bones" HL2 with N2ADR filter board, but 100+W with my PA. Setting the PA gain setting to a higher value (I figured 51.8 dB would be a nice starting point as the bare HL2 does 5W and my PA does 100, hence 13 dB of gain) lets me lower the output slightly (to about 80W), but nowhere nearly as reliable as SDR-Console for example.

I tried it with the current testing Gateware and with 68p4.

73s,

Mathis DB9MAT

[Don Solberg]

Mathis,

You obviously have more drive power than you need.  Have you considered putting in an input attenuator?  I can easily vary my amplifier's output from about 500 watts down to as little as 10 or 15 watts.  That is with a 4db attenuator.  My amplifier was built to work with an Elecraft KX3 and K3/10.  I need about 10 watts of drive to get the full 1KW out of my amp.  

I use the PA gain settings that Steve recommended.

Don K9AQ

[Mathis Schmieder]

I would agree if it wasn't working fine with SDR-Console.. I'll remove my PA and attach the N2ADR filter board to see if it works then.

[Mathis Schmieder]

Okay, I think I found the problem. With PowerSDR (and piHPSDR, for that matter), the HL2 produces about 1W of output power even with the drive level set to 0 or 1. Afterwards, it's quite linear. With SDR-Console, I need to set the drive level to about 75 to hit 1W.

I'll try reducing the HL2's gain and maybe increase attenuation between the HL2 and my PA.

Thanks & vy 73,

Mathis, DB9MAT

[Mathis Schmieder]

Yep. I have not soldered a 200 Ohms resistor to R55, bringing the gain of the HL2 PA down. This way, I can get at least some dynamic range in the PowerSDR drive level setting. I'll put a bigger attenuator between the HL2 and my PA.

Thanks for your advice, Don!

73s,

Mathis, DB9MAT

[Don Solberg]

Mathis,

I use the N2ADR board with the HL2, so that maybe the difference.

Don K9AQ