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TX Level control

 

I am trying to use any of the ways to change TX level to reduce drive to my PA on PSK modes
so that linearity is good. I am aware that the range of adjustment is limited, but I only need 3dB
or so of reduction.
?
If I use the spot button and associated slider I can vary the output power between 0.0 and 6.1W
on 80m as shown by the power meter at the bottom of the window. Perfect!
?
If I use the Config->HL2->Bands window to set a TX level of 10 on 80m (rather than the 255 max) and
use PTT to TX on FM I still get 6.1W, the level is not reduced.
?
If I use Config->Config and adjust the TX level down from 100% I still see no reduction, the output is
still 6.1W
?
This is on Windows 10 but I also see the same effect on Linux Mint. I tried the latest Quisk release and
also 4.2.37
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I am sure I have seen this work properly before so I must be doing something wrong.
Any ideas please?
?
73,? Neil? G4BRK
 

If I use the Config->HL2->Bands window to set a TX level of 10 on 80m (rather than the 255 max) and
use PTT to TX on FM I still get 6.1W, the level is not reduced.
Well, the HL2 only "looks" at the upper 4 bits of that value.
 

Hi Christoph,
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Yes, but I would still expect to see a change in output, which I do not.
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I just reprogrammed the gateware to include TX on another HL2 and tried the same experiment.
On this one I see the expected change in power output with the Config->Config TX Level slider
and the band settings.
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So it looks like there is a problem with the original HL2 hardware. That may be difficult to fix :-)
I tried a gateware reload but still get the same result.
I may have to repurpose this one for RX only service.
?
Thanks/73,
Neil? G4BRK
 

Please check the version of the gateware. The Tx level control should provide 7.5 dB of adjustment. There is gateware that enables more receivers but omits Tx. Be sure you are not using this gateware.
?
Jim
N2ADR
 

Hi Jim,

Thanks for the reply.

I am using 73p2 file hl2b5up_main.rbf - this is identified as 4 RXs by SparkSDR
If I load hl2b5up_cicrx.rbf? with 10 RX and no TX then the TX does not operate, as expected.

I tried loading the factory gateware (shorting PTT and KEY to GND on the front panel) -
this also identifies as 73p2 with 4 RX and still shows the problem.

A different HL2, also with 73p2 main, works correctly and the TX power varies by approx 7.5 dB
with the Config->Config TX Level slider.

So it looks like a hardware problem on the first example, possibly a faulty AD9866 chip as the
TX level is set within the chip, presumably via a register which is written by Quisk.?
This seems a bit unlikely as I haven't seen any other issues with the operation of the HL2,?
but I don't have any better suggestion.

73, Neil? G4BRK





On Wed, 12 Mar 2025 at 17:32, jimahlstrom via <jahlstr=[email protected]> wrote:
Please check the version of the gateware. The Tx level control should provide 7.5 dB of adjustment. There is gateware that enables more receivers but omits Tx. Be sure you are not using this gateware.
?
Jim
N2ADR

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