Output power control

Andrew - G0RVM

The Power output slider on SSDR (2.6.1) is great and gives granular control over a 100W range (Flex-6600).  At a setting of 1 my SPE amplifier generates about 120W; at 2 it generates about 380W.  I would like to have increased granularity of control when using CW so a higher setting - perhaps 5 or 10 - results in 380W or thereabouts.  Put another way, I'd like to configure the upper limit of the SSDR Power output slider to a value - perhaps 50W - and distribute that across the entire range of the slider control.  Hope that makes sence.

I don’t think the upper limit of the SSDR Power control is configurable so the only way I can think to achieve greater control is to add an attenuator in the transmission line between the Flex and the amplifier.  The problem with this approach is that with a single antenna the transmit/recieve path is shared.  Thus the attenuator needs to be removed from the receive path, preferably automatically via transmit/receive switching.

Just wondering if I'm missing something? Perhaps SSDR can be configured differently?

Thanks,
Andrew
G0RVM

Jim Gilliam

Scaling the power output control to better tailor driving a linear amplifier is a great idea. Maybe it can be implemented in future updates.'

Perhaps something like this:

0-25
0-50
0-75
0-100

Jim, K6QE

ctate243

"I don’t think the upper limit of the SSDR Power control is configurable "

Settings >> Radio Setup >> TX tab >> Max power  Change 100 to your desired max output power.

Dwayne_AB6A

When I ordered my amp to match my 6600, I was able to specify the input range and chose 50W -> 1000W vs 5W -> 1000W and other options. Learning more about my amp, I found it is using the A1000-100-11X 10dB pad https://www.barryind.com/pdf/Attenuator/Power_Flange/A1000-100-11X.pdf to control input attenuation. Worst case (and a nice Sunday project) is a small circuit that incorporates a pad mounted to a heatsink together with a relay that will switch the pad inline/offline with PTT.

Your amp may already have a pad installed in the transmit path but just the wrong one for your use case and it may be a quick swap to achieve the desired input range.

Andrew - G0RVM

I'm not in front of SSDR right now but I didn't think that re-scaled the Power output control just set an upper limit....

Andrew - G0RVM

Thanks Dwayne.  Yes, that is the design I was considering. :-)  I currently have an external 10dB attenuator that I was thinking of using if needed.  Cheers.

Dwayne_AB6A

The hard part is switching it in and out of the transmit path

Andrew - G0RVM

Thought I’d just update this post to describe the hardware solution I now use as it seems to work well.  The scaling of the SSDR Power slider control remains a more elegant solution tho as the additional kit would not be required......A future version Flex?

I inserted a DX Engineering DXE-RTR-2 and a 50W 10dB attenuator between the Flex 6600 and the SPE amplifier.  The RTR-2 splits the transmit and receive paths so the transmission path is: Flex ANT1 -> attenuator -> RTR-2 -> Amplifier -> Tx/Rx Ant and the receive path is Flex RXB IN <- RTR-2 <- Amplifier <- Tx/Rx Ant.

A Flex Tx Relay output is connected to the RTR-2 to provide a T/R switch signal.  It should be possible to cascade the Tx Relay signal from the RTR-2 ACC PTT port to the amplifier but this doesn’t seem to work for me. Instead I use another Flex Tx Relay output to switch the amplifier.

Hope that’s clear and maybe helps someone else.  ;-)

Andrew
G0RVM

Dwayne_AB6A

Nice Did you poke around inside your amp to validate if there was the possibility of inserting a pad in the internal transmit path?

Andrew - G0RVM

Hi Dwayne.  No I didn't.  I took the lazy but expensive approach ;-)

Tim - W4TME

Power control scaling is not a feature of SmartSDR.