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TOPIC: High SWR Protection?

High SWR Protection? 14 Apr 2022 17:29 #1

  • PyraZ
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Hi,

I was wondering if the SunSDR2 Pro has any type of high SWR protection. I couldn’t find any information on if the radio would shut off transmission if SWR is above a threshold or something. If it doesn’t have any protection how delicate is it? Will I break something if I attempt to tune something at 5-10 watts with a 5+ SWR for a second or two? Really don’t want to break my radio when messing around with different antennas.

Thanks in advance!
PyraZ
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High SWR Protection? 15 Apr 2022 06:57 #2

  • Rome
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Hello,
SWR-based protection is not implemented in SS2PRO, it's not afraid of high-SWR since the max output power is 20W max. Among our TRXs we've implemented SWR-based protection in SS2DX and MB1. Still, we do not recommend to work with SWR higher than 2.

FYI:
How to adjust TX output power per band:
When you use the Tune button in ExpertSDR2/3, with the Tune slider at 100%, TRX sends a carrier signal on the air with maximum output power. The Tune slider is a special control of the output power for the carrier signal in tuning mode. For all other modes, for normal operations, you should use the Drive slider. This carrier has a stable amplitude and you'll be able to set the max output power of the transceiver for each band. Then you can set the Drive slider to maximum and TRX will send the same output power as in Tune mode.
Note: Power correction coefficients are adjustable numbers, they are not equal to real output power e.g. coefficient 5 on 10M does not equal 5W, it can be 8 or 10W. Coefficients are not the same for every band, so please be careful and start from lower values. That's how we suggest adjusting output power per band.

The output power is not linear across all bands. Each band requires its own amplification coefficient for the PA to operate, based on the fact that they are physically different (capacitors, ferrite rings, etc.).
We adjust amplification coefficients so with Drive 100% each band could have about 20W at max in Tune mode. Higher Drive values are more or less in line, but lower values below 30-35% may vary, at the moment we cannot change that. So setting a value of 5, which is a quarter from the max 20, may result in 5 or 10w output power.
Роман, Roman
Expert Electronics
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High SWR Protection? 22 Apr 2022 23:42 #3

  • K3CDY
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Rome wrote:
FYI:
How to adjust TX output power per band:
When you use the Tune button in ExpertSDR2/3, with the Tune slider at 100%, TRX sends a carrier signal on the air with maximum output power. The Tune slider is a special control of the output power for the carrier signal in tuning mode. For all other modes, for normal operations, you should use the Drive slider. This carrier has a stable amplitude and you'll be able to set the max output power of the transceiver for each band. Then you can set the Drive slider to maximum and TRX will send the same output power as in Tune mode.
Note: Power correction coefficients are adjustable numbers, they are not equal to real output power e.g. coefficient 5 on 10M does not equal 5W, it can be 8 or 10W. Coefficients are not the same for every band, so please be careful and start from lower values. That's how we suggest adjusting output power per band.

Hi Rome -

I'm a bit confused by your statement highlighted above. I thought that the Tune and Drive levels were completely independent. My procedure was to Tune first, note the percentage setting, and then manually set the Drive to the same percentage.

You seem to imply that I can set the Tune to some percentage (50%, for example), and then set Drive to 100%, and the radio will only transmit at 50% during normal operation. I tried this and it certainly does not seem to work this way.

What am I missing?

73, Bill K3CDY
73
Bill
K3CDY
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High SWR Protection? 23 Apr 2022 16:43 #4

  • N8SDR
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K3CDY wrote:
Rome wrote:
FYI:
How to adjust TX output power per band:
When you use the Tune button in ExpertSDR2/3, with the Tune slider at 100%, TRX sends a carrier signal on the air with maximum output power. The Tune slider is a special control of the output power for the carrier signal in tuning mode. For all other modes, for normal operations, you should use the Drive slider. This carrier has a stable amplitude and you'll be able to set the max output power of the transceiver for each band. Then you can set the Drive slider to maximum and TRX will send the same output power as in Tune mode.
Note: Power correction coefficients are adjustable numbers, they are not equal to real output power e.g. coefficient 5 on 10M does not equal 5W, it can be 8 or 10W. Coefficients are not the same for every band, so please be careful and start from lower values. That's how we suggest adjusting output power per band.


Hi Rome -

I'm a bit confused by your statement highlighted above. I thought that the Tune and Drive levels were completely independent. My procedure was to Tune first, note the percentage setting, and then manually set the Drive to the same percentage.

You seem to imply that I can set the Tune to some percentage (50%, for example), and then set Drive to 100%, and the radio will only transmit at 50% during normal operation. I tried this and it certainly does not seem to work this way.

What am I missing?

73, Bill K3CDY


I'm not sure that's correct:

For one the Drive and Tune mode are not Linear- to begin with this has been an issue with many of the V3 versions,

if you set tune at say for example 40 % and lets say you get around 25 watts out in tune

If you set Drive at 40% your peaks won't be 25 watts in some cases, there Higher and others there lower there is no consistently between them.

I would not count on using that method esp. with a solid-state amp which can be picky on input power

With the Tube amps there is certainly more cushion
73 Rick
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