Hi All

I have a SUNSDR Pro2 and I have heard that the power output can spike to 40w for a few milliseconds and could damage solid state PA amplifiers.

Is this statement correct, is this not a software / firmware issue that can be resolved like in the case of the Elecraft K3 issue a few years back?

I'm looking to build a PA using LDMOS BLF188XR but i've been warned that power spikes from the SUNSDR Pro2 can kill these expensive LDMOS units?

Help appreciated

Jim M0CKE

Hello Jim
I've been working with SDR2 Pro and an LDMOS power amplifier for two years (Expert 1.3K) and has never had problems with it.
Unusually high power peaks I could determine neither with the PEP Wattmeter LP-100A nor with the oscilloscope.

73, Hubert HB9JND

Hi Jim,

I have used my SUSNDR PROII with a Juma 1000 on my holiday style trip to Z2 and 5B. Approx 3500 QSO`s in a "pileup style" conditions.
Have not yet experienced any issue. The resent Expedition to Saint Brandon worked with SUNSDR and I think it was Expert 1.3K and no problem if I understand this correct.
www.saintbrandondx.com/en/ 70000 QSO`s

73 Rune LA7THA

Ok some mentioned spikes ,i want to buy the pro and drive the acom 700s or the 1200s but i think i get the 700s .Why some mentioned spikes and driving that amps is dangerous ,is the pro create spikes is that in software is spikes really excist?

NTZANIS wrote:
The following info was published in Telegram test group in early Oct'22 (Alpha stage):

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Regarding power "jump", which we all have reported earlier.

Conditions: first TX after power up transceiver or first TX after switching to new band. And assumption was that this "jump" will affect sensitive (MOSFET or LDMOS) external power amps.

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My latest measurements are showing that there is no real power "jump". However, according to EE, current power meter tries to 'emulate' analogue (needle) reading - and that what have confused us all.

My proof is as following, below.

Setup
- 100W dummy load
- Power from SS2DX below 20W.
- AD8310 based SWR/Power meter, displaying actual FWD and REF voltage reading, plus power in watts decimals; measurement interval is 1ms.

If you set playback speed (I use VLC) to 0.25, (or, alternatively, go by frame), it is easy to see, that in the first recorded example the ESDR3 power meter "jumps" to 16.6W, then "returns and stabilizes" to 15.1W (representing deviation of 1.5W - that is really big). At the same time, the external power meter detects output power in range from 18.5 to 18.7W (deviation of 0.2W and is not on start TX only, but across all TX period, which means this might be construction deviation or interference).

The following few tests in recording are to display, that the above behaviors remains constant in all scenarios in question: switching between bands, or stop-start SS2.

Hopefully, this will clear the misinterpretation.

I have already spoken to EE, they will see if it is possible to make different modes to in-build power meter, i.e. make is switchable (by user) between "emulation" and "real".

If you can make your own tests on your SS model - this would be good. I did not check any model except DX.

Video: mega.nz/file/PVpE1YpI#jHltLel5PgpZcjxevuE9gNEpbsqmpGoIwK8P6abYIO4

hello I have an amp from sv2rif Greece with my sunsdr 2 pro nickel function you will see Dimitri very nice 73's

www.dxworld-e.com/shop