Hi Lukas, Why not put a 20 or 30 dB attenuator on your amplifier input? If you consider the attenuator & PA as a single "assembly" this will just reduce the gain of your assembly.
Rob On Tue, Nov 10, 2020 at 12:17 AM Lukas Haase via USRP-users < [email protected]> wrote: > Hi Marcus, > > This is a great idea. > Unfortunately PIN diodes rarely exist as "coax" modules (but rather MMICs > to be integrated on a board). > > The few coax modules I found from Mini-Circuits and RF-Lambda are for high > powers (>0dBm). > For me, the max. output would need to be ~ -16dBm. > > Best regards, > Lukas > > > Gesendet: Montag, 09. November 2020 um 22:53 Uhr > > Von: "Marcus D Leech" <[email protected]> > > An: "Lukas Haase" <[email protected]> > > Cc: [email protected] > > Betreff: Re: [USRP-users] Limiting output power, best approach to > connect HPA? > > > > A limiter diode is often used in situations like this. > > > > Sometimes a simple hardware solution is best—it relies only on > semiconductor physics and not correct software. > > > > Sent from my iPhone > > > > > On Nov 9, 2020, at 9:40 PM, Lukas Haase via USRP-users < > [email protected]> wrote: > > > > > > I need an output signal of ~32dBm (at 900 MHz). > > > I have a MiniCircuits ZHL-25W-272+ high power amplifier (25W). > > > The gain at 900 MHz is ~49.2. > > > Hi, > > > > > > > > > I would also like to filter out harmonics (USRP as well as PA) with a > VLF-1000+; the max input power is 10W (40dBm), so more than what I want to > obtain (32dBm). > > > > > > My approach would be to connect the USRP output to the ZHL-25W-272+ > and the VLF-1000+ filter afterwards. > > > > > > Hence, the USRP should output a maximum of 32dBm-49.2dB=-17.2dBm. > > > > > > I can achieve this by setting the TX Gain to 0dB and adding a digital > backoff in my samples of ~5.9dB. > > > > > > I think this should work but I am little bit concerned about safety if > the software fails for some reason or the wrong program is started > accidentially. The USRP can output up to 22dBm which would destroy the HPA > and filter (and what follows). > > > > > > Is there a way to program a power limit in advance? > > > What is the best/recommended way to handle this situation? > > > > > > Thanks, > > > Luke > > > > > > > > > > > > > > > > > > > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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