I’ve built a couple of PGA103 preamps using W6PQL board. They work great Sure hard to beat for performance/$. Follow it with a band pass filter if necessary. FWIW there is an optional “stabilizing” circuit shown in his schematic. I highly recommend it. I also run them on 3.3v; hardly any performance difference but they sure run cooler at 50ma vs. 100ma Several years ago, I built four PGA103 amps on my own boards without that stabilization circuit, running [email protected] Heatsinking wasn’t good. Every one died. Round file. But these new ones at lower voltage on a board with much better heat dissipation and the input circuitry are doing just fine. I haven’t done noise figure characterization yet. Gain (at 3.3v) is ~20db.
Ed Krome K9EK
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On Dec 8, 2020, at 5:03 PM, Zach Metzinger [email protected] wrote:
On 12/08/20 15:54, Chris Busch wrote:
I personally prefer a Lindenblad or quadrafilar helix for an omni antenna. My 2M Lindenblad is approx 10db worse than my Az El tracking CP yagi. If I were relying on an omni, I’d definitely consider using a good GasFET preamp, but ymmv.
I haven't attempted the 2m Lindenblad yet, but it's something I'd like to try.
On the LNA front: I'm currently interested in in the Minicircuits PGA103+ device (on W6PQL's page https://tinyurl.com/yyd5mx4b ) for the excellent IIP3. This is an internally-matched E-PHEMT device, much more rugged (and affordable) than GaAsFET devices of the past.
I have a cellphone "watertower" near me, pumping out stuff all over the band, but mostly 600-750 MHz, easily seen as -40dBm signals on a 2m rubber ducky stuck to the front of my spectrum analyzer. Some sort of input filtering, or a crazy-high IIP3 followed by appropriate filtering, is a must at my QTH.
--- Zach N0ZGO
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