The HP K22 had a specified noise figure as <7.5dB (I'm guessing its NF is not around 1dB) and the measured noise floor -175dBc/Hz at 10kHz and up at 400MHz from the datasheet. Since I've had a need for a low-gain (2-4dB) isolation amp at the 100-500MHz range, I've experimented with a cascode design with Infineon's BFR106. Measured PN: -151dBc@100Hz, -161dBc@1k, -171dBc@10k and -178dBc at 100k and up (@400MHz). P1db should be around +15dBm and the NF was not measured yet. Cheers, Leon > > ---------- Forwarded message ---------- > From: John Miles <john@miles.io> > To: "'Discussion of precise time and frequency measurement'" < > time-nuts@lists.febo.com> > Cc: > Bcc: > Date: Thu, 9 Jan 2020 22:23:23 -0800 > Subject: Re: [time-nuts] low phase noise, noise floor and noise figure > amplifier at 400MHz > > Any suggestions on topologies, transistors, white papers, etc? I'm > > considering the NXP BFU590Q silicon bipolar transistor, which I have used > in > > a transformer feedback configuration at 100MHz with less than -180dBc/Hz > > PN. > > You could take a look at the approach behind the option-K22 amplifiers that > were sold by HP for use with the 3048A. I've got one of those but I needed > a couple more of them at one point, so I built some (literally) quick and > dirty copies with BFG591 transistors with good results. > > I've mentioned them before on here, I think. There are a few photos and > plots at http://www.ke5fx.com/k22.htm . Basically a CE amplifier with an > LED-referenced bias stage originally suggested by Bruce Griffiths. > > A single stage won't deliver the gain you're after, but these amplifiers > are > relatively well-behaved and can be cascaded at will. That was the original > intent with the K22, which consisted of two independent amps in one box. > If > you want to use the K22 amps to keep oscillators from injection locking, > you > pretty much have to cascade them due to lack of reverse isolation. The > homebrew hack job is similar to the HP original in most respects including > that one. > > I'd be inclined to use a dual-emitter part (BUF590G) instead of the > BUF590Q, > if I were building more of these. > > -- john, KE5FX > > > > >

The phase noise specifications for an amplifier are meaningless if the input signal level isnt specified. Bruce > On 11 January 2020 at 03:27 Leon Pavlovic <leon.pavlovic@gmail.com> wrote: > > > The HP K22 had a specified noise figure as <7.5dB (I'm guessing its NF is > not around 1dB) and the measured noise floor -175dBc/Hz at 10kHz and up at > 400MHz from the datasheet. > > Since I've had a need for a low-gain (2-4dB) isolation amp at the > 100-500MHz range, I've experimented with a cascode design with Infineon's > BFR106. Measured PN: -151dBc@100Hz, -161dBc@1k, -171dBc@10k and -178dBc at > 100k and up (@400MHz). P1db should be around +15dBm and the NF was not > measured yet. > > Cheers, > Leon > > > > > > ---------- Forwarded message ---------- > > From: John Miles <john@miles.io> > > To: "'Discussion of precise time and frequency measurement'" < > > time-nuts@lists.febo.com> > > Cc: > > Bcc: > > Date: Thu, 9 Jan 2020 22:23:23 -0800 > > Subject: Re: [time-nuts] low phase noise, noise floor and noise figure > > amplifier at 400MHz > > > Any suggestions on topologies, transistors, white papers, etc? I'm > > > considering the NXP BFU590Q silicon bipolar transistor, which I have used > > in > > > a transformer feedback configuration at 100MHz with less than -180dBc/Hz > > > PN. > > > > You could take a look at the approach behind the option-K22 amplifiers that > > were sold by HP for use with the 3048A. I've got one of those but I needed > > a couple more of them at one point, so I built some (literally) quick and > > dirty copies with BFG591 transistors with good results. > > > > I've mentioned them before on here, I think. There are a few photos and > > plots at http://www.ke5fx.com/k22.htm . Basically a CE amplifier with an > > LED-referenced bias stage originally suggested by Bruce Griffiths. > > > > A single stage won't deliver the gain you're after, but these amplifiers > > are > > relatively well-behaved and can be cascaded at will. That was the original > > intent with the K22, which consisted of two independent amps in one box. > > If > > you want to use the K22 amps to keep oscillators from injection locking, > > you > > pretty much have to cascade them due to lack of reverse isolation. The > > homebrew hack job is similar to the HP original in most respects including > > that one. > > > > I'd be inclined to use a dual-emitter part (BUF590G) instead of the > > BUF590Q, > > if I were building more of these. > > > > -- john, KE5FX > > > > > > > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.