Bruce Griffiths wrote: > Rick Karlquist wrote: >> Bruce Griffiths wrote: >> >>> He's made similar comments before. >>> It actually isnt that difficult to achieve an isolation amplifier phase >>> noise floor below -170dBc/Hz if one is careful to use appropriate >>> parts, >>> design techniques, and the input signal level is high enough. >>> The real problem is verifying that performance. >>> >> The 10811 production engineers searched for a long time for >> a low noise buffer amplifier and settled on the ANZAC AMC-123. >> The data sheet refers to a patent that reads like >> a construction article. You can make your own if you can find >> an old 2N5109 transistor. >> >> Rick Karlquist N6RK >> >> > The Tyco/MAcom version of the AMC-123 datsheet doesn't refer to a patent. > Is a variant of a Norton CB transformer feedback amplifier? > > One would need to cascade a number of these to achieve a reverse > isolation of 120dB. > Whilst I dont have any 2N5109's, I do have several 2N5943's. > > Bruce
Fortunately, there is a paper copy of the 1989 Anzac catalog in the N6RK technical library. Not everything is on the internet. The patent number is: 3,624,536 Yes, 2N5943 is interchangeable with 2N5109. You could even get away with an old 2N3866. Do NOT substitute a microwave transistor. It will typically have higher base spreading resistance (bad) and a uselessly high Ft for 10 MHz work. For example, BFR90. Any time-nuts subscriber in good standing should be able to duplicate this design from the info in the patent :-). This patent is referenced in many amplifiers in the catalog. There are some amplifiers that are basically like the 123 on steroids. Even higher intercept, but bring your heatsink, these are barnburners. Rick N6RK > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
