[time-nuts] f-multipliers from VHF to 10 GHz

[Bruce Griffiths]

Macom also do NLTL comb generators which are much quieter than SRDs:
https://www.macom.com/products/product-detail/MLPNC-7100-SMA850

Bruce
> On 16 May 2020 at 09:14 Gerhard Hoffmann <ghf at hoffmann-hochfrequenz.de> wrote:
> 
> 
> No, no, no, it's not that bad :-)  I should not post here in the middle 
> of the night. Sorry to cause that confusion.
> 
> Minimum  is -90 dBc @ 50 Hz, or let's say @100 Hz @ 10 GHz.
> that would equal -110 dBc at 1 GHz,   or -130 dBc @100 MHz, BTDT.
> 
> And then, the ~4 MHz difference between TX and RX frequency could be
> done by a SSB mixer with a non-multiplied crystal. We would have some
> common mode noise, but the RX-TX difference would be fairly constant.
> It would not de-correlate over the 10 mm run length, not at low
> offsets where it counts.
> 
> The -110 was only meant for "Don't care about multiplied white noise
> floor", not in the sense of a spec but in the sense of "guaranteed
> harmless". It's not such a great relaxation after all, it could be
> 20 dB looser.
> 
> The question was really only about a _simple_ multiplier chain. The
> style used in ham radio 10 GHz transverters has too many stages,
> GaAS-Fets with 1/f and pipe cap filters. Too complicated.
> 
> Macom still make a SRD diode, but probably it is easiest to phaselock
> a ceramic puck or an on-chip VCO to a 100+ MHz crystal. The offset-
> mixing removes the need for a low reference frequency or fractional
> voodoo.
> 
> cheers, Gerhard
> 
> 
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