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Old 6th Jun 2019, 1:25 am   #18
Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
Posts: 1,694
Default Re: Marconi 2024 not powering up

Yes, the 2024 can be a very good signal generator for certain tasks. In terms of phase noise it is at its best across carrier frequencies of 10MHz-20MHz. This is because it uses division to get down to these frequencies. This puts it in the same ballpark as the very best lab sig gens for close to carrier phase noise in this frequency range. Up at higher frequencies towards UHF the close in phase noise performance of this sig gen is only average.

The other key feature is that the on board DSP based modulation is referenced to the main 10MHz reference so if you buy a 2024 with the accurate/expensive OCXO option the onboard modulation is extremely accurate in terms of the modulation frequency. A 1kHz modulation tone should be accurate to within a few uHz for example. This can be very important in some cases where you want to lock everything (including the modulation) to a common frequency reference. It also has an option for a high performance pulse modulator and this can be very useful if you want to generate pulsed signals that are 'blanked' to a very low level with accurate timing. Back in the day, these features set this sig gen apart from a lot of the competition in this (medium) class of signal generator. Even today this sig gen will outclass a lot of modern alternatives in these areas.

The weak points in terms of performance are in the ALC/levelling because the amplitude accuracy (vs frequency) for this sig gen is fairly mediocre by todays standards. It wasn't that great 20 years ago and I think the designers of this sig gen got this bit wrong. Also, the ultimate noise floor is average at best and I think it is not as good if you buy the high power option that goes up to +25dBm. I'd recommend using the attenuator lock feature to try and squeeze the best out of it here. Otherwise, the wideband noise floor performance is less than impressive on the +25dBm version of this sig gen. I think this is because they compromised the gain distribution in the signal path to accommodate an ALC system that supported up to a +25dBm capability.
Regards, Jeremy G0HZU

Last edited by G0HZU_JMR; 6th Jun 2019 at 1:31 am.
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