Aeroflex IFR3413 IFR3414 IFR3416 Signal generator

[G0HZU]

Apart from a few (unsuccessful?) repair threads, there doesn't seem to be much info on Eevblog about the IFR 3413, IFR 3414 and IFR 3416 sig gens from Aeroflex / IFR.

I've attached the datasheet below.

The aim of this thread is to discuss the good and bad points about these sig gens and how they compare to the competition. I'm a long time user of these sig gens having used many of them at work for about 20 years and I also have a few of them here at home.

At first glance, these sig gens look quite similar to the older Marconi 2023/4/5 analogue sig gens and they share a similar layout. However, the IFR 341x generator is a vector signal generator, and this allows almost any form of modulation to be generated up to about a 50MHz bandwidth using the I and Q inputs of the vector modulator.

The vector modulator(s) used in these sig gens have high performance, and this allows these sig gens to generate digital modulation with very low distortion on an adjacent channel. To maintain the low distortion through the whole signal path to the output, these generators also feature high performance amplifiers in the signal path.

This is great for manufacturers of modern wireless systems, as they can use these sig gens to produce spectrally pure test signals with various forms of digital modulation.

The power consumption is quite high compared to a classic analogue generator such as the Marconi 2024. These generators also run quite hot internally and they produce a fair bit of fan noise when fully warmed up. The amount of fan noise may depend on the version of the hardware. It appears the later models have improved thermal management so they run cooler and quieter and should be more reliable.

The 4GHz IFR 3414 typically consumes 125W when running. Compare this to just 70W for the Marconi 2024 and just 25W for the Marconi 2022. Both these sig gens produce significantly less fan noise than the 341x series.

These IFR 341x sig gens are generally quite expensive on the used market despite their age. This is probably because of the high performance they offer via the vector modulator and there may be regular industry demand for drop in replacements when they fail.
They were designed to be serviced via module swapping and so there isn't much info available for component level servicing. This makes it difficult for companies to get these generators repaired when they fail and this probably maintains demand for working examples.

The close to carrier phase noise is quite high on these sig gens because the vector modulator operates up at UHF and this is downconverted to lower frequencies when applicable. So the phase noise at (say) 14MHz is as high as the phase noise up at UHF. This makes this sig gen a poor choice if you expect low phase noise across the HF bands and into VHF. The phase noise really is quite high on this generator across HF and into VHF.

I can post up some performance plots and add info about reliability and what often fails on these sig gens.

Does anyone here have one of these generators? Has it been reliable and are you pleased with it?

[G0HZU]

If you begin to exploit the full potential of the IFR 341x sig gens, you can do some fairly advanced things using the vector modulator. For example, the waveform in the image below is an 8MHz wide NPR waveform that I set up using lots of tones transmitted at the same time.

If you transmit enough tones , the signal will look like wideband noise. If you then mathematically extract some of the tones from the waveform you can make a notch in the noise at an offset and width of your own choosing. This forms the basis of a noise power ratio generator. In the example below, I've generated over 800 (eight hundred) tones centred on 1.2GHz using the IFR3414 and I've also added an NPR notch 50dB deep and you can see this notch in the waveform below. All this is done on a PC and then the waveform is sent to the IFR 3414 via the vector modulator inputs.

There are over 800 tones  spaced at about 10kHz apart in the waveform below. This is why it is about 8MHz wide. Several tones have been deleted from the waveform in order to create the NPR notch. It's also possible to have many more tones than this. I tried again with 5900 tones for example. The more tones, the closer the waveform resembles white noise.

There is a dual arbitrary waveform generator option (option 5) for these sig gens and this is fitted internally on the main control board so this can be programmed to produce custom waveforms. However, I think the best performance will come from modulating it externally as in the example above.

I'm not sure how capable the dual arb generator is in the Siglent SDG2042X or the alternatives. In theory at least, it could be used to drive the I and Q inputs of the 341x vector modulator to provide waveforms like the one pictured below. A lot depends on how much memory the SDG2042X has and how easy it is to load waveforms into it. If it can do this, then the SDG2042X and an IFR341x would make up quite a versatile system.

Has anyone tried modulating the IFR 341x series with the Siglent SDG2042X? I've been tempted to buy one but I don't know how easy it is to generate compatible waveforms and load them into the 2042X to generate custom waveforms with the IFR 341x sig gens.