What are the affordable high quality RF generators ?  - Page 1
Forum section: electronics / rf-microwave

author: electronic_guy
author_rank: Regular Contributor
timestamp: February 27, 2021, 05:16:03 am
content: Hi,I'm new to the RF electronics. I'm trying to buy a RF generator for my experiments. Can you recommend a high quality RF generator please. I'm focusing on the surplus market where I can have R&S, HP/Agilent/keysight, MarconiI read the spectrum analyzer buying giude on eevblog and bought a CMU200. It would be really useful if someone can post a similar buying guide to RF generators.Thanks a lot.

author: bob91343
author_rank: Super Contributor
timestamp: February 27, 2021, 06:20:42 am
content: It would be easier if you would tell us your budget, and what you want of the generator. Frequency range, modulation, stability and accuracy, etc.My favorite rf generator is the HP 8657B which I see on ebay for around $400. I also have a AN/URM-25D which is a very good general purpose analog generator from 10 kHz to 50 MHz.

author: electronic_guy
author_rank: Regular Contributor
timestamp: February 27, 2021, 11:36:46 am
content: Thanks for the info.My budget would be about $1000 including shipping. The frequency range is from kHz range to 3 - 4 GHz. For the modulation, I would like to have all types of analog and digital modulations, AM, FM, PSK, FSK, ASK and also pulse modulation would be nice to experiment with. Though I suspect if its possible to have all these in a single equipment.Stability and accuracy wise, I do not know of it that much to define it quantitatively. How it affects the measurements. Just have a general sense that the more stability and accuracy is better.It would be valuable to know how people usually start with RF. I mean the equipment that they usually need at the beginning and would be useful in the long run.

author: coppercone2
author_rank: Super Contributor
timestamp: February 27, 2021, 09:32:49 pm
content: hmm how do people start out with RFlate night fear and self loathing (OH LORD WHY CAN'T I SIMULATE) over a bottle worrying about things in your circuits that few others understand and the money depends on how much discipline you have over your ebay accountit depends entirely on how much you love it. it's pretty hard corei.e. it is like buying a welder. who puts a guideline over what you play around with in a garage??? Some people will just save up for a high end transistor miller and others will find some kinda overweight transformer based atrocity in the scrap yard...These standards don't exist with anything, even DC. Some people you work at will have a 6.5 digit meters and stuff on a work bench for testing light bulbs but others will do expensive work with ancient 3.5 digit stuff thats 50's years old. Do they care?? not really.. half the people working at those places probobly figured out how to measure voltage judging by the spark it makes. It's practically like a x-wing targeting system in star wars.. some old guy is going to tell you something long the lines of 'just plug it in and listen to what kind of grunt it makes...' And its not wrong to do that either most of the time, they usually know what they are doing.. the hard core investigations are sparse, lead to dead ends and often unwelcome.

author: xmo
author_rank: Regular Contributor
timestamp: February 27, 2021, 10:46:35 pm
content: Your CMU has a decent signal generator function built in, but a standalone generator can offer advantages. Quality metrics are signal purity such as harmonics, spurious, and especially phase noise. Those things matter for some tasks and not so much for others. Lower phase noise = higher cost. Like most things, buy the best you an afford.If you want to explore digital modulation, you want a generator with a digital modulator. At a minimum, that means I&Q inputs. Some digital generators also can create the digital modulation with internal options like ARB generators, but you can use an external ARB source with any generator that has I&Q inputs.Because the wireless industry is moving so fast, there are a lot of powerful instruments that aren't up to the latest technology that can be had for reasonable prices. The CMU is an example. Likewise there are ARB generators that originally cost a bundle and now can be had for peanuts. A R&S AMIQ will do basics and a more capable AMU200A is still pretty affordable.R&S offer free waveform creation software so you can experiment with basic digital modulation without investing big money.Some generators you can consider are the R&S SMIQ, SM300, and SMV. The SM300 is a cute little guy and can sometimes be had close to your budget. SMV has better specs but will cost more.The Agilent ESG family has many suitable models and sometimes show up at reasonable prices. You will need to study datasheets and manuals and watch auction sales to get an idea what will best fit your goals. There are also other brands you can consider such as Anritsu and Aeroflex/IFR/Marconi. You will need to do some homework.You can always come back here with questions when things are unclear.Also, as others have warned, it's not to late for you to get out while you still can. If you keep going down the RF road - one thing leads to another. You will need high quality, double shielded test cables, adapters, couplers, splitters, attenuators, mixers, samplers, probes... the list goes on and on.

author: xmo
author_rank: Regular Contributor
timestamp: February 28, 2021, 12:13:29 am
content: Also, there are amplifiers, terminations, loads, power meters, sensors, phase shifters, connector gauges, detectors, burst triggers, and - if you get into network analyzers - calibration kits and phase stable test port cables.You have been warned.

author: DaJMasta
author_rank: Super Contributor
timestamp: February 28, 2021, 12:29:03 am
content: Agree that SMIQ, SM300, or ESG-D generators are probably some of the best options in that pricepoint. The Marconis are good but I feel like they can be a bit overpriced for the performance/age imo, still could be a good option if you find the right price. There are some more modern options I'm not as familiar with, but there are some options to 6GHz or so that are much smaller that would fit in the budget - though you're going to get fewer built in I/O channels and some degree of lack of features/specification. One nice benefit of the older big generators is that they often have a mechanical attenuator, so you get built in very low output capability for testing radios and amplifiers, plus you can sometimes find a unit with particularly interesting options already installed (though you're not likely to be able to license or upgrade something after the initial purchase).A vector generator or at least a vector modulator being built in for an external I/Q signal really goes a long way, as you then can get virtually any modulation scheme you want with a two channel arb gen.

author: rfclown
author_rank: Frequent Contributor
timestamp: February 28, 2021, 01:11:37 am
content: Quote from: electronic_guy on February 27, 2021, 11:36:46 amMy advice might not be much help, because my start with RF was not as a hobbyist. I was an electronic hobbyist, but didn't do RF until someone else was paying for the equipment (Motorola). We used mostly HP. I started with HP8657A/B (in 1986) and ended with MXGs (in 2009). Got laid off. At that point I started buying on eBay so I could do contract work. I bought what I was familiar with. First generator I bought was a HP8657B, but sold it as soon as I scored an ESG. These aren't cheap, but I buy them with built in ARBs so I can generate any waveform (within the limits of the sampling clock). It's been many years since I bought one, but when I did, I'd try to get them <=$1200 (with arb option). I had to be patient. I have E4431B and E4432B (2G and 3G) models. The last ESG model (E4438C) has a power supply that if it goes out, costs about $1500 on eBay to replace (ouch).I don't know if any of that was worth typing. I really like my ESGs, and would buy them again for what I paid for them... but I didn't buy them for hobby, and I didn't compare with anything else. I bought what I was very familiar with. I had LabVIEW code I'd written to generate waveforms and upload waveforms.I'm remembering now that the first ESG I bought didn't have the arbs. I bought a wavetek dual arb for it. That was a pain to use. Sold it once I got an ESG with arbs.

author: electronic_guy
author_rank: Regular Contributor
timestamp: March 01, 2021, 03:06:12 pm
content: Thank you so much for all the valuable insights.

author: szoftveres
author_rank: Regular Contributor
timestamp: March 02, 2021, 08:25:38 am
content: I just got an EMC model 502 from eBay for about $40 shipped. Needed some soldering work, otherwise works great. 100kHz to 100MHz, modulated. Cannot beat the price