rf-consultant signal generator - Page 1
Forum section: electronics / general

author: ealex
author_rank: Frequent Contributor
timestamp: October 08, 2014, 10:34:36 am
content: HelloI intend to start working on RF things - RX and digital modes + software for processing it- i've already built a mixer front end around LT5517 quadrature demodulator ( i've attached the KiCad project and a picture of the PCB if anyone needs it + a picture from pcb-pool during manufacturing, all the work is based on "GR1 1021 KTH-SDR WIDEBAND RECEIVER" )For the clock generator i'm using a SI570 based device but the square wave output is generating a lot of harmonics that are visible on the received signal, and i can't shield them from the receiver.for a better signal generator i'm looking at the rf-consultant signal generator :http://www.rf-consultant.com/calibrated-signal-generator/do you have any experience with it ? does it meet the published specifications ? also, is there any other alternative in the price range ? ( ~ 325 usd for me, including shipping )Best regards,Alex.

author: eurofox
author_rank: Unknown
timestamp: October 08, 2014, 11:15:21 am
content: Quote from: ealex on October 08, 2014, 10:34:36 amI got one and it is working well, I sold it to a member of eeblog when I bought my HP RF generator.You have 2 version depending of calibration.The only thing I dislike was the user interface, you got 2 <> version, one based on an "exotic" development and an other one based on NI.The guy is correct, no problem.You have now many different version, just check with google "RF generator USB" from China at low cost, USA, France and I suppose they all use the same IC.I hope this help.eurofox

author: ealex
author_rank: Frequent Contributor
timestamp: October 08, 2014, 12:15:05 pm
content: thankseurofox, i'll look for other types.that one looks the best - including an attenuator and wide bandwidth + some basic calibration, as i don't have access to proper tools + some documentation i could see - got something on the website .the user interface is no problem - i could write another one if i need to - i might have to write one for linux - some command line tool at least, i'll ask the seller about the interface chip - from one of the pictures it seems to be a FTDI.

author: nctnico
author_rank: Super Contributor
timestamp: October 08, 2014, 01:07:54 pm
content: Quote from: ealex on October 08, 2014, 10:34:36 amThis design is based on an chip from Analog devices. This chips produces a massive amount of harmonics because it also outputs a square wave. KJDS is about to sell some Agilent E4421B signal generators. I suggest you buy one of those.

author: ealex
author_rank: Frequent Contributor
timestamp: October 08, 2014, 02:43:11 pm
content: That design is based on ADF4351 (http://www.analog.com/static/imported-files/data_sheets/ADF4351.pdf) - from it's data sheet i don't see anything related to square wave output.I could find something on a website - "Analog Devices ADF4351 PLL. Unfiltered square wave output so you see harmonics." so ...The Agilent E4421B is nice, i had one at a former job, but i can't afford something like that - on ebay they go for around 1000$ + ~ 100$ shipping, and 24% over that import taxes -> i'll have to pay at least ~1400$ for one ...I've seen KJDS's E4421B - way out of available cash ...any "decent" source of a sine wave ? maybe i'll end up getting a VCO designer's kit from mini-circuits, and make a PLL from scratch - this is the hard way that will take too much time + still the problem of no proper equipment

author: nctnico
author_rank: Super Contributor
timestamp: October 08, 2014, 04:13:27 pm
content: Quote from: ealex on October 08, 2014, 02:43:11 pmThat is the problem with that chip. A couple of years ago I put one on a board to build my own generator and found out the output is a square wave. The second and third order harmonics specification are a clue. The ADF4351 is intended to be used in a narrow frequency range with filtering to remove the harmonics.

author: eurofox
author_rank: Unknown
timestamp: October 08, 2014, 04:23:09 pm
content: Quote from: ealex on October 08, 2014, 02:43:11 pmYou can use as well a YIG oscillator, you can find the quite cheap on ebay.They output a clean signal with usually an high level.

author: Fraser
author_rank: Super Contributor
timestamp: October 08, 2014, 05:08:02 pm
content: I own a couple of the 'RF Explorer' spectrum analysers for quick and dirty tests. The designer has followed up with a 6GHz signal generator. It is more of a signal source than a full RF sig Gen but may be worth consideration ? It is certainly good value for money at $179, and it can work as a tracking generator with the RF Explorer, which I also recommend. With the pair you can plot filter and amplifier response curves as well as antenna testing. The free PC software is always improving and I also bought the reasonably priced Touchstone 3rd party software. The PC connectivity increases the units capabilities no end with nice plots and waterfall displays etc. Great for signal ingress tests.My lab test equipment is Advantest, R&S, Marconi and Agilent gear but sometimes you do not need such expensive test gear depending upon what your needs are. Its nice to have a spectrum analyser and signal generator in a small package for mobile 'go/no go' tests or interference testing.Take a look here:http://micro.arocholl.com/index.php?option=com_content&view=article&id=48:introducing-rf-explorer&catid=40:article&Itemid=64http://rfexplorer.com/Sig Gen is here:http://micro.arocholl.com/index.php?option=com_content&view=category&layout=blog&id=3&Itemid=50I bought mine from SEEED Studio and it is on its way to me:http://www.seeedstudio.com/depot/RF-Explorer-Signal-Generator-RFE6GEN-p-2074.htmlAlso note that there is a Chinese unit available that contains the signal generator IC of the RF Consultant and a simple spectrum analyser. They also sell a nice little broadband RF noise source to enable simple bandpass testing on amplifiers and filters. It cost me around $80 delivered but requires a PC to operate.I bought a couple but have yet to play with them.There are two versions depending upon the synth chip used:138MHz to 4.4 GHz ~$6535MHz to 4.4GHz ~$85RF Noise Source ~$23.50Auction links:35-4G4http://www.ebay.com/itm/35MHz-4-4GHz-35M-4-4G-USB-SMA-Source-Signal-Generator-Simple-Spectrum-Analyzer-/291250000159?pt=LH_DefaultDomain_0&hash=item43cfda511fhttp://www.ebay.com/itm/35M-4-4G-USB-SMA-signal-source-signal-generator-simple-spectrum-analyzer-/121372351807?pt=LH_DefaultDomain_0&hash=item1c425b1d3f138-4G4http://www.ebay.com/itm/138MHz-4-4GHz-USB-SMA-signal-source-signal-generator-simple-spectrum-analyzer-/111471545837?pt=LH_DefaultDomain_0&hash=item19f438cdedNoise Sourcehttp://www.ebay.com/itm/New-noise-source-simple-spectral-trace-the-source-/131247951494?pt=LH_DefaultDomain_0&hash=item1e8efcce86

author: G0HZU
author_rank: Super Contributor
timestamp: October 08, 2014, 07:44:50 pm
content: I would always recommend people to 'buy good' when it comes to signal generators if you want to play with RF. You can get by with a cheap DMM or scope but the thing that will reward you the most in terms of what you spend is the signal generator.If you get deeper into RF design then obviously you will start looking at VNAs and spectrum analysers but my advice is to dig fairly deep when buying a sig gen. Or at least be patient and try and buy a used bargain from the top brands like Marconi/IFR/HP.The ADF4351 based sig gens listed in this thread all represent good value for money but they are very restrictive in what they can do apart from putting up a cw tone with reasonable level and frequency accuracy.If you are on a tight budget and your soldering skills are up to it I would recommend you make a homebrew version of the 4.4GHz sig gens above. The ADF4351 chip is quite hard to solder correctly but you could probably get one as a free sample from AD. So you would just need to add a USB interface and a cheap MCU chip on the PCB. The code to control them is fairly simple.You could get the cost right down and maybe have two or three of them to use as crude cw sources. Pretty soon you would realise how limited they are as cw sources but you could maybe buy a used 1GHz sig gen like a little Marconi 2022 and mix it up to higher frequencies using the ADF4351 board and an external mixer.That way you can crudely expand the frequency range of the Mi 2022.The other advice I can offer is to avoid anything that is big and heavy unless you have loads of room and a huge workbench. So that rules out the usual classics like the HP8640 or HP8642 or the Marconi 2017/8/9. They are just too big and the HP8640/2 models are stupidly heavy. I have a couple of big old Mi2019s and I've owned them for nearly 20 years and they are too big for what they can deliver in 2014. I've upgraded to smaller, lighter and better generators that have more frequency range and better RF performance.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: October 08, 2014, 07:54:16 pm
content: Quote from: eurofox on October 08, 2014, 04:23:09 pmHow are these Ebay YIGs?Reliable???

author: Fraser
author_rank: Super Contributor
timestamp: October 08, 2014, 08:00:50 pm
content: Wise words from G0HZU,My first Rf sig gen was a Marconi 2022. I now own three of them ! Sadly the price of the 2022 has rocketed over recent years and they can often achieve GBP400+ in e*ay auctions. I paid around GBP150 for each of mine several years ago. One was brand new, Ex MoD unissued surplus (2022E).I was luck enough buy an Agilent E4421B recently for an excellent price and its in as new condition. I have yet to get time to play with it but it may topple my R&S SMG off of favourite sig gen slot in my lab. It certainly has better frequency coverage but time will tell as to whether I like its performance and user interface.I have also owned a Marconi 2019 and that was a good unit but a little large for the workbench (19" x 24")I also found a Hameg RF signal generator at a good price but that unit has intermittany button operation so I would be careful buying a Hameg as that may be a weakness in the design. I also hate the rotary encoder on the Hameg....it feels wobbly and cheap.Aurora

author: eurofox
author_rank: Unknown
timestamp: October 08, 2014, 09:15:02 pm
content: Quote from: SoundTech-LG on October 08, 2014, 07:54:16 pmI bought one that go from 3,2 to 14 Ghz, 15-17 DB output and quite stablehttps://www.eevblog.com/forum/projects/building-a-microwave-generator/msg498242/#msg498242

author: ealex
author_rank: Frequent Contributor
timestamp: October 09, 2014, 08:09:16 am
content: thanks for all of your repliesthe Marconi 2022 seems nice, i found one for ~ $452.00 excluding taxes and shipping ( ~ $776 overall ) - i might consider it.the ebay ones seem also built around ADF4351 - they do not have the gain block and programmable attenuator stages the rf-consultant hassome of the current problems i have with the LT5517 are because i'm feeding to much power in the LO input ~ 5-7dBm ( based on the rms oscilloscope voltage on the input ) instead of therecommended range of -15 to 0 dBm

author: ealex
author_rank: Frequent Contributor
timestamp: October 09, 2014, 08:46:25 am
content: btw - how big and heavy is the Marconi 2022 ? i have a friend that's coming over from USA and he might be able to pick it up if it's not huge

author: Fraser
author_rank: Super Contributor
timestamp: October 09, 2014, 12:04:44 pm
content: Weight is 7.5kg and it is designed to be a portable field use instrumentFull spec with dimensions may be found here:http://www.gxk.org.uk/Marconi-2022E/Marconi-2022E-info.pdfIt is well known and much loved sig gen in the amateur radio community so user and service manuasl are esily found using Google.Aurora

author: ealex
author_rank: Frequent Contributor
timestamp: October 10, 2014, 11:26:13 am
content: no luck, damn iti might just rip my budget apart and get a Marconi 2022C - i found one on e*bay, a lot of cosmetic damage, but nothing serious.i've also seen these 'toys' :HP 8656B Synthesized Signal Generator 0.1-990MHzHewlett Packard HP 8657A SIGNAL GENERATOR 01-1040 MHz Israel, damaged chassis - looks bad, outer case rippedGoldstar SG 88 52022-399V Signal Generator 10kHz-1GHz - looks just like Marconi 2022C

author: eurofox
author_rank: Unknown
timestamp: October 10, 2014, 12:47:12 pm
content: Check on ebay France and UK, Germany, many below 500 Euro's but you will not find them on ebay.com because they did not enable international when they post it.

author: ealex
author_rank: Frequent Contributor
timestamp: October 10, 2014, 03:10:34 pm
content: good hinti've found a Rohde & Schwarz SMS2 form france - it looks like a nice toy, but huge - 12kg) - added it on the list - over 200$ cheaper + it's got the original documentation and schematics + looks like it was kept in a clean environment .i might settle for that one if i can find no problems maintaining it alive - now i'm looking over the service and usage manual from bama archive -http://bama.edebris.com/download/rohdeschwarz/sms2/Rohde%20&%20schwartz%20SMS%202%20Service%20%20Eng.pdf

author: ealex
author_rank: Frequent Contributor
timestamp: October 13, 2014, 09:33:48 am
content: I went for the Rohde & Schwarz SMS2.I'll post a full tear down once i get it - clean-up, capacitor check and replacement, firmware back-up, etc.thanks for your comments.

author: G0HZU
author_rank: Super Contributor
timestamp: October 14, 2014, 12:08:29 am
content: The R&S SMS2 looks to be a very nice generator. Assuming it works OK it is a class above the Mi2022 in most areas of performance and it is a reasonable size/weight as well

author: Fraser
author_rank: Super Contributor
timestamp: October 17, 2014, 04:35:52 pm
content: R&S is considered the Rolls Royce of equipment manufacturers, but tends to be very expensive as a result.I have several pieces of R&S kit and can confirm the statements on high quality. The down side is that R&S are not hobbyist friendly and charge eye watering spares prices (if they agree to supply at all that is). Service manuals can be very hard to find for more modern pieces of kit like my SMG 1GHz Signal Generator. Reliable kit though so hopefully little need of a service manualIt should also be noted that though I love my Marconi 2022 units, they were a 'cut down' light weight unit designed for field portable use. The UK military had the E version in their inventory for fast deployment and use (a TCXO instead of a slow to stabilse OCXO). The specs on the 2022 are not as good as many larger bench type signal generators but they are still adequate for non critical hobbyist use. The weakness in the 2022 is in its use of a specific hybrid amplifier type. They are Philips OM series units and can fail for no known reason. I have plenty of stock for mine thoughThe OM345 appears to suffer the most failures and can still be obtained if you hunt around, but prices can be quite high at around GBP20 each (they originally cost only GBP3 !) I found a seller offering them for GBP8 each so bought a few as insurance. I have oonly had one failure in 10 years of owning my three 2022's though.Aurora

author: ealex
author_rank: Frequent Contributor
timestamp: October 18, 2014, 07:59:27 am
content: i managed to find a user and service manual for R&S SMC - i did not see any hard to find part at a quick glance.after the first check i will replace all big electrolytic caps. if they show any sign of old agethe only thing that could be hard to track down is the firmware - the eeprom can fail, i will back it up asap once i get the unit.it's in the post now - it should arrive in ~ 3 days

author: Fraser
author_rank: Super Contributor
timestamp: October 18, 2014, 09:57:02 am
content: On units taht use an LCD display, this can be a challenge to source especially if they are custom as on my CMD series units. Many standard and high qulaity components are used in R&S equipment. It is the volatile memeory that must be considered with older units. Two R&S power meters that I own have voltaile Calibration memory that is supported by a Lithium cell. Losing teh lithium cell causes loss of alll calibration dataAn EEPROM should be more reliable but can be corrupted if you are unlucky.Aurora

author: ealex
author_rank: Frequent Contributor
timestamp: October 22, 2014, 08:54:52 pm
content: update:got the unit, almost in one piece - the package had a nasty accident - the only damage was a broken plastic knob on the handle, nothing to complain about.the unit is very clean ( even the fan - it got 4 pins ? and not very loud ) - looks like it was kept in an lab / university environment - there are some dBm conversion formulas taped on top.got full schematics in perfect condition - i'll try to scan them sometime in the future - over 100 pages, and some schematics are almost a meter long. i've browsed them and they give a lot of debugging info - every bit is very well explained + there are a lot of tables for the digital section - enough info to be able to rebuild it from scratch if it ever fails.got it running - i have some RF signals out and the interface is responding / played a little with the attenuators and FM modulation - the DS1052 frequency counter can work up to 380MHztook a peek inside - it stinks of blown electrolytic capacitors - and 2 from the power supply blew their caps long ago.i've seen some strange deposits on all 2.54 headers - some white crystals, almost look like snow - only on those connectorsno other traces of corrosion - i don't know how those caps blew up without any damagethere is no EEPROM inside - this version uses a 8049 microcontroller with 2K of ROM and an external RAM chip + a dedicated GPIB contoler.the unit is built like a brick - 15 kg , thick aluminum bars / sheet metal all over, and each sub-module got at least an extra layer of shielding - all internal RF connections are made with rigid coax. the best part is an included raiser board - so i can debug each module outside the unitthere are 2 blocks that look to be kept at a controlled temperature - the local oscillator embedded in a big aluminium block and on a board that got some cavity filters a shielded box filled with foam that looked like it had melted.most of the IC's are from 1978-1980 ... older than me- there are no signs that it was ever repaired, or even opened in the last 20 yearsno photos for now, i'll make a short tear-down when i replace all big PSU caps.also, i've seen a lot of ~ small caps that look like they've been molded in Bakelite - brown color with inscriptions like "470/16" and polarity markings on top.the "strange" caps look like these:http://www.schenk-audio.de/JogisForum/ROE_rote_Becher.jpgshould I try to replace as many as possible ? or just go for the PSU ones first and then replace the others only when they fail ?

author: ealex
author_rank: Frequent Contributor
timestamp: October 23, 2014, 09:24:25 am
content: I've located the suspected capacitors:C5 - 4700uF 40V, 55x35mmC12 - 4700uF 40V, 55x35mmC8 - 10000uF 40V, 80x35mm - the one that was blown,C1 - 22000uF 16V, 80x35mmIt seems that i can't find C8 at TME or Farnell - this sucks ... i'll have to improvise something - series / parallel combinations or keep searching.i don't want to search for them on ebay and wait another month for some 30 year old capacitors.

author: ealex
author_rank: Frequent Contributor
timestamp: October 23, 2014, 09:55:58 am
content: Update: i was an idiot looking for the wrong part : i should have searched for "snap-in"C5 and C12:http://ro.farnell.com/cornell-dubilier/slp472m050c5p3/cap-alu-elec-4700uf-50v-snap-in/dp/2333507C8http://ro.farnell.com/cornell-dubilier/slpx103m050e7p3/cap-alu-elec-10000uf-50v-snap-in/dp/2333492C1http://ro.farnell.com/epcos/b41231c4229m/cap-alu-elec-22000uf-16v-snap-in/dp/1839274now i have to wait for those parts to arrive .it would be interesting if i can keep the original capacitor cases - mount the new ones inside because they are smaller