hybridfree/eevblog-posts huggingface dataset:
$r + 4C + 1 FPGA == Radio Challenge - Page 1
Forum section: electronics / rf-microwave

author: antti
author_rank: Contributor
timestamp: March 29, 2017, 07:05:40 am
content: As subject, the challeng is to use 8 passive components, 4 x R, 4 x C and one FPGA (any Xilinx 7 series is ok) to create a Radio receiver with frequency coverage over 500mhz.Challenge announcement at Xilinx bloghttps://forums.xilinx.com/t5/Xcell-Daily-Blog/Antti-s-Trenz-Challenge-Build-a-500MHz-radio-receiver-with-4/ba-p/757338

author: daveshah
author_rank: Unknown
timestamp: March 29, 2017, 08:50:34 am
content: What a funny coincidence, given my project only a couple of days ago

author: antti
author_rank: Contributor
timestamp: March 29, 2017, 09:01:18 am
content: Yes, I read your GTx but honestly, I found your post LATER, and its totally different approuch!

author: daveshah
author_rank: Unknown
timestamp: March 29, 2017, 10:20:46 am
content: I wasn't implying anything - just thought it was interesting. This certainly looks like a better approach for lower frequencies and will be much more sensitive I'm sure. I'm definitely going to have a play with it as I'm interested in SDR type stuff.

author: antti
author_rank: Contributor
timestamp: March 29, 2017, 10:31:40 am
content: yes its pretty cool, the technical details will get explained and published as soon as the challenge is completed..
Harmonic mixers - Page 1
Forum section: electronics / rf-microwave

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: March 26, 2017, 06:59:59 pm
content: Question for the RF gurus: What makes a mixer suitable for use as a harmonic mixer? When searching for harmonic mixer parts on ADI or Linear's website, one can find mixers that multiply the LO by two, I'm interested in a higher multiplication ratio (x5 or higher). Christopher Marki has a couple of videos on Youtube explaining that driving the LO port of a double-balanced mixer with a harmonic-rich signal (square-wave drive) doesn't always give expected results because the LO balun's limited bandwidth won't pass the higher-order harmonics. What would I need to look for when selecting a downconverting mixer to allow me to get a 1x5 or 1x6 IF? Thanks.Marki's video:

author: jjoonathan
author_rank: Frequent Contributor
timestamp: March 27, 2017, 01:11:24 am
content: (Everything I said in this post is wrong -- ignore it.)
ICOM IC781 - Page 1
Forum section: electronics / rf-microwave

author: Harb
author_rank: Regular Contributor
timestamp: March 19, 2017, 05:26:53 am
content: G'day everyone,I moved a while ago, and packed up my Ham Station which in itself was one hell of an exercise........but I had 2 of my old radio's packed away in the storeroom both in need of repair.They are both IC781's and since I got my new radio's I didn't make the time to put into fixing them, but I now have a use for them and will have to make the effort to get them out and do the repairs.They both suffer from the dreaded Power Supply / Regulator fault , which was very common in these radio's, so at least its a well known problem with an acceptable fix.My problem is, I have never had the lids of these particular radio's, and I am told the power supply boards are an absolute pain to remove........they say its a near full disassemble of the radio...I know its not going to make a whole lot of difference, but I am just trying to prep myself lol.....anyone done it ?Cheers 73'John VK2XYP

author: TheSteve
author_rank: Unknown
timestamp: March 19, 2017, 05:48:25 am
content: I haven't done it but do I adore the IC-781. You can probably find lots of support on the Icom 781 support group on yahoo groups.If nothing else when you do it please post pictures and details here.

author: NA5WH
author_rank: Contributor
timestamp: March 19, 2017, 07:13:33 am
content: IC-781 ... think that was the first HF rig with the bandscope... I do remember it was one of the radios that I wanted when I first started looking at ham radio (when my friend got licensed).I remember seeing a photo journal of a tear down, but I can't seem to find it right now. Love to see your progress when you go through it.

author: Harb
author_rank: Regular Contributor
timestamp: April 01, 2017, 02:20:38 pm
content: Yeah thanks for the replies.....There is a little bit of stuff on the web......doesn't really look like a big deal, so I will just knuckle down and do it.I will definitely record it and put it up on my YouTube channel in case anyone else is interested.Will come back here and let you know when I do that
Question on PSK - Page 1
Forum section: electronics / rf-microwave

author: DavidDLC
author_rank: Frequent Contributor
timestamp: March 11, 2017, 01:18:32 am
content: I don't know about PSK, I was just reading about it, and I have the next question:How is the change on the bits from 1 to 0 or 0 to 1 synchronized with the sine and cosine wave ?My question is based on the attached block diagram.

author: ataradov
author_rank: Super Contributor
timestamp: March 11, 2017, 02:22:14 am
content: It does not have to be synchronized. And in general, it is impossible to synchronize them.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: March 11, 2017, 02:35:06 am
content: Alex, thanks for your answerSo is the change in phase at zero crossing ?If yes, how is this achieved ?

author: ataradov
author_rank: Super Contributor
timestamp: March 11, 2017, 02:39:32 am
content: Quote from: DavidDLC on March 11, 2017, 02:35:06 amNo, phase changes when it needs to change. It does not affect anything. Things don't look good, but it does not matter for transmitters and receivers.Plus, transmitters are rarely done this way, with a single multiplication. Typically you form baseband I/Q signal at some low frequency in a digital domain, pass it through the DAC, and then use quadrature mixer to bring it up to to the final RF frequency. This messes things up a lot towards the end anyway.PS: And since the fist stage is digital, you can pick a baseband frequency that will work nicely.

author: w2aew
author_rank: Super Contributor
timestamp: March 11, 2017, 06:12:23 pm
content: Quote from: DavidDLC on March 11, 2017, 02:35:06 amThe baseband signals are filtered, so the phase change occurs slowly, across many, many RF cycles. If you made the phase change instantaneously at the carrier zero crossing, you'd occupy a very large bandwidth (bad).

author: DavidDLC
author_rank: Frequent Contributor
timestamp: March 25, 2017, 07:01:19 pm
content: I cannot visualize your comment w2aew. Can you explain a little bit more, maybe some pictures or drawings will help.David DLC

author: ataradov
author_rank: Super Contributor
timestamp: March 25, 2017, 07:10:20 pm
content: Here is a screenshot from a real radio modem model.As you can see, "bits" are not sharp squares, but a filtered signal. If they were sharp, they would occupy infinite spectrum, and FCC will be all over you.

author: Howardlong
author_rank: Super Contributor
timestamp: March 25, 2017, 08:26:39 pm
content: Furthermore, it might be easier to consider how BPSK works first rather than QPSK.The baseband filters applied to PSK are a whole area of comms engineering. There is the classic engineering trade off between several sometimes conflicting requirements including SNR/CNR, intersymbol interference and spectrum use (maximum energy within a channel with minimal spectrum regrowth). Which filtering is used is determined by the application, which in turn drives the priorities of the aforementioned parameters.
Isolated RF box - Page 1
Forum section: electronics / rf-microwave

author: DavidDLC
author_rank: Frequent Contributor
timestamp: March 23, 2017, 07:28:54 pm
content: Can we build an isolated RF box using Aluminum ?What is the best material to build one ?David DLC

author: DavidDLC
author_rank: Frequent Contributor
timestamp: March 25, 2017, 03:34:39 am
content: Thanks for the information.David DLC
Wilkinson combiner coil induction measurement question - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: March 21, 2017, 10:37:32 am
content: If I plug my desired frequency (137.55kHz yes, kHz, I am inputting 0.13755MHz) into this on line calculator I get a figure for the two coils of 81.82uH eachhttp://leleivre.com/rf_wilkinson.htmlI have two coils prepped with a few excess turns, and can measure with a calibrated Philips LCR meter at 1kHz, or I can try and measure them with an AIM4170 antenna analyzer at 137khz. Is it important to measure and trim them at 137khz or not please? Can I assume the on line calculator is assuming measurement at the operating frequency?

author: Andy Watson
author_rank: Super Contributor
timestamp: March 21, 2017, 10:56:26 am
content: Try the Skin depth calculator at 1kHz and 137kHz. I think it might have a significant effect on the Q of your coils - i.e. I think you should test at 137kHz.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 21, 2017, 11:25:44 am
content: If they're air core, use this:http://hamwaves.com/antennas/inductance.htmlThe network Q is quite low, so the Q of the components will have only a small effect (i.e., Q > 10 gives < 10% losses, roughly speaking).BTW, why use a Wilkinson divider instead of a wideband transformer splitter? No need for tuned components, just one winding (well, and a few taps and such) and a lump of ferrite.Tim

author: Chris Wilson
author_rank: Super Contributor
timestamp: March 21, 2017, 12:53:23 pm
content: Thanks for that Andy, I will use the AIM4170 to verify the impedance then, as the calculator cited above gives different turns to the one I used.

author: Chris Wilson
author_rank: Super Contributor
timestamp: March 21, 2017, 12:56:52 pm
content: OK, understood, thanks for that. The reasons i am using a combiner are two fold. Someone with similar amps to combine has buikt it and it apparently works well, and I am not qualified to design a good output transformer. plus I don't know where to source a suitably efficient core to handle the combined power as the FT-240-78 material one used in each amp seems as big as I can get in that material (designed for the frequency) and it already runs slightly warm. Specifics on what to try welcome
Advice on SDR architectures for low noise L-Band reception? - Page 1
Forum section: electronics / rf-microwave

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: March 31, 2017, 06:54:19 am
content: So I want to build a receiver specifically for use with radio astronomy and hobby deep space network experimentation. Ive noticed a lot of guys out there doing satcom and such are using nice direct conversion HF SDRs with down converters in front. So this got me thinking if someone were to build an SDR from scratch for low noise microwave reception what would be the best route? I two different thoughts and Im not really sure wich path to follow or if either is the best way.First idea is kind of a dual conversion unit. The idea is to build a highly capable 1-50mhz or so HF SDR and use it primary as an IF for an L-Band/10.6ghz down converter. This route allows one to use a lot of quality stuff not available at microwave frequencys, and much easier filtering. Ive never seen anyone do it but I was thinking that using two H-Mode mixers like thesehttps://www.sv1afn.com/fsa3157hmodemm.htmlwould make for a killer quadrature detector which would then pipe in to a 16 or 24bit high speed adc and off to the DSP stage. And of coarse in front of the basically HF SDR one would switch in high quality down conversion units for each band.The second idea, and im not even sure if it would work would be to make a direct conversion unit that covers 1420-1700mhz or maybe make a few different tayloe detectors, one for each microwave frequency. From what I understand the center frequency the tayloe detects is equal to the speed at witch the I,q,i-,q- are switched at? So how could one switch the detector at microwave frequency's? Then obviously pipe that straight in to a hi res hi speed ADC.So im not really sure which route is going to be the best to start down, I know doing something may get pretty pricey but thats not really the concern here its designing the SDR possible for space use without using JPLs crazy cryogenic ruby pre amps and active super conductor based mixers etc etc...
Online IQ Samples - Page 1
Forum section: electronics / rf-microwave

author: rheb1026
author_rank: Regular Contributor
timestamp: March 11, 2017, 10:30:30 pm
content: Is there someplace online where I can download IQ sample data? I'm looking for like 10 seconds to a minute worth to test out some software demodulation and filtering I'm working on. Ideally I'd like 20m and 40m band, voice and cw. I have an RTL dongle, but the signals I receive are pretty abysmal inside my apartment (and the cheap dongle has so many spurs anyway). I have a decent 2m antenna, but both ham and airband activity is so infrequent that I can never seem to catch much - by the time I click the record button it's gone.I tried doing some searches online, but couldn't find anything.

author: hendorog
author_rank: Super Contributor
timestamp: March 11, 2017, 10:39:58 pm
content: Have you tried ATIS? That transmits most of the time if you are in range. You could take your SDR closer to the signal

author: cncjerry
author_rank: Unknown
timestamp: March 12, 2017, 12:18:38 am
content: Look at the SDRsharp site. It records and reads IQ files. I think they distribute some as well, maybe with the program. It's pretty cool as if you record 96khz or even 192khz of bandwidth you can tune around thru it at a later time. There are sound cards that can record even wider bandwidths with higher sampling rates.

author: donmr
author_rank: Regular Contributor
timestamp: March 12, 2017, 06:32:34 pm
content: Or fire up gnu-radio and make some (read an audio file).

author: cncjerry
author_rank: Unknown
timestamp: March 17, 2017, 04:49:38 pm
content: I didn't think of it before, but just about any audio editing software can make an I/Q file. I used them for testing. You just use the program to synthesize a sine wave and then use the same program or edit it to offset the sine wave into the second channel by 90 degrees. Pretty easy. If you don't have a program, I think Audacity is free on a mac. There are a lot of others. If you really get stuck, PM me and I will send you a file with 1000hz stereo I/Q.

author: Artlav
author_rank: Frequent Contributor
timestamp: March 17, 2017, 05:06:26 pm
content: Signal Identification Wiki -http://www.sigidwiki.com/wiki/Signal_Identification_GuideMany of their examples come with sample IQ files
How to get rid of phantom signal from SDRPlay? (SDRUno) - Page 1
Forum section: electronics / rf-microwave

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 15, 2017, 05:11:10 am
content: When ever I open my SDR the station it was last tuned to always has a phantom signal stuck on that location on the spectrum. When you tune up and down that signal always remains at that spot. Really annoying. In this screen shot I'm trying to pick up ADSb, which is strange I can't see it but there are 4-5 airplanes that I can pick up right now if I start dump1090.

author: usagi
author_rank: Frequent Contributor
timestamp: March 15, 2017, 10:04:00 am
content: LO leakage causing DC spike in the spectrum. limitations of the hardware design.some software can null it out, or you can use offset tuning.

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 15, 2017, 04:16:09 pm
content: Quote from: usagi on March 15, 2017, 10:04:00 amHow do you use offset tuning? it doesnt seem adjustable.
Any good DIY radio receiver/transmitter projects ? - Page 1
Forum section: electronics / rf-microwave

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 15, 2017, 05:15:31 am
content: I'm looking for a simple project where I can send some data over VHF or UHF. Best would be a kit where you solder it together, then I can attach it to a home made antenna. I'm just looking for it to do something simple like send the temperature, nothing in particular, I just want to learn how to send data, then experiment with how far I can put it with as little transmitter power as possible. Or even just a beacon. I found some beacon projects but they are on Shortwave bands and I want something with a small antenna.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: March 15, 2017, 09:45:51 am
content: It's not quite DIY but have you looked into those 433 MHz data modules?

author: ptricks
author_rank: Frequent Contributor
timestamp: March 15, 2017, 01:08:01 pm
content: I don't know of any kits specifically, but have a look at the talking electronics site where he details on how to build such a thing.http://www.talkingelectronics.com/projects/27MHz%20Transmitters/27MHzLinks-3.html
Help: Pls identify this part. - Page 1
Forum section: electronics / rf-microwave

author: dhiru90
author_rank: Newbie
timestamp: March 19, 2017, 05:21:39 am
content: Hello Respected members,Pls help in identifying the following part for some gsm freinds.Hints, don't know if could be useful:http://www.triquint.com/products/p/CMY210Can be up/down converters that converts the GSM frequencies to carry them over the cable.Thanks Everyone.

author: Neganur
author_rank: Unknown
timestamp: March 19, 2017, 10:23:05 am
content: no idea. The mixers were somewhat easier due to the company logo but the 5680...too generic.
Generate 125MHz signal to feed circuit? - Page 1
Forum section: electronics / rf-microwave

author: NeoxSys
author_rank: Newbie
timestamp: March 13, 2017, 04:09:45 pm
content: Hi everybody, I'm currently working on my research project at my uni and I need to feed a circuit with a 125MHz signal (not higher than 1mVp amplitude). My circuit has a low input impedance at that freq.The problem is that actually there isn't any signal generator available and I'm in a little hurry to finish this off. I was wondering if there is asimple cheap way to generate this signalfrom a Crystal or a resonance circuit without wasting too much time. I don't even care if it is a sine or a square, it will have only testing purposes.Thanks in advance.EDIT: what I want to do by now is to tune this input LC with the help of a oscilloscope, so I only need a signal band near the 125MHz freq

author: cncjerry
author_rank: Unknown
timestamp: March 13, 2017, 04:38:25 pm
content: 5V supply and a 125Mhz packaged crystal oscillator and Bob's your uncle. Less than 10 bucks. There probably is a 3.3V version as well.

author: NeoxSys
author_rank: Newbie
timestamp: March 13, 2017, 05:31:44 pm
content: Quote from: cncjerry on March 13, 2017, 04:38:25 pmSomething like this?http://uk.rs-online.com/web/p/crystal-oscillators/6676445/What is the terminal named OE or /ST ?

author: james_s
author_rank: Super Contributor
timestamp: March 13, 2017, 05:39:13 pm
content: All the information you need should be in the datasheet.OE is typically Output Enable. You will have to tie that pin to ground or Vcc (check the datasheet) to enable the oscillator. It works like a power switch.
SX1243 Matching - Page 1
Forum section: electronics / rf-microwave

author: ivofena1
author_rank: Newbie
timestamp: March 14, 2017, 07:36:46 pm
content: Hey guys, I'm in a bit of a pickle and needed some help. I don't know if any of you have used the Semtech SX1243 Sub Gig transmitter, but I've been struggling to match a helix pcb antenna to it. For one I've been trying to figure out how to get the output impedance of the transmitter... For the antenna I'm able to get all the info using the miniVNA Tiny but I don't know what to match it to.. Any help would be appreciated.Edit: I forgot to mention the frequency used is 315Mhz
Arduino based SNA's and antenna analyzers? - Page 1
Forum section: electronics / rf-microwave

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: March 12, 2017, 05:20:39 am
content: Currently I just use an airspy, directional coupler and noise source. I was wondering if it would be possible to make one of these poor mans analyzers up in to the ghz using a noise source instead of a DDS or synthesizer? I would think it should be maybe just a matter of calibrating the noise source in to some table first?Secondly and kind of stupid if I am staring at a return loss curve of lets sat -14db, how can I derive or the impedance of the antenna in ohms?
NRF24L01+ noisy spectrum; genuine / counterfeit - Page 1
Forum section: electronics / rf-microwave

author: VaZso
author_rank: Newbie
timestamp: March 11, 2017, 01:33:48 am
content: Hi,My colleague and me have found some interesting details about NRF24L01 chip.I have put a somewhat long storyhere(sorry for cross-linking).We could successfully identify which chip is genuine and which is counterfeit by measuring current after powering them up. We have also made some destructive tests before to see if our modules really have original ICs inside.I am writing here as I hope there are professionals here who know much more about RF regulations than us and have more experiences in this area.I haveposted a messagein the above mentioned thread with some photos / videos made of a Rohde&Schwarz spectrum analyzer (EMI tester) while it was measuring our transmitter / receiver which worked with NRF24L01+ ICs.There were some noises in the spectrum with every modules of us and we don't really know how should we handle the situation.As many company use this chip from Nordic Semiconductor, I assume they should meet the requirements of regulations, but it would be good to hear it from someone who has deeper knowledge about this.We mainly would like to use it in Europe / EU, but informations about other parts of the world may also help...Also, we found a module (RF24L01F20) which seems to also have FCC / CE / IC certifications.What is your opinion about this (unwanted noise in spectrum)?Thank you your help in advance.
HP438A vs. Agilent E4419B - Page 1
Forum section: electronics / rf-microwave

author: EVlab
author_rank: Contributor
timestamp: March 21, 2017, 07:49:30 am
content: Hi all!I need a dual channel power meter for my hobby lab.Prices for E4419B are still high in comparison to the 438A. When taking a look at the specs the only major difference I could find out is the measuring speed.Can someone tell about the speed and if it is a big concern?I would also appreciate any comments which one to get!Best, Simon

author: slurry
author_rank: Regular Contributor
timestamp: March 21, 2017, 08:01:53 am
content: You should also ask you the question, what kind of signal do you intend to measure?To measure a CW-signal you will not need high measuringspeed at all, if you want to go cheap the 438 is good enough,to be more futureproof the 4419B or EPM-442 is a really good choice.Regarding the costs, on ebay a E4419 goes for about €300-400 and each of, say 4148A, powerheads costs about €400-500As a very good alternative you may also consider two R&S NRP-Z11 with Z4 USB-adapters, the software is really good and they run you about €500-600 each.

author: MarkL
author_rank: Unknown
timestamp: March 21, 2017, 03:08:35 pm
content: One major advantage of the E4419B is that it supports sensors that have the calibration table in EEPROM, so you don't have to enter the calibration factors manually as you change frequency (but still have to enter the frequency). It's also compatible with the E series sensors, which have a wider dynamic range.The E4419B also supports older sensors that don't have the EEPROM table. Once nice feature is that you can enter the full table and the E4419B will store it for you. Then you can recall the table for that particular sensor when you connect it.I would get the E4419B if you have the budget for it.I have two 438A units, but I don't use them very often. The one advantage is that they have full service manuals with schematics, so they can be repaired easily. If the calibration table entry one day became too much of a nuisance, I could automate it using the GPIB interface.
VSG25A /RF source  - Page 1
Forum section: electronics / rf-microwave

author: real69
author_rank: Newbie
timestamp: March 05, 2017, 08:05:13 am
content: Signal Hounds VSG25A is it good for testing Frequency Responses,1dBCompression Point , ip3, Pushing Figure etc (<0dBm) or should i go for much expensive Rigole/keysight RF source ?
How to choose a correct RF amplifier - Page 1
Forum section: electronics / rf-microwave

author: Anirudh_THABJUL_SB
author_rank: Contributor
timestamp: January 24, 2017, 11:33:28 am
content: Hello Everyone,I am Anirudh THABJUL. I am an Electronic engineer working in a company called Second Bridge, Paris.We are using LBEH59XUHC chip which consists of Wifi & Bluetooth in combo (for your reference, I have attached the datasheet with this post)For increasing the performance in our application, we need better Bluetooth range than we have 50M at present . In order to improve the performance of bluetooth on our existing PCB, We are planning to add an additional amplifier between antenna and our LBEH59XUHC chip.Please help me in choosing correct amplifier? If possible, please let us know what are the parameters do we need to consider for choosing the correct amplifier.What is the optimum gain needed to increase the bluetooth performance more than 50M.Thank you.Regards,Anirudh THABJUL

author: retrolefty
author_rank: Super Contributor
timestamp: January 24, 2017, 11:45:06 am
content: What range are you looking for? Were you planning on amplifying the device's receiving sensitivity or it's transmit output power? Either one could be the limiting factor, as perhaps the antenna at either end of the bluetooth link you be the limiting factor.Not sure slapping a single chip in will succeed.

author: rfbroadband
author_rank: Unknown
timestamp: February 15, 2017, 06:21:08 am
content: If I understand the data sheet correctly you are using a module that contains the antenna switch, frontend filtering within your module, which means your RF antenna interface is a RX/TX interface!. You will need to get access into the RX chain within the module to insert an LNA, which basically means you have to re-design the module.

author: RadioNerd
author_rank: Regular Contributor
timestamp: March 04, 2017, 10:47:52 am
content: There are bidirectional WLAN amplifier designed for this purpose. They work by sensing the output power of the transmitter. As soon as a transmission is detected, they switch into TX (Power amplifier) mode, otherwise they act as a LNA.I am not sure whether these work also with Bluetooth.An example:http://www.rflinx.com/products/amplifiers/2400/sa/But there are many other similar devices
I need a 25mhz carrier + 2100hz square wave from my linear-will this do it - Page 1
Forum section: electronics / rf-microwave

author: stevie3d
author_rank: Newbie
timestamp: March 04, 2017, 06:53:55 pm
content: Would a 25MHz Dual-channel DDS Arbitrary Waveform Function Signal Generator work, specs are:Sine WaveNormal Modes:0.01Hz~25MHz Square Wave 0.01Hz~6MHzTriangle Wave 0.01Hz~6MHzSawtooth Wave 0.01Hz~6MHzArbitrary Waveform 0.01Hz~6MHzTTL Digital Signal Wave 0.01Hz~6MHz
RF Test Board - Page 1
Forum section: electronics / rf-microwave

author: danadak
author_rank: Super Contributor
timestamp: February 06, 2017, 03:43:12 pm
content: Hi, I am looking for some ideas, layout, for an RF test board, using verticalSMA connectors. General ideas, for testing passives, maybe some low polecount filter solution's, working with VNA to establish characteristics.Layout in Eagle would be a plus.Regards, Dana.

author: tggzzz
author_rank: Super Contributor
timestamp: February 27, 2017, 10:52:14 pm
content: Make some generic 3-component and 6-component T-filters and pi-filters using 0805 SMD R,L,C. Make sure the track has 50ohm impedance (or 75ohm, I suppose).Make a long track and see how close it is to 50ohms.

author: Unknown
author_rank: Unknown
timestamp: February 28, 2017, 02:03:14 pm
content: It depends on what frequencies you want to measure up to and what accuracy you are after. For low frequency stuff (up to a couple of hundred MHz) you could make something like this:http://www.sdr-kits.net/Webshop/products.php?84&cPath=5. It shouldn't take long to whip up something like that in Eagle using a vertical footprint for the SMA connectors. You can make and characterise your own SOLT standards as described in the PDF. For higher frequency / high accuracy though you will start to get into custom shielded enclosurescontrolled impedance lots of $$$ etc.

author: RadioNerd
author_rank: Regular Contributor
timestamp: March 03, 2017, 11:04:13 pm
content: Must the connectors be vertical or are you also OK with edge mount SMA connectors?
How to create a FET model from datasheet in ADS? - Page 1
Forum section: electronics / rf-microwave

author: MajorEE
author_rank: Contributor
timestamp: March 12, 2017, 06:40:13 am
content: I'd like to simulate the MRF1535N transistor for a VHF amateur radio amplifier in ADS, however, there is no model for this transistor. How would I go about creating a model from the specifications in the datasheet to simulate the system? I realize that without the actual die parameters it would not be perfect, but it should give me a little bit better confidence than simply throwing a matching network on both sides and saying "that should work", right?I've searched through Keysight's videos as well as some of the literature and I have no idea where to begin. Any help would be appreciated!

author: rfeecs
author_rank: Frequent Contributor
timestamp: March 12, 2017, 07:11:07 pm
content: What do you want to simulate?The datasheet gives S-parameters and large signal matching parameters.With that, you should be able to design with some confidence, much better than if you did a crude model:http://www.nxp.com/assets/documents/data/en/data-sheets/MRF1535N.pdfThe datasheet doesn't give enough information to make an accurate model. The typical way to make a model obviously is to fit the model parameters to measured data for the part. Starting with DC parameters, measure IV curves. For a power device, you may need to use pulsed IV curves to reduce thermal effects. Then you adjust the model parameters so that simulating the IV curves matches up with the measurement. Then go on to RF parameters, mainly capacitances, and package inductances. Again, you simulate and match up measured S-parameters to simulated. All this is a lot of work, so you have expensive programs like ICCAP to automate the process. Or go to a company like Modelithics and pay them a lot of money to do it for you.But obviously you are not going to do that. The best you can do from the datasheet alone is simulate the model for the transistor only and try to fit parameters to the little data that the datasheet provides. I would say this is not worth the effort, except for your own education on playing with the model parameters and learning what each one does.As I said, the datasheet already gives you what you need to design a power amplifier. Use the large signal output impedance provided, or calculate it from your load line and bias point. Design the output match and bias network. Then use the S-parameters to design the input match and bias network. You can simulate gain using the S-parameters. This should get you close enough. The rest is tuning.

author: rfeecs
author_rank: Frequent Contributor
timestamp: March 12, 2017, 07:22:47 pm
content: You probably saw this page:http://www.nxp.com/products/rf/rf-high-power-models/models-for-ads-keysight-advanced-design-system:RF_HIGH_POWER_MODELS_KEYSIGHTUnfortunately, no model for the MRF1535. Maybe MRF1550 is closest, but it has about twice the capacitance of the MRF1535.
increase ISM band transmitter and receiver range - Page 1
Forum section: electronics / rf-microwave

author: Danesh_SA
author_rank: Contributor
timestamp: February 22, 2017, 05:37:31 pm
content: Hello ,I need to have data link range about 500m indoor (there are many walls and building between transmitter and receiver). the receiver has spring antenna and transmitter has cheap chinese 434 mhz antenna.the result was not bad but i need more coverage .i teardown afew reciever devices and i found this circuit antenna block works good (i connect the output of saw filter to receiver ANT pin), it has saw filter after antenna BUT what is the blue component after antenna(RTC1)?2-how can i implement this antenna on my reciever , wich components are important(saw filter,blue component,inductor...)?3-how can i improve the transmitter range , which antenna should i use?(frequency = 433 MHz)
Keysight network analyzer E5061B - Page 1
Forum section: electronics / rf-microwave

author: AGRAIL
author_rank: Contributor
timestamp: February 20, 2017, 05:32:36 pm
content: Just receive this device for one project and already configure it for the purpose.But to perform all this measurements manually can cause additional mistakes .Due to this I would like to automate this process .I already connect to device via telnet using 5024 .But when I saw this manual (http://anlage.umd.edu/Microwave%20Measurements%20for%20Personal%20Web%20Site/E5062A_Programmers_Guide_E5061-90042.pdf)looks like it will take more time that I have .Maybe anyone have some example of code how to initialize this device via telnet ?Is it posible to setup device manually and only get value from the markers ?I found this command :CALC{1-4}:MARK{1-10} - but device ignore it and only beeping with error.Thanks in advance .

author: G0HZU
author_rank: Super Contributor
timestamp: February 20, 2017, 08:32:12 pm
content: Never used Telnet or that analyser but try this::CALC1:MARK1 ON:CALC1:MARK1:FUNC:TYPE MAX:CALC1:MARK1:FUNC:EXEC:CALC1:MARK1:X?Does this turn on marker1 and then do a search for max and then tell you the frequency of marker1 ?

author: AGRAIL
author_rank: Contributor
timestamp: February 21, 2017, 02:25:22 pm
content: Yeap , that was my fault - I use {} in commands. Now it`s provide me data as I need .Thanks
Can a radio rf section be aligned without access to signal gen with modulation? - Page 1
Forum section: electronics / rf-microwave

author: Specmaster
author_rank: Super Contributor
timestamp: February 17, 2017, 12:06:03 am
content: I thought that I would have a go at restoring an old HMV transistor radio MW/LW and FM. It has become very clear that the RF section has been messed about with and requires realigning. Years ago I had a signal generator with modulation built in that gave me a 400hz signal that could be used to detect when each section was tuned correctly.My current signal generator does not have the ability of modulation so I was wondering if there was another way of doing the alignment using the standard signal generator and an oscilloscope or is that not possible?

author: SingedFingers
author_rank: Frequent Contributor
timestamp: February 17, 2017, 01:02:48 am
content: This. Best thing is tune to a known station, tweak the VFO can until you are on top of the dial and station at the same time, then tweak the IF cans until it is loudest. Don't really need a signal gen for AM radios.

author: Specmaster
author_rank: Super Contributor
timestamp: February 17, 2017, 01:06:31 am
content: No this radio is a portable MW / LW and FM radio for listening to commercial broadcast stations in the UK. It has no SW or transceiver capabilities at all.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 17, 2017, 01:24:39 pm
content: A few 1n914 diodes, some resistors, a pair of decoupling caps, maybe a small inductor, and you have a crude but workable AM source with the existing signal generator. Your using the diodes as PIN switches or PIN attenuator.Steve
Therapy Microwave - Page 1
Forum section: electronics / rf-microwave

author: Goja
author_rank: Newbie
timestamp: February 14, 2017, 03:08:19 pm
content: Hello!Has anyone experience with a therapeutical microwave?I have a "BOSCH Radarmed 12s253" with 250W continuous power and the right emitter for that power and also the manual. (It was free btw.)So far I made it light up a fluoresence tube, but it doesent get warm at all. I tried it with a joghurt cup of water under the emitter.It would be usefull for me, to kill wood-worms in some antiques.First I'd like to know if i made some sort of user-error, by placing a cup of water under the emitter.How warm does this supposed to get?I will send some photos, when its warmer in my garage. There is an impressive transformer in it, for only 250W output (1600W peak).See you!

author: rollatorwieltje
author_rank: Unknown
timestamp: February 14, 2017, 03:34:09 pm
content: In a microwave oven the radiation is bounced around in the cavity until it's all absorbed by the food. In your case most of it will probably just go straight through or scatters. 250W also isn't really that much, even if you manage to dump all of it in your cup of water it will still take a long time before it boils. Boiling a glass of water from room temperature takes roughly 31Wh (ignoring losses), so if you can dump all the energy into the glass it would take roughly 8 minutes.

author: Goja
author_rank: Newbie
timestamp: February 14, 2017, 03:51:37 pm
content: The longest time I tried, was about 10 Minutes. Also the ambient temperature was around 0 degrees Celsius.So next time, I will test it with a larger container, to cover the whole area of the emitter.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 14, 2017, 04:53:53 pm
content: Keep youreyes, and testicles(if male) away from the emitter. If it truly is microwave, your corneas and lens are very, very, sensitive to uWave adsorption.Cataracts are a known hazard for microwave workers. Exposure can be cumulative as well. Unfortunately the only way you can know if you have a safe dose is to measure the field with a calibrated probe or fully shield the emitter. Microwave shielding is a bit of an art form, as well. From what I'm reading devices like this are primarily used for diathermy for things like breast cancer.Steve

author: Goja
author_rank: Newbie
timestamp: February 14, 2017, 05:09:02 pm
content: For shure! That's why I tested it with water and the emitter pointing down.2.45GHz plusminus 50MHz, that should be in the microwave range.I was also concerned about my electronic devices, so i tested the microwave in the garage and not upstairs in my livingroom.... Yeah, maybe also because of the weight. It is about 54,5kg according to the manual.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 14, 2017, 11:57:59 pm
content: Being a former medical service engineer, I'd also guess it looks at transmitted and reflected power from the load, and makes a decision about radiating or not. I'm sure the manual would spell that out. I know I if I sold that device in the USA, it would spend more time checking for safety then radiating.Steve
Spectrum Analyzer Accuracy - Page 1
Forum section: electronics / rf-microwave

author: damn_dirty_ape
author_rank: Contributor
timestamp: February 16, 2017, 09:45:32 pm
content: Hello,I have two spectrum analyzers that are giving me very different results.Using the first analyzer, I used the 'channel power' measurement function on a local FM station. The result is about 39.5 dBuV.I then unplug the first analyzer and plug in the second one at the antenna feed. Using all the same settings, the new result is 30.97 dBuV.I'm not trying to do certification testing or anything, so accuracy isn't crucial, but a 10 dBuV difference is a lot.The two analyers are the Anritsu MS2720T and the Keysight N9343C. They advertise .5 dB and 1.3 dB accuracy, respectively.Are the channel power measurements (39.5 dBuV and 30.97 dBuV) inside the range of variability that you would expect, or am I doing something wrong?Thanks,Peteedit: i accidentally a word

author: w2aew
author_rank: Super Contributor
timestamp: February 16, 2017, 11:25:42 pm
content: Are you certain that you have the same Channel Power settings (channel BW, RBW, detector type, etc.) for each analyzer? Make sure that there aren't any amplitude corrections on one of the analyzers.

author: Kalvin
author_rank: Super Contributor
timestamp: February 18, 2017, 01:55:31 pm
content: Compute the error in dB and see how much that is compared to the advertised accuracies. You may also want to check how far you are from the noise floors of the instruments.

author: German_EE
author_rank: Super Contributor
timestamp: February 18, 2017, 04:27:36 pm
content: Depending on where your antenna is I would expect to see a change of 9uV as you moved around the room. The only way I would consider testing two spectrum analyzers side by side is a signal generator, three calibrated lengths of coax and a resistive 50 ohm splitter. Just for good measure I would swap the connections over after the measurement and see if I could repeat the results.Finally, if two spectrum analyzers give different results then the obvious next step is a third spectrum analyzer. See the 'Test Equipment Anonymous' post in the General Chat section.
BF998 active antenna preamp - Page 1
Forum section: electronics / rf-microwave

author: awallin
author_rank: Frequent Contributor
timestamp: February 08, 2017, 06:58:32 pm
content: I tinkered together this (see pictures) active antenna preamp, mostly inspired by the PA0NHC mini-whip circuit:http://www.pa0nhc.nl/Miniwhip/indexE.htmThe output coupling-capacitor, tuning-capacitor, and BNC-connector are through-hole which somewhat detracts from the "SMD-deadbug" styleIt seems to work quite well!I made a ferrite sleeve loop coil with 10pcs 10mm diameter 200 mm long ferrite rods and 0.3 mm PU-coated copper wire. My first try showed about 25 mH on an LCR meter which was too much. Even at minimum capacitance of my 65pF tuning-cap the resonance frequency was too low. This indicated about 140 pF of input/parasitic capacitance in the resonance circuit even with the tune-cap set to minimum!? That could probably improve a lot with a proper PCB and layout?Anyway by removing almost half of the turns I got the inductance down and resonance frequency up to spec.Does it make sense to include a second stage (op-amp?) with amplification also? Most circuits I've seen (mini-whip etc) just use a unity-gain emitter-follower to drive a (long) 50-ohm coax to the receiver.Hopefully this could be used with a coax-loop antenna also, similar to this one:http://www.qsl.net/df3lp/projects/lfloop/index.html

author: Co6aka
author_rank: Unknown
timestamp: February 08, 2017, 11:41:27 pm
content: Scroll down to his "SOLDERWICK CHRONICLES" section and read his articles:http://home.earthlink.net/~christrask/
RF Explorer ghost signal - Page 1
Forum section: electronics / rf-microwave

author: Boson
author_rank: Newbie
timestamp: February 03, 2017, 02:03:45 pm
content: Bought RF Explorer 6G combo, investigating. First think 4900-5100MHz flooded with RF but then disconnect antenna and walk around. Houston we have a problem! Is this normal and present on every RFEDevice brand new - no abuse.

author: arocholl
author_rank: Newbie
timestamp: February 05, 2017, 12:32:26 pm
content: Hi, this is actually a known limitation in the low band noise floor adjustment.The factory calibration process ensure the power reading is accurate for all range, and therefore some noise floor discontinuity happens, this is normal in all spectrum analyzers of all brands, although in this case we recognize is higher value than ideally expected.We are working in a new firmware to be available shortly which will flat the noise floor significantly and still keep calibrated amplitude reading wideband.CheersRF Explorer Team
FM transmitter Line Clicks - Page 1
Forum section: electronics / rf-microwave

author: xan
author_rank: Regular Contributor
timestamp: February 27, 2017, 07:59:49 am
content: Hi Everyone,like title i want to investigate on clicks on a fm transmitter line working on a specific FM frequency, some friends say that dust on oscillator component make this kind of clicks... could be right ?You have experience with this kind of clicks?? there is something i can understand from this output? i expected to ear only noize but no clicks!!!Thank's

author: DimitriP
author_rank: Super Contributor
timestamp: February 27, 2017, 08:25:20 am
content: I've heard that before,Sounds like it's picking up noise from somewhere, could be something as simple as a bad PS on an internet routerWhere is this transmitter located ?As for the dust on the oscillator , that should be easy to check but they are probably wrong

author: xan
author_rank: Regular Contributor
timestamp: February 27, 2017, 08:31:42 am
content: Transmitter is located at about 1,200 meter above sea, no internet connection is provided there, there is only FM line TS on place.
Electrical conductivity sensor - Page 1
Forum section: electronics / rf-microwave

author: dizgah
author_rank: Regular Contributor
timestamp: January 28, 2017, 05:53:43 pm
content: I'm searching for a mature EC sensors for using in a hydroponics greenhouse,But unfortunately all devices I found are unreasonably expensive or proprietary worked on their own solution.Does any one have any suggestion?WBR.
Distribution amplfiers - comments on schematic/PCB? - Page 1
Forum section: electronics / rf-microwave

author: awallin
author_rank: Frequent Contributor
timestamp: January 28, 2017, 12:33:31 pm
content: I've thrown together another iteration of my 1PPS + 10 MHz distribution amplifier designs:https://goo.gl/photos/WB8fYd4jzba7nXH18Performance is good overall but there is always room for improvement for the next version:- the long trace that feeds the outputs on the op-amp design seems to "ring" causing gain-peaking - some impedance matching or design change would be required? what?- fed at +/-12VDC the regulators get quite hot, better move them far away and maybe thermally isolate with a slot in the PCB?- I've used 2k@100MHz ferrites a lot - maybe this is overkill/paranoia but I should probably build an LNA and verify the regulator/PSRR performance- on the 1PPS board length-matching the traces didn't fully work as there is still 200ps channel skew. 200ps corresponds to 36mm of propagation at 0.6c which seems like too much??- any other good/bad things you RF gurus out there see with the designs?(these might go on github and/or ohwr.org if they improve a bit further and there is interest..)thanks!Anders

author: mmagin
author_rank: Frequent Contributor
timestamp: January 28, 2017, 05:43:47 pm
content: I'm very interested to hear what the experienced folks have to say about the length-matched traces. I'm not sure if those squiggles are okay, but I'd love to hear why my intuition is right or wrong.Do you have a list of all the performance metrics you want this design to achieve? It seems like a much more serious approach than the usual 'just get reasonably clean 10 MHz to all of my test gear'.
Heads-up: AM sideband noise in RF amplifiers - Page 1
Forum section: electronics / rf-microwave

author: Co6aka
author_rank: Unknown
timestamp: January 23, 2017, 12:09:44 am
content: In case y'all haven't been following Leif SM5BSZ's series on just how significant AM sideband noise really is, and how it can be greatly reduced, here are his latest videos documenting his research:See his previous one or two videos to see how he discovered the presence of the noise.Fantastic discovery!
Measurement of Radar Cross Section using a VNA - Page 1
Forum section: electronics / rf-microwave

author: Bud
author_rank: Super Contributor
timestamp: February 03, 2017, 05:01:15 am
content: For you Radar aficionados, an interesting Application Note from Anritsu on using a microwave VNA to measure radar cross section parameter of objects:https://dl.cdn-anritsu.com/en-us/test-measurement/files/Application-Notes/Application-Note/11410-00604B.pdfThe link from the VNA to the object and back is represented by an equivalent 2-port network and a formula is derived to calculate the radar cross section from VNA S21 measurements. A metal sphere with a known cross section is used as a reference standard. Also time gating feature of the VNA is used to cut off clutter. It is fun to read the article if you understand VNAs and a little bit of Radar.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 03, 2017, 10:12:10 pm
content: That is just ever so Cool, Thanks! Something to try this weekend.. !Steve

author: KE5FX
author_rank: Super Contributor
timestamp: February 03, 2017, 11:42:41 pm
content: Don't forget HP's original take on the subject:AN 8510-2.

author: Bud
author_rank: Super Contributor
timestamp: February 04, 2017, 06:13:58 pm
content: Very nice, thank you!