hybridfree/eevblog-posts huggingface dataset:
ARRA 4164-20 Directional Coupler - Page 1
Forum section: electronics / rf-microwave

author: attaboy
author_rank: Newbie
timestamp: April 12, 2020, 01:48:54 am
content: Well, after many years of struggling by with an "RF Explorer" spectrum analyzer, I finally pulled the trigger on a "big boys" SA, a Siglent SA3032X Plus. So with that, ya gotta have some Coupling or Directional Bridges. One I scored from evilbay is an ARRA 4164-20. The company still exists, but it is in New York and totally shut down, and there is ZERO documentation on any site I could dig up, including the manufacturer.It's supposed to be a 2.0Ghz to 4.2 GHZ -20dB unit, but there is NO markings or engravings or stamps, as to what connector is what, like In, Out, and Dut. It looks like a Mini-Circuit's, but the perpendicular terminal is off-set. I'm kinda going full circle here, as I built a PACO V-70 in 1959 .. a Christmas present, and I still have it.Any clues on my evilbay purchase would be greatly appreciated. Take care guys and gals .. be safe.P.S. And again thanks for the discount code .. every little bit helps.

author: TheMG
author_rank: Frequent Contributor
timestamp: April 12, 2020, 02:43:45 pm
content: Actually due to the internal construction of a typical stripline directional coupler, most of them do in fact have the coupled port slightly offset.Based on that, I've indicated in the attached picture my "educated guess" on which ports are what.

author: attaboy
author_rank: Newbie
timestamp: April 14, 2020, 06:24:58 pm
content: Thanks for taking the time to "paint" the info and post the photo. Mine has the Exact same model number, but is an SMA version and is considerably smaller, like a Mini-Circuits only slightly rectangular. I also have a larger (used) 200w version with "N" type connectors, and another from the Ukraine waiting at the post office. I'll get it sorted out. Really looking forward to using my new "big boys" SA with these devices. The specs on WiFi products are always subject to "verification"
Agilent 8560EC (for sale) - Page 1
Forum section: electronics / rf-microwave

author: Electro Fan
author_rank: Super Contributor
timestamp: April 13, 2020, 02:48:34 am
content: If this happened to be in good operating condition and if a buyer happened to be close enough in the Colorado area just in case they had to use the 30 day return, this might be a reasonable deal.https://www.ebay.com/itm/Agilent-8560EC-Portable-Spectrum-Analyzer-With-Mass-Memory-Module/193419449892?epid=1103470523&hash=item2d08b29624:g:P3oAAOSwsddekkkg
AD9551 Development Board - Page 1
Forum section: electronics / rf-microwave

author: TeddyPython
author_rank: Contributor
timestamp: March 19, 2020, 01:43:56 pm
content: I'm trying to get an AD9551 signal generator development board working with the AD9551/52 Evaluation software found here:https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/EVAL-AD9551.htmlI'm running win7 64bit, and discovered that there might be some issue controlling through USB with a 64 bit OS. I therefore downloaded the AD Evaluation Board Programmer to rewrite the EEPROM to allow for 64bit operation. I get a confirmation that my rewrites complete successfully as shown below:But when I go back to the AD9551/52 Evaluation Software, it still cannot detect a board has been connected. This is despite the USB STATUS LED flashing, which should indicate it is working, as per the instructions on pgae 3 here:https://www.analog.com/media/en/technical-documentation/user-guides/UG-002.pdfDoes anyone have any suggestions as to what I can try to get this working?

author: coromonadalix
author_rank: Super Contributor
timestamp: April 11, 2020, 03:58:11 am
content: Sometimes on 64 bit you have to start your software in admin mode, i'm on 64bit, and i play with serial terminals softwares, and some of them crashes if not in admin mode ?? The 64 bit kernel is sometime pickyIs your drivers correctly installed for your cypress usb interface ? no errors in device manager ? does your vid / pid enumerate correctly ?

author: TeddyPython
author_rank: Contributor
timestamp: April 12, 2020, 12:54:01 pm
content: Thanks for the reply coromonadalix.I tried opening the AD9551 software in admin mode, but still the same issues. Device manager seems to detect it fine, though after a couple of seconds I hear the "disconnect" sound play (though the device still remains on the device manager list). I'm 99% sure it it enumerates correctly as it reads back the correct number when I use the board programmer.
How put the President Randy II, Lafayette Urano, K-po Panther, Jopix CB-413,... - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 16, 2020, 02:20:36 pm
content: Month ago I dissaamblyed the Radio to see what is wrong with the Audio Jack. The was coverd by a Shield and I but them away because i could not solder. (). Last week someone had Time to look at it under a microscope and we swap the Audio Port. Now the interresting question where does the Screws goes?!The Radio got sold under different Brands and look like this:http://www.cbradio.nl/kpo/kpo_panther.htmWhen I took it a part 2 Washer fall out. Thats the biggest problem I have no clue where the goes?!From some Video the black Screws goes on the Mainboard and the 2 Washer fit on the Black Screws.Now I found no thing where the washer as spacer would fit?!Thanks
2nd and 3rd to 10th harmonic powers of FEM - Page 1
Forum section: electronics / rf-microwave

author: thelearner
author_rank: Contributor
timestamp: April 11, 2020, 06:12:42 am
content: Hello,What is the recommended value of harmonic power?I am usingSKY66423-11FEM for my design. In the datasheet, it is specified as +7dBm for 2nd harmonic and -42dBm for 3rd to 10th. So canI select the FEM for my design?We are using it forLoRaModulation.Datasheet of the FEM -https://www.skyworksinc.com/-/media/SkyWorks/Documents/Products/2801-2900/SKY66423_11_204566H.pdfTIA
Please help me identify those chips - Page 1
Forum section: electronics / rf-microwave

author: daslolo
author_rank: Regular Contributor
timestamp: October 16, 2019, 10:34:31 pm
content: I'm trying to understand how multi billion dollar company do RF.

author: ataradov
author_rank: Super Contributor
timestamp: October 16, 2019, 11:09:06 pm
content: Micron parts are:MT41K256M16TW-107 IT:R (D9TCQ) -https://www.micron.com/support/tools-and-utilities/fbga?fbga=d9tcq#pnlFBGAMT29TZZZ4D4BKERL-125 W.94M (JWB30) -https://www.micron.com/support/tools-and-utilities/fbga?fbga=jwb30#pnlFBGASkyworks part -https://store.skyworksinc.com/products/detail/sky8574311-skyworks/605024/Others - no idea.

author: daslolo
author_rank: Regular Contributor
timestamp: October 21, 2019, 01:04:45 am
content: Thank you.So it's mostly memories, one weird P1 chip nobody knows what it does and can infer to be an image processor, some ie1000 that are possibly RF chips but nobody knows what they are.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: October 21, 2019, 11:05:49 am
content: What kind of device is this from?The way modern RF is done is usually one of four ways:- very, very crude and simple circuits using a few discrete transistors to make as cheap a product as possible. (old wireless baby monitors and such might have worked this way).- Using one of the billion off-the-shelf ICs that do radio for you - modulators/demodulators for everything you can imagine. So many different bluetooth/wifi/zigbee/etc single-chip solutions out there. Take the 5.8 GHz wireless video links used in drones - almost all of them are built based on the same pair of chips (RX and TX) from richwave, iirc.This is how mobile phones will usually do it - they have some SoC from Qualcomm or such that does 99% for you. Might add a PA and LNA or something, but all the rest is on a single chip. Thing is, a lot of these chips don't have public info out there - you need to talk to sales to see what they can offer you.- Designing an ASIC to do it for you: If you have high budget this can be useful - high speed MIMO links or such use ASICs usually (though here too you start to see off-the-shelf chips that do everything for you). This is what you find when you open up Nokia or Huawei or Erricson base-stations - bunch of custom silicon/InP/SiGe etc. combined with high-preformance analog discretes and off-the-shelf MMICs from ADI and Hittite etc...

author: daslolo
author_rank: Regular Contributor
timestamp: October 21, 2019, 07:02:40 pm
content: It's from a set of goggles receiving digital video on the 5.8Ghz band

author: trvr
author_rank: Newbie
timestamp: April 10, 2020, 11:05:52 pm
content: I came across the package with the HBCVQ mark too and wanted to find out what it was. I found your blog post during my search and I was later able to determine that the chip is an image signal processor from Aptina Imaging designed specifically to work with Aptina image sensors. Aptina is no longer around since it was acquired by ON Semi in 2014.
Sunair RT 9000 and MD 9188 - Page 1
Forum section: electronics / rf-microwave

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 07, 2020, 03:04:42 pm
content: I have a working RT 9000 and am attempting to get the accompanying modem to work, I cannot get the modem to be recognized by the transceiver. I would like to try the system out on ALE but need the modem to work.Does anyone have any experience with the Sunair 9188 modem? Perhaps there is an incompatibility with some program on the EPROMs??Any help would be appreciatedWally KC9INK
How "Voltage Variable Attenuator" ICs actually work? - Page 1
Forum section: electronics / rf-microwave

author: hanakp
author_rank: Regular Contributor
timestamp: April 03, 2020, 11:06:28 am
content: Hi all, I needed a relatively low-frequency (10-250 MHz) variable attenuator for one project, preferably solid-state one. There are ICs called Voltage Variable Attenuators which offer such functionality, and I found two possible candidates, MAX19794 and IDT F2255:https://www.maximintegrated.com/en/products/comms/wireless-rf/MAX19794.htmlhttps://www.idt.com/us/en/products/rf-products/rf-attenuators/f2255-wideband-voltage-variable-rf-attenuatorBut how do they actually work? The IDT ones allow input levels as high as 28 dBm (or 16 Vpp), which is well beyond their 5 V supply voltage. The datasheets have absolutely no information about noise, which is... suspicious. There is no mention whether the attenuator works continuously or in discrete steps. Moreover, the IDT products are bidirectional. How is that possible? The attenuator is a some sort of passive structure on the chip? I searched Maxim, IDT and Analog Devices websites for white papers or other documents with explanation, but I found none.

author: TheMG
author_rank: Frequent Contributor
timestamp: April 03, 2020, 11:46:26 pm
content: I'm going to hazard a guess that these are PIN diode attenuators with some of the DC biasing circuitry built in.The requirement for DC blocking capacitors on both the inputs and outputs does suggest that there is some DC biasing involved, which would mean most likely PIN diodes.The amount of RF conducted by PIN diodes depends on the amount of DC bias. It's bidirectional as the RF signal is AC anyways, and PIN diode attenuators are normally constructed in a symmetrical design in order to provide a controlled matched impedance on both input and output. From the RF signal's perspective, the PIN diode is essentially a passive device, acting much like a variable resistor, that is why the signal can be much larger than the supply voltage, which is used only for biasing.These would in fact be continuously variable, except of course limited to the DAC resolution for that Maxim part.

author: rfeecs
author_rank: Frequent Contributor
timestamp: April 04, 2020, 05:10:48 pm
content: These are typically done using FETs as variable resistors. The attenuator is passive and bi-directional, like a pi pad for example.
Why was 9 KHz channel spacing chosen for medium wave AM radio? - Page 1
Forum section: electronics / rf-microwave

author: AndersJ
author_rank: Frequent Contributor
timestamp: March 30, 2020, 07:17:22 pm
content: Can anyone explain the reason for using 9 KHz?I believe 10 KHz is used in some regions.When/why is one better than the other?

author: babysitter
author_rank: Frequent Contributor
timestamp: March 30, 2020, 07:20:07 pm
content: The neighbour carrier will be a beep high enough to get supressed by the filters.With 9 kHz you can cram more stations into the same part of the spectrum.

author: iMo
author_rank: Super Contributor
timestamp: March 31, 2020, 11:41:52 pm
content: The medium wave band plan incl. channel spacing is rather a subject to several international agreements made 80-100 years back.. You may google on it, it started after WWI.

author: bsdphk
author_rank: Regular Contributor
timestamp: April 01, 2020, 08:47:36 am
content: The 9kHz spacing came much later.The Danish "Kalundborg" transmitter only changed from 245 to 243 (and 1061 to 1062) kHz in 1982.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 02, 2020, 12:23:04 pm
content: Why does some Channel broadcast with a much higher channel spacing?

author: RoGeorge
author_rank: Super Contributor
timestamp: April 02, 2020, 12:32:38 pm
content: I'll assume this comes from the fact that the telephony bandwith was 3.5kHz, so they left some 1kHz margin, and because AM modulation will require the double of that around the carrier, then 4.5kHz * 2 = 9kHz for one AM channel.Just my 2 cents, no idea if that's how it was.

author: Zoli
author_rank: Frequent Contributor
timestamp: April 04, 2020, 05:18:59 am
content: The medium wave carriers wasnt't always on a multiple of 9kHz; the switch happened in the 70's(sorry, but my brain is fuzzy after all those years, regarding the date)when it was a 1kHz shift(+1kHz, something like 899->900kHz, IIRC), to make all the medium wave AM frequencies multiple of 9.

author: johnkenyon
author_rank: Regular Contributor
timestamp: April 04, 2020, 02:02:06 pm
content: Quote from: Zoli on April 04, 2020, 05:18:59 amhttps://en.wikipedia.org/wiki/Geneva_Frequency_Plan_of_1975QuoteIn the UK this resulted in all the national BBC AM radio stations moving around the dial and in some cases swapping band (Radio 2 LW>MW, Radio 4 vice versa). This happened some time in the late 70s.
Finding 6-14 GHz amplifier with SMA - Page 1
Forum section: electronics / rf-microwave

author: Aiy
author_rank: Regular Contributor
timestamp: April 01, 2020, 09:54:09 pm
content: Hello everyone,I am looking for a cheap alternative for packaged 6-14GHz amplifiers.I need 24 amplifiers in separate modules,12-20 dB gainSMA in/out+5V <100mAsmall formfactorSomewhat shielded<50 USD per pieceSo far I've only found ERA-1SM+ and other base-band amplifiers on Aliexpress and eBayMiniCircuits modules are nice but ~180 USDLotussys LNA for 2-18GHz is also ~180 USDA module like this onehttps://www.ebay.com/itm/TQP3M9008-50MHz-4GHz-2-4G-RF-Low-Noise-Amplifier-Module-20DB-High-Linearity-LNA/114127038082but with MiniCircuits GVA-123 for exampleAnybody got any ideas?Best regards

author: OwO
author_rank: Super Contributor
timestamp: April 02, 2020, 04:54:37 am
content: BFP840

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 02, 2020, 12:30:53 pm
content: Maybe from that company:https://www.ebay.com/str/gpiolabs
Raspberry Pi TV broadcaster - Page 1
Forum section: electronics / rf-microwave

author: EvolveRedux
author_rank: Newbie
timestamp: March 21, 2020, 06:38:23 am
content: Hi, I know this is a broad question but is it possible to broadcast a video by an analogue or digital signal with a Raspberry Pi or would I need a modulator. Any help would be greatly appreciated.

author: Ian.M
author_rank: Super Contributor
timestamp: March 21, 2020, 09:52:59 am
content: You need a modulator. As the PI has a baseband composite video (CVBS) output, to generate an analog TV RF signal, all you need to do is to hook that up to a modulator that accepts CVBS video in. N.B. the resolution sucks when using the Pi's CVBS TV output!

author: Lukas
author_rank: Frequent Contributor
timestamp: March 21, 2020, 01:07:29 pm
content: If you don't really care about harmonics and stuff, there you are:https://github.com/F5OEO/rpidatv

author: EvolveRedux
author_rank: Newbie
timestamp: March 22, 2020, 02:21:26 am
content: So are you saying it is possible to transmit but it would be very low resolution?
rydberg recievers? DC-Daylight - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2020, 03:27:24 pm
content: https://www.osapublishing.org/DirectPDFAccess/E8ABCE78-964E-A0DB-83CD13D813728AD5_407275/oe-27-6-8848.pdf?da=1&id=407275&seq=0&mobile=nohttps://phys.org/news/2020-03-scientists-quantum-sensor-entire-radio.htmlGame changer? how will this effect the RF worldHow do these things work, are they tuned with a laser like a YIG is tuned with a field, or is it a broadband output that needs preselection afterwards?I can't really find any mention of noise floor, Q, etc

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2020, 05:04:59 pm
content: I am afraid this is just one of those "American researchers found news / jokes" or research proposals in the hope to get more funding. It does not sound they have really achieved anything, just found an area where the they think it is not too obvious that it does not work. The more they don't understand the more they can offer as possible benefits before thegoes on.Chances are those quantum thingies need low temperature and high vacuum - so a tiny receiver that needs a truck load of cooling and pumps.Even if the receiver part works, single atoms are horribly ineffective antennas. Using quantum mechanics does not mean they are no more bound by the limits from thermodynamics / electrodynamics.

author: OwO
author_rank: Super Contributor
timestamp: March 21, 2020, 06:21:13 pm
content: Depends how much gain the whole contraption has. You can already receive DC to daylight with electrically small antennas, and with sufficiently low noise figure (amplifier input-referred noise floor < antenna noise floor) you already have optimal receiver sensitivity (you can not do better). It's a matter of how low of a noise figure you can achieve that dictates how small of an antenna you can use. If this thing actually senses E fields and output a strongly amplified signal I can see it being used in consumer applications where antenna size is an issue (wearables etc) but not military applications. You still need a big (or narrowband) antenna for transmit.

author: coppercone2
author_rank: Super Contributor
timestamp: March 22, 2020, 02:04:48 am
content: Quote from: Kleinstein on March 21, 2020, 05:04:59 pmyes, the article sounds a bit like brass wind chimes at night.. a bit creepy because this would have a ton of research uses (standard size broadband receivers for EMI testing for instance). (in case people don't get it, the military likes brass, well everyone but the people under brass, they probably want to bury brass in the woods after they clean enough toilets).
Measuring LCR over 100kHz ? - Page 1
Forum section: electronics / rf-microwave

author: MathWizard
author_rank: Super Contributor
timestamp: March 21, 2020, 10:34:33 am
content: I've seen LCR meter's, like a common cap. tester, only go to 100kHz (which is fine for a lot of stuff). I know reactance, and real parts act like entire LCR circuits. The measured values can change a lot just from 60Hz to 100kHz. Yet when I make an inductor for 90MHz, aside from trying to calculate the value, is there any point at all to use a measured value at only 100kHz ? Is it better to make a test circuit and just look at it on a scope to figure it out ?Now I'm afraid to look at the prices of better/faster LCR meters.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2020, 10:52:00 am
content: At higher frequencies the parts are usually no longer pure R, C or L. So it is more about a general higher frequency impedance measurement. These instrument are than called network analyzers (vector ir scalar form). From the impedance curve on can than fit LCR parameters of a equivalent circuit that can be more or less adequate.The measurement at some 100 kHz is relatively simple and at least good for the limiting properties.

author: bd139
author_rank: Super Contributor
timestamp: March 21, 2020, 11:16:42 am
content: Yep. Grab a NanoVNA and look at it. Gets a lot more complicatedhttps://owenduffy.net/blog/?p=17298
New portable 6GHz VNA on eBay - Page 1
Forum section: electronics / rf-microwave

author: Aiy
author_rank: Regular Contributor
timestamp: March 08, 2020, 07:58:08 pm
content: Hi everyone,I just found a new 6GHz VNA called VNA6000P on eBay which is quite affordable at 800-ish USD.https://www.ebay.com/itm/1M-6GHz-Portable-Vector-Network-Analyzer-VNA-Analyzer-3-2-Display-VNA6000P/114142071631Has anybody got any idea what it is?From the front panel it looks like it could be full 2-port, but the item description is sparse..Best regards

author: joeqsmith
author_rank: Super Contributor
timestamp: March 08, 2020, 08:32:33 pm
content: I thought I had seen where the version after the Nano V2 was released was going to be 6GHz and they plan to still keep the cost down.The one you linked appears it could be a 2-port system but I could not find any details about it.Maybe this is talking about it? I don't have an account and can't seem to view it.https://www.eevblog.com/forum/rf-microwave/chinese-vna-up-to-6ghz/

author: Aiy
author_rank: Regular Contributor
timestamp: March 17, 2020, 09:15:41 pm
content: Maybe it could be this designhttp://www.yl3akb.lv/content/vna_v2/vna_v2.phpI wonder why they don't show it with the power and GUI on.Guess we'll have to wait for somebody to review it
Bandstop Filters With Extended Upper Passbands - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: March 29, 2020, 09:54:49 am
content: I have a question onBandstop Filters With Extended Upper PassbandsWhat does it exactly mean by θ ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 29, 2020, 11:57:39 am
content: Electrical length, I would suppose. I... don't know enough TL analysis offhand to know why t, tau, theta, length (x?) or other symbols might (or might not) be chosen. Also electrical length in terms of angle, since theta is usually angular. Guess that could be a thing as well.If you're seeing lots of trig functions with just thetas as arguments, it's definitely electrical angle. If it's with other stuff, you should be able to figure it out with dimensional analysis (a trig function's argument is always dimensionless, or at worst, has dimensions of radians or other angle, if you're treating angle as a unit).Tim

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 31, 2020, 08:00:52 am
content: Indeed, from what I remember of filter design these are usually electrical length in degrees. Usually filters and matching networks are designed around some hypothetical reference frequency f0, and then you scale them so f0 becomes your center frequency of choice.
Varactor diode identification - Page 1
Forum section: electronics / rf-microwave

author: harrimansat
author_rank: Regular Contributor
timestamp: March 12, 2020, 09:52:54 am
content: Can any helpme to identify this diode type? Is a Tektronix 491 band C oscillator. Is a thread ceramic diode, 2mm aprox. 2 to 4 GHz, AFC.

author: harrimansat
author_rank: Regular Contributor
timestamp: March 15, 2020, 08:12:13 pm
content: I attach photos diodes, one is a MA45601

author: TheMG
author_rank: Frequent Contributor
timestamp: March 16, 2020, 12:29:31 am
content: I wouldn't be all that surprised if this was a special part manufactured specifically for Tektronix for use in this application. It's not uncommon to find unobtainable parts like this in test gear.If you can figure out roughly what the characteristics of the diodes should be, maybe you can find a modern equivalent. It would likely be SMD though so would require some fudging to get it retrofitted.
ts-850 atu iffy? - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: March 13, 2020, 08:46:14 pm
content: Hi all ive tried to adjust the null as per page 103 of the service manual,section 24.i couldnt seem to get it anywhere near spec into a dummy load,manual says 50mv or less,since doing this i notice the auto tuner never stops,thats into a 50 ohm dummy load or my antenna with an swr of 1.2-1,the motors whir for a seccond but it stays in transmit and thats all it does,is this related,im not sure which was to procced with this,any pointers folks?,cheers m3vuv 73
Dayton Hamvention 2020 - Cancelled - Page 1
Forum section: electronics / rf-microwave

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 16, 2020, 02:02:14 am
content: Hi group,The 2020 Dayton Hamvention has been cancelled.link:https://hamvention.org/committee-cancels-hamvention-2020/https://hamvention.org/73Jay_Diddy_B

author: Mark19960
author_rank: Regular Contributor
timestamp: March 16, 2020, 02:17:17 am
content: Would they have been allowed to have the event if they didn't cancel it??Some states have said that gatherings of 50 or 100 people are not permitted.Don't know about Ohio. But it's a good idea to defer things for now.
CG-2000 tuner schematics - Page 1
Forum section: electronics / rf-microwave

author: oh6lsl
author_rank: Newbie
timestamp: March 09, 2020, 08:13:21 am
content: HiHave anybody found a CG-2000 antenna tuner schematics from internet?I have a problem. Sometimes tuning is not happening. SWR detector has been checked and relays has been checked.JanneOH6LSL
DMR - En and Decoder? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 11, 2020, 08:18:47 pm
content: HiMaybe I will try to build my own Repeater for DMR Tier 1 Device.Is there a DMR Chipset who can handle that?Thanks

author: eb4fbz
author_rank: Regular Contributor
timestamp: February 13, 2020, 09:38:18 pm
content: I only know of 2 "hardware" DMR solutions: Sicomm (now CML) SCT3258TD/3268TD and HongRui HR_C3000/5000/6000.The big players use DSP implementations.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 02, 2020, 08:42:18 pm
content: Du you know a Price for? I could not found them Online.

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 07, 2020, 11:55:36 pm
content: I found that Module:http://www.samhoo.com.cn/index.php?m=Product&a=index&id=257&l=enDoes anyone know similar one?
Si5351 C Code - Page 1
Forum section: electronics / rf-microwave

author: CJay
author_rank: Super Contributor
timestamp: March 05, 2020, 09:50:37 am
content: More coding related really but I think most users who'd be able to answer would be RF enthusiasts...Does anyone actually calculate the register values for these chips or does *everyone* just use the Jason Mildrum library or Clockbuilder software to create VFOs/fixed outputs?

author: bd139
author_rank: Super Contributor
timestamp: March 05, 2020, 10:32:23 am
content: Right up my streetNeither. I use something based on the AVR I2C Si5351A library from hans summers:http://www.qrp-labs.com/synth/si5351ademo.htmlThe code is dead simple, well documented, easy to understand and actually works properly unlike all the other car crashes out there. Key thing is it shows how things are calculated.Edit: Just a point on the Si5351A, it causes horrid nasty clicks on some frequency transition boundaries I assume due to PLL register changes. Haven't worked out how to kill them. I'm concentrating these days on using analogue VFOs with 10 turn pots (particularly the one in the K8IQY 2N2/40 which seems to be unrealistically stable) and using an MCU to display frequency. Also a lot less power hungry!

author: bd139
author_rank: Super Contributor
timestamp: March 05, 2020, 01:49:19 pm
content: That's rather interesting - will read that thread in detail later. Thanks for the link

author: radiolistener
author_rank: Super Contributor
timestamp: March 05, 2020, 08:36:38 pm
content: Quote from: CJay on March 05, 2020, 09:50:37 amyes, there is nothing complicated. Most of published libraries has some bugs or just not efficient as it should be. So, it's better to learn AN619 and write your own implementation. Since there is a lot of ways to use si5351, I'm afraid there is no universal and efficient way to implement it for any possible case, so implementation will depends on your needs.

author: radiolistener
author_rank: Super Contributor
timestamp: March 05, 2020, 08:40:53 pm
content: Quote from: CJay on March 05, 2020, 12:12:34 pmclick is related with PLL reset. When you perform PLL reset, it will disable output for several milliseconds. It leads to clicks. But PLL reset is required when you change PLL frequency. But there are some tricks which allows to reduce PLL reset call. In short, it depends on what frequency range you're want to use for sweep. By using specific sequences you can omit PLL reset in some cases.The problem with PLL reset is that you cannot be sure that PLL works ok and output frequency is correct if you didn't perform PLL reset after PLL registers change. But when you doing PLL reset, it will needs to disable output for some millisecond period.When you don't change PLL register, you're don't needs to perform PLL reset and can change frequency within band with no clicks.

author: ardf
author_rank: Contributor
timestamp: March 06, 2020, 08:55:15 am
content: I usedhttps://github.com/pavelmc/Si5351mcu/library in my ARDF projects. I don't use Arduino, so I converted the code to C.
Es'Hail-2 (QO-100) out of band emissions and help to understand - Page 1
Forum section: electronics / rf-microwave

author: msimunic
author_rank: Contributor
timestamp: December 05, 2019, 01:40:40 pm
content: HiI'm trying to find Es'hail-2's out of band emission specifications.The only information I found is basically saying "No transmissions should be made beyond the nominal edges of the transponder passbands."OK, this is obvious, but in real life there is no brick-wall filter.Es'Hail-2's band plan says nothing about out of band emissions.What I'm trying to find is specifications on how much emission is allowed in neighbor channels.Is this in the order of -20 dBm, -30 dBm, .... -60 dBm (hard to achieve)?I can't find ITU specs for 10.45 - 10.50 GHz (amateur band) for satellite transmitter (downlink).Such specifications are defined for ie. mobile communications and DTV channels in the spectrum below 1 GHz.Also, maybe I'm searching for the wrong keywords. I'm not sure (do not understand enough) how out of band emission is defined.Is it defined as relative to passband, relative to carrier (dBc) or something else?Please, can anyone help me understand?I would appreciate some references to the documentation and/or standard specifications.

author: msimunic
author_rank: Contributor
timestamp: March 04, 2020, 04:03:55 pm
content: Funny to readhttps://qrznow.com/new-qo-100-band-plan/when nobody answers the original question.Not a single word.

author: eb4fbz
author_rank: Regular Contributor
timestamp: March 04, 2020, 05:40:57 pm
content: Your local regulations apply
my antenna vna pics - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: March 10, 2020, 01:06:57 pm
content: Hi all can folks have a look at the pics and give me your views,its 2 80m mobile whips in a dipole config for nvis on a spot frequency of 3.775 Mhz

author: m3vuv
author_rank: Super Contributor
timestamp: March 10, 2020, 01:12:30 pm
content: here we go some more

author: m3vuv
author_rank: Super Contributor
timestamp: March 10, 2020, 01:14:46 pm
content: and some more.

author: m3vuv
author_rank: Super Contributor
timestamp: March 10, 2020, 01:20:26 pm
content: and the last ones,btw this is for nvis local inter G

author: DH1AKF_Wolfgang
author_rank: Contributor
timestamp: March 10, 2020, 04:57:37 pm
content: Please let us know about the geometry of your antenna. A simple parallel resonant circuit with tapping gives the same results...73, DH1AKF

author: m3vuv
author_rank: Super Contributor
timestamp: March 13, 2020, 08:51:14 pm
content: heres a small pic of it
That one Russian FTP site that I won't say the name of - Page 1
Forum section: electronics / rf-microwave

author: angrybird
author_rank: Regular Contributor
timestamp: February 27, 2020, 12:12:44 am
content: There was this Russian FTP site. Had all the radio software on it - The good stuff - Decoders/demodulators, the stuff you don't find anywhere else.I took it for granted and now it seems to be gone. IP is there but no FTP services running and username/password does nothing.Does anyone on here know what happened to it? If you don't know what I'm talking about, you haven't heard of it.I wish I would have archived it all when I had the chance.PM me

author: m3vuv
author_rank: Super Contributor
timestamp: March 02, 2020, 08:25:22 am
content: The site you didnt mention!!,i will answer after my new crystal ball gets delivered.
Crossed yagi : phasing ? - Page 1
Forum section: electronics / rf-microwave

author: jujun
author_rank: Regular Contributor
timestamp: March 13, 2020, 12:51:00 pm
content: Hello,I just got an old 19 elements cross yagi for UHF. I want to use it in circular polarisation.What I don't understand is that the two folded dipoles are 20cm apart. This doesn't seem to provide a 90° shift, but more.I found that the resonant frequency of the antenna at feed point is in the UHF amateur band (no surprise) 430-440Mhz.Why the two polarisations are not 90° appart? Maybe there is a reason for it?Should I correct it with a little more coax length on one side?Thank you for your help

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 13, 2020, 02:14:36 pm
content: Could you post a picture? Might help clarify things a bit.

author: jujun
author_rank: Regular Contributor
timestamp: March 13, 2020, 03:28:23 pm
content: I will take a pict of the actual antenna soon.Here is a shematic found on the web that explain how it should be.
Photo challenge - microwave identification needed  - Page 1
Forum section: electronics / rf-microwave

author: ghiltfsy78
author_rank: Newbie
timestamp: March 02, 2020, 11:42:23 pm
content: Hi everyone,I was hoping for some help. My microwave isn't working properly and finding a user manual has proven extremely difficult. I was really hoping, that someone would know what the actual model is or how I can find the user manual.Please see the photos of the front and the back sticker attached.Thanks in advance

author: StillTrying
author_rank: Super Contributor
timestamp: March 03, 2020, 12:58:14 am
content: Itlooksthe same as the SHARP R28STM to me, the user manual might be close enough.www.sharphomeappliances.com/r28stmI'm not sure it's the right type of microwaves for this section.
Tools for broadband impedance matching? - Page 1
Forum section: electronics / rf-microwave

author: mark03
author_rank: Frequent Contributor
timestamp: February 20, 2020, 08:27:05 pm
content: Suppose I'd like to design a lumped-element, broadband matching network. That is, given Zload as a [complex-valued] function of frequency, synthesize an LC network which minimizes some error criterion over a target bandwidth. Zsrc may be assumed to be resistive, or it could be complex, or also frequency-dependent---I am interested in both cases.A simple example would be a dipole antenna matched to a 50-ohm source, where the user wishes to achieve the lowest possible reflection coefficient over a specified bandwidth. Ad hoc solutions exist (seehttp://www.arrl.org/files/file/QEX_Next_Issue/Nov-Dec2018/Leeson.pdf) but in the 21st century it seems there should be a proper computer-aided way to tackle this.From what I can glean using google, there are a few tools/methods:1) something called the "Real Frequency Technique" (from a paper by Carlin in 1977), but no free implementation that I can find.2) GRABIM: grid approach to broadband impedance matchinghttps://ia800807.us.archive.org/19/items/BroadbandImpedanceMatchingUsingGRABIM/March1999-p68.pdfbut again no software/tool available AFAICT.3) QUCS wideband matching tool. I am not sure which method this uses.Any suggestions?

author: rfeecs
author_rank: Frequent Contributor
timestamp: February 20, 2020, 10:10:18 pm
content: All the high end RF design software has this built in.Keysight ADS:https://edadocs.software.keysight.com/display/ads2009/Introducing+the+Impedance+Matching+UtilityAWR:https://awrcorp.com/download/faq/english/docs/Users_Guide/iMatch.htmBut in practice, often it is done just simulating using the Smith Chart and by experience adding the appropriate components, looking at the match, manually tuning ... iteratively. Most simulators also have an optimizer that will adjust component values until the goal is achieved.

author: mark03
author_rank: Frequent Contributor
timestamp: February 20, 2020, 10:30:06 pm
content: Thanks. I should have mentioned that I'm a cheap hobbyist so unless there is some free option, I'm out of luckBut this explains the fall-off in papers and articles around the 80s/90s era... all the professionals have it.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: February 21, 2020, 08:27:19 pm
content: Ltspice and sim smith i think its called
Helical antenna manufacturers for 865MHz / 868MHz frequency band - Page 1
Forum section: electronics / rf-microwave

author: madhu.wesly01
author_rank: Regular Contributor
timestamp: March 10, 2020, 09:13:10 am
content: Hi,I'm working on a LoRa radio device and was hoping to discuss some antenna alternatives. Can anyone suggest helical antenna manufacturers available in India for 865MHz / 868MHz frequency band?TIA.

author: beanflying
author_rank: Super Contributor
timestamp: March 10, 2020, 10:02:56 am
content: Start with having a good look at this search result from Andreas Spiess. Also keep an eye out for links in the video descriptionshttps://www.youtube.com/channel/UCu7_D0o48KbfhpEohoP7YSQ/search?query=lora+antennas
radar for object detection  - Page 1
Forum section: electronics / rf-microwave

author: Martinizhr
author_rank: Newbie
timestamp: February 17, 2020, 08:44:07 pm
content: Hi everyone,I'm newbie when it comes to radars and need some help.I want to make a radar that can detect people/objects from the back of the car when it is reversing.I have demo position2go kit, but I can't seem to configure it to detect reliably.Sometimes it detects when nothing is there and sometimes it doesn't detect objects(people), and usually it detects "ghosts" (short blimps).I have been using Infineon's radar GUI for that tests and it seems easy to setup but it just doen't work.Does anyone have any experience with radars for object detection?Is it just me or position2go demo doesn't work as they claim?Please help me, I can compensate you for your help, I just need that to work.Thanks for any reply in advance.

author: LakshmiN
author_rank: Contributor
timestamp: February 18, 2020, 12:34:16 pm
content: http://www.ti.com/tool/TIDEP-0090

author: rhodges
author_rank: Frequent Contributor
timestamp: February 18, 2020, 03:28:58 pm
content: Would a microwave "motion sensor" be useful? The RCWL-0516 is cheap and seems to be pretty sensitive. It might be more sensitive than you want, you might have to change a resistor to reduce its range.

author: Martinizhr
author_rank: Newbie
timestamp: February 18, 2020, 11:09:05 pm
content: Quote from: LakshmiN on February 18, 2020, 12:34:16 pmI have seen that radar too. I think I will order it and test it to see how it performs.Quote from: rhodges on February 18, 2020, 03:28:58 pmI have tested it and there were several problems with it. First I couldn't change it's detection angle and second is that it detected movement if I moved it, even if it was facing the sky without any obstacles around it. So positioning it in a moving vehicle is not an option because of vibrations.
Struggling to connect 0.034 mm (0.86 mm) coax to PCB - Page 1
Forum section: electronics / rf-microwave

author: ezalys
author_rank: Frequent Contributor
timestamp: February 20, 2020, 12:32:15 am
content: Hey all,I have a somewhat spatially constrained design where four pieces of 0.034 mm (0.86 mm) coax need to connect to a PCB. If I use SMA connectors, that eats up most of the cross-sectional area of the 1" tube everything needs to fit in. I therefore need to use MMCX, MCX, SMP, or something similar. This design needs to work well up to 1.5 GHz, so nothing too fancy. The coax is spec'd this diameter for reasons that aren't electrical and the diameter is fixed. Where can I find right-angle MMCX/MCX/SMP connectors that are compatible with this coax? Why is it so rare? Google isn't turning up very many results.If needed, I don't mind just soldering the coax to the PCB and end-launching. Is this done in professional designs? The coax never really needs to be disconnected, but connectorizing would be better.Best wishes,Evan

author: DaJMasta
author_rank: Super Contributor
timestamp: February 20, 2020, 12:35:07 am
content: They're not all that durable for multiple removal/connection cycles in my experience, but what about U.FL connectors? They're widely used for SMD connections to wifi or GPS antennas.

author: rfdave#gmail.com
author_rank: Contributor
timestamp: February 23, 2020, 02:00:11 am
content: Which dimension is metric, and which value is Imperial?Does the manufacturer of the coax have suggestions for connectors? I wouldn't consider soldering down the coax to be a solution other than for 1 or 2 units.

author: Rerouter
author_rank: Super Contributor
timestamp: February 23, 2020, 03:36:48 am
content: Another vote for U.FL but also plan some strain relief, due to there tiny size they can be tugged out if you load them up too much.

author: daqq
author_rank: Super Contributor
timestamp: February 23, 2020, 10:26:09 am
content: Would this help?https://uk.farnell.com/avx-interconnect/009178001001006/connector-idc-coax-rg178-50ohm/dp/1891148QuoteTo the best of my knowledge, yes, but reluctantly, mostly in cheaper devices.
A7105 radio chip, passives, RF magic - Page 1
Forum section: electronics / rf-microwave

author: MarkR42
author_rank: Regular Contributor
timestamp: February 16, 2020, 05:57:46 pm
content: Hi,I've been using the A7105 (https://files.banggood.com/A7105%20Datasheet%20v1.4.pdf) chip on a pre-built module ("MD7105-SY" on Aliexpress etc) to make my own RC receivers. This is working ok, (I have the firmware / software basically working) but I am interested in finding a way to do it without the module, in particular because the module uses an incredibly large crystal which is very inconvenient for my application.The module only contains the A7105 chip, a PCB antenna, a crystal, and a bunch of passives. The module schematic isn't available and I've not successfully reverse-engineered it, however it is using very tiny passives (0402 or smaller?)I've looked at the application circuit in the datasheet (page81) , and there are a *LOT* of passives, 18(ish) capacitors, 2 resistor and a couple of inductors, as well as the crystal.I don't understand RF stuff very well, so please, can anyone explain to me (or link to a suitable reference source)* What do all these passives around the antenna do?* Is there any obvious way of reducing the component count without affecting functionality? (e.g . C17 and C18 appear to be duplicates, as far as I can see they're connected in exactly the same place in the circuit, maybe there is some arcane reason to use 2x 1pf cap instead of 1x 2pf)* C13 and R2 look weird, I suppose it's a power decoupling thing, or maybe startup sequencing?The datasheet doesn't explain much what these parts do, and I don't have much other doc (even in Chinese) - it is a Taiwanese company and I *need* to use this chip to interoperate with other devices which also use it (probably).

author: radiolistener
author_rank: Super Contributor
timestamp: February 17, 2020, 06:40:01 am
content: Quote from: MarkR42 on February 16, 2020, 05:57:46 pmC18 is a part of LC filter, it should be the same as C16. C17 is a part of antenna matching circuit. There is critical even PCB layout and even solder amount. Also, there is critical Q-factor for capacitors and inductors. So, you cannot remove it with no affect on receiver/transmitter performance. And you're needs to use very good quality (RF-grade with high Q-factor) components at these places.Quote from: MarkR42 on February 16, 2020, 05:57:46 pmThis is VCO frequency control input, which is very critical, so it's better to leave it as is, according to datasheet recommendation.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: February 17, 2020, 09:04:44 am
content: I think C13 and R2 will be to stop high frequency oscillations in the VCO/PLL circuits. L3 C12 etc are connected to the internal voltage regulator, so they are setting the bias point to output amp with L3 blocking RF going back into the power system, L2 and C10 are high pass filtering the input pin, the other part of the input circuit, C16,17,18 and L5 is low pass filtering. C6 is Dc blocking.At a guess. Microwaves are a mystery to me, i am a lower part of HF kind of guy LOL
Dual-band Wireless Routers - Page 1
Forum section: electronics / rf-microwave

author: jam04
author_rank: Newbie
timestamp: February 17, 2020, 04:08:53 am
content: How do dual-band wireless routers work?I'm working on a project design (i.e. rectifier) that i need to operate at two frequencies and learning about dual-band devices would be a major help in my case. Any form of schematic diagram or block diagram would be greatly appreciated. Thanks in advance

author: ejeffrey
author_rank: Super Contributor
timestamp: February 17, 2020, 04:19:18 am
content: Most if not all are dual radio. So two separate radios, one for each band. They are combined with a frequency diplexer to let them share antennas.