hybridfree/eevblog-posts huggingface dataset:
NIST - National Institute of Standards Tree? - Page 1
Forum section: electronics / rf-microwave

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 28, 2017, 08:03:29 pm
content: I have heard the term "shade-tree mechanic".But here is what Google satellite-view identified as the NIST in Ft.Collins, Colorado.Is this what Dave means by "kinda how 'ya doin"?https://www.google.com/maps/place/NIST+Radio+Station+WWV/@40.6683978,-105.0398255,154m/data=!3m1!1e3!4m5!3m4!1s0x876934b040547107:0x987903210de784fb!8m2!3d40.6796942!4d-105.042429

author: jmelson
author_rank: Super Contributor
timestamp: November 28, 2017, 10:11:44 pm
content: Quote from: Richard Crowley on November 28, 2017, 08:03:29 pmTry looking up their Gaithersburg, MD location. At least for some time after 9/11, they had all references to the campus purged off the maps. No public signs, no phone book entries, just a guard shack with a blank sign board next to the gate.Jon

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 28, 2017, 11:13:30 pm
content: Quote from: jmelson on November 28, 2017, 10:11:44 pmGoogle identifies one of the antenna towers as "WWV" and you can see the NIST "campus" amid the antenna farm (although not labeled).

author: denverpilot
author_rank: Regular Contributor
timestamp: November 29, 2017, 05:35:44 am
content: Quote from: Richard Crowley on November 28, 2017, 11:13:30 pmI believe much of their “campus” is away from the antenna farm, over closer to Boulder in “normal” office spaces. NCAR also has a large facility in Boulder.The antenna farm was in the “middle of nowhere” when I was a kid. Now it’s being encroached on by the millions who have moved to the Front Range area since then. 8 million plus and counting. Getting too crowded around here.
Got the urge, help me, please - Page 1
Forum section: electronics / rf-microwave

author: cncjerry
author_rank: Unknown
timestamp: November 11, 2017, 11:48:36 pm
content: I was in HRO in Oakland and they have a set of Kenwood twins I've never seen before and seem to be priced right. I didn't know Kenwood had twins and I've been into amateur radio for 47yrs. Anybody know anything about them?Just what I don't need.Thanks, jerry.

author: sycho123321
author_rank: Regular Contributor
timestamp: November 12, 2017, 01:11:44 am
content: These what you talking about?https://www.hamradio.com/detail.cfm?pid=31-001814

author: cncjerry
author_rank: Unknown
timestamp: November 12, 2017, 01:50:46 am
content: yep. I had never seen them before and these look to be in great shape. I read where they were imported by Henry Radio back in the day.

author: GreyWoolfe
author_rank: Unknown
timestamp: November 14, 2017, 11:16:54 pm
content: If you are interested in buying them, make sure the interconnect cable is there. They are made of pure unobtanium, though I haven't looked to see if there was a way to replicate them. I have 2 sets of them here that were donated to my club that I will be trying to sell. I will be selling them cheap as they don't have the cable, aren't in the best of shape, but do have the speaker. A project for sure for anyone that wants to take them on. I am hoping to find a local buyer for both sets at a good price as I don't want to go through shipping.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: November 15, 2017, 04:27:12 am
content: I covet the Kenwood Twins.
BNC Connectors compatibility - Page 1
Forum section: electronics / rf-microwave

author: 001
author_rank: Super Contributor
timestamp: November 14, 2017, 10:34:24 am
content: Hi!I`gonna make few BNC RG58 paches for my gear (FG, Scope etc. all my works BELOW 100Mhz)BUT I see around only two types of ruged BNC connectorsOne is 75Ohm Neutric (well, it is truly 75Ohm and needs RG59 but build WERY well since it is Neutric)And other sturdy variant is some china "soldering+nut" type wich is fitted to RG58 but center pin looks so thin like common video 75Ohm BNCsWhat the way?I`m google for it and many peoples says what diameter of center pin is a horrible problem.

author: dmills
author_rank: Super Contributor
timestamp: November 14, 2017, 01:16:49 pm
content: If the connectors are correct then for BNC the pin geometry is the same between 50 and 75 ohm parts, but the insulating sleeve extends further in one variant.Thus 50 ohm and 75 ohm BNC parts should mate without damage (This is **NOT** true for N type connectors!).There have however been some BNCs made that did not meet normal specifications, I forget who the guilty party was, but someone stuffed this up, so there were some 75 ohm parts around that did not behave well with 50 ohm mates.I am surprised by you having trouble finding proper 50 ohm parts, Telegartner/Huber-Schurner/MA-Com/Amphenol should all have the good stuff I would expect.@100MHz it probably does not much matter, unless you are trying to make metrology grade measurements, so use whatever comes to hand.Regards, Dan.

author: 001
author_rank: Super Contributor
timestamp: November 14, 2017, 02:45:14 pm
content: Quote from: dmills on November 14, 2017, 01:16:49 pmI`m far from "golden billion" lands and simply cabbage parts what I seeSanx for quick answer

author: David Hess
author_rank: Super Contributor
timestamp: November 14, 2017, 04:23:09 pm
content: I have found that using double shielded cable makes for a much more reliable interface between the connector and cable.

author: fcb
author_rank: Super Contributor
timestamp: November 14, 2017, 05:16:31 pm
content: Try to use the correct impedance BNC for your application (scope's, RF are 50ohm, video is 75 ohm). Whilst damage from the wrong impedance BNC is unlikely, I've certainly had problems with different BNC's centre pins spoiling sockets - tends to be more brand specific though and I can't remember the details (back in the 90's).

author: dmills
author_rank: Super Contributor
timestamp: November 14, 2017, 05:37:55 pm
content: There was someone doing horribly broken '75' ohm BNCs back then, I cannot remember who it was, but a load of the evil things got into the TV production game and caused all sorts of pain.There is something to be said for NOT buying the cheapest connectors you can find, unreliable test leads are annoying (But you have not discovered the horror of expensive RF leads until you acquire a network analyser).Regards, Dan.
RF transistor biasing issue - Page 1
Forum section: electronics / rf-microwave

author: Teknow
author_rank: Regular Contributor
timestamp: November 13, 2017, 11:34:37 am
content: Considering ,among others, an AVGO RF transistor biasing Application Note 1293, some questions arise for which I could find no answer.The Vce of a variety of RF transistors at hand is 10 Volts. If I strictly follow the instructions of biasing RF and general purpose ones setting Vce to be 0.5 Vcc then Vcc has to be 20 Volts.However I have been biasing RF transistors according to the Data sheets where Vce is 10 Volts but I used a power supple for Vcc 12 or 13.5 and sometimes 15 Volts and never 20 Volts as this is sometimes not practical (especially when car battery operated). Does the RF transistor also go into saturation this way even when the circuit design is for FM applications?In some data sheets for Class C power amplifiers Vce is 13.5 Volts for instance, should the Vcc then be 27 Volts or is Vcc the same voltage as Vce in this case?So should Vce always be half Vcc. Is this a rule for RF transistors too?

author: rfeecs
author_rank: Frequent Contributor
timestamp: November 13, 2017, 05:49:57 pm
content: Quote from: Teknow on November 13, 2017, 11:34:37 amThat only applies to biasing with a collector resistor. Typically for RF circuits you bias through an inductor, particularly for power amps. So Vce will be approximately equal to Vcc.Here's another biasing article:http://www.qsl.net/va3iul/Bias/Bias_Circuits_for_RF_Devices.pdfOn page 4 you will see a class C circuit biased through an inductor.

author: Teknow
author_rank: Regular Contributor
timestamp: November 14, 2017, 07:03:18 am
content: Thank s a lot RFeecsActually I looked at this one some time ago and its almost in agreement with Bowick's and Sayre's ideas on the subject. But I happend to find some designs which support my understanding of the data sheet, mainly adopting the suggested Vce and Ic without the necessity of applying a Vcc which is 2 times Vce.Here is an example which supports what I mean.Vcc is 10 volts Vce is 8 voltshttp://www.qsl.net/yu1aw/LNA/bfp196peng.htm
50 Ohm BNC Feed Through  - Page 1
Forum section: electronics / rf-microwave

author: xzswq21
author_rank: Frequent Contributor
timestamp: November 12, 2017, 04:29:40 pm
content: HelloI want to buy some BNC 50 Ohm Feed Through (BNC or SMA).but do you know any product from mini-circuits company? I checked and I didn't see any Feed Through.Thanks

author: tggzzz
author_rank: Super Contributor
timestamp: November 12, 2017, 06:00:55 pm
content: Have you considered:asking MiniCircuits directly; they might know the answer better than we dolooking at the answer to the identical question you asked 8 hours earlier

author: ahbushnell
author_rank: Frequent Contributor
timestamp: November 12, 2017, 06:01:13 pm
content: Digikeyhttps://www.digikey.com/products/en/connectors-interconnects/coaxial-connectors-rf-adapters/374?k=&pkeyword=&pv69=4&FV=f0005c%2C14f80001%2C1f140000%2Cffe00176%2C14f00048&mnonly=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=100I misread the question.But digikey has terminators.

author: xzswq21
author_rank: Frequent Contributor
timestamp: November 12, 2017, 06:36:33 pm
content: Quote from: tggzzz on November 12, 2017, 06:00:55 pmI asked them before but I didn't receive any solutions :|they told me this is not a good solution to convert the input impedance of your Oscope to 50R :| , they didn't mentioned anything about the Feed Through.actually they are right, now I want to build an active adapter.

author: Gyro
author_rank: Super Contributor
timestamp: November 12, 2017, 06:52:08 pm
content: A feedthrough terminator is as good as it is possible to get if the scope doesn't have an internal terminator. An active adapter would add complexity and probably additional noise too.There's no reason to insist on buying one from MiniCircuits though.

author: xzswq21
author_rank: Frequent Contributor
timestamp: November 13, 2017, 08:53:34 pm
content: Quote from: Gyro on November 12, 2017, 06:52:08 pmYes, You are rightI know such products from Rigol, Pomona and some low price feed through as follow:https://www.fasttech.com/products/6767500(actually there are two 100 Ohm resistors inside, after buying some of them have 100 Ohm impedance! it depends on your chance!)some people build one at home, others use BNC T Adapter+50R Capline.

author: jpb
author_rank: Super Contributor
timestamp: November 13, 2017, 09:17:39 pm
content: High bandwidth scopes generally have a 50 ohm option. For low bandwidth scopes (say up to 200MHz), then the solution posted by xzswq21 of using a t-converter and a 50 ohm termination probably works ok. Though the response by minicircuits is probably right as you would have 50 ohms in parallel with the RC of the input to the scope.My scope does have 50 ohm input as an option but it is limited to 5Vrms before damage so sometimes I've used a T-connector and 50 ohm termination on the 10Mohm input when working with signals I suspect might be quite large.
US -> GSM/ Iden Range? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: November 21, 2017, 01:46:08 pm
content: HiWhat was the Coverage in ~2000 with an GSM/ Iden Phone?Here an Youtube Channel about the 11.9 have an theory that Cellphones dont work onboard an Aircraft.I know as an CB/ PMR446 user that the Radio Waves can travel with an very low output power very far.Another question is are Window in the Aircraft big enough to lett the Waves truth the Window?
Ferrite chokes and transformers at 433MHz? - Page 1
Forum section: electronics / rf-microwave

author: orolo
author_rank: Frequent Contributor
timestamp: November 12, 2017, 01:34:12 pm
content: I'm experimenting with Microchip's (now obsolete)MRF49XA. I have a very good kit of Johanson SMD caps, but I lack SMD inductors, and I can't linger too much with this experiment, so I've decided to try ferrites. I intend to feed a resonant loop antenna (about 12cm radius). I have several doubts I'd be grateful to have them cleared before the pain of building the twin of this circuit to send/receive. With one model I can at least check if there is MCU connection and programming before moving on.1. The differential RF IO of this chip is open collector, so I need a choke to Vcc for both pins. I've made a choke out of several bifilar turns of 0.1mm wire around a FT-23-43, and the connected them as a differential mode choke (see attachment). Is this reasonable/will it work?2. To feed the antenna, I plan to use a 1:3 transformer made out of a FT38-67 toroid, followed by a short (few cm) run of two cables taken from an IDE drive (hopefully, around 150 ohms impedance) directly into the antenna.3. I will have to add some inductance to both RF outputs to compensate for the MRF49XA's output capacitance. I was thinking tiny air core coils, carefully computed from theHamwaves inductancepage. Can I add just one inductor to one output for all the inductance, or is it better to make two, half value, one for each output? In this latter case I have more trouble with board space and coupling.This is my first UHF circuit, I'm doing it in a hurry, and I don't have much experience nor test equipment to check if this is good. I know that the ferrite option will be very lossy, both in copper and core, but except for that, the concept is at least doable or just silly?Thank you for your time.I tried posting the image as "jpeg" and the forum didn't recognize that extension. Then renamed to "jpg", and the forum listed this post as already posted. So I don't know if this will result in multiposting. Sorry for the inconvenience.
Antenna working on metal surface - Page 1
Forum section: electronics / rf-microwave

author: blueskull
author_rank: Unknown
timestamp: November 06, 2017, 08:23:27 pm
content: My first post in this section here. Is there a type of antenna that can operate "ON" a metal ground plane?Looking for 2.4GHz~2.5GHz antenna for WiFi+BT.Can be adhesive flex PCB antenna or ceramic chip antenna.I know ceramic patch antenna will work, but the smallest I can find is 12mm*12mm, which is too big for me.I also came across the 3M "on-ground" antenna, but from its app note, it seems a ground clearance is recommended, so it's not truly "on-ground". Correct me if I'm wrong.Target size: less than 9mm wide, 20mm long and 5mm thick.Any suggestions?

author: CJay
author_rank: Super Contributor
timestamp: November 06, 2017, 08:40:39 pm
content: I was going to suggest grabbing a copy of the Pi 3 schematics as it's got a ceramic antenna that's roughly 2x5mm and there may be a hint of a part number but the 'schematics' seem to be pinouts of the connectors which is somewhat useless.

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 06, 2017, 08:46:59 pm
content: You mean an existing GND plane? Or a PCB you're designing that should have an as-solid-as-possible GND plane?Something like this:https://www.digikey.com/product-detail/en/proant-ab/PRO-OB-440/1532-1001-2-ND/4895679maybe?

author: Ice-Tea
author_rank: Super Contributor
timestamp: November 07, 2017, 02:29:09 pm
content: Too bad they are a bit big, or they'd fit the bill rather wellhttps://www.lsr.com/embedded-wireless-modules/antennas#flexpifa

author: cdev
author_rank: Super Contributor
timestamp: November 08, 2017, 12:17:26 am
content: A flex PCB antenna would be better. If you have a bit more room inside your case, use it.Even just a wire enclosing a small loop in your flex PCB would likely be better.Taoglas is a reliable company and their circular ceramic patch GPS antennas are quite decent. I would trust them as far as quality, however that said unless you need it to be in a very small space don't.Before you commit, if I were you I would get at least one, preferably a few of each antenna you might use so you can try them out in a real world test before buying a bunch of any of them.Its hard to find a really small 2.4 GHz antenna that performs well at a long distance.The one that is in the Raspberry Pi 3 doesn't perform super well.

author: hagster
author_rank: Frequent Contributor
timestamp: November 12, 2017, 09:53:03 pm
content: Could you make a slot antenna?. It would mean cutting a thin slit in the metal (or finding an area where there is a natural gap between sections), but slot antennas are really efficient.
Oh Dear!! - Page 1
Forum section: electronics / rf-microwave

author: German_EE
author_rank: Super Contributor
timestamp: November 10, 2017, 07:37:04 pm
content: Elsewhere on the board we have often talked about GAS or Gear Acquisition Syndrome but normally it applies to test equipment. As ham radio operators we know that there are other possibilities. I've been badI just picked up a Heathkit SB104A, plus the external speaker/power supply, plus the external VFO from a silent key sale. The SB104 has problems and it's going to be my Winter project. It looks great though so my next problem is finding space in the shack.Any SB104 experts out there?
RDA1846 sample code - Page 1
Forum section: electronics / rf-microwave

author: jtronix
author_rank: Regular Contributor
timestamp: November 09, 2017, 11:15:22 am
content: Hi all,I'm looking for sample code for RDA1846 I2C for communication with microcontroller. I got one of the sample from github it won't help me.Also I assume that programming manual for RDA846 is not good many information are missing.
Power (Voltage / Current) inducted in rectangle antenna. - Page 1
Forum section: electronics / rf-microwave

author: Esmundo
author_rank: Newbie
timestamp: November 20, 2017, 09:48:30 am
content: Hello,I have application with similar construction to RFID, however I'm not sure if my calculations are correct. This is crucial for my project because it's supose to by my power supply.I'm trying to calculate what voltage and current would be inducted in rectangle antenna by magnetic flux at specific frequency. I found out that:Code:U = - N * d(Mflux)/dtwhere: Mflux - magnetic flux, N - number of wraps in coil (1 in my case)so if magnetic flux is sine at specific frequency than inducted voltage would be also sine at same frequency. If I want to calculate peak-to-peak voltage can I divide peak-to-peak magnetic flux by half of period of sine wave?Also this is eqution that I've found for calculating current in antenna (coil):Code:I = N* Mflux/Lwhere: L - antenna inductance (page 14 from file below).This is the file that I used for calculation:http://application-notes.digchip.com/022/22-18922.pdfThank you for any help.
RDA1846S equivalent chip? - Page 1
Forum section: electronics / rf-microwave

author: jtronix
author_rank: Regular Contributor
timestamp: November 05, 2017, 06:58:20 am
content: Hi,I've used RDA1846S chip for walkie talkie application but i found that chip is not that much reliable so looking for equivalent chip.Kindly help me to get equivalent IC
Where to start, need to listen to 800-900Mhz range - Page 1
Forum section: electronics / rf-microwave

author: webtop
author_rank: Contributor
timestamp: November 03, 2017, 08:34:46 pm
content: I am trying to reverse engineer a device that uses an RF protocol, that transmits and receives in the 800-800Mhz range.How would I go about building something to help me capture the packets being sent to/from this device, without tearing the device itself apart?If this isn't possible, I can always buy a second copy of the device and solder some wires into the circuit to see what is going on, but before I do that I want to know if there is a circuit I can build to "listen" to this device.Thanks for any and all help. Very much appreciated.Paul

author: metrologist
author_rank: Super Contributor
timestamp: November 03, 2017, 08:46:57 pm
content: I would be looking at the cheap SDR units being discussed here, and some software plug-ins to capture the I/Q data streams and work from there...

author: bjcuizon
author_rank: Frequent Contributor
timestamp: November 05, 2017, 12:21:11 am
content: Yes, cheap $10 dongles will work fine if you want to get a basic signal out of it. And then probably use some kind of virtual audio cable to connect the output of sdrsharp (the sdr software) to the decoding app.

author: hamster_nz
author_rank: Super Contributor
timestamp: November 05, 2017, 12:36:47 am
content: If you can wait till Christmas one of these could be helpful....https://www.crowdsupply.com/lime-micro/limesdr-mini(But you only get a 30MHz band at a time, which might not be you are after....

author: scatha
author_rank: Regular Contributor
timestamp: November 05, 2017, 04:07:25 am
content: I'd definitely lift the lid and see if there is an easy way to access the baseband data (transceiver SPI ports, etc). If so it will be much, much quicker to do this rather than capturing the IQ data, establishing the modulation/coding scheme, then demodulating.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 05, 2017, 05:43:28 am
content: I just watched a really excellent YouTube video: Michael Ossmann: Simple RF Circuit DesignMr. Ossmann designed very popular products like HackRF One, Ubertooth One and YARD Stick One, etc.One of the most valuable parts of the presentation was his recommendation to use SDR as a great budget-price form of test gear. Highly recommended.https://youtu.be/TnRn3Kn_aXg?t=57m30s
Teardown of a Ericsson Radio Base Station RBS3206 (cell site amplifier) - Page 1
Forum section: electronics / rf-microwave

author: madsbarnkob
author_rank: Frequent Contributor
timestamp: October 27, 2017, 07:47:45 am
content: All high resolution pictures:http://kaizerpowerelectronics.dk/teardown/ericsson-radio-base-station-rbs3206-teardown/The RBS 3206 macro is an indoor Radio Base Station with one to four carriers and one to six sectors at 20/40 Watt RF output power per carrier.Besides the teardown and circuit analysis, there is also a deeper look into ceramic resonator filters, for some of the other components I have explained about these in earlier videos:Up/Downconversion explained:https://youtu.be/qO127zY3voE?t=865SAW filters explained:https://youtu.be/qO127zY3voE?t=963Doherty amplifiers explained:

author: 4CX35000
author_rank: Regular Contributor
timestamp: October 29, 2017, 10:33:03 am
content: Doherty is 1930's technology, heavily used by high powered medium wave transmitters running up to 600 KW.At unmodulated carrier the Class B stage (Carrier) is saturated, whilst the Class C stage (Peaking) is turned off. At Peak Envelope power, both stages should be saturated and therefore giving maximum efficiency. From memory the power efficiency of the amplifier looks like a bathtub curve were maximum efficiency is at 0% modulation or 100% modulation, and least efficient at 50% modulation.

author: madsbarnkob
author_rank: Frequent Contributor
timestamp: October 31, 2017, 08:25:09 am
content: Quote from: 4CX35000 on October 29, 2017, 10:33:03 amActually it is most effiecient at 50% and 100%, the "bathtub" you refer to is between 50% and 100%.
Is China broadcasting DRM for DPRK and spamming the 80 meter ham band? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: October 31, 2017, 03:02:14 am
content: Several years ago, DPRK was experimenting with digital TV in the DVB-T format, also, it appeared with Chinese assistance.I don't know if they still are.This came to me via a Japanese blog, link below (In Japanese so- Google Translate)http://drmnainfo.blogspot.com.au/2017/09/drpk-in-drm.htmlhttps://swling.com/blog/2017/09/north-korea-now-broadcasting-in-drmhttp://blog.livedoor.jp/bh5ea20tb/archives/5430503.html
Is it feasable to try and build a detector for 10MHz to 40GHz ? - Page 1
Forum section: electronics / rf-microwave

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 30, 2017, 09:15:44 pm
content: I recently bought an R & S vector network analyser but someone has ripped out one of the detectors ( and damaged a lot of plumbing ). Is it feasable to try and build another one ?. The service manual gives a test for it as with 0dBm input, between 2-10GHz the output should be -210mV.Here’s a picture of the remaining one.Any ideas ?Ken

author: Kire Pûdsje
author_rank: Regular Contributor
timestamp: October 30, 2017, 10:24:44 pm
content: Where is it used?It just looks like a resistive power splitter with a diode detector.If you have the space (and do not need the bandwidth), you could try with just a splitter and a crystal detector. Crystal detectors up to 18 GHz are easily obtained on ebay.Is it the detector for stabilizing the synthesizer output power?In that case one of these LTC5596 demo boards with some opamp circuitry might work.Or you could even try it open loop, connecting the bottom input and the top output.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 30, 2017, 11:51:40 pm
content: I think it monitors the power out of the A400 module, which eventually goes to port 1. Here is a jury rig, pict6885 I fitted one of those Russian 3A121A GaAs detector diodes that are supposed to be good for 40GHz. shorted inputs together, pict6886 it sort of works !. In the service menu, pict6889 is the good detector, pict6890 is the jury rig one. pict6893 is a 3GHz LPF fitted between measuring ports. sort of usable !!!Ken
Ballistic Velocity Radar - Page 1
Forum section: electronics / rf-microwave

author: Bud
author_rank: Super Contributor
timestamp: October 29, 2017, 04:56:16 pm
content: A few teardown pics of aBallistic Velociy Radarmade by LabRadar were reported in Microwave mailing list:https://www.dropbox.com/s/tyz2ohhhyj2q7pp/MPB_0437.JPG?dl=0https://www.dropbox.com/s/ttn9hjklfupwjh1/MPB_0430.JPG?dl=0https://www.dropbox.com/s/bm5v81qgpp58t46/MPB_0489.JPG?dl=0
Measurements ADL5324 and ADL5545 - Page 1
Forum section: electronics / rf-microwave

author: max-bit
author_rank: Frequent Contributor
timestamp: November 01, 2017, 05:06:53 pm
content: Measurements of ADL5324 and ADL5545See more :http://www.rflab.pl/rflab_wp/2017/11/01/pomiary-adl5324-i-adl5545/exp:
Passive repeater engineering - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: October 11, 2017, 02:30:58 am
content: This is a technique used to extend the line of sight in RF by means of what is essentially a mirror.https://web.archive.org/web/20120215205137if_/http://www.valmont.com/userfiles/file/specialty_structures/Catalog161A.pdf

author: 4CX35000
author_rank: Regular Contributor
timestamp: October 28, 2017, 09:59:35 pm
content: Quote from: cdev on October 11, 2017, 02:30:58 amThe method was used by the BBC in Scotland to distribute television to the transmitters. The link transmitter in the valley near to the main roads and the power network and the passive site located up the hill were there was no reasonable transport access and no power.The passive reflector can be a flat panel or back to back SHF dishes with a waveguide connecting the dishes.More about the link from page 30 of the BBC Engineering magazine.http://downloads.bbc.co.uk/rd/pubs/archive/pdffiles/engineering/bbc_engineering_106.pdf
Anritsu Spectrum Analyzer  I/P attenuator replacement  MS710a - Page 1
Forum section: electronics / rf-microwave

author: rickells
author_rank: Regular Contributor
timestamp: May 09, 2017, 06:18:55 pm
content: Trying to find a replacement attenuator for the Anritsu MS710a input attenuator.Does anyone have experience repairing Anritsu SA's input amplifiers or attenuators ?Would it be possible to use an Analog Devices (Hittite) chip attenuator as a repair ?thank you

author: KaZjjW
author_rank: Newbie
timestamp: May 09, 2017, 09:01:22 pm
content: Hi,are you talking about the frontend RF att? (mechanical, Z3 in the service manual)

author: rickells
author_rank: Regular Contributor
timestamp: October 26, 2017, 02:43:10 pm
content: hi,Not certain what the problem is, but when I input an appropriate signal, I get No response from the 710a SA.My guess is that the I/P amp is dead or the I/P Attn is not working.All other functions appear to be working on the front panel.The Calibrator O/P, when fed into a different SA, is spot on.Not sure where to start ... Does on have to take apart the inner shields to get at the I/P amplifier & Attn circuits for testing ?Or, can one simply reach appropriate test points when the outer case is taken off ?
OOK demodulator (10 MHz in, 12kbps UART out) ; - Page 1
Forum section: electronics / rf-microwave

author: Warhawk
author_rank: Frequent Contributor
timestamp: October 22, 2017, 02:20:55 pm
content: Hello Everyone,I am reverse-engineering communication between my oldFutaba 12Zmodel hobby transmitter and the 2.4 GHz RF module. That thing is quite over-engineered for today's standards. It was designed back in 27/35/40/72 MHz times and when the 2.4 GHz came they had to find a way how to make it compatible with their high-end model. For this reason, there is UART-like communication between the base unit and the 2.4 GHz module using OOK modulation (fmod=10 MHz). This was originally used to modulate the old MHz band modules. The 2.4 GHz module has an RF demodulator, MCU, and RF ASIC which explains the price back then. I guess that was the only way how to do it back then.Now comes my question. How would you implement the demodulator?At the moment I do it discretely as shown in the attached picture. A simple AC-coupled amplifier boosts the signal and an envelope detector does demodulation. Then I feed the signal to a comparator in the MCU which inverts the signal and does level-translation for the UART periphery. It works in general but I somehow feel It could have been better. I was also looking at MAX9930 or LTC5507. What do you think about it? How would you do it if you needed something like this for a commercial product?I guess you're curious why I am doing this: I'd like to use FrSky protocol using TI's CC2500 and learn something new.Thanks for any thoughts.Jiri :]
Using the Raspberry Pi as a DVB-S modulator & transmitter without extra hardware - Page 1
Forum section: electronics / rf-microwave

author: Bicurico
author_rank: Super Contributor
timestamp: October 21, 2017, 08:58:07 am
content: Hi,I came across this:(Immediatly ordered the ADALM-Pluto, of course, but now the waiting begins... Backorder should arrive Dec, 5th)From here I "discovered" this:https://github.com/pabr/leansdrAnd then I ended up here:https://github.com/F5OEO/rpidatvOf course, I spent two days figuring things out until I managed to get the first result:http://vma-satellite.blogspot.pt/2017/10/can-it-be-real-dvb-s-modulator-and.htmlPerhaps this is old news for you guys, but if so, WHY didn't you tell me?Cheers,Vitor

author: denverpilot
author_rank: Regular Contributor
timestamp: October 21, 2017, 10:57:37 am
content: Heh. I think that using the GPIO pins as a nasty modulation source has been done for a while now. Bunch of broadcast FM range projects doing that.The square waves make for some evil splatter all around the thing though. Most folks recommend a good output filter to get rid of the hash.Of course the super low power helps keep the nastiness pretty much localized to your shack unless you hook the thing to a big outside gain antenna. Then watch out who you’re blasting with it.

author: denverpilot
author_rank: Regular Contributor
timestamp: October 21, 2017, 10:58:50 am
content: P.S. But yes. It’s still wicked cool anyway.And I hadn’t seen the ATV hack. That’s a new one on me! Like.

author: Bicurico
author_rank: Super Contributor
timestamp: October 21, 2017, 11:30:57 am
content: I knew about the previous hacks like RF radio transmitter (https://github.com/F5OEO/rpitx), but actually producing a DVB-S signal is quite cool!Now, while I wait for the Pluto SDR, I am setting up a whole Raspberry Pi image for SDR...Also, beefing up my Ubunto virtual machine.I really want/need to learn more about GNUradio. It is amazing what people put together and it makes me aware that I don't know sh*t about any of this...Regards,Vitor
Chinese Step Attenuator - Page 1
Forum section: electronics / rf-microwave

author: rcbuck
author_rank: Frequent Contributor
timestamp: October 30, 2017, 09:53:22 pm
content: Has anyone purchased one of these? If so, how is performance?https://www.ebay.com/itm/New-Adjustable-Variable-Attenuator-N-5W-0-90dBi-DC-2-5GHZ-50ohm-RF-Coaxial-8-key/121673362151?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D48741%26meid%3Dea0594366fc0454b82193f85517c2094%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D141688658691&_trksid=p2047675.c100005.m1851I would use it in the 1-60 MHz range. Since it says it works at 2.5 GHZ, I would think performance would be excellent in the HF range. The only downside is it has N connectors. But those are required for the GHz range rating.
FW: FINAL CALL: Microwave Update Registration -- due this weekend! - Page 1
Forum section: electronics / rf-microwave

author: KE5FX
author_rank: Super Contributor
timestamp: October 19, 2017, 09:15:13 pm
content: (Forwarded from the WA1MBA microwave list -- I usually go to this conference when it's held on the west coast, but won't be able to make it this year. It is very much worthwhile if you're into this stuff.)We are just one week away from the start of Microwave Update 2017.This is the final call for full conference registration. Please go towww.microwaveupdate.org(Registration Tab) to sign up now!Cutoff for full conference registration is Monday night.Full conference registration includes all four days (two days of presentations, labs and vendors), the Proceedings book and CD, Friday and Saturday lunches, Saturday banquet dinner, speaker and door prizes. Check out the Home, Schedule and Content tabs for more details.We are now also offering a Saturday only registration option which includes the Saturday presentations, labs and vendors, the Proceedings book and CD and Saturday lunches. It does not include Saturday dinner and door prizes. Please join us for the premier international amateur radio microwave conference!Mike Lavelle, K6ML, and Jim Moss, N9JIM, conference co-chairs.----------------------------------------------------------------------------------------------------------------------For more information on the conference, please check outwww.microwaveupdate.orgMicrowave Update 2017 will be held on October 26-29, 2017 in Santa Clara, California (Silicon Valley / San Francisco Bay Area). The MUD conference is dedicated to microwave equipment design, construction, and operation. It is focused on, but not limited to, amateur radio on the microwave bands. Since 1985, this annual conference, targeted at microwave radio enthusiasts, generally has attendance of about 100 Amateur Radio Operators from around the world.We have secured a deep discount on a block of hotel rooms for Microwave Update.The rate includes WiFi, breakfast, parking and airport shuttle.This block of rooms has been released and may be booked by others.Check the Hotel tab to see if discounted rooms are still available.To reserve your room, simply go towww.microwaveupdate.organd click on the Hotel tab._______________________________________________Microwave mailing listhttps://www.mailmanlists.us/mailman/listinfo/microwave
What is involved in making a broadband "90 degree hybrid" - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: October 01, 2017, 09:00:55 pm
content: I would like to make a 90 degree hybrid so I can make four arm antennas and have them work properly.I have no idea of how to go about doing this. Some other four arm antennas do include structures that do this but I dont understand them. Alternatively, are there any cheap broadband 90 degree hybrids available for SMD that cost under 10 each and are available in smaller quantities? (less than 10 at a time)This would be for approximately 1.1 to perhaps 1.7 or ideally slightly more than 2.2 gHz Main usage would be fooling around, basically antenna experimentation using GPS and satellites as the test signals.I should say here that for single frequency antennas, at lower frequencies, one can use a quarter wavelength stub made with higher impedance coax to get a 90 degree phase shift.. so its likely something similar could be done with microstrip for a single frequency antenna.

author: hendorog
author_rank: Super Contributor
timestamp: October 02, 2017, 07:13:19 pm
content: There are some SMD couplers on ebay, likely not quite an exact match for your frequency range.Search for 'Hybrid Coupler'

author: KJDS
author_rank: Super Contributor
timestamp: October 04, 2017, 08:04:10 pm
content: Look at Anaren's Xinger range of couplersIPP do similar things and Mini-circuits may have something too.

author: Kire Pûdsje
author_rank: Regular Contributor
timestamp: October 16, 2017, 07:13:10 pm
content: If you want microstrip. try branch line couplers.For 50 ohm, you might need a double section version to reach the bandwidth.If you have the opportunity to make the antenne impedance 100 ohm, BLC's could give you very wideband perfomance.

author: cdev
author_rank: Super Contributor
timestamp: October 16, 2017, 11:26:20 pm
content: Kire,***Thank you***Indeed, "Branch line coupler" was the term I needed to know..Also, this will work handily... especially for single band antennas..This will likely work well for "single band" (GPS L1 + Glonass + Beidou + QRSS) antennas.100 ohms is likely a better match to most of the experimental antennas I fool around with than 50 ohms.

author: Kire Pûdsje
author_rank: Regular Contributor
timestamp: October 17, 2017, 03:43:34 pm
content: If your manufacturing process has the accuracy, you might also want to have a look at Lange couplers.In a PCB process you can replace the bondwires/bridges by 0 ohm resistors.
Use of a CDN for radiated emissions testing.  - Page 1
Forum section: electronics / rf-microwave

author: trevwhite
author_rank: Frequent Contributor
timestamp: October 13, 2017, 03:52:17 pm
content: Hi, had posted this message in reply to another post but think it's probably a topic of its own.Had an led driver connected to an led pcb fail initial radiated emission testing. Got the following update from the led driver manufacturer when asking about their emissions testing."Measurement of Radiated electromagnetic disturbances (Radiated Emissions) in band 30-300MHz - normally you have to have chamber with special antenna in 10m distance from DUT, but there is alternative method called "CDN method" and this measurement we provide to them. "Anyone got any links to how CDN method is implemented and what is required? It sounds interesting if that can be used instead of a test chamber for initial pre approvals testing.TrevSent from my SM-G950F using Tapatalk

author: chris_leyson
author_rank: Super Contributor
timestamp: October 13, 2017, 05:13:03 pm
content: Coupling/Decoupling network originally designed for coupling RF into cables for immunity testing but it was found that they worked backwards as well and there is some correlation with radiated emissions. They're a high frequency version, 30 to 300MHz of a LISN but I think their use is limited to certain applications and "luminaries" is one example. It's a lot easier than a 30m test site and I would love to find out about some of the theory behind CDN measurement principles.
Homemade vs Commercial 1:4 balun - Page 1
Forum section: electronics / rf-microwave

author: rheb1026
author_rank: Regular Contributor
timestamp: October 11, 2017, 04:50:52 pm
content: I'm in need of a 1:4 balun for a personal project I'm working on to convert a 50 ohm impedance to a 200 ohm impedance for an op amp input.I have two commercially made 1:4 baluns kicking around my parts bin and thought I'd try putting together a quick prototype since I'm not terribly confident in my abilities in the RF area.The commercially made balun (Pulse Electronics CX2074NL) turned out to be very imbalanced in my quick test (~25% amplitude imbalance).I then decided to quickly throw together a homemade 1:4 balun using a small #43 binocular core and 26 AWG magnet wire. The amplitude imbalance in my handmade balun was about 8% at worst.I was really hoping to just be able to buy a premade balun to use on my board, but this quick test has me a little concerned. Just for completeness I did the test setup in the same way for both baluns: 50 ohm signal generator across the balun primary with the secondary terminated with a 200 ohm resistor. I'm scoping both sides of the output resistor.The datasheet for the commercial balun doesn't specify the imbalance, where as some others I looked at from Mini Circuits and MACOM had this specification. Is this balun I have just a crappy one?
rf transistor matching - Page 1
Forum section: electronics / rf-microwave

author: salviador
author_rank: Regular Contributor
timestamp: October 10, 2017, 01:38:00 pm
content: I have any low power transistor work in vhf , I polarized DC for an optimal working point.My question , If I do not know s-parameters of transistor, how can I build matching network in Input and output?If I connect Bi-Directional Coupler and connect reflect channel in oscilloscope and forward in second channel oscilloscope and with network L/C tuning for see in oscilloscope low reflection and maximun forward, is correct?

author: John_BS
author_rank: Newbie
timestamp: October 11, 2017, 10:34:21 am
content: Yes, what you've said is basically correct. It is difficult to give very specific advice regarding the amplifier, as we don't know how you are using it: I'm assuming it's class A?Points to watch:1. If you change the output loading /match, it will reflect back into the input match, so either make sure you're happy with the output before matching the input, or perform the matching iteratively.2. The coupler should ideally have a directivity spec better than the match you wish to acheive, say by 10dB or so.3. If you're matching the input to obtain maximum forward gain, and are not trying to achieve a high return loss (for critical filter termination, for instance), a figure of about 12db is adequate.4. The coupler should be fed from a good 50 ohm source; a 6 or 10dB pad on the input to the coupler is a good idea.5. Ditto the 'scope terminations need to be close to 50 ohms to prevent standing waves on the measuring ports. If your 'scope has significant input capacitance, 6 or 10db pads direct on the inputs will help with this.John

author: salviador
author_rank: Regular Contributor
timestamp: October 11, 2017, 12:20:01 pm
content: Thank you very much John, very clear
#141 Yaesu FT-101ZD Display problem - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: October 02, 2017, 11:56:39 am
content: The 101ZD has returned. This time with another problem.

author: AF6LJ
author_rank: Unknown
timestamp: October 10, 2017, 12:53:35 pm
content: Hopefully I can get around to watching this ...Been busy lately.
Looking for an Avantek amplifier or equivalent - Page 1
Forum section: electronics / rf-microwave

author: CNe7532294
author_rank: Regular Contributor
timestamp: September 24, 2017, 06:24:36 am
content: Tried looking for a product guide or catalog but can't find this. Anyone here have a catalog for this? I'm looking for an Avantek SPP90 type or series amplifier (cascade?) from 10MHz to 3000 or 4000MHz. I'm wondering if a Teledyne/Cougar 6043 (6000MHz yes but only thing close to meeting specs) or something similar can replace this. Specs I need are a package SMTO-8, 10 to 3000MHz at least, ~100mA DC current, 15V+ DC volt, other specs to be added later.

author: CNe7532294
author_rank: Regular Contributor
timestamp: September 25, 2017, 12:00:13 am
content: That cougar part won't do actually. Its 0.45 inch. Looking for the 0.25 inch package. I did however find an alternate for replacement.https://www.sierraic.com/SPP90

author: CNe7532294
author_rank: Regular Contributor
timestamp: October 09, 2017, 09:28:59 am
content: Well I found an interesting read.Google searched "Avantek_Modular_and_Oscillator_Components_2nd_ed.pdf"The package type is called "Planar Pak" (Avantek's trademark name). It is PP-25 and details an application note of the package type. I still can't find or cross reference this to the actual component however. Will search more.
alinco dr-m06 hum when ctcss is on. - Page 1
Forum section: electronics / rf-microwave

author: Jesset1996.5
author_rank: Regular Contributor
timestamp: November 07, 2017, 12:22:49 am
content: I have a alinco dr-m06 that i am using as an echolink node and every time it transmits with the ctcss on it produces an audible hum on the the output frequency, but this is only when the ctcss is turned on. I have looked at the service manual to see if there's any adjustments and there is one that adjusts the ctcss/dcs modulation. Would this be what i am looking for to solve this issue? What test equipment would i need to fix this?I would really hate to have to get another radio as these 6m radios are up in the $200-$300 range. I would much rather fix what i have.I would appreciate any insight anyone can provide on this.Thanks

author: peppper
author_rank: Contributor
timestamp: November 12, 2017, 01:12:19 am
content: You need to filter the CTCSS out. Blocking it going into Echolink.Take a look at this pagehttps://forums.radioreference.com/streaming-broadcasting-audio-recording/204469-diy-ctcss-filter-streaming.htmlit should give you enough information to build a small notch filter that will block the sub audible tones.Once you have that built you should stop people complaining of the buzzing

author: peppper
author_rank: Contributor
timestamp: November 12, 2017, 01:27:55 am
content: Or even better here. Using a High Pass filter as opposed to a Notch Filter. Then you would not be limited to a single frequency.http://www.repeater-builder.com/projects/pl-filter/plf-index.htmlRepeater-Builder has a Metric Ton of radio related information that I found extremely useful when I built my EchoIRLP node and repeater.
RF parts sourcing - Page 1
Forum section: electronics / rf-microwave

author: xaxaxa
author_rank: Regular Contributor
timestamp: September 26, 2017, 08:04:34 pm
content: Has anyone else noticed that in the past year or so all the rf parts manufacturers discontinued all their useful parts?For example the bfg425w low noise amplifier transistor for up to 5GHz; the suggested alternative is much more expensive, and there are no similar transistors at the old price point anymore.See also the cmy210 rf mixer for up to 2.5GHz from triquint; Since they've turned into qorvo, most of their useful rf parts are gone. If you look at the "mixer" category on their website, all they have left are downconverters for satellite tv.I can't even find a good mixer for LF to >=2.5GHz anymore; the closest I can find is the LT5560 which is far more expensive at about $2, and it has worse linearity than the cmy210. Similar story for LNA transistors; fairly decent transistors with fT>20GHz and low noise figure used to be available for $0.3; now they are 2x more expensive and with far fewer choices.What happened to the industry? It seems like people stopped caring about RF and all these companies have turned to the IoT hype instead.

author: denverpilot
author_rank: Regular Contributor
timestamp: September 27, 2017, 07:37:58 am
content: The effect of SDR gaining lots of ground in Commercial RF products, perhaps?

author: Antonio84e
author_rank: Contributor
timestamp: September 27, 2017, 08:42:11 pm
content: There have been a lot of mergers and acquisitions too, which has forced to some companies discontinuing a lot of their products in favour of the others.

author: cdev
author_rank: Super Contributor
timestamp: September 30, 2017, 01:09:06 am
content: Deindustrialization, consolidation, disinvestment, etc.