hybridfree/eevblog-posts huggingface dataset:
RS-UV3 an $89 Transceiver Sheild - Any thoughts?  - Page 1
Forum section: electronics / rf-microwave

author: Cliff Matthews
author_rank: Unknown
timestamp: February 22, 2016, 12:27:36 pm
content: IEEE Spectrum did a hands-on review a couple of days ago.http://spectrum.ieee.org/geek-life/hands-on/hands-on-a-ham-radio-for-makersIs this a good way for Nubies to start ham Radio?

author: voltz
author_rank: Frequent Contributor
timestamp: February 22, 2016, 12:49:52 pm
content: Great!. But would like to see SSB.There's a massive interest in Arduino and Raspberry Pie shields right now, this one is very cool indeed. I think i want one just to play with

author: GreyWoolfe
author_rank: Unknown
timestamp: February 22, 2016, 12:54:55 pm
content: It might be fun to play with but there are much cheaper ways to test the waters. The shield is $90 USD and only puts out a 1/4 watt. I just picked up at the Orlando Hamcation, a Baofeng UV-82 dual band handie-talkie for $40. It's bigger than the UV-5R+ and fits my hand very nicely. Even does broadcast FM receive so I can listen to my favorite radio station.

author: AF6LJ
author_rank: Unknown
timestamp: February 22, 2016, 03:46:22 pm
content: That's Cool... I see a small APRS radio.......

author: cdev
author_rank: Super Contributor
timestamp: February 23, 2016, 01:39:23 am
content: It's a conventional three band rig on a PC board?

author: dennisandersen73
author_rank: Newbie
timestamp: March 01, 2016, 11:48:33 am
content: For a new radioamateur that would depend of several factors.Such as programming skillssoldering skillspatienceamount to spend on .200mW transceiveramateur licens category (in Denmark the entry level licens does not grant access to homebrewed equipment)the level of frustration when it doesn't worksome might love the challenge while others might hate it and be scared away.but nice little board.

author: nealz
author_rank: Unknown
timestamp: March 02, 2016, 06:21:15 am
content: Looks cool ill check it out. I need to hack some more Ham gear.
High-performance (S/C/X/K band) FMCW/FSK/CW radar on sale - Page 1
Forum section: electronics / rf-microwave

author: lynnandsky
author_rank: Newbie
timestamp: March 02, 2016, 12:51:21 am
content: Hi there,Ancortek radar evaluation kit supports FMCW (Sawtooth, Triangle), FSK, and CW operation modes. If you are interested in FMCW SAR/ISAR imaging, FMCW radar for through-the-wall imaging and target detection/tracking, micro-Doppler analysis, or heartbeat/respiration sensing, this would be the perfect kit for you! We have fully tested our radars for these interesting applications.This sale event will end on March 31st, 2016.The main benefits of Ancortek radar are:1) Raw data could be streamed into Matlab for signal processing. You will have access to I and Q data, and implement your own signal processing algorithms. Matlab GUI could be provided.2) The processor module is compatible with all the RF modules. If you need S, C, X, and K band radars, you just need to buy one processor module and different RF modules.3) All the radars have a typical output power of 20dBm, which will meet your power requirements in most cases, without radiation concerns. Power amplifier could be added if larger detection range is desired.4) Light-weight, low power, and portable. It’s convenient for field trials. Raw data could be saved into either .mat file or .dat file for post-processing.5) You will have access to example Matlab processing codes for FMCW ISAR imaging, Range-Doppler map, and micro-Doppler analysis, etc.To learn more, please visitwww.ancortek.comproducts page. You could also find some application videos on youtube.Please don’t hesitate to contact me if you have any question. I could be reached at baokun.liu@ancortek.com. I will be very happy to help you.Best,Baokun LiuSenior Electrical EngineerAncortek Inc
Arria V FPGA RF Development Kit - Interface - Page 1
Forum section: electronics / rf-microwave

author: Eric_the_EE
author_rank: Contributor
timestamp: March 01, 2016, 05:21:50 pm
content: Hello All,I am an undergraduate EE student working on a project using the Arria V FPGA RF Development kit (https://www.altera.com/products/boards_and_kits/dev-kits/altera/kit-arria-v-rf.html).I'm trying to figure out how to interface the FPGA with the TI DAC on the RF daughter board. But unfortunately, there is no documentation on the interface between these two boards.Has anyone else ever used this kit successfully? Any source files you are willing to share to get me started?

author: John_ITIC
author_rank: Frequent Contributor
timestamp: March 01, 2016, 09:32:35 pm
content: This defines the interface. You need to look elsewhere for the specs of your daughter cards.https://www.altera.com/en_US/pdfs/literature/ds/hsmc_spec.pdf
Datasheet/Pinout for a Narva "Typ 2" TCXO - Page 1
Forum section: electronics / rf-microwave

author: Torrentula
author_rank: Regular Contributor
timestamp: March 01, 2016, 07:00:51 pm
content: Hello again!I am currently looking for a datasheet / pinout diagram for a Narva "Typ 2" TCXO, see attached photos.As far as I know these Narva TCXOs were manufactured in the GDR for military purposes (so the sequence 04 83 might well mean this thing was manufactured in 1983).I figured this would be the best place to ask, considering that there are more than a few people from Germany active on this forum who might be most likely to have information on these.Thanks,EliaEDIT: I have contacted the eBay seller and he pointed me to a piece of kit that used this reference oscillator: the EKD300 built by Funkwerk Köpenick. The schematics (including pinout) can be found here:http://dl6lim.darc.de/ekd300_e.html

author: German_EE
author_rank: Super Contributor
timestamp: March 01, 2016, 07:45:51 pm
content: All the information I can find is for the type 4 oscillator. I will keep looking.

author: Torrentula
author_rank: Regular Contributor
timestamp: March 01, 2016, 08:41:52 pm
content: Quote from: German_EE on March 01, 2016, 07:45:51 pmYeah there seems to be more information available on the type 4 TCXO. I've even found an article from the August 99 issue of "Funkamateur" where they have a pinout diagram available.No such luck for the type 2.Quote from: German_EE on March 01, 2016, 07:45:51 pmThanks
Firmware on github for DMR/MOTOTRBO scanning - Page 1
Forum section: electronics / rf-microwave

author: apelly
author_rank: Unknown
timestamp: January 31, 2016, 05:34:33 am
content: Found this via slashdot. Fairly sweet.QuoteStory:http://phasenoise.livejournal.com/1142.html?nojs=1Toob:

author: FLIP
author_rank: Contributor
timestamp: March 01, 2016, 06:26:14 am
content: may not nbe too long before /x\ patch this (unless they have already) been a while since ive had a play around on the DMR side of things with decoding usinf DSD+, these days im back to project25 and good old smartzone with a bit of flex and pocsag on the side.i`ll have a TRBO radio to play with in a month or so, so will report back too see if this still works, it will be interesting as most features for TRBO require a EID from moto and the cps phones home to ensure you payed for the features, having said that it will be interesting too see if the latest cps/depot will still work and if it keeps this setting open when written to the radio
Bluetooth profiles - Page 1
Forum section: electronics / rf-microwave

author: farsi
author_rank: Regular Contributor
timestamp: March 02, 2016, 06:56:58 am
content: Hi,I am playing with a small BlueGiga BLG113 based board.But I am a bit confused how to use the GATT to read data from the board. I can detect the service UUID of the peripheral, as well as different characteristics.But trying to read from a characteristic only gives the name of the attribute not the "value".Anyone here has some good debugging tricks?Thanks!
ISM band antenna selection - Page 1
Forum section: electronics / rf-microwave

author: HSPalm
author_rank: Regular Contributor
timestamp: February 16, 2016, 09:08:48 am
content: Hi,I'm making a product with a radio-on-chip device from TI and was hoping to discuss some antenna alternatives. Which ISM band is not chosen yet. It wall have an enclosure of maybe 5x5cm. Antenna must be omni-directional.Direct soldering/pcb solutions:PCB antennaChip antennaSpiral/spring typehttp://www.banggood.com/10-Pcs-433MHZ-Spiral-Spring-Helical-Antenna-5MM-p-932781.htmlSolder stripped coax or wire (monopole) and curl it up inside the box.Connector solutions:SMA connector and cutout in enclosure for whip antennaSMA or U.FL connector and cable gland or wire protrusion for stripped coax monopoleCost is a factor, but firstly I'd like an idea of what is the best/worst solution in terms of coverange/range. Of course the ideal solution is something soldered directly to the pcb and it's done when you close the lid, but not sure how much it affects range compared to the best solution.Any input is appreciated, and I gladly accept even more solutions that I haven't thought of already.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 16, 2016, 06:24:05 pm
content: There is a fundamental trade-off between coverage and gain. The most and least (respectively) you can get is a dipole or loop, which do not receive signals along the rotational axis. (A 1/4 wave whip is equivalent, it just has a ground plane replacing one element.)There is no such thing as a true isotropic antenna, because EM waves are transverse and will always cancel out along some axis (which comes from what's called the Hairy Ball theorem).If by "omnidirectional", you mean all directions within a plane, that's okay: place the dipole vertically (perpendicular to the plane of 'sight') and you will cover all compass directions.You can even get some gain back, by using a vertically taller (e.g., colinear) antenna, which restricts reception to be closer to the plane. (The more precise you want the radiation pattern in a given direction -- in this case, closer to parallel in the plane -- the longer the antenna must be in the same direction. Again, trade-offs all over the place.)ISM bands are not very wide (low bandwidth), so you will not need a large (wide bandwidth) antenna. An overly small antenna will cost you in terms of precision (needing to be tuned) and efficiency, so don't expect too much.Tim

author: HSPalm
author_rank: Regular Contributor
timestamp: February 19, 2016, 09:51:59 am
content: Thanks for replying. Yes, I meant omnidirectional as in all directions in the compass plane, but of course I'm limited in regards to directing the antenna precisely if I loop it inside a junction boxWhat I did was just to attach an U.FL connector so I can experiment with different types of antennas. U.FL -> SMA are quite common, and I can also make different types of antennas with an U.FL pigtail.
GSM/UMTS antenna selection for a small device - Page 1
Forum section: electronics / rf-microwave

author: Mad ID
author_rank: Regular Contributor
timestamp: February 16, 2016, 12:51:58 pm
content: Hi,I'm using a Quectel UC20-E 3G modem.The operating bands should be 850/900/1800/1900/2100MHz. The PCB size is small, i.e. 31x63mm. I guess that PCB is too small for a ground-dependent PCB antenna like PIFA.I have found this antenna from Molexhttp://www.digikey.com/product-detail/en/1052630002/WM9670-ND/3918565The drawback is price (3$ @ 1000pcs) and it is very big (107mm long).Can someone point me in the right direction, what antenna type would fit this design? Any recommendation for a particular antenna?Thanks.
Question about DTV frequency allocation in Europe - Page 1
Forum section: electronics / rf-microwave

author: fubar.gr
author_rank: Unknown
timestamp: February 13, 2016, 12:09:26 pm
content: I don't know if RF regulation matters belong in this forum, but here it goes:There has been a kerfuffle lately in Greece, because the government wants to limit the number of over the air DTV broadcast licences to just 4.To back this decision up, they introduced a study from Florence School of Regulation. I don't have access to the full text, but here are the conclusions:http://www.ereportaz.gr/wp-content/uploads/2016/02/eui-greece_final_report_excerpts.pdfWhat strikes me as odd is this one:QuoteIt doesn't make any sense. How can an international agreement limit the multiplexes (or does it mean multiplexers?) to a certain number?For what it's worth, there are over 30 nation-wide channels broadcasting right now in Greece.
TRIO DIP Meter DM-801 pics - Page 1
Forum section: electronics / rf-microwave

author: RobertoLG
author_rank: Frequent Contributor
timestamp: February 09, 2016, 09:39:23 pm
content: the pictures aren't super quality, but that's what I can do, hope you enjoyhere is the manual, if somebody wanna take a lookhttp://www.radiomanual.info/schemi/ACC_instrument/Trio_DM-801_user.pdf

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 09, 2016, 09:55:50 pm
content: Beauty!

author: Muttley Snickers
author_rank: Unknown
timestamp: February 09, 2016, 10:42:44 pm
content: Very nice overview, I've never torn mine down and never had a need to really as they are a great and super reliable piece of equipment, yours could perhaps be a cheap nasty knockoff of my Kenwoodwhich I have had for well over 20 years. I remember when I first got it for the purpose of building antennas I ran around checking the resonant frequency of everything in sight, the kettle, the toaster, the clothes line but I could never catch the neighbours cat.Many thanks for the great pictures, here is one of mine to compare.

author: RobertoLG
author_rank: Frequent Contributor
timestamp: February 09, 2016, 10:52:26 pm
content: nope, genuine stuff made in japan

author: Muttley Snickers
author_rank: Unknown
timestamp: February 09, 2016, 10:57:30 pm
content: It was a joke, they are exactly the same meter badged as Trio or Kenwood and perhaps other brands.....

author: vk6zgo
author_rank: Super Contributor
timestamp: February 10, 2016, 04:51:04 am
content: Quote from: Muttley Snickers on February 09, 2016, 10:57:30 pmKenwood & Trio are the same company.Back in the day,(early '60s) in Oz,their products were sold as Trio,then later as Kenwood.Apparently they stayed Trio in some countries.I have a 1980s TM201A 2m rig that came from the UK,& has the Trio name.(great little radio--only cost $40 at the Hamfest,as it had no mic)The same thing bought in Aust or the USA was a Kenwood.

author: pa3bca
author_rank: Regular Contributor
timestamp: February 10, 2016, 10:38:49 am
content: Quote from: Muttley Snickers on February 09, 2016, 10:57:30 pmLike my 1975 "Leader" LDM-815 Tr DIP METER

author: Muttley Snickers
author_rank: Unknown
timestamp: February 10, 2016, 11:07:18 am
content: Oh wow very nice....I'm petty sure that the book that was supplied in the box with my Kenwood actually belongs to your unit, it has the schematic on the back page.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 10, 2016, 12:28:37 pm
content: Very niceAll I have is the Heathkit GD-1B

author: AF6LJ
author_rank: Unknown
timestamp: February 10, 2016, 03:50:19 pm
content: I have a heath GD-1B and a Millen dipper.The Millen needs to be recapped but works reasonably well.
#28 Yaesu YO-100 scope monitor troubleshoot and repair - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 07, 2016, 09:36:38 pm
content: In this video we take a look at the YO-100 scope monitor.We will only use out senses to locate the problems without the use of test gear. We will test a capacitor with a cheaptester. Lets have a look at what we find.

author: Vgkid
author_rank: Super Contributor
timestamp: February 07, 2016, 11:18:41 pm
content: Thanks for the video. I have noticed that in the same piece of gear some of those matushita(panasonic) caps will be good , while others will be bad. Even in the same circuit.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 08, 2016, 12:09:28 am
content: Quote from: Vgkid on February 07, 2016, 11:18:41 pmThanks for watching and you are welcome.I agree. I checked the other caps and they all checked good. So it was just the one cap that had failed. I think that is pretty good for the age of this old piece of gear.

author: AF6LJ
author_rank: Unknown
timestamp: February 08, 2016, 03:09:54 pm
content: Good video...I always love it when the easy ones come my way.The Heathkit SB-610 scopes tend to loose the power transformer due to insulation breakdown.I have one in the garage that had the CRT filament winding short to the core...

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 08, 2016, 03:57:36 pm
content: Quote from: AF6LJ on February 08, 2016, 03:09:54 pmThanks Sue,I did this repair for a friend of mine I do not get to see much of. Sent him a mail last night and got a mail from him this morning and he was excited to see it workingI wonder what CRT they used in the 610? I have found that when I was working on my SM-220 the CRT came from a popular oscilloscope from that era. I am sure the 610 would be the same. The transformer can be re-wound if you are up to the task.

author: AF6LJ
author_rank: Unknown
timestamp: February 09, 2016, 03:33:14 pm
content: Quote from: Radio Tech on February 08, 2016, 03:57:36 pmThey used a 3RP1The SB-620 I have (two of) use a 3RP7.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 09, 2016, 08:03:18 pm
content: Quote from: AF6LJ on February 09, 2016, 03:33:14 pmWell good news is you can still find the 3RP1. Bad news is they are around $130 bucks.I will look through my junk box and see if I have one. that tube was produced between 1945 and 1960.

author: AF6LJ
author_rank: Unknown
timestamp: February 10, 2016, 01:59:58 am
content: Quote from: Radio Tech on February 09, 2016, 08:03:18 pmThe one in my SB-610 was made by Toshiba of Japan in the seventies.They were still making them then.
Magnetic sensor for rotor - Page 1
Forum section: electronics / rf-microwave

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: February 09, 2016, 03:37:35 pm
content: In the follow up of my K3NG rotor interface, that the objective it's to replace the Yaesu controller.Looking at the 4O3A new rotor genius <http://4o3a.com/index.php/products/station-automation/rotator-genius> that is working with an magnetic sensor, on the boom of the antenna, I was thinking to do the same with an HCM5883L or similar sensor inside an IP66/67 case and UTP cable till the interface.Question is would the sensor be affected by RFi when talking or not?Most of the time, first the rotor is turn, then the PTT is push to make the QSO, so maybe this is not the problem, only if the chip get's stuck and don't send any info.Any sugestions?
Use two cheap digital (optical) USB sound cards for diversity reception? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 08, 2016, 10:41:44 pm
content: Please excuse me if this is a bit speculative..I recently bought a "Syba" "SD-AUD20101" for around $10, and for the money, despite my disappointment that it doesn't sample at 192 KHz as its vendor claimed, its still quite a good value. (Ive seen other similar USB dongle sound cards, for as little as $2- but I doubt if they have as good sound quality and include an optical output)So these cheap USB sound dongles, which use a Via vt6230 chip, even have direct digital out, they have a SPDIF optical output in the form of a red LED that sends digital data through an optical cable, sharing the output miniplug, which also is useful I would think because it lets you get a precise timing, that you can't get with USB. (musicians always bitch about the lack of precise timing with cheap sound cards, better clocks are one of the reasons pro level sound cards are more expensive)-I don't know if it would matter so much to most people that they had an optical out but it might make a substantial enough difference for SDR, because the SN is better and no ground loops, which I suspect would be a big thing in the soundcard sdr context.. Also, perhaps, timing, both pairs could not just share the same crystal, their outputs could also be interleaved.. again, not so knowledgeable about this, just speculating..-The RTLSDR (running two or three dongles from one crystal) has been used for passive radar, because the locked timebase allows comparing (two receivers and) direct and reflected signal's timing relationships.If the dongles use a crystal, (lets just assume that they do have a crystal, I don't know that for a fact..) anyway, you likely get the rest already..See here for the inspirationhttp://kaira.sgo.fi/2013/09/passive-radar-with-16-dual-coherent.html (alsohttp://kaira.sgo.fi/2013/09/16-dual-channel-coherent-digital.html)Suppose you make two side by side receivers, sharing the same local oscillator, of course since they will be tuned to the same center frequency. But two antenna inputs, as well as two separate sets of i and q output, digitally connected to the computer sound cards as well, via the low noise high dynamic range, synchronized timing optical outs.Would that offer an advantage over a single receiver - making it more useful for long distance reception under severe fading or be useful data for getting rid of - canceling out noise?Might be worth trying it out, given their low cost.
Help with Microstrip-Length Formula - Page 1
Forum section: electronics / rf-microwave

author: SaabFAN
author_rank: Frequent Contributor
timestamp: February 07, 2016, 01:34:56 pm
content: HelloI have been struggling since friday evening to understand the Formula given in a lecture-manuscript to calculate the length of a piece of Microstrip that is part of a filter.One of the Formula in question is this one:I have managed to find the real world counterparts of all the Variables, exceptFrom digging through wikipedia-articles and other sources, the small Omega-Letter with a small c could be the cutoff-frequency, or the circular frequency, but using those values does not yield 11,04mm of length.Could you guys tell me what this variable is and does in the circuit, or where my error lies? I'm rather new to this particular field of electronics and do this only as a hobby.btw. This is the presentation where the slide is from:http://ntuemc.tw/upload/file/20110321102525847f2.pdf

author: KJDS
author_rank: Super Contributor
timestamp: February 07, 2016, 02:13:50 pm
content: A little light background reading of the mathematics of microstrip lineshttps://fenix.tecnico.ulisboa.pt/downloadFile/3779573460329/design%20of%20coupled%20microstrip%20lines.pdfAlternatively,http://www.awrcorp.com/products/optional-products/tx-line-transmission-line-calculatoruses the same equations.

author: nctnico
author_rank: Super Contributor
timestamp: February 07, 2016, 03:14:40 pm
content: I think the images above come from a book called 'Microstrip filters for RF/Microwave applications'. The design of these filters and the formulas used are explained in greater detail then these slides. I highly recommend to buy this book if you want to get into microstrip filter design.The wc is the radians per second at the filter's center frequency.

author: SaabFAN
author_rank: Frequent Contributor
timestamp: February 07, 2016, 03:22:27 pm
content: Thx for clearing that up, nctnico.Btw. I just looked for that book: 140€ on Amazon!Why are books covering this topic so damn expensive?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 07, 2016, 03:37:44 pm
content: I'm not entirely sure where the slide is going, but it looks like it's calculating microstrip in terms of lumped equivalents (using the transform theorem). Then, w_c should be the characteristic frequency of that segment, which is general will be a small ratio away from the cutoff frequency. How much depends on the type chosen (Butterworth/Chebyshev/..) and position in the filter.But I might be wrong about that. Assuming you have an instructor, ask them to be sure.Quote from: SaabFAN on February 07, 2016, 03:22:27 pmBecause almost no one has to design them?..Tim
Synchronizing wireless data aquisition nodes - Page 1
Forum section: electronics / rf-microwave

author: luky315
author_rank: Regular Contributor
timestamp: February 02, 2016, 01:10:49 pm
content: Is there a simple way for synchronizing a couple (4 to 12) wireless sensor nodes (max. 10m distance) to get a "simultaneous sampling" effect? The sampling rate is only 10sps, but the resulting jitter over time and temperature has to be better than 1µs.I don't have other hard requirements and the nodes are line powered, so a low power wireless standard is not required.Any suggestions?

author: Neilm
author_rank: Super Contributor
timestamp: February 02, 2016, 07:12:05 pm
content: A bit more information would be useful - is this just for triggering or would the results be read out over it? Are the sensor in line of sight to the receiver?

author: Kilrah
author_rank: Unknown
timestamp: February 02, 2016, 07:26:14 pm
content: One of those extremely basic RF modules:https://www.sparkfun.com/products/10534There's zero processing on them, you're driving/getting stuff straight from the modulator/demodulator so no variable delays.

author: Jeroen3
author_rank: Super Contributor
timestamp: February 02, 2016, 07:34:41 pm
content: Do you need instantaneous synchronisation or can it take a while?This concept maybe?Although 1 uS might be extremely difficult to achieve without external source (such as gps).

author: C
author_rank: Super Contributor
timestamp: February 06, 2016, 07:50:33 pm
content: You might look at loran-cThe master sends out a pulse.The slaves receives the pulse and after a delay for each slave sends out a pulse.master gets time for master sync pulse to time when master receives slave pulse, the time delay.For what you want, delay has two parts.1. Master to slave sync time2. Slave sync time to master.For #1 you have master transmitter delay, air delay, slave receiver delay and delay to sync.For #2 you have slave delay from sync, slave transmitter delay, air delay, master receiver delay.Could help to change #2 by a fixed amount so the master has better data to work with for a correction message to slave.
Help me! Need a simple low power, low cost wireless "On/Off" switch! - Page 1
Forum section: electronics / rf-microwave

author: DivineChaos
author_rank: Regular Contributor
timestamp: February 05, 2016, 02:13:47 am
content: Hey guys,I recently posted a thread over in the Beginners section about how to design a simple wireless on/off switch. I have had some suggestions, but nothing really worth merit, so I've decided to come over and ask the wireless expertsI think the biggest hurdle is perhaps I may not be explaining myself clear enough.I have two "slave" devicesA.K.A LED'sthat need to "know" when a third device, a USB dongle, has received power and when the USB dongle has lost power. Basically it is as simple as that. But it doesn't seem to be that simple-- USB dongle is powered, sends signal stating that its powered, and when the USB dongle has lost power, the receivers decide that it is then time to turn off because they are no longer "hearing" a specific signal.-- By "know" I mean, to receive the signal and be able to "tell" an MCU (or whatever is most simple) onboard the slave device to turn ON an LED, and when the USB has lost power, to "decide" to power down into "listening mode" and turn OFF the LED.Some google searches reveal that there are MCU transmitters. Do they Receive as well as transmit? This may not work because the "brain" cannot be inside the USB dongle because when it loses power, well, it has lost power and cannot do anything. It willnothave battery backup.Other searches reveal that there are MCU transceivers. This would work for the slave devices, but they are expensive ($5 each?) and overkill. The slave does not need to transmit anything, only listen, and I'd need 3 of them and that would drive the cost of my project UP by about $15.A perfect match would be an MCU Receiver. It would eliminate needing a receiver AND an MCU separately because it is integrated, but alas, I cannot find them.Is using an MCU even necessary for just turning an LED on wirelessly?A couple things of note:1. No line of sight.2. Minimum of 30ft signal distance through a wall or two made of wood and drywall. Maximum distance 50ft. This is negotiable.3. Relatively low cost. My total budget for the 3 devices to function is around $10.4. ReceiversA.K.A the LED'scan tolerate anadditionalload of 3.3v @ 20mA5. USB Transmitter can use a maximum of 5v @ 500mA6. Legal use of "wireless technology" because this MAYsomedaybecome something that Icouldsell.7. Hand solderable with a heat gun and/or Hakko 888d, for prototyping. I *think* I can solder TQFN well enough. SOT-23, .5mm pitch is easy for me.8.The most important of all, KISS. (keep it simple stupid)9. Size limitation. USB dongle can't be any larger than a standard thumb drive(basically the size of your thumb)and the receivers cannot be larger than your two forefingers side by side in length and height.(basically about 1/2inch taller than a standard 2x AA battery holder and about the same width)Can you guys over here in RF land help me out?
Rotary encoder for homebrew Si570-based SDR - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 04, 2016, 03:28:36 pm
content: IMHO, knobs add substantially to the user experience when tuning any radio related device. But SDRs are digital, so knobs need to be brought into the mix in other ways than by variable capacitors.Good example - use of USB DJ CD mixing encoders.. i.e. "Hercules" etc. paired with HID key mapping software to create a good approximation of a tunable radio experience. But they are likely overkill for basic SDR applications.This looks like a good learning experience.http://ea4nz.ure.es/encoder/encoder.html
How is inside a helicoidal ham-radio antenna in rubber ? - Page 1
Forum section: electronics / rf-microwave

author: 1enry1
author_rank: Contributor
timestamp: February 01, 2016, 07:51:19 pm
content: in the ham-radio dualbander handy like Kenwood TH-79 or th-f7 ect....used a dual band 144 - 430 Mhz helix inside the rubber antenna, where is project and function in the two bands ?thanks, best 73

author: Paul Rose
author_rank: Regular Contributor
timestamp: February 01, 2016, 09:17:04 pm
content: Not sure if I fully understand the question.What makes the helix a dual band antenna, or how well do these work on each band?I found the following:http://herwig.mobimail.de/2m-en.htmwhich shows that they typically don't perform very well, especially not on both bands.

author: 1enry1
author_rank: Contributor
timestamp: February 02, 2016, 09:19:17 am
content: thanks !both...my question on this rubber antenna on handy , is :1) where is inside ? and how is the tecnical and RF sulution to work it ?2) in how mode function in 144 and in 430 mhz ?best 73

author: WA5PSA
author_rank: Newbie
timestamp: February 02, 2016, 01:19:08 pm
content: Are you asking how it switches from one band to another? If so...there is no switching. If you transmit on 144, then the 2meter section will present the best impedence match to the transmitter, and the RF energy will simply follow that route.Sent from my SM-N910V using Tapatalk

author: Chalcogenide
author_rank: Regular Contributor
timestamp: February 02, 2016, 01:27:22 pm
content: Here is an explaination in Italian, as obviously 1enry1's is not a native English speaker:L'antenna è semplicemente fatta in modo tale per cui l'impedenza è "decentemente" adattata in entrambe le bande. Non c'è nessuno switch, nessuna parte attiva, e nessuna diversa modalità di funzionamento. Per questo, le antenne bibanda tipicamente sono peggiori di un'antenna monobanda (che invece è quasi perfettamente adattata nella banda di funzionamento).

author: 1enry1
author_rank: Contributor
timestamp: February 02, 2016, 01:32:10 pm
content: thanks to all...have a schematic diagram to has built inside the rubber antenna ?tnx and 73

author: dexters_lab
author_rank: Unknown
timestamp: February 03, 2016, 05:02:48 pm
content: these might help if your able to read english?https://en.wikipedia.org/wiki/Helical_antennahttps://en.wikipedia.org/wiki/Rubber_ducky_antenna

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 03, 2016, 05:33:32 pm
content: Here are some plans if you want to make one yourself:http://www.cqham.ru/rubberduck.htm

author: 1enry1
author_rank: Contributor
timestamp: February 04, 2016, 08:20:35 am
content: GREAT , thanks to all !i try an very interesting article in this rubber ANTENNA on this web site of an amateur radio collegue :http://rodolfo-parisio.jimdo.com/nuovi-articoli-2015-bis/best 73 :-)
Sizing antenna feed trace? - Page 1
Forum section: electronics / rf-microwave

author: reagle
author_rank: Unknown
timestamp: February 02, 2016, 04:38:18 pm
content: Typically you would make a 50 ohm trace to feed an antenna, based on the distance to the ground plane and the trace width. That makes sense. But what about feed that's not over the ground plane? Many chip antennas specify no plane under, but still want a 50 Ohm feed. How does one size it?

author: Kelbit
author_rank: Regular Contributor
timestamp: February 03, 2016, 08:16:36 am
content: As soon as you leave the ground plane you are no longer in a microstrip regime and the fields are no longer confined to the space between the trace and the ground plane, so your feedline will start radiating. As you are connecting to an antenna this is not necessarily undesired behaviour.If it's for a chip antenna, usually the manufacturer will have a prebaked layout available in gerber or DXF format. Sometimes it's not available online but you can get it by emailing their applications engineering department.
RF 433Mhz module - Page 1
Forum section: electronics / rf-microwave

author: victorgozman
author_rank: Newbie
timestamp: February 02, 2016, 08:59:51 pm
content: please I bought a RF module(RB-Ite-108) that operates at a frequency of 433Mhz. please I need to find out which Rf protocol it uses for communication. A picture of the module is attached below.

author: Kilrah
author_rank: Unknown
timestamp: February 02, 2016, 09:05:34 pm
content: It doesn't use any, you have to specify one yourself.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 02, 2016, 09:09:15 pm
content: send it 5-10Kbps digital pulses, the other end will receive the same...

author: JimRemington
author_rank: Regular Contributor
timestamp: February 02, 2016, 09:30:25 pm
content: Many people use ATMega328/Arduinos and the VirtualWire or RadioHead libraries (i.e. driver code) with those modules.http://www.airspayce.com/mikem/arduino/VirtualWire/I've used them for years for remote environmental sensors. They work pretty well, with a range of up to 300 meters using proper balanced dipole antennas.

author: victorgozman
author_rank: Newbie
timestamp: February 02, 2016, 09:32:47 pm
content: Thanks for your repies. pls does it make use of any radio frequency standard such as WiFi, ZigBee, zwave etc.

author: Kilrah
author_rank: Unknown
timestamp: February 02, 2016, 09:34:49 pm
content: No.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 02, 2016, 09:47:26 pm
content: Wifi is 2.4GHz yours is cheap china 433MHz what are you talking about? want a wifi? buy 2.4GHz transmitter. this cheap china is protocol heaven you can do whatever you like if you are up to it, this is the old school radio modulation... but only 433MHz carrier, hence signal must be much slower than that, you send it 1Mbps, it'll only good for mm transmission..
Low cost cable to program Icom IC-2730 ? - Page 1
Forum section: electronics / rf-microwave

author: 1enry1
author_rank: Contributor
timestamp: February 01, 2016, 07:48:17 pm
content: the original icom cable is too expencive over 40 dollars !!i read that is possibile to built home made with a 3-4 dollarschip to convert TTL uart to usb ...you have info or diagram to built this interface home-made ?best 73 tnx
Parts indentification - Page 1
Forum section: electronics / rf-microwave

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: January 28, 2016, 03:05:34 pm
content: Hi,I've one schematic that I'm trying to make for a new board, some of the parts have one letter next to the value, but I've no clue what is the letter, perhaps precision components?The parts are:C - 0.01pF BC - 0.1 pF FC - 0.001pF BC - 4pF CHC - 27pF SLAnd also there are two obsoletes 2SC945AQ what would be a good sub for this one?I'll try to post the schematic later.

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: January 29, 2016, 10:11:56 am
content: Looking at google could the letters be the tolerance of the capacitors?B - +- 0.1pFF - +- 1%But can't find the CH or SLI'll try to make the schematic with Kicad and post it here.Schematic add.

author: TimFox
author_rank: Super Contributor
timestamp: January 31, 2016, 11:15:06 pm
content: Are the first three components (capacitors) values typos for microfarads? 0.001 pF is not feasible.

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: February 01, 2016, 08:29:30 am
content: Yes, they are typos, should be uF, all the capacitors

author: crispy_tofu
author_rank: Super Contributor
timestamp: February 01, 2016, 11:01:47 am
content: According to this document:http://www.rockby.com.au/DSheets/10059.pdfCH: 0±60 (ppm/°C), -25 to +85 °C temperature rangeSL: +350 to -1000 (ppm/°C), +20 to +85 °C temperature range

author: crispy_tofu
author_rank: Super Contributor
timestamp: February 01, 2016, 11:04:25 am
content: Further sources:http://www.passivecomponent.com/poeproduct/Disc_Web_Files/CC1.pdfhttp://www.peterparts.com/%5CCatalogPages%5C17%5C3150.pdfhttp://www.farnell.com/datasheets/1524357.pdf

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 01, 2016, 11:47:46 am
content: QuoteLooks like silicon NPN, 50V 100 mA, pinout ECB. Low speed switching, audio amplifier. The "Q" indicates hfe135-270 range.You should be able to use many different common NPN here, you may have to bend the legs around to fit the pinout.BC546, NTE85, etc. You might even be able to use 2n3904 or BC337 types, depending on the actual circuit. Just beware of the pinout differences.

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: February 01, 2016, 11:59:47 am
content: Thanks guys for the help.
#27 TROUBLESHOOTING AND TESTING A  VIEWRS ICOM IC-745 - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 01, 2016, 02:15:00 am
content: #27 TROUBLESHOOTING AND TESTING A VIEWRS ICOM IC-745In this video I troubleshoot a viewer from South Carolina IC-745. We also have a peek at the PIEXX replacement ram board.Replacement trimmers from ICOM:4610000100 (CV05A0601 CTZ51A 6pF) $2.92 each4610000110 TRMR CV05C1201*VCT51C 12pF $2.92 eachPiexx boardhttps://www.piexx.com/?main_page=product_info&products_id=26
Question about making 433MHz antenna - Page 1
Forum section: electronics / rf-microwave

author: amwales
author_rank: Regular Contributor
timestamp: February 09, 2016, 09:06:14 pm
content: I want to make a 1/4 wave 433MHz antenna. Should I be concerned about the type of wire I use.I understand that it needs to be 173mm long but is it ok to use silicone insulated stranded copper wire?

author: davebb
author_rank: Frequent Contributor
timestamp: February 10, 2016, 12:59:04 am
content: Hi yes that will be fine, use the thickest wire will give you the best band width, but at 433mhz it will be wide ,don't forget your counter-poise/ground is half of your antenna, if I was you I would make a halfwave ant and get some gain.Dave 2E0DMB

author: GreyWoolfe
author_rank: Unknown
timestamp: February 10, 2016, 01:14:28 pm
content: To add to that, you want to think about which type of antenna will work better for your application-an omnidirectional or a beam antenna. The beam will give you gain at the expense of front to back and side to side rejection. Otherwise, Dave is on the mark with a 1/2 wave or better to get gain. Gain is good!Tom, NW0LF

author: Unknown
author_rank: Unknown
timestamp: February 11, 2016, 02:37:18 pm
content: To answer your question about making a 1/4 wave, the type of conductor you use doesn't matter. One point to note though is that the length you quoted 173mm is the free space wavelength. It will be slightly shorter in a piece of copper wire, more like 168 / 170mm. if you are using it for a receiver then it won't really make much difference, but if using it for a transmitter you will need to trim it to resonance either by using an SWR measurement or by trimming for maximum radiated signal. The ground system you use and the environment will also affect the length slightly.
Fixing 1962 Philips L4X25T SW receiver - Page 1
Forum section: electronics / rf-microwave

author: Cliff Matthews
author_rank: Unknown
timestamp: February 03, 2016, 12:22:18 pm
content: I picked-up a Philips L4X25T last week, cleaned it up, loaded it with 6 new C cells and crossed my fingers.. (didn't work this time). What I get is a tremendously loud tone around 500hz and no switch, control or any thing I wiggle inside affects it. Quite likely this thing is going to need some recapping, but it looks worth the effort. Since the tone seems somewhere around the speakers resonance, I thought I'd ask what are the chances that one of the TO-1 output transistors is bad? The schematic shows an output stage that looks very odd..

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 03, 2016, 01:10:08 pm
content: A 1962? That is over 50 years old. First thing I would do is start replacing those old electrolytic capacitors.I am not saying this as just being a "parts changer" but from experience.

author: Cliff Matthews
author_rank: Unknown
timestamp: February 03, 2016, 02:18:48 pm
content: Quote from: Radio Tech on February 03, 2016, 01:10:08 pmAgreed (and subscribed, thanks!), but since the audio stage is totally DC isolated and the tone is so mind-blowing, wouldn't checking those transistors be a deal-breaker? (It'd be a shame to re-cap if those transistors were pooched and not reasonably obtainable).

author: Cliff Matthews
author_rank: Unknown
timestamp: February 03, 2016, 02:25:43 pm
content: The prospect of getting OC-74's on ebay looks good..http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xtransistor+oc74.TRS0&_nkw=transistor+oc74&_sacat=0

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 03, 2016, 09:10:04 pm
content: Quote from: Cliff Matthews on February 03, 2016, 02:18:48 pmYes I agree, checking the transistors can not hurt at all. Also any high value resistors should be checked, just to be sure they are in tolerance. Also I would check that transformer to make sure there is no shorts, looks like a pc mount? May be able to lift component leads to get a good check.And thanks
Computer modularized analogy to ham transceiver construction - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: January 17, 2016, 04:31:08 pm
content: What do people think about the concept of using existing computer chassis form factors for componentized modular builds of SDRs. It seems like a no-brainer to me. That way people's purchases can be incorportated into their future rigs, etc. The ham community should cooperate on more projects so that components can interoperate, also the 5 1/2 inch drive bay size is large enough for small radios, like is done with avionics.

author: AF6LJ
author_rank: Unknown
timestamp: January 17, 2016, 04:58:26 pm
content: Making standardized modules isn't a bad idea. I could see this happening with homebrew projects. I don't see the likelihood of this happening in the industry. But hay....It would be good.

author: cdev
author_rank: Super Contributor
timestamp: January 17, 2016, 06:55:07 pm
content: It certainly would be good for case-reuse, and make it easier to manage RFI.

author: dmills
author_rank: Super Contributor
timestamp: January 18, 2016, 12:51:11 pm
content: I am not sure I see it.I mean we have Eurocard as a standard for some things, but really a radio has quite a few subsystems that have very different needs in terms of form factor...I have a rig done as a set of eurocards (Except for the input BPF, TX Power amp, Output LPF & power supply), but doing the whole thing as a set of identical modules is a huge ask (or a huge radio).The PA for example often defines (and is defined by) the cooling and thermal design of the entire set, and things like LPF filter banks (and even RX BPFs) can be more then slightly on the large side.Regards, Dan.

author: rfdave#gmail.com
author_rank: Contributor
timestamp: January 23, 2016, 11:55:34 pm
content: Kind of like the HPSDR?http://openhpsdr.org/This is very common in professional radio designs. Here's an examplehttp://irf-solutions.com/tuners/iwr-6800/

author: cdev
author_rank: Super Contributor
timestamp: January 24, 2016, 07:22:30 pm
content: Small, mountable, well shielded, common ground plane, etc!
strange static or microphonic radio squeal - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: January 26, 2016, 01:57:23 am
content: I'm hearing an interesting phenomenon with tonight's low humidity, that seems to involve microphonics, when tuning my simple preselector, it must involve static electricity-I've read that direct conversion style (softrock, etc) receivers can have microphonic issues, but Ive never experienced it quite like just now.So, I've been fooling around with preselectors and the current configuration basically only uses a single toroid and a single variable cap, the input and output and a parallel circuit involving the cap are all windings around the same toroid. the input and output both have 2 turns through the T50-2 toroid and the winding that is going to the cap has around ten turns. So i am tuning around trying to find the peak using the regular band noise to see where it resonates best when it starts making this very strange squealing sound, listening to it I realized that it must be static discharge..I dont think its where the RF peak is, its somewhere else.Also, the radio was behaving as it would when there is DC getting in there with the noise floor going way up and way down, semi randomly.The radio is a softrock and looking at it closely and probing around with a toothpick, I can tell that the board is also exhibiting some kind of microphonic activity, but only when the the preselector is tuned in a certain way does it elicit this behavior.See attached screenshot - it was taken while both the microphonics and the weird squealing were occurring. If you look closely, you can see some strange fuzzy/moire activity superimposed onto the "center discontinuity".. that seems to be caused by the static discharge or whatever it is. (the antenna does have a DC path to ground)Anyway, I thought it was interesting. It must be in part because of the winter dryness.
"American Radio Supply" - Page 1
Forum section: electronics / rf-microwave

author: djacobow
author_rank: Super Contributor
timestamp: January 25, 2016, 09:26:42 pm
content: Anybody ever order stuff from these guys: American Radio Supply? (http://www.americanradiosupply.com/)I put in an order with them 9 days ago and haven't heard a peep beyond the original order confirmation that came through immediately. I paid with PayPal, and of course that was debited immediately.I've written them a couple of times and left a voice mail message, too, with no response.Not even sure what steps to take other than contacting Paypal to reverse the payment.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: January 25, 2016, 09:59:46 pm
content: I've dealt with them before and have had no problems. They generally have a good reputation.They've had a bit of rough weather in Georgia the past weekend, maybe they are having some trouble due to that. It's a small business with only a few employees.

author: djacobow
author_rank: Super Contributor
timestamp: January 25, 2016, 10:41:14 pm
content: Quote from: alsetalokin4017 on January 25, 2016, 09:59:46 pmYeah, I finally got a return message a few hours after calling. It looks like they did ship my order last week (mostly) but it had come back due to a damaged shipping label. So it's going back out again, except for a huge roll of rg-213 which I suspect is being drop-shipped from wherever it comes from.