hybridfree/eevblog-posts huggingface dataset:
How often to get new ARRL handbook? - Page 1
Forum section: electronics / rf-microwave

author: djacobow
author_rank: Super Contributor
timestamp: August 24, 2017, 04:15:37 am
content: Every one? Once a decade?

author: edavid
author_rank: Super Contributor
timestamp: August 24, 2017, 04:31:09 am
content: Once a decade works for me, but you can easily find a pirate e-book of the current year and decide if it's worth buying.

author: chrisl
author_rank: Regular Contributor
timestamp: August 24, 2017, 04:42:48 am
content: I have been getting one once a decade.

author: bd139
author_rank: Super Contributor
timestamp: August 24, 2017, 07:34:57 am
content: My newest copy is 1988

author: TheDane
author_rank: Regular Contributor
timestamp: August 24, 2017, 12:56:29 pm
content: I go to my local library, and they sometimes have the newest version available for me to check out.- not much news there, but sometimes it is worth the walk if I need some specific info. Most tech stuff is google'able if you know what to search for. Beware though, not all sites are as informative - fakenewsEdit - added:The newer versions seems to have included digital radio a lot more/better.

author: spudboy488
author_rank: Regular Contributor
timestamp: August 25, 2017, 11:45:59 am
content: I have 1997 at work used mostly for formulas, etc. that don't really change. I'm not sure what I have downstairs but, to be honest, with the internet, there's really not a need, for me at least, to have a copy of the latest and greatest. Google is your friend if looking for info on a project.

author: MrTurk
author_rank: Newbie
timestamp: September 04, 2017, 03:06:59 pm
content: Nothing changes frequently in HAM universe, get a used hardcover on eBay for once.Nexus 5 cihaz?mdan Tapatalk kullan?larak gönderildi

author: AF6LJ
author_rank: Unknown
timestamp: September 04, 2017, 03:31:54 pm
content: I try for twice a decade, I have been buying up older ones.I have...193819431949195019551961196519721974198019902010For anybody who does boat anchors the old ones are a must have, along with at least one edition of Bill Orr's handbook. (the west coast handbook)The only handbook I don't have that I really want is the 1915 Handbook.I have a friend who maintains a complete set of handbooks.The first one is interesting reading.
Looking for MOLEX 52660-2651 Plugs - Page 1
Forum section: electronics / rf-microwave

author: dekagon
author_rank: Contributor
timestamp: August 14, 2017, 03:24:08 pm
content: Hello together,I need your help finding some plugs from Molex. The Molexnumber was 52660-2651.They are going obsolet in 2010 and unfortunately Molex had no successor brought into the market.Is here anybody who mybe have two or four plugs in their plugboxes or can supply me with informationson other plugs maybe from 3M or someone else which are compatible with the MOLEX one?I would be lucky to get my X72 rubidium frequency standard running...Thanks a lotChris

author: dj831
author_rank: Regular Contributor
timestamp: September 01, 2017, 03:32:38 pm
content: HiDekagon, I will let you know when I receive mine (I had the last one from US seller you probably had yours)That remark, since it really looks like connectors used by Smart Serial connectors of Cisco devices (just Google for WIC-2T, HWIC-1T, or HWIC-2T). I will put one of my cables in it when I receive it.Have a nice day.
parts choice for higher power active circulator - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: September 01, 2017, 09:06:16 am
content: What are some good op-amp choices for making a DC-low frequency circulator with 'decent' power handling capability that would pretty much work?I was going to build this,http://techlib.com/files/RFDesign3.pdfbut i figure, if you have something in mind, I would not mind more power handling capability and bandwidth. I don't have much experience in dealing with analog circuits that run above much more then a MHz so I am not familiar with the lay of the land as it comes to op-amps, being stable, etc.Things I had in mind:http://www.analog.com/en/products/amplifiers/operational-amplifiers/current-feedback-amplifiers/ad8009.html#product-overviewIs there a downside to using a CFB amplifier for this?

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2017, 02:45:09 pm
content: I remember when that active circulator article was first released and have it in paper form.The AD8009 is a fine choice with both higher bandwidth and higher output current then the CLC406 which is also a current feedback operational amplifier. Note however that the physical construction and layout is more important as the frequency goes up so it may be better to use a slower part initially.
Adding COR (Carrier operated relay) to a alinco dr-06t? - Page 1
Forum section: electronics / rf-microwave

author: Jesset1996.5
author_rank: Regular Contributor
timestamp: September 08, 2017, 11:49:21 pm
content: I have a dr-06t that i am using for a 6m repeater and i am using an id o matic controller but as with all controllers i need a cor input. My question is how do i hook this up on a dr 06t? I have seen it done on other radios and ht's but never on the dr-06t. Any help would be greatly appreciated as this is the final step to get my repeater on the air.ThanksJesse J Trimble , AC8WP.
LO Evaluation Boards - Page 1
Forum section: electronics / rf-microwave

author: mbtronix
author_rank: Newbie
timestamp: August 29, 2017, 12:18:17 pm
content: Hello all,I am working on forming a budget for my group's senior project design, a super-heterodyne receiver (spectrum analyzer).We are still working out some of the specs,' but are needing a figure to present to the university to get funding.Looking at the block diagram that our system design will closely follow (see attachments), the most costly items would be the LOs'. We are considering 3 mixing stages, where only the last would be a fixed crystal, and the first two would be synthesizers.Considering we do not want to do layout on the GHz stuff, we would be looking to order an eval board from TI or ADI, which from what I observe, approach $300 for a wideband synthesizer (we want a system bandwidth of 2.5-3G).Besides that, we will be ordering from mini-circuits connectorized filters and mixers, and laying out the rest of the signal chain after the 3rd IF.Doing a quick ebay search, I was able to find a board worked up with an ADF4351 for $30, but definitely, it makes me consider the quality of the performance. Does any one have any thoughts regarding this?Any ideas on how to save on system cost?I would appreciate any feedback that can be given.Thanks,MB

author: Neganur
author_rank: Unknown
timestamp: August 29, 2017, 08:21:28 pm
content: That looks pretty much like Scotty's spectrum analyzer.Perhaps you can use his design as inspiration regarding the VCOs to use (e.g. ROS1500, ROS2150)I don't recommend using an adc integrated in an MCU for this btw, they most of the time don't have the performance you are looking for. Rather use external ones and interface via for example SPI.PS, those ADF boards aren't bad but they are perhaps not as spurious free as you would like them to be. I have the AD eval board if you want some scope shots etc. OTOH, maybe you're not looking for stellar performance in which case the cheap eBay ones probably work fine to prove a concept etc.

author: mbtronix
author_rank: Newbie
timestamp: August 30, 2017, 01:02:52 pm
content: Thanks Neganur for the response!I plan on using an ic with a pll and integrated VCO, such that, to minimize parts and in turn minimize boards that need to be ordered. I am taking this path as I do not want to perform layout until the 2nd or 3rd IF.Thanks for bringing up about the ADC part of the design. That was something under consideration, and I was considering interfacing with a SAR.Do you have the ADI evaluation board or the China built evaluation board? I would be really interested in observing a phase noise measurement (at carrier frequency of 3GHz or so) if you have the means.
Scientific Atlanta Noise Generator (4661) RF Connectors - Page 1
Forum section: electronics / rf-microwave

author: kiheiman
author_rank: Contributor
timestamp: August 23, 2017, 12:16:30 pm
content: I have a Scientific Atlanta 4661 RF Noise Generator. All of the modules inside the box are interfaced together with short 75 ohm coax cables with quick disconnect connectors. The connectors look very similar to QMA connectors, but of reverse polarity. However, the 4661 box came out in the late 70s and the QMA connectors did not come out until the 2000s. Does anyone have any idea as to the model of these connectors? I need to interface to standard connectors so that I can test the modules. The attached snapshot shows the male connectors.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: August 23, 2017, 07:58:50 pm
content: Try the document provided HEREhttps://www.eevblog.com/forum/beginners/help-identify-connector/msg1262901/#msg1262901

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 23, 2017, 08:21:25 pm
content: Try to find it here:https://en.wikipedia.org/wiki/List_of_RF_connector_typeshttps://en.wikipedia.org/wiki/Category:Coaxial_connectorsBut it looks like the DIN 1.0/2.3..I'm not too sure. I'll update later.

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 23, 2017, 10:45:13 pm
content: Is the cable you pictured above used for board-to-board interconnect?There you go..I found it!It turns out it is a mini-smb connector.https://www.amphenolrf.com/145104-08-06-00.htmlIf not it might be the standard smb connector.If you want to interface it with modules with common connectors like sma, you might need these:SMA to SMB adapterjust be sure to verify the size/dimensions to avoid hassle.*I'm not affiliated with the companies mentioned above.

author: kiheiman
author_rank: Contributor
timestamp: August 30, 2017, 04:29:38 am
content: Thanks for the replies. It appears that the connector is a SMB 75 ohm. I had only looked at generic SMB connectors and noted that they were too small in diameter. The 75 ohm unit appears to be the same size as my connectors.RegardsClint
low frequency (0-10MHz) antenna driver (voltage vs current source) - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 28, 2017, 09:38:57 am
content: Is there any benefit to using a current source to drive an antenna?http://mri.tamu.edu/nsf_goali_files/Nam-2006-1.pdfDoes anyone actually do it though? I was thinking of using a power-howland AC current source to drive it.

author: voltz
author_rank: Frequent Contributor
timestamp: August 28, 2017, 10:02:20 am
content: Without actually reading that PDF in detail and just from thinking first principles, i would think it makes very little or no difference.Its all 'power' at the end of the day, either with more voltage than current or more current than voltage. But the result is always the same, power.I suppose transmission lines are better driven at higher voltage than current to reduce resistance losses. But unless your feeders are very long and running at high power, i suggest there's no real difference. If anything, voltage driven would be better.Maybe there is another reason why current fed would be better. Just can't think of one!
Is this Narda Horn / Gunnplexer Antenna Build complete / correctly built? - Page 1
Forum section: electronics / rf-microwave

author: emc2guru
author_rank: Newbie
timestamp: August 28, 2017, 10:09:15 am
content: I got this from an ex-amateur radio guy and was wondering if anyone could provide any information it. I know nothing about it and dont know if it is a complete antenna. Also,does it look to be wired correctly at the Gunnplexer. I don't know if this guy was just randomly connecting things together or if it was build with a purposes in mind. Below is the "flow chart" of components, I also attached photos, thanks in advance!Narda 640 Standard Gain Horn (Freq. 8.20-12.4 GHz) -> Narda 601A (Freq. 8.2-12.4 Gc) -> Narda 601A (Freq. 8.2-12.4 Gc) -> Gunnplexer MA-87141-1 10.295 GHz -> BNC, + / - wires

author: voltz
author_rank: Frequent Contributor
timestamp: August 28, 2017, 10:43:11 am
content: It looks like a complete head and antenna assembly. Although it would need a power supply, modulator circuit and IF receiver to get the thing working as a transceiver.Some info here from a similar model:http://www.qsl.net/n9zia/pdf/ma87127.pdf10Ghz, 10mW.More info in this article from the 70'shttp://cahabatechnology.com/aa4pg/hrmag/hamradiomag/HamRadio Magazine 1978 Issues 1-12/08 August 1978.pdfstarts around page 12.
ADLAM PLUTO SDR Hardware shielding.  - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 23, 2017, 05:55:13 pm
content: Thought this merited its own thread, since the other thread is focused on the software side.It is completely unshielded.I was thinkin either to cut out copper or nickle silver templates and wrap it, grounding it to the SMA connectors, but I was worried that the distributed capacitance of the shield might detune some kind of factory calibration.Short: Do microwave designers take the shield can into account when they design the circuit, or have to (typically) modify the circuit after the shield can is made?Do you think it will be alright, or should I put it in a larger box on standoffs and route extension cables to the box faces? Like, put 1 or 2 inch plastic standoffs on the bottom of the SDR body, glue it inside of a metal box (so its sitting 1 or 2 inches above and bellow the sides of the box, and use short SMA cable extensions of good quality to bridge it to the box ends.It can do up to 6 GHz with the modification, I never actually built any kind of circuit that runs on microwave frequencies (only used test equipment) in this area, so I am not sure what will happen.My hunch tells me it won't make a difference, but I figure before I waste a bunch of copper I'd ask. it looks like you only have 0.75cm between the plastic body of the casing and the PCB.What spot tests would be appropriate to run on something modified like that to verify its accuracy? I am scared it will bite me in the ass some how in an unexpected way.
ridged pyramidal horn antenna (rectangular), effect of freznel lens - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 22, 2017, 07:19:43 pm
content: I don't mean a lens horn (the conical shape one), but a regular pyramidal horn that has a lens on it. The lens I speak of looks like a ziggaraut made of concentric ovals, with the spacing between the elevation planes approximately 1cm and a depth of 1.5cm over the area of the horn apature.How much of an effect does it have? Does anyone have pictures of radiation patterns differences because of lens being placed in front of the horn?
low cost, reliable RF detector badge (passive) - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 16, 2017, 11:25:30 pm
content: What is a recommendation for making a RF detector badge, to indicate if (possibly dangerous) leakage is occurring?LED? Neon Bulb?What should they be attached to? Tuned antennas for the frequency of operation?I imagined something like 5-10 fat diopole antennas in a pocket protector, each covering like 1GHz hopefully.How about broad band detection? I.e. only having one circuit.

author: CopperCone
author_rank: Super Contributor
timestamp: August 17, 2017, 01:57:30 am
content: No, I am looking for something to wear on your person around power equipment.Of course you can have a SA hooked up, but I mean something akin to a radiation exposure badge.I know if you stick neons infront of a powerful microwave, or CFL, they light up, but I am wondering if that can be tuned for personal protection.Kind of like a passive spectrum analyzer you can put in your pocket that will have different lights light up if significant RF fields are present for whatever reason.So you don't slowly cook yourself, risk your eye sight, etc (see the RF injuries thread I made for more details).I thought a series of fat dipoles might work, if each is pretty wide band (like 500-1Ghz), so then you can have different lights to give yourself protection. It seemed like it would fit in a pocket protector (like revenge of the nerds).So if they light up, you might want to check your gasket seals, antenna direction, etc. (perhaps you just made a forgetful error)

author: CopperCone
author_rank: Super Contributor
timestamp: August 17, 2017, 02:24:42 am
content: ima stick a LED to a hardline loop and see what happens I guess

author: dmills
author_rank: Super Contributor
timestamp: August 17, 2017, 07:19:22 am
content: Log detectors (Analog devices and such) are probably your friend.Personally I incline to the view that such things should be largely unnecessary, I mean you have the only keys to the power supply interlock switch on your person right? Lock and tag applies just as much to high power RF as it does to HV).Calibrating something mounted close to the skin is hard, doubly so in the near field.73, Dan.

author: CopperCone
author_rank: Super Contributor
timestamp: August 22, 2017, 07:04:08 am
content: Well I made it, Will test it soon. I used a red LED and a loop thats approximately 2 inches in diameter made of rg141 hardline.I think its a good idea to have a passive detector in addition to an active detector, since the reliability is higher. They should be used in tandem.Do I expect the thing to light up ever? not really. but why not? It's a simple measure to take in case shit hits the fan.
Has anyone ever seen an SDR design that uses a QSD to feed a fast 100MSPS+ ADC? - Page 1
Forum section: electronics / rf-microwave

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: August 08, 2017, 09:09:31 pm
content: I have a few nice 16bit LT 105MSPS ADCs laying around and I've been thinking about trying to design an affordable HF SDR with a broad(~10mhz) instantaneous bandwidth. Something more along the lines of an SDR-IQ/FLEX system. I know these expensive higher end HF SDRs all use DDC with and FPGA/ASIC. Could something with comparable performance be made by feeding a QSD in to a nice ADC then doing DSP work on a faster micro or even something like an allwinner a10?I have searched and searched for an SDR using something like a soft-rock or any QSD to feed a fast ADC and I can't find anyone using anything besides audio codecs for some reason, 48khz of bandwidth sucks so I cant figure out why no one has done this, unless the performance is no better than using a cheap tuner chip. From what I understand you can switch a QSD up to 1ghz so this gives the ability to build a wideband SDR or a really performance focus narrowband SDR.This is all kind of just thoughts here but if one could build a QSD SDR that does DSP on a micro or streams to a PC and gets close to DDC performance, it seems like a great inexpensive way to build a nice low noise base to down convert other bands too! Especially if you dont have to have 105MSPS ADC, a 40MSPS is much cheaper! Some micros like the NXP's even have 80MSPS ADCs built in if your willing to go down to 12bit.

author: mark03
author_rank: Frequent Contributor
timestamp: August 08, 2017, 10:37:47 pm
content: Wouldn't you be hard-pressed to get the data out of the ADC at those speeds, without an FPGA?If the idea is that getting rid of the FPGA makes this a substantially easier project, I would suggest otherwise. At those frequencies, good layout, and keeping digital crud out of the front end, is the bigger challenge. That's what I heard from the openhpsdr folks (the best-known direct-sampling design).Don't forget to factor into your supposed cost savings that you now need two ADC channels instead of one.I also believe it's difficult to get that kind of bandwidth out of the Tayloe-style QSD, due to finite source impedance and reasonable capacitance at the four phase outputs, but I'm not an expert.More interesting (to me) would be a moderate-bandwidth QSD-based receiver which is designed around fast and high-resolution successive-approximation ADCs, say 1 to 2 MSPS, rather than a sound card.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 12, 2017, 08:08:39 pm
content: Beaglebone can do 100MSps, but I don't see much advantage using that instead of a FPGA.

author: CopperCone
author_rank: Super Contributor
timestamp: August 22, 2017, 06:58:54 am
content: well its probobly alot easier to program it and test algorithms with high probability of intercept signals before going to fast FPGA detectors.
vlfrx-tools - interesting program, also might be useful for eclipse - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: August 19, 2017, 05:27:26 pm
content: VLFRX-Tools (http://abelian.org/vlfrx-tools/)looks like a program that might have all sorts of useful features, its primarily a VLF receiver that works with a number of input options (including rtlsdr, probably in direct sampling mode..as well as with a sound card - direct input.. have to check that out tonight) It also it has some timing related features it seems.http://abelian.org/vlfrx-tools/notes.htmlThere are specific instructions for setting up the input RC network so that the proper instant is registered as the start of the PPS pulse.Looks interesting. Wonder ifthese plotswere made with it?Ive never seen pps run into a sound card but its possible it could work..Its apparently important to use an rc network on the input, and how its set up is important for accuracy.---RC ValuesSuitable R and C values for pulse shaping can be estimated as follows. GivenRin = input resistance of the sound card, ohms;Vf = full scale input amplitude of the soundcard, volts;Vp = pulse amplitude out of the GPS, volts;Pw = pulse width, secondsthenR = Rin * (1.25 * Vp/Vf - 1)C = Pw/(pi * Rin * (1 - 0.8 * Vf/Vp))
CMU200, a few newbie questions.. - Page 1
Forum section: electronics / rf-microwave

author: popoka
author_rank: Newbie
timestamp: August 17, 2017, 10:33:02 am
content: May i introduce myself? My name is Olaf, 41, and i live in Cologne/Germany.I just bought a CMU200 V.30, and i hope i can use it to play around in my HAM shack.I bought the V30, because i want to have the 50W power input stage. Unfortunatly this unit has a sticker on the RF1, that tells me: 2W max.Is that because of the B99 option, that is built in? Can i change it back to 50W (i.e. by removing this option ?)?Maybe someone can help me with that problem.Another issue: On the main screen a message is blinking every 10 sec. that shows: Reference frequency not locked.Does that mean that there is a problem?Best regards, Olaf

author: CJay
author_rank: Super Contributor
timestamp: August 17, 2017, 11:25:54 am
content: There are others who may know more detail but I believe there are mechanical differences between the 2W and 50W versions, there is a heatsink and fan on the 50W version that's not on the 2W version so it's not as simple as just removing B99.Reference frequency unlocked, I would suggest checking your machine has internal reference selected and that the reference oscillator board is seated correctly.Service manuals are easily available via google but if you have problems finding them just ask.
orbital bitcoin network, bullshit or ??? - Page 1
Forum section: electronics / rf-microwave

author: WastelandTek
author_rank: Frequent Contributor
timestamp: August 15, 2017, 04:46:35 pm
content: https://blockstream.com/2017/08/15/announcing-blockstream-satellite.htmlpretty vague, not a lot of details, no uplink gear listed in the BOMhttps://github.com/blockstream/satellitesuper slick rollout videohttps://youtu.be/lbx7NAnVeGcIguessitcouldwork, on some level, using terrestrial SMS as uplink...but methinks I smell that age old odor.thoughts?

author: CopperCone
author_rank: Super Contributor
timestamp: August 15, 2017, 04:51:03 pm
content: I don't know, for a financial system you would need back up satellites ready to go at a moments notice in case of faulty anti satellite weapons tests, north korea, solar flares, etc... would be a disaster if your reliant on it.It's certainly possible. No reason why some rich guy can't go to a company that makes satellites and have them design it. You would also need a network to maintain global coverage.Also, how do you prevent denial of service attack if it uses a common protocol to communicate with you with no registration and stuff?
do vacuum tube devices (microwave) act as parasitic frequency mixers?  - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 15, 2017, 04:28:32 am
content: Do microwave buffer amplifiers (Traveling wave tubes) act as mixers? (i.e. unwanted signal going into them and being mixed into some other frequency).Do they act like mixers that make more 3rd harmonic then 2nd harmonic (since they have corrosive metal (do they?) in them) but no PN junctions?Or does some other effect take place?

author: CopperCone
author_rank: Super Contributor
timestamp: August 15, 2017, 05:42:44 am
content: well, as far as power devices go they are the only approachable low budget solution for wide band power amplifiers (that tend to operate at 1 or 2 octaves)...A solid state solution would run like, 20,000$... however with TWT you might only be buying a few minutes or hours of run time from them due to age.

author: CopperCone
author_rank: Super Contributor
timestamp: August 15, 2017, 05:49:04 am
content: btw, I am interested to know because I want to determine how much isolation (by isolators) is required to prevent harmonic generation for an experiment that I am conducting. I don't want 'crosstalk' between the amplifiers causing harmonic generation, as it is confusing the results of the non linear junction detector experiment.If the device is known to be a horribly inefficient mixer, perhaps I can ease the isolation requirements (adding 80db of isolation at a high power level to a particular channel is rather pricey).
vacuum tube amplifier reflection sensitivity? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 15, 2017, 05:45:45 am
content: Is damage from reflections a 'averaged' thermal phenomena? Or does it relate to spot heating capable of doing damage much under the 'rating' of the device? (this is for traveling wave tubes)Can you run them at a low power level (say 70% of rating) and just have them absorb the reflections without damage? (say its 20% reflection)Or is the heating incurred by reflective absorption much greater then the heating caused by efficient generation of energy that is properly transmitted into the load?
slyvania TW-956K traveling wave tube specifications? - Page 1
Forum section: electronics / rf-microwave

author: CopperCone
author_rank: Super Contributor
timestamp: August 14, 2017, 10:39:06 pm
content: All I can find on this guy is that it was an early development, 1959, from a electronics publication. Claims to be broad band.It's rather large and appears to have TNC connectors.Can anyone guess at the specifications of this guy (bandwidth, power)? And voltages required for operation?I would guess it has a power output of at least 5+ watts given its size. maybe more. its rather heavy and magnetized. Kind of reminds me of kirks phase rifle from the original series of startrek. (because of the cooling fins, colorful hv wiring and general shape). If you used active magnets to focus it.. it would probobly look similar with the coils and whatnot.
Antenna placement 868MHz - Page 1
Forum section: electronics / rf-microwave

author: fantasy2
author_rank: Contributor
timestamp: August 05, 2017, 10:21:30 am
content: Probably a very simple questions for all the experts here.I'm very restricted in the available space to place an antenna for 868MHZ ISM range.Below some pictures of the possible orientations. Option 1 would be the best, but then the antenna would stick out of the housing, which doesn't look nice and is more challenging to make it water proof.Everything will be placed in an ABS housing.Black = PCB contour with ground planeBlue square = RF moduleBlue rectangle = AA battery on other side of the PCBWhat would be the least worse situation?Option 4 is a helical antenna but the gap between a metal pin of the AA cell holder is 1mm max.Another option would be to place the helical antenna behind the PCB like below. Is this realistic?

author: IkariShinji
author_rank: Newbie
timestamp: August 11, 2017, 10:28:34 pm
content: Not an expert. Here is my 2 cents.By the look of your helical antenna, it is in normal mode, so it is not very much different from a monopole.IIRC, if you put a monopole very close to the ground plane in parallel, the radiation efficiency will drop a lot.I will go with either #2 or #4.The easiest way is always to just mount it and measure the output power. Please update the results if you could.
ASK Transmitter Problem - Page 1
Forum section: electronics / rf-microwave

author: Danesh_SA
author_rank: Contributor
timestamp: August 11, 2017, 08:05:10 pm
content: Hello ,Recently I design a system and i use ASK 315 Mhz module with Pt2262 ,i use the circuit that i attached and i use 5V relay instead of 4 tact switchs and control them with MCU,the module voltage is 5v. the problem is: the module is always HOT! and when i send nothing the module draws 110ma @5v and when it transmite something it draws 110ma @5v too!1-how can i turn off module when it not transmite anything?2-Does the system warm up affect on module shorten range of transmition in long time(appr. 12 month and 8hours turn on every day)?

author: xtoffer
author_rank: Contributor
timestamp: August 11, 2017, 09:06:14 pm
content: You could switch the power to the module on and off with some sort of transistor if it does not have a power down or enable pin. However 110 mA seems execessive. More information on which module, and the actual schematic would maybe help. If the module is the kind I think it is I would expect something in the order of ~10mA.

author: Danesh_SA
author_rank: Contributor
timestamp: August 11, 2017, 09:48:16 pm
content: Thank for your reply xtoffer,this module is much powerful and here is my schematic:is it possible not to use PT2262 and directly connect the module to USART i found some projects on this subject , but is itreliable?
#133 Kenwood VFO 230 Repair - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: August 09, 2017, 12:29:20 am
content: In this video we have a look at the Kenwood VFO-230.Viewer sent it in complaining of unstable display

author: voltz
author_rank: Frequent Contributor
timestamp: August 09, 2017, 08:58:05 am
content: Always an issue when the fault doesn't show itself. At least you found some dry joints and fixed those. What else can we do?My only other course of action would be to get the lid on, allow the unit hours to get right up to temperature and just let it run.If there are any unstable components, it should start to show up eventually.Good chance its fixed. Or the problem may be elsewhere as you said.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: August 10, 2017, 12:37:46 pm
content: Quote from: voltz on August 09, 2017, 08:58:05 amYes I agree, "what else can we do".The unit ran all day yesterday with cover installed and did not miss a beat. I feel comfortable letting it take the journey back home.
Microstrip two port network design tips  - Page 1
Forum section: electronics / rf-microwave

author: Cacao
author_rank: Contributor
timestamp: August 06, 2017, 11:03:06 am
content: Can anyone give me advice on designing two port network, here is the plan:https://ibb.co/jCHVevOperating frequency: 2-3GHzThank you guys!

author: Howardlong
author_rank: Super Contributor
timestamp: August 06, 2017, 12:04:51 pm
content: That's a directional coupler, which is either a three- or four-port device.In your case it's configured as a three port, the "fourth port" goes directly to a dummy load.

author: Cacao
author_rank: Contributor
timestamp: August 06, 2017, 01:44:49 pm
content: Quote from: Howardlong on August 06, 2017, 12:04:51 pmCan you give me some things to consider when designing it?

author: hendorog
author_rank: Super Contributor
timestamp: August 06, 2017, 08:20:04 pm
content: It is probably simpler to get good results with an RF directional bridge instead of a coupler for a beginner.Assuming you don't need to handle high power.Good info on both approaches can be found in this impressive VNA project:Coupler:http://hforsten.com/cheap-homemade-30-mhz-6-ghz-vector-network-analyzer.htmlBridge:http://hforsten.com/improved-homemade-vna.html

author: BigBoss
author_rank: Regular Contributor
timestamp: August 06, 2017, 08:35:07 pm
content: Quote from: Cacao on August 06, 2017, 11:03:06 amIf you don't have a possibility to reach a EM simulator, I'd recommend you to use commercial products such ashttp://www.yantel-corp.com/en/products/datasheel/DC/DC2500P02.pdfThere are also other different manufacturers.The component that you're looking for "Directional Coupler".It's a 4 port device and forward and reflected power can easily be measured.

author: Cacao
author_rank: Contributor
timestamp: August 09, 2017, 02:48:12 pm
content: Do you guys know how can I change the operating frequency of a wilkinson power divider such as this into 2.5GHz?https://www.cst.com/academia/examples/wilkinson-power-divider

author: Cacao
author_rank: Contributor
timestamp: August 09, 2017, 03:52:09 pm
content: Here is the function of this network. As I supply a microwave signal (2.5GHz) into one of its ports, that signal will go to the probe that is attached to some material. The reflected signal from the probe then will be detected by the rf detector. Do you think a power divider or a directional coupler can be used?
Video: Visualizing the operation/function of an antenna tuner... - Page 1
Forum section: electronics / rf-microwave

author: w2aew
author_rank: Super Contributor
timestamp: July 17, 2017, 06:10:57 pm
content: My latest video shows how the Smith chart on a VNA can be used to visually see the operation & function of a typical transmatch (antenna tuner):

author: MattSR
author_rank: Regular Contributor
timestamp: July 17, 2017, 09:02:48 pm
content: Yes please to a further video explaining the Smith chart in more detail (along with transmission lines of course)Cheers,Matt

author: AF6LJ
author_rank: Unknown
timestamp: August 03, 2017, 12:16:54 am
content: The Smith Chart video will be relatively short, they are fairly simple and very handy.

author: w2aew
author_rank: Super Contributor
timestamp: August 03, 2017, 02:20:00 am
content: Quote from: AF6LJ on August 03, 2017, 12:16:54 amHmmm - well, if I want to explain what each of the 7 scales of the chart are, plus the 10 or 11 radially scaled axis - that would be a decent length video itself. Then, explaining how to plot complex values, how they "move" with frequency or added transmission lines - another decent length video. Of course, then we should talk about impedance matching, using lumped elements and stubs - that's a few more videos... I've been trying to mentally parse the list of topics to start formulating my videos...

author: xtoffer
author_rank: Contributor
timestamp: August 03, 2017, 08:04:30 pm
content: Quote from: w2aew on August 03, 2017, 02:20:00 amThis sounds like a very good planI have recently gotten into the RF side of things and I can't stress enough how welcome this would be. I'm not usually very verbal but I like your take on things. Recently watched the reflected pulse coax one.

author: AF6LJ
author_rank: Unknown
timestamp: August 08, 2017, 02:33:55 pm
content: Quote from: w2aew on August 03, 2017, 02:20:00 amI forgot about all that, being an RF tech I tend to take some things for granted.
Anyone know a coaxial cable for 0-2GHz  - Page 1
Forum section: electronics / rf-microwave

author: Cacao
author_rank: Contributor
timestamp: July 19, 2017, 02:05:13 pm
content: Can anyone help me find a coaxial cable that has a 0-2GHz frequency of operation and also has a BNC or SMA termination. Your help is much appreciated. Thank you.

author: alm
author_rank: Super Contributor
timestamp: July 19, 2017, 02:10:54 pm
content: Voltage/power level? Length? Acceptable attenuation? VSWR? Mechanical requirements?Any piece of wire will pass some signal at 2 GHz.

author: tggzzz
author_rank: Super Contributor
timestamp: July 19, 2017, 03:37:20 pm
content: Quote from: Cacao on July 19, 2017, 02:05:13 pmSeethis, then gohere.

author: daqq
author_rank: Super Contributor
timestamp: July 19, 2017, 05:10:11 pm
content: Try:http://uk.farnell.com/c/cable-wire-cable-assemblies/cable-assemblies/rf-coaxial-cable-assemblies

author: bjcuizon
author_rank: Frequent Contributor
timestamp: August 07, 2017, 06:28:28 am
content: You may find some here:http://www.mouser.ph/Wire-Cable/Cable-Assemblies/RF-Cable-Assemblies/_/N-bkrix?No=200&P=1z0x0emZ1yzsqvfZ1yzsqvgand here:http://ph.rs-online.com/web/c/cables-wires/coaxial-cable/coaxial-cable-assemblies/?searchTerm=bnc%20cable.It may be a bit hard to find a cheap price and the one that suits your needs. I know its really hard to find these things in the Philippines sometimes. (I can say that cause I'm a Filipino myself) The ones on our local stores just don't cut it. They usually just order it from a cheap supplier in China.

author: ejeffrey
author_rank: Super Contributor
timestamp: August 08, 2017, 04:43:24 am
content: Almost any coaxial cable will work to 2 GHz for some values of "work". Ordinary Rg-174 and RG-58 cables are normally specified as "up to 1 GHz." If all you care about is transmitting signals over a short distance (a few meters), they work fine at 2 GHz and even higher. Their impedance, loss, leakage, and phase stability are not great at high frequency due to the braided shield construction, but they usually will get the job done.It's hard to say if those limitations will be an issue without knowing your application.
LDMOS Amplifier Construction - Page 1
Forum section: electronics / rf-microwave

author: German_EE
author_rank: Super Contributor
timestamp: August 06, 2017, 01:03:40 pm
content: A series of eight YouTube videos on the construction of a high power LDMOS amplifier.This fellow must be very brave or a single man because he joins the two halves of the heatsink together using solder paste and the heat from his electric cooker. If I tried this SWMBO would have words. Also, those transistors are 177 Euro each from Mouser.

author: David Hess
author_rank: Super Contributor
timestamp: August 06, 2017, 05:30:41 pm
content: Quote from: German_EE on August 06, 2017, 01:03:40 pmI have done the same thing using normal flux cored solder and a cutting torch head to get enough distributed heat but the electric cooker probably yields better results. I assume the real pros use an argon filled electric furnace.

author: BigBoss
author_rank: Regular Contributor
timestamp: August 06, 2017, 07:01:55 pm
content: I believe that he'll pay a electricity invoice very badly..
Questions about phased array beam steering - Page 1
Forum section: electronics / rf-microwave

author: Ben321
author_rank: Frequent Contributor
timestamp: August 06, 2017, 05:53:55 am
content: This usually is a technique applied to radar, but it also can be used with non-electromagnetic waves (mainly ultrasound, such as for hospital ultrasound imaging). I'm trying to figure out just who's phase what is being shifted (which signal is being delayed). Usually there's a carrier wave (one signal), being amplitude modulated by a pulse (another signal). So lets say you had microwave carrier wave with a frequency of 1GHz, and it was being amplitude modulated by a rectangular pulse waveform with an on time of 0.1ms (0.0001s) and an off time of 100ms (0.1s). If I wanted to steer the beam, which signal would I apply the delay to? Would I apply it to the carrier wave (a sinusoidal wave), or to the pulse wave (repeating rectangular pulse)?Or would I apply the delay to both waveforms simultaneously, to make sure that the phase of the carrier wave relative to the start of the pulse was always the same?

author: ataradov
author_rank: Super Contributor
timestamp: August 06, 2017, 06:29:48 am
content: It is applied to your final signal you want to steer. Imagine generating non-steered signal, apply whatever modulation you like. Then emit the same same signal from multiple emitters with their phase shifted.

author: David Hess
author_rank: Super Contributor
timestamp: August 06, 2017, 03:07:23 pm
content: The phase adjustment is applied to the carrier either before or after amplitude modulation.

author: ataradov
author_rank: Super Contributor
timestamp: August 06, 2017, 05:54:52 pm
content: I'm not sure about ultrasound, but in radio location this will not work. Radars use modulation to increase distance resolution (often BPSK with modulation according to M-sequnces or Barker codes). If you apply modulation after the phase shift, then when you receive the signal back, you have only one option - to shift the whole thing, which will mean that modulation will not be in-phase at the summing stage.
HP 141T Spectrum Analyzer LCD Upgrade - Page 1
Forum section: electronics / rf-microwave

author: vk2seb
author_rank: Contributor
timestamp: July 31, 2017, 11:12:42 am
content: Just a heads up to anyone else who owns one of these ancient 141T Spectrum Analyzer mainframes, I'm working on some firmware for an STM32F7 touchscreen development board to act as an upgrade for the display on it.At the moment, I have:- Real-time spectrum display with graticules etc, that works on the slowest up to the fastest timebase- A waterfall display mode- A normalization function that makes insertion loss measurements much easier.Here's a video of it working (lots of other RF stuff too on my channel if you're interested):Code is available on github (very hacky at the moment):https://github.com/schnommus/stm32_hp141_lcdMuch more work planned for this (want to use all the extra data available on the tracking preselector connector on the back for more features).I'll post updates in this thread

author: AF6LJ
author_rank: Unknown
timestamp: August 03, 2017, 12:10:11 am
content: This is great, a baseband back end for an old workhouse.I get a grin when I think of the half dozen PC boards and the 5602 processor in my 8569B that does the same thing.

author: KE5FX
author_rank: Super Contributor
timestamp: August 03, 2017, 01:14:57 am
content: Very nifty. What's your bootup time like?

author: vk2seb
author_rank: Contributor
timestamp: August 03, 2017, 06:55:19 am
content: Quote from: AF6LJYep, it's ridiculous how much power you can get for a few bucks these days...Quote from: KE5FXCode is all bare-metal, no OS so it boots up in a few milliseconds, definitely faster than the old CRT took to warm up.Waiting for the analyzer LOs etc to warm up to frequency is really the bottleneck though.

author: KE5FX
author_rank: Super Contributor
timestamp: August 03, 2017, 07:02:55 am
content: Quote from: vk2seb on August 03, 2017, 06:55:19 amAh, I see. For some reason I thought you were running Arch Linux on the board at runtime, as well as to host your development environment.Do they offer a development kit like that one with a bigger/better LCD?

author: fcb
author_rank: Super Contributor
timestamp: August 03, 2017, 05:09:45 pm
content: Very very cool.I had a 141T and it was the HEAVIEST piece of kit I ever owned before my Fluke 5215A.I seem to remember I had the matching tracking generator and it went upto 18GHz!

author: KE5FX
author_rank: Super Contributor
timestamp: August 04, 2017, 07:42:49 pm
content: Just to be sure,thisis the board you're using?

author: Jay95
author_rank: Newbie
timestamp: August 05, 2017, 11:09:03 am
content: Nice work!I knew I shouldn't have given away the 141T that I had

author: AF6LJ
author_rank: Unknown
timestamp: August 06, 2017, 08:35:50 pm
content: Quote from: fcb on August 03, 2017, 05:09:45 pmYes it did.There was also a preselector you could get also.
Loop antenna to multiple receivers - Page 1
Forum section: electronics / rf-microwave

author: medical-nerd
author_rank: Regular Contributor
timestamp: August 05, 2017, 08:34:00 pm
content: HiyaI have a Wellbrook ALA1530 active loop antenna that I want to connect to a number of shortwave receivers simultaneously.What is the best method of doing this? Do I need to build a distribution amplifier, or would a simple splitter be effective? What is the best way of isolating the receivers from each other?The receivers would be commercial and homebrew.Cheers

author: borjam
author_rank: Unknown
timestamp: August 05, 2017, 08:38:12 pm
content: Quote from: medical-nerd on August 05, 2017, 08:34:00 pmA splitter would be the best way. Despite losing several dBs, the Wellbrook amplifier would make up for that loss.
Yaesu FTDX 560 - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: July 30, 2017, 08:06:48 pm
content: Here is a classic radio I picked up this week end.

author: German_EE
author_rank: Super Contributor
timestamp: July 30, 2017, 08:25:58 pm
content: Forty seven minutes of vintage tube goodness, it is however 22:23 here so this little treat will have to wait until tomorrow, as will the two chocolate donuts in the fridge.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: July 30, 2017, 08:45:26 pm
content: Quote from: German_EE on July 30, 2017, 08:25:58 pmOh yes. 20 tubes in this old classic rig.Better wait till tomorrow my friend. Those chocolate doughnuts sound yummy!

author: voltz
author_rank: Frequent Contributor
timestamp: July 30, 2017, 10:31:06 pm
content: Nice restoration project. Looking good! and is that a Super S i see on the bench?

author: Radio Tech
author_rank: Frequent Contributor
timestamp: July 31, 2017, 12:43:27 am
content: Quote from: voltz on July 30, 2017, 10:31:06 pmThanks, should be a fun rig to restore. And now that I see it works will be fun.And you are correct. 1200 Super S. Great unit.

author: German_EE
author_rank: Super Contributor
timestamp: July 31, 2017, 02:00:37 pm
content: Is the S Meter supposed to operate backwards?

author: Radio Tech
author_rank: Frequent Contributor
timestamp: July 31, 2017, 03:53:30 pm
content: Yes, Believe me it got me too when I fist started working on it. Was thinking why is the s-meter pegging out. But zero is on the right side of the meter. Also the VFO is backwards from most rigs. Got to love those Japanese design engineers.

author: AF6LJ
author_rank: Unknown
timestamp: August 03, 2017, 12:05:10 am
content: That backwards S-Meter is common the Swan 350 I have is the same way.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: August 03, 2017, 01:33:21 am
content: Quote from: AF6LJ on August 03, 2017, 12:05:10 amForgot about those. Although I have 3 of them you are correct. May have had something to do with left handed cigarettes in the late 60's.....

author: AF6LJ
author_rank: Unknown
timestamp: August 03, 2017, 08:03:55 pm
content: Quote from: Radio Tech on August 03, 2017, 01:33:21 amThe one my friend has is also an FTDX-560 in the orginal box, with the manual, looks like someone just pulled it out used for a few weeks and put it back in the box.

author: medical-nerd
author_rank: Regular Contributor
timestamp: August 04, 2017, 02:30:59 pm
content: HiyaI have a similar FRDX400 receiver and it is one of the most sensitive receivers I own. It is a joy to tune and has very little drift once warmed up. Its a shame that it doesn't cover broadcast bands as the sound is so good.Cheers
R&S SK001 exciter - Page 1
Forum section: electronics / rf-microwave

author: iw2fiv
author_rank: Newbie
timestamp: August 06, 2017, 10:36:53 am
content: At a flea market I bougth an SK001 R&S exciter with Control panel GB002I haven't the interconnection cable and I don't find it on common market anyone can help me?I'm looking for any info about itAnyone knows the rf power out ?Thanks Carlo IW2FIV