hybridfree/eevblog-posts huggingface dataset:
Help please to identify this mystery object - Page 1
Forum section: electronics / rf-microwave

author: MisterHeadache
author_rank: Regular Contributor
timestamp: May 13, 2022, 03:39:36 pm
content: I've had this guy in my junk box for years, it came with a grab bag of stuff. On the outside it sure looks like a crystal or mechanical filter, but I cannot find any info about it online. Filtronix is now a different kind of filter company, and searching for 'Filtronix 487-006' yields the extremely rare zero hits in Google.Full text on it reads:FiltronixType 487-0065.5-2.7 72-29If it turns out to be a really good bandpass filter, I may use it in a future project. If not, then it's going in the rubbish bin. Or I might take a stab at it with my signal generator and SA to see what it does.Any thoughts what this is?

author: Grandchuck
author_rank: Super Contributor
timestamp: May 13, 2022, 06:00:49 pm
content: Crystal filter with 2.7 kHz bandwidth centered at 5.5 MHz. Just a wild ass guess! If so, makes for a SSB application.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 13, 2022, 08:17:48 pm
content: probably similar to the one used in SWAN-350C SSB Transceiver (SSB or C-F filter?) i dont know what is it but i have a feeling that Grandchuck is not telling us everythinghttps://www.mhrep.com/product/swan-350c-original-c-f-filter-model-5-5-2-7-used/https://www.roetta.it/ik3hia/pages/Hamradio/swan350c.htmgoogling more "ssb filter 5.5-2.7" reveals more relatives of look alike...CW /SSB 2.7K narrowband filter compatible with YF-122S module For YAESU FT-817/818/857/897 MURATA CFJ455K13at least you can sell it at $50-80... maybe filtronics or filtronetics have some relation? ymmv.

author: WattsThat
author_rank: Frequent Contributor
timestamp: May 13, 2022, 08:51:23 pm
content: That’s a Heathkit format part number, date code sure fits. Don’t have my master list to look it up, you might be able to find a list on the web.

author: MisterHeadache
author_rank: Regular Contributor
timestamp: May 18, 2022, 06:39:27 pm
content: Mystery solved. I had a window of opportunity this week to put it on a network analyzer (see below picture), and if the printing were interpreted to mean its application was for a USB filter for a 5.5MHz carrier, then that makes sense. A 2.7kHz bandwidth is believable based on this data. It has good symmetry in both tails, so conceivably it could be used for LSB if the carrier were shifted up accordingly. There’s ripple in the passband, but I just did a quick solder connection to RG316 coax and it also may have a higher impedance than the 50 ohms of the NA. Not sure what max power it can handle, though - I tested it at 0dBm.I had no luck digging deeper for a Heathkit part number, though.Thanks Grandchuck for the tip, you put me on the right track. Now I might just be able to use this little guy for a future homebrew SSB transmitter project…
Misnomer on two type/division wifi transmitter & receiver ? - Page 1
Forum section: electronics / rf-microwave

author: abdulbadii
author_rank: Frequent Contributor
timestamp: May 20, 2022, 02:32:56 pm
content: How is it being said that two fully different division wifi transmitter (router, modem wifi, etc) and receiver (wifi adapter), but it the receiver must transmit back reply to server or otherPlease explain up to giving usefulness, thanks before
Sanyo TA-395 schematic - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: May 17, 2022, 06:57:26 pm
content: maybe this is OT, in such a case either move this elsewhere or delete it (or just tell me to do so and I'll accomplish)As for the topic. I'm seeking for the schematic of that old "walkie talkie"; did my homework, but aside from some videos, was unable to find a schematicany idea / pointer ?
TheRadioBoard - Page 1
Forum section: electronics / rf-microwave

author: 6gv5
author_rank: Newbie
timestamp: May 14, 2022, 07:45:13 pm
content: If anyone over here was registered at TheRadioBoard (.com), the sad news is that the site in its old incarnation is probably gone forever, the good news is that a few old users have set up a temporary group to keep them in touch. I already pointed them here, and they're probably looking for someone to help with the migration of the old PhPBB message base to a new place.The new group ishttps://groups.io/g/TheNewRadioBoard

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: May 16, 2022, 05:58:33 am
content: Also there's a new web-based Radio Board forum here:https://lad90000.wixsite.com/radioelectronics/forum
HC-12 Channel setting and retention - Page 1
Forum section: electronics / rf-microwave

author: Jester
author_rank: Frequent Contributor
timestamp: May 17, 2022, 01:06:23 am
content: I'm finalizing the firmware for a HC-12 project.These HC-12 modules come from the factory with default settings; CH1, 9600 baud etc. The user can modify the module settings with AT commands and the limited data sheet states that these settings are non-volatile.In my application I will program the channel to something other than default channel and the HC-12 will forever use that channel. I'm trying to decide if I should just set the channel once when it is programmed in production (and rely on the non-volatile feature) or reprogram it every time it powers-up, just to be sure that if it looses its marbles, power-cycling should get it back to the correct channel. I don't expect this will be powered up and down continuously or often, it should be powered up 24-7 with the occasional power outage, so don't expect to encroach on the unspecified endurance limits with occasional power ups.Thoughts; once or every power-up?
Test Lab costs for RF testing without full Bluetooth compliance.  - Page 1
Forum section: electronics / rf-microwave

author: MrRT84
author_rank: Newbie
timestamp: November 07, 2019, 09:33:21 pm
content: Hi all,I’ve some questions about RF certifikation, compliance and pre-compliance tests in test labs. Basically, we got a quote from a test lab which seems very expensive and i can not estimate if all tests are neccesarey or not.But first, I will give you with some basic information.We use a EFR32BG1x SoC from SiLabs.We use the Silabs BLE stack but do not want to use "Bluetooth" (as a name) nor the Bluetooth logo.We just wanna compley with the IEEE 802.15.We hope to skip all those expensive bluethooth RF testing.The end product will be certified for the EU, US and JP.We know, that we have to make extended EMC tests to comply with FCC / CE… like the EN 300328, EN 301489 and FCC Part 15.But what are the bare minimum tests and COSTS for a 2.4 GHz device without all those bluetooth naming and licensing stuff (+Bluetooth SIG = 8.000 USD)?If we do not want to make full bluetooth compliance does it make seens to use a pre-certified module like the BGM13S? We would have to make EN 300328, EN 301489 and FCC Part 15 tests anyways? So, if we do not want to name it „Bluethooth“ Device nor use the Bluetooth or BLE Logo, what are the benefits of using such modules, besides reducing riskes of failing EMC tests?Does anyone have some numbers or information how much such tests cost?Do we really need to make a bluetooth full conformance (BT Core spec. 5.1 or lower) test?What about the Bluetooth BQC Service, TCB Service and RCB Service? Do we have to use such services, if we do not use bluetooth?I’m thankful about any information and experience on that.Thanks

author: Smokey
author_rank: Super Contributor
timestamp: May 01, 2022, 09:00:28 pm
content: Bump for an interesting question that never got an answer. Especially the part about being BLE "compatible" without using the Bluetooth name.
Wireless community networks? Software? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: April 24, 2022, 12:50:45 pm
content: Does anybody know of any good options to build a wireless community or "mesh network"? in a contiguous area?With commodity off the shelf wireless gear? I live in a self-contained "neighborhood" that could support such a community, but don't know of any good software to do this.

author: Stinson108
author_rank: Newbie
timestamp: April 28, 2022, 04:54:25 pm
content: Start with a Google search for Hamnet. Reports of its death are premature. Buy an old Linksys router or two and experiment. Disregard the equipment specifications you find most easily on the web. You want an *older* one with more memory (yes, the older ones had more RAM). Once you have the basic firmware running, then you'll add more features that take more memory.
S2LP maximum transmit power problem - Page 1
Forum section: electronics / rf-microwave

author: can47
author_rank: Contributor
timestamp: April 28, 2022, 11:56:09 am
content: hi,I am trying to transmit at maximum power using S2-LP. I set the configuration registers using S2-LP DK Application tool version 1.3.4. I set output power as 14dBm, check the MAX power box, choose HPM mode (in PM mode section), set 1600mV SMPS voltage level. According to datasheet at maximum tx power S2LP consumes about 20mA. However, I did never measure more than 12mA (including STM32L051 uc consumption).After that I opened an example project from CubeMX, project name is "S2868A1_P2P". I also tested with same nucleo board (L053) and reached about 30mA at maximum power. However using the same configuration registers I could not able to reach maximum power.Is there any configuration that I missed?best regards,Can İNEL
Whatever happened to Australia's 10 gigabyte Wifi Chip? ANy day now? Vaporware? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: April 21, 2022, 05:56:28 pm
content: This looked good, but now where is it?http://web.archive.org/web/20080229011745/http://www.zdnet.com.au/news/hardware/soa/Australia-s-10-GiFi-chip-promises-wireless-5Gbps/0,130061702,339286253,00.htm

author: madires
author_rank: Super Contributor
timestamp: April 21, 2022, 06:26:42 pm
content: 3 GHz bandwidth for 5 Gbit/s and a range up to 10m (LOS!) doesn't sound like a WiFi killer.

author: cdev
author_rank: Super Contributor
timestamp: April 21, 2022, 06:49:32 pm
content: Quote from: madires on April 21, 2022, 06:26:42 pmThat is very short range indeed.. Inside a building might need 20 or 30 M. Two meters is basically on the same (big) desk.

author: Marco
author_rank: Super Contributor
timestamp: April 21, 2022, 08:18:10 pm
content: Hell, whatever happened to Shahriar's 32Gb/s chipThe killer application for this stuff has always been VR and VR hasn't had huge success. Having something which can only survive maybe one bounce on a good day isn't too useful for most applications. Maybe once Apple's headset launches there will be a need for superfast near-LOS communication. Though I still fail to see the advantage over just going optical.

author: cdev
author_rank: Super Contributor
timestamp: April 24, 2022, 02:27:21 am
content: If you have LOS you should be able to go miles.. and even more..into space..with high bandwidth...

author: Marco
author_rank: Super Contributor
timestamp: April 24, 2022, 02:40:43 am
content: Generally the ISM frequencies are on sections where the atmosphere has a large dip in transparency.

author: jhalar
author_rank: Regular Contributor
timestamp: April 25, 2022, 04:14:56 am
content: Quote from: cdev on April 21, 2022, 05:56:28 pmThe research organisation (NICTA) that is mentioned in the webpage article stopped operating in 2016. It no longer exists.

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: April 25, 2022, 06:24:07 am
content: Quote from: cdev on April 24, 2022, 02:27:21 amExcept for that pesky inverse square law.

author: Shock
author_rank: Super Contributor
timestamp: April 25, 2022, 09:42:05 am
content: I think you will find the current government in Australia cut funding to it either directly or indirectly in their previous term. They are up for election in a few weeks.I don't forgive them for the lies they perpetuated about making the NBN (national fibre internet network) cheaper and better "Lets keep the decades old copper for the last few hundred meters to peoples houses" what morons.
Upcoming Keysight Webinar - Page 1
Forum section: electronics / rf-microwave

author: xmo
author_rank: Regular Contributor
timestamp: June 06, 2021, 04:35:38 pm
content: I received this email that I thought might interest other RF junkies:Demo: PNA-X Spurious TestDr. Joel Dunsmore will walk through a 20-minute demo showing optimized spurious testing with the enhanced PNA/PNA-X new DDS source.In this webinar series Dr. Dunsmore will demonstrate:• Close-in carrier spurious• Higher-order mixing products• Spurious vs. LO drive levelJoin this Keysight webinar to learn how to optimize spurious tests on the PNA/PNA-X.Date: June 16, 2021https://connectlp.keysight.com/SpuriousTest-Americas?elq_cid=1130946&cmpid=ELQ-14600&elqCampaignId=14600&elqTrackId=2FE217D7C4FF72BD38DC574DD1E4E6B9&elq=ba1aa6467a24496da8e3fb5eff8200a8&elqaid=30097&elqat=1&elqCampaignId=14600

author: joeqsmith
author_rank: Super Contributor
timestamp: June 06, 2021, 09:26:32 pm
content: uBlock Origin has prevented the following page from loading:Odd.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: June 07, 2021, 12:16:31 am
content: I got a "confirm your country" modal -- maybe that's what upset uBlock?

author: A.Z.
author_rank: Super Contributor
timestamp: April 26, 2022, 12:05:34 pm
content: Quote from: joeqsmith on June 06, 2021, 09:26:32 pmnot so much, the message explains that the domain is on a "blacklist" due to privacy issues, it probably collects fingerprints and data and sells them

author: cdev
author_rank: Super Contributor
timestamp: April 26, 2022, 12:29:51 pm
content: Ublock Origin, which I also use, can subscribe to a bunch of ad oriented lists. You can select which ones you want to use.. But cannot edit them. (unless you do so and put the new list on your own server, which isnt hard)

author: cdev
author_rank: Super Contributor
timestamp: April 26, 2022, 12:32:32 pm
content: Chance is, the first part of the URL is okay, its usually the part after the ? that I find likely to be problematic/privacy endangering..Quote from: xmo on June 06, 2021, 04:35:38 pm
Frequency to Voltage Stability - Page 1
Forum section: electronics / rf-microwave

author: danigund
author_rank: Newbie
timestamp: April 22, 2022, 04:04:27 am
content: I am trying to understand the behaviours I am seeing when using an AD652 in the FVC mode.(pg 15 ofhttps://www.analog.com/media/en/technical-documentation/data-sheets/ad652.pdf)I conducted a series of measurements of the output voltage (Vout) across a wide range of input frequencies (each of which was held constant for the duration of the measurement) and found that Vout experienced instabilities (fluctuating periodically) at particular frequencies that coincided with multiples of the clock frequency (2.5MHz). I'll attach my graphs below.I have set up an LTSpice simulation but am having difficulty reproducing the circuit.I'd appreciate any help in fixing my simulation and understanding:1. Why the output voltages follow the linear ramping pattern--> Is this due to sampling and aliasing effects (particularly since it is symmetric about the clock frequency)?2. Why the residual linearity instabilities are greater on the negative slopes--> Could this be related to propagation delays in the digital circuit?
flared telescoping antenna RF fingers choice? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: April 21, 2022, 03:18:19 pm
content: I would like to make a brass telescoping antenna using brass tube that is silver plated. I found nesting brass tubing before but I wanted to put flares on top of each of the tubes, so there could be RF fingers that contact the nested tube. Like, imagine you put RF fingers inside of a funnel so that if you put a rod in the funnel the RF fingers touch it. it should be easy to flare torch heated brass with a flaring tool.It's a little bewildering to try to choose a strip of RF fingers.. so I was hoping that someone works on alot of RF seals might be able to list some plausible choices/series for RF fingers. Perhaps someone has samplers unused since the dark ages that come to mind? I am not sure how to pick this out without buying way too many samples... it might come down to someones intuition hopefully. I don't know if they have RF fingers that might have a 'ball' on the tip rather then just stamped brass that might be safer for plating. It needs to be a good sliding rf contact.Otherwise I was thinking to spot weld small copper spheres to beryllium copper spring wire hooks and arrange them on drilled holes like a chirstmas wreath in a funnel.

author: cdev
author_rank: Super Contributor
timestamp: April 21, 2022, 06:17:02 pm
content: This is for making better shielding that's durable/reusable for cases?

author: coppercone2
author_rank: Super Contributor
timestamp: April 21, 2022, 07:50:52 pm
content: It is to make the joints between a telescoping antenna, the fingers are typically used for chassis seals but maybe you can repurpose them. I suppose it could be used for a telescoping shield umbilical too.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: April 22, 2022, 01:07:48 am
content: Maybe some related information could be found in the catalogue as well as the custom part design guides of Tech-Etch?https://techetch.com/They are partnering with Feuerherdt in Germany, where I was even able to noodle a samples pack of many variants out of them!https://www.feuerherdt.de/de/produkte
RF impedance matched traces - Page 1
Forum section: electronics / rf-microwave

author: CMCCOLL
author_rank: Newbie
timestamp: May 09, 2022, 08:27:21 am
content: Hi,I am new to doing RF 2.4Gz ble PCB's and looking into impedance matched traces.My current design runs into the problem where there is no space for the antenna to be on the same side of the PCB as the BLE radio, is it possible to route an impedance trace from the top layer to the bottom layer through a VIA?Is there such a thing as impedance matching the vias or is this not required as the vias is so short?Cheers,

author: richard.cs
author_rank: Super Contributor
timestamp: May 09, 2022, 09:03:18 am
content: Layer change on RF tracks isn't really desirable, but often necessary. The most important thing is to ensure that where there is a layer change there is a path for the return current. e.g. if you have a 4 layer board and you via from the top to the bottom, the return current which is flowing in the layer 2 ground plane under the top track needs to get to the layer 3 ground plane so it can flow above the bottom track. Basically this means you need ground vias very close to your layer transition.

author: cdev
author_rank: Super Contributor
timestamp: May 09, 2022, 11:58:04 am
content: @evb149 thank you for your links. Vias are so important in home rf construction.
New Rf sampling modality alleged to sample from "DC to daylight"  - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: April 13, 2022, 09:21:31 pm
content: Does anybody have any impressions or knowledge about this?will this make extremely wide range of sampling available anytime soon?https://phys.org/news/2021-02-quantum-entire-radio-frequency-spectrum.html

author: mawyatt
author_rank: Super Contributor
timestamp: April 14, 2022, 12:52:05 am
content: Interesting technology, although they didn't give much detail on how this works. Certainly the frequency range and applications are quite valid!! Need to look into this more, thanks for postingWe were working on similar needs for wide-band spectral analysis for the same reasons given before retiring a few years back . We coined the name "RF Spectral Imager", and a patent (11125794) was issued late last year covering some of the technology involved, while some was kept as trade secret.https://patents.justia.com/patent/11125794The patent covers the techniques which employ CMOS technology that's similarly utilized in camera CMOS imager chips. A key feature was using a special technique where the NMOS device "remembers" the last drain current even tho disconnected at the gate and drain (gate oxide charge capture). The device is configured for current mode operation and becomes a RF Sampler Pixel of the RF input current, thus an RF sampler Pixel type memory element. These RF Pixel Memory elements are arranged such to that allow Current Mode FFTs to be performed in Real Time with Discrete Time Continous Amplitude fashion by utilizing the NMOS device characteristics as the FFT weighing functions, and followed by many high resolution ADCs like used in camera chips which read the rows and columns.Since the RF Pixel Memory is very small, thousands or even millions of RF Pixel Memory elements, all the Real Time current mode FFT circuitry and Frequency Bin ADCs can all be integrated onto a single silicon CMOS chip!!These unique Spectral Imager Chips could be dynamically configured to do "other" things than FFTs for specific proprietary uses.Best,

author: mawyatt
author_rank: Super Contributor
timestamp: April 14, 2022, 12:45:54 pm
content: Should add that this RF Pixel Sampler can operate to >40GHz in modern CMOS, and the Current Mode FFT is fast and has the unique "Computational" attributes of FFT Addition/Subtraction by simple wired OR Drains, and FFT Multiplications by simple Device Size/Scaling. So all the required FFT Computations are handled in the Real Time Analog Domain by means of simple scalable Current Mirrors, no Smoke thoBest,
Unknown MC BLK-6-N+ Power Rating - Page 1
Forum section: electronics / rf-microwave

author: ROFLCat
author_rank: Contributor
timestamp: April 12, 2022, 08:49:58 pm
content: Hello everyone,One of my friends recently acquired an N-type DC-block from Mini-Circuits and was amazed by the lack of any information on the maximum power handling capabilities of this DC-block. We looked everywhere, but to no avail.I was wondering if anyone experienced could provide any info on this particular issue.I have attached an image of the device if anyone was curious and didn't want to Google it xdThanks in advance <3

author: TheMG
author_rank: Frequent Contributor
timestamp: April 13, 2022, 07:42:33 pm
content: Have you tried contacting Mini-Circuits and asking them?
'Make' project Long range text message  - Page 1
Forum section: electronics / rf-microwave

author: congruentsquare
author_rank: Contributor
timestamp: April 05, 2022, 03:17:41 pm
content: Hi,I remember getting an e-mail for a long range text message radio device in my 'Make' e-mail newsletter. It uses the Low Frequency band to send text messages over 20 miles to other transmitters. I can't seem to find it. Does anybody know what I am talking about?

author: cdev
author_rank: Super Contributor
timestamp: April 05, 2022, 04:13:55 pm
content: So its SMS over VLF, NVIS, or similar?

author: RoGeorge
author_rank: Super Contributor
timestamp: April 05, 2022, 05:18:18 pm
content: Sounds like LoRahttps://en.wikipedia.org/wiki/LoRa
Build ideas for ROB733 (scrapbox finding - full diferential 100MHz LM733/SE592)? - Page 1
Forum section: electronics / rf-microwave

author: RoGeorge
author_rank: Super Contributor
timestamp: April 17, 2022, 06:06:23 pm
content: Found through the scrap boxes a few 14 pins DIP of ROB733, the Romanian version of LM733, uA733, SE592, etc. fabricated about 30-40 years ago at a former Romanian institute for electronics, called "ICCE".Tested the ICs on a breadboard, and 4-5 of them seem to be working reasonably OK.It's a full differential 100MHz amp single resistor/impedance amplification adjustment that requires no additional parts to work, just power. Destined for video amplifiers, RF filters, pulses, etc.https://www.ti.com/lit/ds/symlink/ua733.pdfAny ideas what to build out of them?

author: Gyro
author_rank: Super Contributor
timestamp: April 17, 2022, 06:30:11 pm
content: A high frequency differential probe?Gain option 3 looks the best bet, X10 gain, 200MHz bandwidth and 250k input resistance. You could terminate both outputs*and AC couple one of them to a scope probe. Input capacitance looks to be only 2pF.EDIT:*... assuming that you actually need to terminate the outputs.
Attention ham radio operators with 10 meters. Say hello to Juno! - Page 1
Forum section: electronics / rf-microwave

author: vk2hmc
author_rank: Contributor
timestamp: October 09, 2013, 12:38:05 am
content: NASA spacecraft Juno, bound for Jupiter, will have a earth fly-by Wednesday this week.NASA asks all Hams for help with a experiment:http://www.jpl.nasa.gov/hijuno/--marki

author: cdev
author_rank: Super Contributor
timestamp: April 06, 2022, 11:50:23 pm
content: Are you certain the URL specified isnt wrong?

author: RoGeorge
author_rank: Super Contributor
timestamp: April 07, 2022, 12:06:02 am
content: That was in 2013.

author: TheSteve
author_rank: Unknown
timestamp: April 07, 2022, 12:29:46 am
content: hah - 10 meters has been open quite a bit lately though, still not quite enough to go back in time.
Attenuator help - Page 1
Forum section: electronics / rf-microwave

author: mapleLC
author_rank: Frequent Contributor
timestamp: April 02, 2022, 06:50:12 pm
content: Can the community please help me identify who makes high quality attenuators?The main characteristic I need is the preservation of the signal quality being attenuated.

author: TimFox
author_rank: Super Contributor
timestamp: April 02, 2022, 06:57:10 pm
content: What frequency range? Fixed or variable?Pasternack has a good selection of RF attenuators (both kinds), but they are pricy.https://www.pasternack.com/attenuators-category.aspx

author: mapleLC
author_rank: Frequent Contributor
timestamp: April 02, 2022, 07:00:32 pm
content: RF or audio signal ranges - 20 to 20k hz or soThe signal strength would be fixed in terms of amplitude

author: TimFox
author_rank: Super Contributor
timestamp: April 02, 2022, 07:06:38 pm
content: There are many stepped-attenuator (switch with resistors between terminals) available on eBay, etc. for audio (< 20 kHz).Just make sure that the resistor values are not too low (to cause distortion of the driver) nor too high (to avoid frequency dependence with load capacitance).I found some expensive units from a Polish company Khozmo:https://khozmo.com/series_khozmo_attenuator.htmlTheir switches are beautiful, the only ones I have seen with a setscrew to adjust the rotational torque.You didn't specify impedance: other sources have matched-impedance attenuators designed for 600 ohm circuits.

author: mapleLC
author_rank: Frequent Contributor
timestamp: April 02, 2022, 07:15:19 pm
content: Quote from: TimFox on April 02, 2022, 07:06:38 pmThe extremes in terms of impedance would be around 5k and 50k.I need to attenuate between about -3 and -24db either by a series of fixed attenuators or a variable one.

author: TimFox
author_rank: Super Contributor
timestamp: April 02, 2022, 07:52:36 pm
content: The usual packaged fixed attenuators and variable attenuators are for RF frequencies and typically have 50 ohm (possibly 75 ohm) impedance.Fixed audio attenuators are typically 600 ohms, but aren't too common anymore.For your impedance range, the Khozmo units I cited have attenuation steps of around 1.5 dB, which are finer than most stepped attenuators sold for audio purposes.Your best bet would probably be a potentiometer, to give a continuous range of attenuation. You can add a resistor in series with the "low" end to restrict the high-attenuation end of the range. Cermet is the usual choice.Note that the load resistance affects the attenuation value, so you need to calibrate the attenuation yourself in your circuit.To get closer to a constant-dB-per-angle, you can load a linear-taper potentiometer with a fixed resistor (approximately half the potentiometer resistance).The input resistance of this combination will vary with rotation.
New York Times reporting of Ukraine Conflict seems to be incorporating SDRs - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: March 29, 2022, 06:32:27 pm
content: Screenshots of SDR are all around the media. Reporters are intercepting HF and VHF communications.Reporters are receiving and recording the distress calls of beleaguered Russian units calling for help and backup. Antitank and antiaircraft weaponry is being used to great effect by the defensive forces. In response Russian forces are killing civilians caught in the wrong places perhaps trying to return to their homes or families.https://www.nytimes.com/video/world/europe/100000008266864/russia-army-radio-makariv.html.If anybody here is intercepting these signals, please post them, and enough metadata to clue would be listeners in how to find them.

author: A.Z.
author_rank: Super Contributor
timestamp: March 29, 2022, 08:07:47 pm
content: No, sorry.find 'em if you can, if not, then... no

author: cdev
author_rank: Super Contributor
timestamp: April 01, 2022, 11:17:24 pm
content: Think about and hope for the best for one of our brothers from here, who is stuck right in the middle of this mess.Its quite pathetic how the Russians are too resource constrained to get their soldiers anything approaching a professional military radio.(which should be encrypted) Those Russians are getting harassed on the shortwave HF bands!They deserve it. Quite ridiculous how they expected to be welcomed with open arms.. cough..Seems that the Ukrainian security forces have their hands full so no FCC style regulation is going on. Its the least of their problems.CBS News showed an Icom 7300 being used to mock the Russians invading the country with their death trap tanks/ovens..

author: themadhippy
author_rank: Super Contributor
timestamp: April 02, 2022, 02:46:30 am
content: QuoteLike america was hoping to be greeted in Vietnam,Korea,Grenada,libya,afganistan,panama,iraq and multiple other country's since 1945.

author: cdev
author_rank: Super Contributor
timestamp: April 02, 2022, 03:00:38 am
content: As long as their money is green, we dont care about any other colors..

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2022, 03:50:07 am
content: Don't post geopolitics here, I don't care if it disguised as technical.
Which Battery Cable size - Page 1
Forum section: electronics / rf-microwave

author: veedub565
author_rank: Frequent Contributor
timestamp: March 11, 2022, 04:52:38 pm
content: I want to operate my vintage military HF rig from a leisure battery. It is 250W max output, with a rated max power consumption of 640W (CW, key down. )So I reckon 640W at 12V is around 50A.Question is which wire guage is appropriate. I did a bit of research and came up with AWG 4. Just looking for an extra opinion on whether that sounds about right.I'm not actually going to be using it at full power. Indeed I'm only an M7 so 10W max. And even then I use SSB not CW. I thought it prudent though to set things up for what the rig is potentially capable of. Rather than what I use it for now, and then have to upgrade it later.

author: TimFox
author_rank: Super Contributor
timestamp: March 11, 2022, 05:18:39 pm
content: How long a cable do you need? Probably the voltage drop is a more important consideration than wire current rating.

author: geggi1
author_rank: Frequent Contributor
timestamp: March 11, 2022, 10:35:28 pm
content: If the cable is very short (1m) 10mm2 would be sufficiant.In case the cable lis longer go for 16mm2 but keep it as short as possible.

author: veedub565
author_rank: Frequent Contributor
timestamp: March 12, 2022, 07:17:46 am
content: Thanks, its probably only going to be a couple of meters tops.

author: Dehv
author_rank: Contributor
timestamp: March 30, 2022, 09:45:52 pm
content: #4 sounds right, with a fuse compensating for increased amps due to voltage sag as the battery gets down to 10.5v.

author: veedub565
author_rank: Frequent Contributor
timestamp: April 01, 2022, 05:13:21 pm
content: Quote from: Dehv on March 30, 2022, 09:45:52 pmYes that's a good point, as the battery voltage drops it's gonna suck more current to compensate. I hadn't thought of that. I haven't actually gotten around to doing this yet, various other things taking up my time.
12V to 120VAC inverter EMI reduction - Page 1
Forum section: electronics / rf-microwave

author: Dw11in
author_rank: Contributor
timestamp: March 22, 2022, 08:11:23 pm
content: I have a Renogy 1kW pure sine wave inverter that I think has a EMI problem. In the near future I plan to use this inverter to power test equipment where mains power isn't easily accessible. As a test subject I am using a radio receiver which powers on and functions fine however when trying to tune the AM band there is terrible buzzing and no station will come in although FM works fine. I have reason to believe with the AM issue I might have issues with the test equipment if powered by the inverter.I thought about placing a Corcom 10VN1 Line filter on the output of the inverter which I think should clean up the line noise.Any thoughts on this? Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 22, 2022, 08:43:04 pm
content: Would most likely help, yeah. Note that filter ground needs to be referred to chassis or input ground, depending on how things are wired internally. And not with long spaghetti leads, but with wide and short connections, like sheetmetal, or foil tape. (I guess the thing has a metal housing, so that should help?)Tim

author: Dw11in
author_rank: Contributor
timestamp: March 22, 2022, 08:57:29 pm
content: Thanks for the reply, I will give it a try!

author: Dehv
author_rank: Contributor
timestamp: March 30, 2022, 09:48:17 pm
content: You need a "low frequency" transformer based pure sine inverter for radio applications.The heavy, expensive type.
OFDM transceiver chipset / modul or DIY - Page 1
Forum section: electronics / rf-microwave

author: rfspezi
author_rank: Regular Contributor
timestamp: March 17, 2022, 03:26:22 pm
content: I did some research on OFDM transceiver chipsets and moduls in the 2...6 GHz range but couldn't find any products.Does anybody know a source for such moduls or chipsets?Ofcourse there would be the DIY alternative - however i guess nobody here actually did such a project yet?

author: rfdave#gmail.com
author_rank: Contributor
timestamp: March 30, 2022, 02:37:12 am
content: LTE and 5G both use OFDM, as does WiFi. What are you trying to build?

author: rfspezi
author_rank: Regular Contributor
timestamp: March 30, 2022, 06:12:12 am
content: Actually i wanna build a basic OFDM transceiver for experimenting.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 30, 2022, 09:41:49 am
content: ADALM-PLUTO SDR is an educational platform with a Zynq FPGA running Linux to control an AD9363 transceiver. There is a hack to make that work up to 6GHz. Overall, a programmable SDR that can implement any kind of modulation, including OFDM. It can be controlled directly from Linux, or from GNU Radio, Python, Matlab, etc.There is a free SDR book about Pluto SDR (from Analog Devices), and many other examples, University classes, or books from 3rd parties.Here is a random example of a OFDM lab with Pluto SDR:Quotehttps://people.ece.ubc.ca/edc/7860.jan2019/lab5.pdf
Tesla coils  discharge signals - Page 1
Forum section: electronics / rf-microwave

author: lyy611
author_rank: Newbie
timestamp: March 25, 2022, 02:43:39 am
content: I'm trying to make a Tesla coil to simulate tip discharge signals. I use an antenna of my own design to collect the discharge signal，I can't observe the signal in the oscilloscope。The oscilloscope model and waveform are shown in the following figureThe lighter can also simulate a tip discharge, and I will paste the collected signal underneath, but the signal frequency is incorrectCorrect tip discharge signal at 300-700MHZ.

author: lyy611
author_rank: Newbie
timestamp: March 25, 2022, 02:44:33 am
content: tesla coil discharge signal

author: lyy611
author_rank: Newbie
timestamp: March 25, 2022, 02:48:45 am
content: lighter discharge signal

author: lyy611
author_rank: Newbie
timestamp: March 25, 2022, 02:50:49 am
content: tesla coil circuit diagram

author: jonpaul
author_rank: Super Contributor
timestamp: March 27, 2022, 03:03:11 pm
content: Lighter is piezo électrique and generates a fast pulse.scope and probe are ringing. The very fast pulse needs a better set-up to observeYou,have not build Tesla Coil!Just a pulser and transformer. Very bad designSuggest you research Tesla Coils theory and design as well,as high voltage pulse and safety before you proceedBon chanceJon

author: lyy611
author_rank: Newbie
timestamp: March 28, 2022, 01:45:34 am
content: Thank you for your reply, this is indeed a bad design.I guess the sine wave I measured above is a resonant waveform，I used an aluminum plate for magnetic isolationAn unclear pulse signal was observed, but I don't know if it was a fake signal
7805 noise? - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: March 23, 2022, 12:41:11 pm
content: Hi all just wondered if powering an lna inside a radio with a 7805 is ok or are they noisey?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 23, 2022, 12:47:17 pm
content: Impossible to say. Probably, no problem.Tim

author: Kleinstein
author_rank: Super Contributor
timestamp: March 23, 2022, 02:23:35 pm
content: Radio frequency LNAs usually have pretty good decoupling at the supplies and thus don't care much about supply noise.

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2022, 02:37:21 pm
content: 7805 with the correct input and output supply bypass capacitors will be very quiet, and the noise really depends on layout and what you feed in, plus any noise in the load current reflected back to the regulator. Normally you have the input and output capacitors, and then perhaps some ceramics in parallel with them, and even a ferrite bead on the output side, or a small LC filter input and output if you really are after low noise, feeding the 7805 from a well regulated supply, probably a 7809 mounted near it, with the same bypass scheme.
DX Commander back on YouTube - Page 1
Forum section: electronics / rf-microwave

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: March 07, 2022, 07:28:21 pm
content: Many antenna builders subscribed to DX Commander (M0MCX) on YouTube.I certainly gained heaps from Callum's introductions to antenna modelling.His channel got pulled for some unknown reason.Anyway Callum is back at @dx.commander .Like & subscribe etc to help him rebuild.

author: Mark19960
author_rank: Regular Contributor
timestamp: March 23, 2022, 07:38:13 am
content: I went to have a look to see if he knows why they did that to start with.And 2 weeks on, apparently no explanation as to why they did that to Callum.One has to wonder if Youtube is fit for purpose....

author: SeanB
author_rank: Super Contributor
timestamp: March 23, 2022, 02:13:13 pm
content: Probably had 3 copyright strikes in a week, and his email filters got the notices.
Macom MAAM-011162 :  S-Parameters? - Page 1
Forum section: electronics / rf-microwave

author: Uky
author_rank: Regular Contributor
timestamp: March 11, 2022, 09:26:29 am
content: Greetings forum.Is there anyone out there that can provide S-parameter files for Macom MAAM-011162 ?It is a small CATV-amplifier IC in a SOT-89 package. Macom's support page provides a datasheet with a 75 Ohm application onlyand briefly mentions that it is possible to match this device in 50 Ohms.Since I purchased only a small amount of them for hobby use, I don't think that Macom would be willing to answer such a request.Cheers

author: Marsupilami
author_rank: Frequent Contributor
timestamp: March 12, 2022, 06:27:58 am
content: Hey Uky,Don't want to dissuade you from using these forums but man, out of the 13 pages of the datasheet 3 whole pages detail 50Ohm operation, including specs, plots and even recommended tuning component values.Also your mindset is incorrect about asking Macom. Be bold, go bug them! (I mean this in a positive, encouraging way.) If they have the data they will send it to you regardless if you bought none, 1 or 10,000. It doesn't cost them anything. If they don't have the data they would not take it for you unless you buy a million, there is not really a middle ground of you have to be an established professional.Good luck!

author: fourierpwn
author_rank: Regular Contributor
timestamp: March 14, 2022, 08:02:36 am
content: To add to Marsupilami's response; the datasheet does indeed include 50 Ohm operation - see pages 10-13.https://cdn.macom.com/datasheets/MAAM-011162.pdfI agree that it is worth asking for datafiles. Worst they'll do is not respond or say no.If this doesn't get you anywhere, then a handy (free) tool for digitizing data ishttps://automeris.io/WebPlotDigitizer/Attached is a sample for the S21 plot on Page 11 of the datasheet, loaded into the digitizer, axes are calibrated and data points are extracted. Typically, some data points may need to be shifted around as the digitizer isn't always perfect but it gets the job done. Do this for all given S-par data and you can create your own .s2p file, just be sure that you get the same frequency values to ensure the touchstone file can be read properly by any software/equipment you're intending on using this with.

author: Uky
author_rank: Regular Contributor
timestamp: March 18, 2022, 09:06:22 am
content: I downloaded the datasheets and designed/assembled a test board according to the application example.Found it to be unstable when testing it in a fixture with coax accessories that allowed sweeping for reactive loads.So - The need for S-parameters is still there and I will (boaldly) approach Macom in the matter...
Complete NOOB question on PTT & Jacks - Page 1
Forum section: electronics / rf-microwave

author: Tony_G
author_rank: Super Contributor
timestamp: March 15, 2022, 04:28:20 pm
content: Hey All,I'm not a ham radio guy but I acquired a UV-5R to use in testing some of my HPAK RF gear and I'm wondering about the microphone jack on the transmitter.Is this just a normal 3.5mm TRS stereo jack?Basically, I'm creating a 3.5mm microphone jack to BNC pigtail - Originally I used a mono jack but this always engages the push to talk functionality - I'm assuming that the PTT functionality is just taking the other channel part of the stereo TRS and grounding it to tell the UV-5R to transmit (which is why when I use the mono plug it is always triggered).Thanks,TonyG

author: bob91343
author_rank: Super Contributor
timestamp: March 15, 2022, 08:47:06 pm
content: Yes, and yes. You need a stereo plug so that you don't short the PTT.

author: Tony_G
author_rank: Super Contributor
timestamp: March 16, 2022, 12:31:04 am
content: Thanks - Appreciate the education
HP 83620A YIG problem ... - Page 1
Forum section: electronics / rf-microwave

author: br1973
author_rank: Newbie
timestamp: March 30, 2022, 01:23:15 pm
content: Hi I have an instrument "HP 83620A Synthesized Sweeper, 10 MHz to 20 GHz" which after some time that it was turned off I tried to turn it back on.No signal comes out.Unfortunately the display indicates UNLOCK UNLEVEL problems.After carrying out its internal test, the instrument reported the area to be checked: YIG zone.I was looking for documentation and wiring diagrams about it but without success.Does anyone know the pinout of YIG "5086-7505" ? Somewhere there is the BIAS scheme of "5063-0021" ?I wish I could fix it if there is a way.Thank you so much.

author: Maurizio1957
author_rank: Contributor
timestamp: April 01, 2022, 03:43:40 pm
content: I'm fighting with the yto of an HP 8753C ... these YTOs are famous for not lasting many years ...
Looking for multipoint or split stereo Bluetooth audio receivers - Page 1
Forum section: electronics / rf-microwave

author: Zipdox
author_rank: Regular Contributor
timestamp: March 12, 2022, 03:37:34 pm
content: First of, if Bluetooth doesn't fall under RF, feel free to move this thread to the appropriate forum section.I want to build a setup where I have two wireless speakers, one for left and the other for right, connected to a device via Bluetooth. I don't want to repurpose wireless earbuds for this because they almost always have filtering and a class D output, which makes it difficult to get a clean signal from them and power them.The only suitable off-the-shelf product I could find for this isa module from TinySine, but it's rather expensive and requires manually pairing them each use.I did some research and it appears that these earbuds use Qualcomm's TrueWireless technology. So a possibility is to develop receivers myself using some CSR8675 chips or modules myself, but I'd rather not do this.I founda module from Feasycomthat will require some development but Feasycom has its own firmware and claims that this is easy to do over a serial ASCII interface.Do you have any suggestions?Edit: it appears TinySine has a TrueWiress product as well:https://www.tinyosshop.com/tws-bluetooth-audio-receiver-board. I just had to search for "TWS"Edit2: it appears there's aprebuilt amplifier modulethat supports TrueWireless.
Ailtech/Eaton 75xx series noise figure meters - Page 1
Forum section: electronics / rf-microwave

author: xwarp
author_rank: Frequent Contributor
timestamp: March 09, 2022, 08:49:51 pm
content: Anyone familiar with them?I believe they were centered around 30MHz on the input frequency, which would mean that I would not be able to test LNA's outside that frequency without additional signal sources.Is that correct?
VHF high reverse isolation MMIC - Page 1
Forum section: electronics / rf-microwave

author: e.sotillet
author_rank: Contributor
timestamp: March 10, 2022, 06:34:17 pm
content: Hi FolksI'm looking a high reverse isolation MMIC or similar device for a VHF circuit (160MHz). I need at least 45dB of reverse isolation, gain >20dB and P1dBm of 15dBm. I found two cascode devices but one is obsolete (MVC13916) and other (BGA416) has a low P1dBm.There is any alternative to those devices?Best regards