hybridfree/eevblog-posts huggingface dataset:
GDT for RF Amp - Page 1
Forum section: electronics / rf-microwave

author: stcoso
author_rank: Regular Contributor
timestamp: May 09, 2017, 01:31:04 pm
content: Hi guys.. I'm building a little RF Amp and i'm looking for some information To optimize one of the gdt that i'm gonna use.So basically i've got an oscillator (about 14MHz), then a bunch of transistor and finally a totem pole Made with bd139/140. I'm trying to find some data about the output capacitance of these two transistor but with no luck.Thank you in advance.

author: BigBoss
author_rank: Regular Contributor
timestamp: May 10, 2017, 12:47:59 am
content: BD139/140 pairs are for Audio Frequencies, they won't work at 14MHz.

author: mmagin
author_rank: Frequent Contributor
timestamp: May 10, 2017, 01:08:29 am
content: Not sure thats entirely true. At least one datasheet specifies a Ft of 190 MHz:https://www.centralsemi.com/get_document.php?cmp=1&mergetype=pd&mergepath=pd&pdf_id=BD135_SERIES.PDFThat said, a complementary pair push-pull output is pretty uncommon for RF.

author: David Hess
author_rank: Super Contributor
timestamp: May 10, 2017, 02:36:24 am
content: I think of totem-pole output stages as using the same polarity of transistor with one common emitter and one common collector like with TTL. An NPN BD139 and PNP BD140 would be used to make a complementary push-pull (1) output stage.Function generators in that frequency range usually have complementary output stages with series termination and usually shunt feedback which is *not* want you want in an RF output. It will work but the series termination halves the output power and efficiency. Real RF amplifiers have a deliberately mismatched output impedance which lowers power loss in the output transistor raising efficiency.If you really want a complementary push-pull output, then there is a design where the output resistor is a fraction of the output impedance. Positive feedback from the output raises the effective output impedance so the output is matched but losses are still low. It is commonly used with operational amplifiers to implement series termination when the output power needs to be maximized for a given output swing. This shows the general idea and I think it could be made to work at 14MHz:https://www.maximintegrated.com/en/app-notes/index.mvp/id/3390RF amplifiers do not need that kind of complication and it would not work at higher frequencies.(1) Be careful about old documentation. In the past push-pull sometimes meant differential just like now differential sometimes means difference.
CC112x LNA Balun Extra component - Page 1
Forum section: electronics / rf-microwave

author: veryevil
author_rank: Unknown
timestamp: May 02, 2017, 03:56:49 pm
content: Hi, I'm looking into matching a CC1125 to a Skyworks SKY65366-21 (or 11) at 459MHz and I'm trying to understand the LNA Balun from all of the TI Reference designs.In the attached picture I don't understand the purpose of L191.I understand the 4 component balun but not why there is an inductor between the positive and negative inputs on the balanced side?The pic is from the 420-470MHz ref design.Thanks

author: veryevil
author_rank: Unknown
timestamp: May 05, 2017, 12:46:08 pm
content: Apparently its to provide the LNA transistors with a DC Ground path.No idea how its calculated an d it surely must effect the balun values.

author: BigBoss
author_rank: Regular Contributor
timestamp: May 10, 2017, 12:58:25 am
content: A kind of matching has been used in order to compansate the reactive part of the internal LNA.Noise matching is another possibility..
SDR and HAM rigs - Page 1
Forum section: electronics / rf-microwave

author: damn_dirty_ape
author_rank: Contributor
timestamp: May 09, 2017, 05:56:36 pm
content: Do the commercially available HAM trancievers typically have the ability to act as a basic amplifier?I would like to get an amplifier to transmit with my Hack RF, but I would prefer a standalone rig with the ability to use an SDR as a transmit source (if it exists).The setup I'm going for is this:Antenna <---> Commercial Transciever <---> SDR <---> ComputerSo that I can use the transciever by itself or with an external SDR as an option. I looked at a couple product manuals online, for example the Kenwood TS-2000, but I think I might not know the proper termonology to find what I want.Sorry if this is too silly a question for the HAM forum.

author: w2aew
author_rank: Super Contributor
timestamp: May 09, 2017, 06:15:50 pm
content: For conventional transceivers - the answer is generally no. You don't have access to an IF/RF path to connect your SDR. If all you need is an RF PA, then you can build/buy this. Legal use of course requires proper licensing on the bands you wish to operate on, of course.There are many SDR transceivers on the market for ham radio - such as Flex Radio, Anon, etc.
ultra fast and low delay wireless transceiver module - Page 1
Forum section: electronics / rf-microwave

author: nixmd
author_rank: Newbie
timestamp: May 15, 2017, 12:08:01 pm
content: I am looking for a low delay wireless module which can send and receive data in a very short time.Data length is just a few bytes generated by a microcontroller connected by UART/SPI interface.The application requires repetitive send and receive of data in less than 10ms, which means time required to send data and receiving the reply from the second device must not exceed 10ms (repetitively)I had used RXQ2 wireless module which was a really awesome, but for some reasons I have to find another module which can provide me this requirement.Do you have any experience in this field? can you suggest me a replacement for RXQ2 with this requirement?P.S: I have test these modules and none of the could handle this requirement:nrf24l01amplified nrf24l01DRF7020d20HMTRPESP8266MOD (transceiving time was lesser than 10ms but amount of time required by module to be able to accept new buffer of data was much more than 200ms)

author: hcglitte
author_rank: Regular Contributor
timestamp: May 15, 2017, 10:15:23 pm
content: Hi,Have you looked into the cc series from TI? There is a lot more to consider when making specs for a wireless link.Range? Compactness - low frequency gives you longer range (6 dB more per frequency halfing), but the antenna must be larger to achieve good antenna efficiency.So, in practice a higher frequency may yield longer range.The smaller the receiver bandwidth, the lower the noise floor and hence the better receiver sensitivity. But this is at the expense of lower datarate to achieve lower occupied transmission bandwidth to fit the RX bandwidth.Every packet for a normal FSK/GFSK based modem consist of a preamble, sync word, payload and CRC. Some require only a couple of preamble bits.You could use 16 bits sync, but this would lead to a lot of false packets. So there are many trade-offs to consider.I would read up on the basics. I use CC112X from TI. Read all the literature available on their site, and the e2e forum as a starter.
FM trans. Whats eq. to 2n2218 transistor?  - Page 1
Forum section: electronics / rf-microwave

author: yada
author_rank: Frequent Contributor
timestamp: April 19, 2017, 06:51:04 pm
content: I'm building this circuit. It calls for 2n2218 transistor. They don't seem to make that but I have other rf trans and jfets: Which of these will work? Also if I want this to transmit abouve or below the band which parts should I change in value the inductor and the variable cap? I just made the inductor out of magnate wire to one that looks close but have no way of measuring it.ss9018hbuss9018Sbu(whats the difference in S and H?)KSC1674YBU2n5952and2n3819 jfetj211 d743 jfetWhat is a jfet used for? I just ordered a bunch thinking I could use at least one of them. Whats the highest these will go 300MHz?

author: BigBoss
author_rank: Regular Contributor
timestamp: May 08, 2017, 12:21:35 am
content: Don't compare apples and peaches.2N2219 is still available on the market.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 08, 2017, 12:47:53 am
content: For small quantities, Mouser still has some 2N2218 in stock, as well as americanmicrosemiconductorThey are not cheap, but available.

author: medical-nerd
author_rank: Regular Contributor
timestamp: May 08, 2017, 04:26:33 pm
content: HiyaI used a BC107 in a very similar circuit as a child in the early 80's.CheersSteve
Anrtsu MS710a  23GHz Spectrum Analyzer   schematic, manual .. repairs ... - Page 1
Forum section: electronics / rf-microwave

author: rickells
author_rank: Regular Contributor
timestamp: May 04, 2017, 08:04:19 pm
content: hi,Recently acquired Anritsu MS710a powers on fine, but no legitimate I/P signal is displayed.All other functions appear to work, including the internal calibrator signal when tested with a friends SA; including test RF signals(on friends unit).Wondering if the I/P diodes or amp has been blown ?Any hints about possible repairs, & schematics ?Kind of hard to know where to start (disassembly, and PCB identification !) without literature, but the RF/IF stages should look familiar...thank you

author: Simon
author_rank: Unknown
timestamp: May 05, 2017, 06:37:07 am
content: Please DO NOT double post topics, it annoys other users and will get you minimal respect.
RF Demo source similar to Rigol TX1000 - Page 1
Forum section: electronics / rf-microwave

author: tkline98
author_rank: Contributor
timestamp: May 03, 2017, 03:42:53 pm
content: I have a DSA815-TG and want to experiment more with it. I see Rigol makes the TX1000 RF demo boardhttps://www.tequipment.net/RigolTX1000.html?search=truethat works with the DSA815, but it's $1000 and I have not been able to find any used ones online. Is there something similar out there that can create various signals and has filters on it so experiment with?I just remembered there's a buy/sell forum here, and I posed there too.https://www.eevblog.com/forum/buysellwanted/rigol-tx1000-wanted-to-buy/Anyone have a used TX1000 they want to part with?

author: ebclr
author_rank: Super Contributor
timestamp: May 04, 2017, 06:13:48 am
content: This device can do more for lesshttps://www.crowdsupply.com/lime-micro/limesdr

author: hendorog
author_rank: Super Contributor
timestamp: May 04, 2017, 07:04:04 am
content: OT but your link led me to this which is even more interesting:https://www.crowdsupply.com/era-instruments/erasynth

author: tkline98
author_rank: Contributor
timestamp: May 04, 2017, 06:30:33 pm
content: Thanks. That looks very interesting and didn't come up in all my google searching.
Vivaldi Antenna for UWB applications - Page 1
Forum section: electronics / rf-microwave

author: rill17
author_rank: Contributor
timestamp: May 02, 2017, 05:30:29 pm
content: Anybody have a working design with dimensions for a vivaldi antenna in the frequency range from around 3GHz to 10GHz, for either FR-4 or rogers RT duroid 5880,1.57 mm thickness, thanks

author: randsl
author_rank: Contributor
timestamp: May 03, 2017, 04:04:47 am
content: Check :http://wa5vjb.com/products5.htmlIt seems that this guy is selling these ones in ebay as well.

author: randsl
author_rank: Contributor
timestamp: May 03, 2017, 05:02:01 am
content: This one may also serve your requirement:http://www.ebay.com.au/itm/15W-1-35GHz-9-5GHz-UWB-Antenna-Logarithmic-Antenna-/172554033459?hash=item282d059933:g:Tr8AAOSw2gxYtVPO
Help With NRF24L01 transciever - Page 1
Forum section: electronics / rf-microwave

author: traxx
author_rank: Newbie
timestamp: May 03, 2017, 01:52:06 am
content: *****UPDATE*****I have updated the schematic to one that is cleaner and easier to read. Shout out @ataradovHi guys! I'm trying to create a wireless transmitter and receiver for an electric skateboard using Arduino. My setup is as follows:RECEIVERInput Power:5V DCHardware:ATMega 328P-PU Microcontroller running on 5VLinear Voltage Regulator 5V to 3V which then feeds NRF34L01NRF24L01 wireless transceiver running on 3VVoltage Divider for reading LiPo battery levels onlyEverything worked fine on a breadboard setup using through hole components, but when I surface mounted the NRF24L01 and all other components to a PCB, the NRF24L01 had tons of dropped packets during transmission. In an attempt to troubleshoot the issue, I removed the NRF module from the PCB and re-attached it using some 26 gauge solid core kynar wire. This created some separation between the NRF module and the PCB. To my Surprise, I was able to reliably communicate with very few dropped packets or failures. I then shortened the wire and positioned the NRF on the board as pictured below (sans the Resistor) and communication became very unreliable. The only thing that I can assume is that the longer wire is added some resistance, so in an attempt to mimic the resistance, I added a 4.7ohm resistor(the lowest value I had on hand) to the 3V input of the NRF. VIOLA! Communication is working again. Can someone explain why a resistor fixes this issue? I'm transmitting to the receiver from my transmitter bread board setup which worked flawlessly when the receiver was also on a breadboard previously. I have also included images of my schematic and PCB layout below.Let me know if any further information is needed.Cheers!Images

author: ataradov
author_rank: Super Contributor
timestamp: May 03, 2017, 02:18:49 am
content: That antenna is designed to be sticking off the board. The part after the perforation must be as clear from anything else as possible, especially ground planes or traces. Then, running high speed digital traces under the antenna is a bad idea.Why series resistor would change anything - I don't know. Have you checked that power rail with an oscilloscope? It may have oscillations.

author: ataradov
author_rank: Super Contributor
timestamp: May 03, 2017, 02:21:16 am
content: Actually, it looks like you have reversed VIN and VOUT pins on the LDO.Nope, just poor drawing. Seriously, who draws schematics like this?

author: traxx
author_rank: Newbie
timestamp: May 03, 2017, 02:25:28 am
content: I am making sure that the antenna portion will be hanging off the board in my latest revision. As you can see from the first picture, I am sort of trying to simulate that using the kynar wire. As for the schematics, I'm a newbie and just getting started with making electronics for the most part. I'm learning as I go.I only have access to a very basic DSO-138 DIY Oscilloscope.
Kenwood TS-530S - Would You Do This? - Page 1
Forum section: electronics / rf-microwave

author: German_EE
author_rank: Super Contributor
timestamp: April 30, 2017, 03:47:17 pm
content: A friend of mine has offered a Kenwood TS-530 for a bargain price, free, but there's a catch. The PA compartment is a disaster area and it looks as if there has been a small fire in there, the tubes are of course dead and the high voltage winding on the transformer is open circuit.I COULD rebuild the P.A. compartment but as RF power tubes are starting to become rare I also have the option of removing the high voltage stages and fitting a transistor P.A. and a set of low-pass filters. Would you do this? I am not sure about modifying a classic piece of ham radio history but there is a lot of damage and some components may be unobtainable.Note that everything else is OK, the receiver still functions and I can get a signal from the low level transmit drive stage.Comments?

author: WA1ICI
author_rank: Contributor
timestamp: May 01, 2017, 05:07:25 am
content: The 6146B outputs tubes are still generally available - just avoid the Chinese ones. The American 6146W are probably the best ones commonly available, but have lower max ratings than the 6146B, so the final can't be driven as hard.The bad power transformer is the big problem. It can be re-wound, but that will be expensive. The best solution in this case is to find a "basket-case" TS-530S that may look horrible, but has has a working final amp and power supply. Do a parts transplant into your damaged unit, and you can have a nice-looking functional set, assuming your set looked good.I have a TS-520S and like the combination of low-tech solid-state and tube reliability on the final amplifier. It can be kept repaired forever, unlike newer sets with custom ICs, etc.- John Atwood

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: May 03, 2017, 12:37:45 pm
content: Since the TS530S is known to have an excellent receiver another possibility is to put in a broadband solid state amp and operate it as a QRP transceiver. Maybe it could be made on a subchassis so it could easily be removed if you wanted to do the full restoration later.

author: CJay
author_rank: Super Contributor
timestamp: May 03, 2017, 01:06:38 pm
content: Personally, transistor PA and operate it at lower power if not QRP as VK3YE suggested but if you can find a suitable HT transformer then it doesn't look like it'd be terribly difficult to replicate the valve PA or even purchase a replacement, they seem to be available, if sporadically, via eBay.

author: German_EE
author_rank: Super Contributor
timestamp: May 04, 2017, 06:18:17 pm
content: OK, the rig has a new home and it isn't with me. The transceiver was given to someone who has a lot more experience with working on tube equipment than me and he now has the task of rebuilding the P.A. compartment and finding a replacement transformer. I wish him luck!
Colpitts selective xtal oscillator - Page 1
Forum section: electronics / rf-microwave

author: Teknow
author_rank: Regular Contributor
timestamp: April 30, 2017, 09:25:17 pm
content: Considering the following circuit atttachedI am confused and can't understand how the tank circuit, which is open at resonance, and the transistor pass the 2nd or any other harmonic of a crystal of a fundamental frequency of, say, 48 MHz.What frequency is at the output if the tank is open at resonance 48MHz for example?1. How does the tank circuit contribute to or govern the choice of the desired Harmonic at the output if a parallel LC is "open circuit" at resonance?2. How can I calculate L1 and C4 to have the desired frequency at the output?Do I have to include the transistors' output capacitance in calculating the tank circuit? What is formula for that?Many thanks in advance!

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: April 30, 2017, 09:39:42 pm
content: Although the circuit will likely work without it, there should be a 10nF (or similar) bypass capacitor between the positive rail and earth.Now visualise this part of the circuit as being ground (as far as RF is concerned).Note that in the method of coupling chosen C5 needs to be small relative to the value of the capacitor in the tank circuit so it doesn't detune it.Alternative methods of coupling (depending on the input impedance of the following stage) include a tap partway along the coil or a secondary winding.

author: Teknow
author_rank: Regular Contributor
timestamp: April 30, 2017, 10:03:48 pm
content: Thanks for the tips for the next stage + VCC rail coupling. But still the parallel LC is open at resonance and the series is short gets me nowhere in relation to the ciruit.They short what, and they block what?Why does this tank circuit decide what frequency is at the output, how?

author: MagicSmoker
author_rank: Super Contributor
timestamp: April 30, 2017, 10:47:06 pm
content: Quote from: Teknow on April 30, 2017, 10:03:48 pmThe tank circuit doesn't decide the frequency of the output - the crystal does. However, if the resonant frequency of the LC tank is close to that of the crystal's, then it will present a high (not infinite!) impedance to the collector of the common emitter amplifier which is prerequisite for high voltage gain. A bit of positive feedback from the emitter (via capacitive voltage divider C2/C3) and you have yourself an oscillator.
Which RF device/protocol for this? - Page 1
Forum section: electronics / rf-microwave

author: Rx7man
author_rank: Regular Contributor
timestamp: April 27, 2017, 08:20:05 pm
content: Hello, first post for me, been lurking a long time though.I have an automotive application which will be requiring digital comms over a distance about 100 feet, but has to be really reliable at that distance.. Datarate can be low (1kbps would do fine).So.. VHF, UHF, NRF34? 433mhz? LoRa? Bluetooth.. etc etc etcTrying to keep cost down, though I know you get what you pay for

author: kaz911
author_rank: Super Contributor
timestamp: April 27, 2017, 09:31:08 pm
content: One way or full duplex?Moving or steady target?High power or low power? (as in what is available to power radio etc)Encrypted or does not matter?I like TI's sub-1 ghz - does 100 feet without issue.But if it is a hack - WiFi will do with some of the cheap WiFi modules.

author: Rx7man
author_rank: Regular Contributor
timestamp: April 27, 2017, 11:29:44 pm
content: Power consumption is largely irrelevant, steady target, though I will be forced to use an omnidirectional antenna (It would be nice if the antenna is kept within the plastic enclosure of 2"x3"x5", half duplex would suffice, encryption.. bonus, can't hurt right?There will be a fair bit of metal that could cause interferenceThanks.You have a link to one of those TI devices?

author: kaz911
author_rank: Super Contributor
timestamp: April 28, 2017, 06:44:40 am
content: I think doing a design with sub-1ghz would be the nicest but I'm biased ...http://www.ti.com/lsds/ti/wireless-connectivity/sub-1-ghz/overview.pageBut WiFi should do the trick - and many use the ESP series board like below:https://www.sparkfun.com/products/13678

author: Rx7man
author_rank: Regular Contributor
timestamp: April 28, 2017, 08:05:22 pm
content: There is of course no replacement for testing to see what works in the real world.. so I guess it comes down to what's a good place to start from... Is there one I should specifically avoid?

author: Rx7man
author_rank: Regular Contributor
timestamp: April 29, 2017, 02:24:54 am
content: My initial idea was 433mhz, so that kinda helps push me in that direction..Friend of mine sent me this link..http://shop.in-circuit.de/product_info.php?cPath=22_28&products_id=174To me it looks like a very expensive Arduino an off-the-shelf radio module and RS232/485 convertor..As I'm looking and thinking, it would be nice to have some hardware pairing, which would put me towards bluetooth, but I think I might be a little limited until BT5 is readily available, the distance specs, etc on that looked pretty good
Small-scale PCB fab houses for Rogers substrates - Page 1
Forum section: electronics / rf-microwave

author: LukeW
author_rank: Frequent Contributor
timestamp: April 26, 2017, 06:02:27 am
content: Any suggestions for any board houses that can provide relatively low-cost, small scale prototype-friendly boards with RF substrates such as Rogers?In particular I'd like 10 thou RO4350B with a thicker FR4 layer underneath.

author: IconicPCB
author_rank: Super Contributor
timestamp: April 26, 2017, 11:10:26 am
content: 10 thou places You somewhere downunderLet me understand... You are looking for a composite sandwich.... rogers bonded to FR4?Drop me a line
Anritsu and Advantest spectrum analyzer - Page 1
Forum section: electronics / rf-microwave

author: Aakushti
author_rank: Newbie
timestamp: April 23, 2017, 07:34:34 am
content: Hello,Is there a reason why Anritsu and Advantest spectrum analyzer with range of few Khz to 25 or 32 Ghz cost so less when compared to spectrum analyzers of other make ? I'm an undergrad student who is interested in antennas and RF in general and I have put together about 2 grand USD for this investment . The spectrum analyzers are used and seem quite old but for some reason they cost extremely less as opposed to used ones from other big names .Thanking YouRegardsAakushti

author: douardda
author_rank: Regular Contributor
timestamp: April 23, 2017, 08:16:59 am
content: One reason is the total lack of service manual and schematics making them very hard to repair or calibrate. I have an Advantest R3465 and I'm pretty pleased with it so far (still learning how to properly use it) but I got lucky it works fine and seem still reasonably accurate.David

author: DaJMasta
author_rank: Super Contributor
timestamp: April 24, 2017, 11:55:56 pm
content: Also, HP/Agilent/Keysight and Rhode & Schwarz, probably the biggest competitors' brand names command pretty decent price premiums across the market, so it stands to reason other brands making similar products would end up cheaper.I think part, at least on the Anritsu side, is that they seem to emphasize portable units and units designed for antenna testing and requiring an option for regular spectrum analyzer functionality - a lot of people think going into their shopping that they're after a benchtop instrument, and there aren't nearly as many models or as much availability.I've got a portable Anritsu MS2721B, and while the sweep speed is a bit slower than many benchtop units, I quite like it, the level of functionality and noise floor are impressive for the price I paid.
HP 70000 Spectrum Analyzer  (MMS)  repair  query   - Page 1
Forum section: electronics / rf-microwave

author: rickells
author_rank: Regular Contributor
timestamp: April 25, 2017, 08:59:54 pm
content: hi,Wondering if anyone has had experience repairing the HP 70000 (MMS) Spectrum Analyzer series.This is a Mainframe unit with many plug-ins (70900, 70902, 70903, 70905, etc... & goes out to 23 or 26 GHz & possibly further)Would like to share repair experiences and notes,thanks,rick
Blower for a Vaccum tube amplifier  - Page 1
Forum section: electronics / rf-microwave

author: SV1EOR
author_rank: Contributor
timestamp: April 25, 2017, 11:16:51 am
content: I'm looking for a blower for two 4cx250 tubes that can regulate flows according to the measurement of a pressure sensor and a temperature sensor .Anyone who has some idea or experience please send a msg or a link.
VHF video modulator - Page 1
Forum section: electronics / rf-microwave

author: LukeW
author_rank: Frequent Contributor
timestamp: April 19, 2017, 05:10:07 am
content: I'm looking for a simple RF modulator for composite video (audio doesn't matter), outputting video on the VHF band (channel 1, or whatever, doesn't matter really) for ye olde VHF TV.What do you think about the attachment... look plausible?

author: N2IXK
author_rank: Frequent Contributor
timestamp: April 20, 2017, 02:09:35 am
content: Building one would be one way to go, but since TV went digital, thousands of high quality modulators got dumped onto the surplus market, especially when local CATV systems upgraded.I use a Blonder-Tongue AM60-860 unit to provide OTA material for my vintage TVs. It won't cover Channel 1, but it does cover broadcast channels 2-83, as well as cable frequency assignments.Do a search for "agile modulator" on eBay, and you can find one for little more than it would cost to build your own, and it will be a broadcast-quality piece of gear made to run 24-7 for years.
Dick Smith - Amateur Radio - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: April 18, 2017, 11:08:12 am
content: Dick Smith - Amateur Radio & AdventurealsoFirst solo around the world by helicopter, 1983.ABC TV 1978 Inside Story - Dick Smiththis video is just the audio of -Dick Smith - Amateur Radio & Adventure
F Connector Question - Page 1
Forum section: electronics / rf-microwave

author: brims
author_rank: Contributor
timestamp: April 09, 2017, 02:09:41 am
content: I've got an F connector jumper that I need to find more of but I can't seem to figure out what combination of words to use; I've tried combinations of "f connector", "rigid", "panel jumper", and others. I hope this is the correct subforum. I've attached a picture of the connector.

author: Cerebus
author_rank: Super Contributor
timestamp: April 09, 2017, 02:17:35 am
content: The BNC version are called U-links or MUSA links. Try that variants on that.

author: brims
author_rank: Contributor
timestamp: April 09, 2017, 03:50:52 pm
content: Great, thank you. I didn't think about looking at other connectors for similar products.

author: vk6zgo
author_rank: Super Contributor
timestamp: April 12, 2017, 02:09:32 am
content: Quote from: Cerebus on April 09, 2017, 02:17:35 amNo,"MUSA" is quite a different connector to BNCor"F".They are pretty much obsolete , & as far as I can remember "MUSA" is a brand name.

author: Cerebus
author_rank: Super Contributor
timestamp: April 12, 2017, 12:18:01 pm
content: Quote from: vk6zgo on April 12, 2017, 02:09:32 amStrictlyspeaking you are correct, but in practice the bayonet-less slip on 75R BNC* patch panel links are often colloquially called MUSA links in broadcasting. It might not be correct, but it's done in practice and I thought it might be helpful to literally "get on the same  page" in hunting down the F variant as such a misappellation quite often makes it to the page.*Again, technically incorrect as, being missing the bayonet pins, this part can't be aBayonetNeill–Concelman connector but I haveneverheard them called anything other than BNCs.

author: SNGLinks
author_rank: Regular Contributor
timestamp: April 14, 2017, 10:48:18 am
content: This is a MUSA connector.https://en.wikipedia.org/wiki/Musa_connectorThe first pic is a MUSA U-link, the second is of me in the 80s working in a broadcast links truck.The U-links can be seen top right. All the video inputs and outputs went via these links so theequipment could be reconfigured in case of equipment failure or for special needs.
Class D low frequency RF amp question - Page 1
Forum section: electronics / rf-microwave

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 21, 2017, 06:03:52 pm
content: Push pull output, Class D low frequency (136kHz) RF amp, circa 500 Watts. If I want to test it for a few hours into a dummy load does it matter if the low pass filter network usually used to get a sine wave, harmonic free output into an antenna, is not between the output transformer and the dummy load? I want to leave it running overnight and I am modding the LPF and it's in bits until next week. Thanks.

author: MagicSmoker
author_rank: Super Contributor
timestamp: April 21, 2017, 06:30:34 pm
content: If the dummy load is sufficiently resistor-like up to, say, 5-10MHz, then it should be fine. The RMS value of the unfiltered PWM is going to be a little bit higher since there aren't any losses from the filter network, but the only component I'd really watch carefully for the first hour or so is the output transformer as it will definitely run hotter (particularly the windings) as a result of higher harmonic content.

author: awallin
author_rank: Frequent Contributor
timestamp: April 22, 2017, 05:58:49 am
content: Quote from: Chris Wilson on April 21, 2017, 06:03:52 pmCan you share the circuit/chip you are using for this?I'm interested especially if it has analog input...(i.e. it takes a low-power 136kHz AM/PM-modulated signal as input)

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 22, 2017, 06:29:50 am
content: Sure, here's the schematic attached

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 22, 2017, 06:31:13 am
content: Quote from: MagicSmoker on April 21, 2017, 06:30:34 pmOK, that's great, thanks very much for the reply.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 22, 2017, 07:41:36 am
content: Yes, the filter network affects the reactive power seen by the switching transistors and therefore the switching (commutation) transient.Tim

author: Chris Wilson
author_rank: Super Contributor
timestamp: April 22, 2017, 07:46:51 am
content: Quote from: T3sl4co1l on April 22, 2017, 07:41:36 amOK, so in simplistic terms running the above schematic into the dummy load without the filer network is a bad idea then? Cheers Tim, LPF shown in attachment.

author: KJDS
author_rank: Super Contributor
timestamp: April 23, 2017, 06:03:57 pm
content: The LPF has been designed to present an open circuit to harmonics. Without that the amp won't work as efficiently as intended.
Anritsu MS46121 VNA - Page 1
Forum section: electronics / rf-microwave

author: D3f1ant
author_rank: Frequent Contributor
timestamp: April 11, 2017, 10:01:34 pm
content: Anybody have any experience with these things? All opinions and comments appreciated, except those that say I should get a boat anchor VNAhttps://www.anritsu.com/en-US/test-measurement/products/ms46121bI want something for basic chip antenna and pcb loop impedance matching. I have a pocketVNA but don't fully trust it and sick of constantly calibrating.

author: metrologist
author_rank: Super Contributor
timestamp: April 11, 2017, 10:18:47 pm
content: Is there anything in particular you'd want to know? This is a different class of instrument.

author: D3f1ant
author_rank: Frequent Contributor
timestamp: April 12, 2017, 06:57:28 am
content: If you own one, would you recommend? Any peculiarity in using it or other issues? Are they a good buy in this class of tool?

author: metrologist
author_rank: Super Contributor
timestamp: April 12, 2017, 05:01:33 pm
content: I think Anritsu has made some of the best VNAs and they seem to have been making more investments into the ShockLine series. The B models are a new upgrade and this instrument line shares much of the same core software application as the higher class VectorStar instrument line, which has been around for a while. I've never had a problem with software stability. These product lines are designed, built, and tested in the US facility and there should be great support. Product quality should be excellent.That just leaves the functional specs which you could compare with other competitive models to make sure it will do what you want it to do. The measurements you listed are product feature highlights, so it should be a good candidate.

author: hendorog
author_rank: Super Contributor
timestamp: April 13, 2017, 07:16:16 am
content: I just remembered seeing these 1 port devices, might be of interest as a point of comparison:http://www.coppermountaintech.com/products/Ohm-50/category/10/
HP8720C Network Analyser Option 010,001 installation procedure? - Page 1
Forum section: electronics / rf-microwave

author: sanwal209
author_rank: Regular Contributor
timestamp: April 12, 2017, 09:02:56 am
content: Hi,I have bought HP8720C and i have keyword for option 001, 010. Installation of these software is just a software procedure and i am not able to find one for this particular machine not even in service manual. There are procedures for HP8720ES but not for HP8720C. Please help me out in this matter.Thanks
MEGURO FM/VHF STANDARD SIGNAL GENERATOR MODEL MSG-277H - Page 1
Forum section: electronics / rf-microwave

author: Pete67
author_rank: Newbie
timestamp: April 11, 2017, 11:45:15 am
content: Hi,I have recently acquired a very nice vintage signal generator, a MEGURO FM/VHF standard signal generator MSG-277H which appears to be working properly. It operates from 100 to 200 MHz approx and has a decent attenuator and adjustable FM up to +/- 25kHz. it also has a built in 5MHz XO for which can be beat against the main osc for fairly accurate output frequency checking at harmonics of 5MHz I guess.I'd love a copy of the service manual, or even a schematic if anyone knows where to look I'd be most grateful, I have not managed to find anything online. I have in mind a small modification to lower the range of the generator so that it overlaps the full commercial FM band, say from 80MHz to 180MHz, but before I go at it I'd like to check the oscillator circuit to make sure I fully understand it.Many thanks for any pointers!Pete.
Discone antenna for radio receiver + DVB-T antenna, mixed on one cable? - Page 1
Forum section: electronics / rf-microwave

author: mcinque
author_rank: Unknown
timestamp: April 09, 2017, 04:42:13 pm
content: Hello ALL,I would like to install a discone antenna for radio listening on HAM and free frequencies (433, 860) on the same pole of the DVB-T antenna (the only place I can install it)Unfortunately It's very difficult to install another dedicated cable for it.I'm not a RF guy, but I wonder - since it's only receving - if I must/can use some kind of mixer to mix the signal captured by the two antennas and keep using the existing 75R TV cable at the same time.I guess in this case the discone should have a band stop filter for the TV signals to avoid signal canceling due to phase opposition of the signals.I know that a shared cable is a potentially unwanted solution, but I've not other choices (indoor antenna or TV-shared antenna).Thanks in advance for any suggestion/tip!

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 09, 2017, 05:18:38 pm
content: Yes, you need some kind of filter to keep the signals from one antenna reaching the other one, both at the antenna side and at the receivers side.But what makes me wonder more, a discone for short wave signals? The height should be 1/4 of the wavelength of the lowest frequency you want to use it for so that gets out of hand very fast.

author: mcinque
author_rank: Unknown
timestamp: April 09, 2017, 06:10:59 pm
content: You're right, discone and SW doesn't works fine. I listen also HAM (140MHz) and license free frequencies (430/860), so at the moment I have an indoor discone, so I used that term for the antenna. Nevermind. Post title corrected.

author: Co6aka
author_rank: Unknown
timestamp: April 09, 2017, 09:36:12 pm
content: Quote from: mcinque on April 09, 2017, 04:42:13 pmAny antenna is better than no antenna, and an outside antenna is usually much better than an inside antenna. You're only receiving, so just use the ubiquitous 75-Ohm splitter, and if practical equal length cables between the splitter and the two antennas -- I'm presuming one will be above the other on the same pole.Interaction isn't as big a deal as it's made out to be; just try it.
Iron powder core+ferrite materials for noise reduction,mostly? CHEAP? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: May 02, 2017, 02:42:09 pm
content: Does anybody know of a resource for cheap(er) magnetic materials ? Ones that work for RF and not SMPS parts?I especially need to buy a bunch more ferrite split beads in various sizes. It seems as if I never have enough of them when I need them. LOLI use kits and parts for toroids usually but those would be in "critical" applications lol(this is just to quiet my electronics junk mostly. Split beads are usually materials best for VHF and UHF, not HF noise reduction.)HF is very noisy at my QTH.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 02, 2017, 02:52:22 pm
content: I've purchased RF ferrite cores from CWS Bytemark:http://www.cwsbytemark.com/Powdered iron I've purchased directly from Micrometals, though I seem to recall them having a rather high minimum quantity requirement.edit: added specifier "RF", I buy power ferrites from Adams, Dexter and now DigiKey and Mouser (and the former two distributors better get with the program of allowing purely online purchasing because nothing annoys me more than seeing a "line card" and having to call some sales rep to get pricing, place an order, etc...).

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 02, 2017, 04:38:12 pm
content: Snap cores and ferrite beads are available in spades from the usual suspects (Digikey, Mouser, etc.). (A lot of SMPS cores are available from them now, too!)RF and powder cores are more specialty items and you'll need to check Amidon, Dexter Magnetic, Adams Magnetic, etc.Tim
Antenna - Page 1
Forum section: electronics / rf-microwave

author: rckanta
author_rank: Contributor
timestamp: April 10, 2017, 03:23:36 pm
content: In EM wave there is two component one is Electric and other is Magnetic.At the receiver side, Antenna induced a voltage.Where to get the voltage from Electric or is Magnetic fields?And How to induced a voltage across antenna?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 10, 2017, 03:47:36 pm
content: Remember the EM wave is not stationary. It moves. By relativity that is the same as the antenna moving in a stationary wave. And what does a moving conductor in a magnetic field do? It generates a current. Which charges the capacitor that is the antenna. Giving volts. Similar results on charge movement from the electric part of the field. Thinking of it this way also makes it obvious why antenna orientation matters.

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: April 11, 2017, 01:00:12 pm
content: " Where to get the voltage from Electric or is Magnetic fields? "Part of the understanding is you can not seperate electric and magnetic fields in RF , much like a circuit = is one circle or 2 conductors making a loop usually containing components to perform a task .
Rakon VTXO 610 CTR Oscilator Datasheet/Specs? - Page 1
Forum section: electronics / rf-microwave

author: Wollvieh
author_rank: Contributor
timestamp: April 04, 2017, 01:10:58 am
content: Hi,I saved several Rakon VTXO 610 CTR 10.000 MHz (closed cap, not adjustable) Oscillators from 2006 vintage professional Cable TV gear.But I only manage to find datasheets for the VTXO 600. The only reasonable link I get for the 610 is that it is used in the Agilent 53220A frequency counter.Anyone knows the specs for this type or where to get the datasheet?
Opinions on ebay DIY kits - Page 1
Forum section: electronics / rf-microwave

author: NoradIV
author_rank: Contributor
timestamp: April 03, 2017, 03:29:25 am
content: Hello Everyone,I have an oldAudio Reflex AR-620head that is dying. (One problem is probably dirty contacts, the rest is likely related to bad caps).I mostly use this head unit as a headphone amplifier for myAKG k271 MK II.These headphones have somewhat a high impedance and low sensitivity, meaning that the built-in sound card in my computer isn't exactly up to the task.I also like my music pretty loud and bassy, so a decent output is necessary.I am not a crazy audiophile (most of my music is in MP3), I do not care about the lamp thing, I just want something that will be an improvement to my built-in sound card and preferably DIY (I like assembling kits).I found thiskiton ebay. I verified the specs of theTPA6120, which has a 1.5W output and otherwise decent specs.I'd like to know what you guys think.Thanks!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 03, 2017, 04:06:26 am
content: For fifteen bucks it is worth a try. Not much lost if it doesn't turn out as good as you want. But if you do like it you will have to spend some money on a nice case power supply to turn it into a daily user. That piece of the equation might convince me to go for something already packaged up nicely.

author: NoradIV
author_rank: Contributor
timestamp: April 04, 2017, 12:17:24 am
content: Quote from: CatalinaWOW on April 03, 2017, 04:06:26 amIf I like it, a steel case and a proper power supply will be part of it. I like the idea of being able to change the amplifier later if I want, keeping it more "modular".Oh, and I'd rather assemble it myself than order one all made, DIY is a plus for me, since I like assembling them.

author: NoradIV
author_rank: Contributor
timestamp: April 04, 2017, 01:46:24 am
content: Ok, then let me check for another option. I have no knowledge of these designs really. I figured TI was trustworthy, if they publish a HIFI chip, I would have thought it would do what they said it would do.Although, these are headphones, not speakers.
Ten-Tec 2591 2-metre Band Transceiver - Page 1
Forum section: electronics / rf-microwave

author: sonnytiger
author_rank: Frequent Contributor
timestamp: April 02, 2017, 09:42:49 pm
content: I'm posting this to get some information on this little unit or even people's opinion, also if anybody has some suggestions as to how the fix some of the issues with the unit, mainly intermittent sound coming through the speaker. I have a short video on my YouTube channel outlining the issues and just demonstrating the operation a bit.https://youtu.be/sIcT_moJuGMThanks for your interest!
uBITX - Page 1
Forum section: electronics / rf-microwave

author: gibbled
author_rank: Regular Contributor
timestamp: March 21, 2017, 05:00:08 am
content: This project looks interesting...http://www.phonestack.com/farhan/ubitx/ubitx.html

author: SingedFingers
author_rank: Frequent Contributor
timestamp: April 01, 2017, 09:59:53 pm
content: Just stumbled across this. It does indeed.I've built the entire receive chain for the bitx20 with some mods for 40m which was quite good fun, although the LO comes from my Marconi 2019A because I had no variable capacitors around. It was rather interesting. I imagine this would be equally so.
Daytona Beach Tailgate Party on April 8th - Page 1
Forum section: electronics / rf-microwave

author: GreyWoolfe
author_rank: Unknown
timestamp: April 02, 2017, 03:08:21 am
content: I don't know how many bloggers/hams are in central Florida, but my club is having our 4th annual Tailgate Party. If there is any interest, here is the link:https://www.dbara.org/Sometimes there are interesting finds. it starts at 8:00 but people will probably be there around 7:00 AM to start setting up.
What are some dos and donts to building an antenna switching box? - Page 1
Forum section: electronics / rf-microwave

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 21, 2017, 02:38:06 am
content: I have an SDR under my bed that I like to listen to at night, I have three cables coming into the bed room from various locations in the house where the antenna are mounted. I'm kind of bed ridden most night so I want to make a box that can just switch between the long wire SW, the little ADSB dipole under the bed, and the 1m yagi. Best would be have the box mounted to a wall next to the bed. But what kind of switch can handle kHz to 2 Mhz with low noise or dropping db? I know it should be in a metal box. Would a splitter work where you lose 3db on each tap work? or would that create a huge antenna that would just kill the band width of the three antennas? Can you use just a regular three way rotor switch?

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: March 21, 2017, 10:34:51 am
content: For VLF through to low VHF, especially for receiving, an ordinary rotary switch would be fine.Put in a metal box with antenna sockets screwed to it and use switch to switch between the inner contacts.If you don't have a rotary switch you could use two slide switches hooked up in such a way that allows antenna A or a choice of antenna B or C.

author: Chris Wilson
author_rank: Super Contributor
timestamp: March 21, 2017, 01:02:50 pm
content: I have built a few switches, mechanical rotary and relay based for those low frequencies. Up to 2 MHz is pretty easy and either the commercial boxes with sockets on them, or just a rotary wafer switch with the needed positions should be fine. It's when you get higher in frequency or TX'ing big power through them that it gets a bit more involved. I assume 2MHz isn't a typo, it's with you mentioning a Yagi that I wonder if you also receive on VHF??

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 26, 2017, 02:32:09 am
content: I ment up to 2GHz, thats what the SDR can do...

author: HowardNamath
author_rank: Newbie
timestamp: March 30, 2017, 03:26:49 pm
content: These aren't exactly cheap, but here are a couple of Analog Devices RF switch eval boards that might fit what you're trying to do. You could potentially throw one in a project box with a power source and control switches:This is a SP3T RF switch that uses a +5V supply (so you could maybe use a filtered USB supply to power it):http://www.mouser.com/ProductDetail/Analog-Devices-Inc/EV1HMC245AQS16/?qs=%2fha2pyFaduihYW547tXjKjpe0RLSci6Qd7qAjm8N21KTMbV%252bVgCTxA%3d%3dThis is a SP4T RF switch that's a bit cheaper (and lower-performing):http://www.mouser.com/ProductDetail/Analog-Devices/EVAL-ADG904EBZ/?qs=sGAEpiMZZMv9Q1JI0Mo%2ftcrEDU6JWfr1