Are there any off-the-shelf 1.4 GHz SSB AM FM receivers? - Page 1
Forum section: electronics / rf-microwave

author: Ben321
author_rank: Frequent Contributor
timestamp: January 27, 2017, 04:49:06 am
content: I'm looking for a receiver that can receive in AM, FM, USB, or LSB mode, for frequencies at least as high as 1.4204057517667 GHz (this very specific frequency is the 21cm hydrogen radio spectral line, typically used in radio astronomy). Of all the modes though, the one that's most important is USB. If I tune to 1kHz below this frequency while it's in USB mode, if there is hydrogen gas near the receiver's antenna, I should hear a 1kHz tone. Is there an off-the-shelf receiver I can buy that will tune to frequencies that high, and be able to listen in USB mode? I know ICom has some receivers that can tune that high, but they are limited to AM and FM reception in those bands, and USB reception is only permitted in bands below 1.3 GHz. I have an ICom PCR-1000 (computer controlled receiver) and it can use all modes in all bands, but the highest frequency it can receive is 1.299999999 GHz (just short of 1.3GHz). There are other receivers that ICom offers that can tune up above 1.3GHz, but in those higher bands, USB and LSB reception is disabled.Can anybody here recommend a receiver that is being sold commercially (no custom equipment, no modified equipment) that can tune in to the hydrogen 21cm emission, while in USB mode? And if so, what would it cost?

author: cdev
author_rank: Super Contributor
timestamp: January 27, 2017, 05:06:56 am
content: I have had very good luck with a $10 off the shelf RTL2832 R820T DVB-T dongle I bought on ebay. Its the mid size one with the PAL antenna connector (not MCX) It comes in either white or black and has a curved row of holes in a parabola pattern.What could be more appropriate for radio astronomy. I think Markus Leech who is a software developer who works on the Gnuradio project has standardized his hydrogen linereception setupon this particular dongle.That was several years ago.The specific dongle is a good one for mods because it comes on a postage stamp sized PCB and all four corners are ground plane and so it lends itself well to mounting on a larger PCB as a carrier. Also the connections you can make to the capacitors to improve its filtering are easy. (not as important for VHF and above but important if you want to use it for HF reception, (which requires soldering two tiny wires to the chip and having them stay there which is hard, even for an experienced solderer.)Actually, I see its now $6.50 with free shipping.Performance, durability (of the antenna connector) and frequency accuracy of that model is quite good. It receives from 24-1766 MHz.I use it with CubicSDR software and a Planar Disk antenna.An LNA is useful for radio astronomy. You can buy a very good MMIC based LNA with a noise figure well under 1 db for around $35 from Adam in Croatia, if you search on "LNA4ALL" You definitely should use one. You can actually benefit greatly from a double stage LNA in that particular application.You should download some of the plans for inexpensive radio astronomy antennas. You'll need a high gain antenna to get any kind of resolution on your plots. You can build a horn out of cardboard and foam core inside of a discarded refrigerator box. Feed it with a cantenna/waveguide adjusted for optimal performance.

author: David Hess
author_rank: Super Contributor
timestamp: January 27, 2017, 05:08:43 am
content: The usual solution is to use a transverter with an existing HF, VHF, or UHF SSB receiver. Receivers intended for use with a transverter have an offset function so they display the correct frequency.AORmakes SSB receivers which can receive 1.4 GHz but I do not know how well they work and they are not cheap.There is a good list which includes wideband SSB receivers here:http://www.universal-radio.com/catalog/widerxvr/chartw.html

author: Ben321
author_rank: Frequent Contributor
timestamp: January 27, 2017, 08:15:09 pm
content: Quote from: David Hess on January 27, 2017, 05:08:43 amWhere can I get one of these transverters that you speak of? Does any company sell any such item commercially? Or is this something that has to be custom built by the person who's going to use it?

author: David Hess
author_rank: Super Contributor
timestamp: January 27, 2017, 10:27:19 pm
content: Quote from: Ben321 on January 27, 2017, 08:15:09 pmThey are somewhere between custom built and commercially available. The problem will be finding a already built one which covers 1.4 GHz because they are usually designed for as narrow a frequency range as possible to prevent intermodulation problems.QST and QEX magazines occasionally include kit based transverter designs which could be modified for 1.4 GHz.These guys make a kit which could be used with a 2 meter SSB receiver if the local oscillator frequency is changed:http://www.minikits.com.au/eme23-trv.htm

author: tkuhmone
author_rank: Regular Contributor
timestamp: January 27, 2017, 11:09:27 pm
content: I do currently own Ettus B100 SDR (with WBX board 50..2200MHz)- what has been mentioned on the "budget radio telescope" PDF.I have not yet used it for hydrogen receiving, other SDR related testing. I do not have antenna / low noise pre-amp for the reception yet. I think this tread I will follow from now onDoes anyone have experience of Minicircuits pre-amp modules (with SMA connectors) for this purpose ? I saw them on catalog, and some models go below NF=1dB. What I understood that the cost of the modules is higher then... I do have couple of them in box, but those are only 500MHz upper freq limits, if correctly remember.

author: cdev
author_rank: Super Contributor
timestamp: January 28, 2017, 05:32:02 am
content: If you buy an LNA from MiniCircuits basically you will get their reference design in a very nice machined box with a feed through capacitor to filter the DC power. Thats worth the extra money, IMHO. The LNA you get will be broadband.An LNA you make yourself can be designed and adjusted on site to work best on a specific frequency which for many applications might be better.)Its important to put the LNA right at the antenna. Clean coaxial hardware, good quality cable, good quality connectors, make sure to get all the flux off. ... shortest length of cable you can until you get to the LNA..

author: tkuhmone
author_rank: Regular Contributor
timestamp: January 28, 2017, 01:51:25 pm
content: How much the recommended bandwidth in case of low noise pre-amp (1st after antenna) would be for hydrogen line radio receiving ? Is it like 100MHz, 50MHz or even less ? At least the LNA4ALL seem to be wideband version, ie 28...2500MHz.I know that MiniCircuits make also SMA modules as bandpass filters. To me it is not clear yet, if the first low noise amp is narrowband enough -> does it make the filtering before LNA useless...?

author: cdev
author_rank: Super Contributor
timestamp: January 28, 2017, 03:24:06 pm
content: Are you folks aware of the simplicity of building your own? Why not do that?You would save a lot of money. The typical MMIC only requires a very few other components.By bandwidth I meant optimized generally for a range of frequencies, but you can also roll off undesired ones.Seems to me that sharp BPF like you seem to be describing would likely have too much loss. The feed structure of your antenna and the fact that it's pointed at the cold sky should be enough. Assuming it rejects signals coming from the sides and back well.You should ask a radio astronomy expert. I am just speculating here.

author: David Hess
author_rank: Super Contributor
timestamp: January 28, 2017, 07:53:45 pm
content: Quote from: cdev on January 28, 2017, 03:24:06 pmThe original poster asked about complete solutions so that is what I concentrated on.QuoteAny input filter of used does not need to be *that* sharp. An over coupled cavity filter can have a loss below 0.1dB. The over coupled helical resonator I built for the 2 meter band which covers a large part of the band has a loss of about 0.05dB at its center frequency.I doubt input overload around 1.4 GHz with a skyward pointing dish antenna is a problem so the narrow filter if used can be placed after the low noise amplifier.

author: Silveruser
author_rank: Regular Contributor
timestamp: January 29, 2017, 02:16:16 am
content: Sort of going back to the OP. I have an ICOM R7000 and it seems to stay in SSB above 1.4 just fine. Is there any easy way to verify it is really working? The seems to several signals of some varity up there. Nothing on the freq mentioned but then this receiver has been touched since it was new, shortly after it was introduce.

author: Ben321
author_rank: Frequent Contributor
timestamp: January 29, 2017, 05:52:24 am
content: Quote from: tkuhmone on January 27, 2017, 11:09:27 pm2200MHz? Where did you find an SDR that can tune that high? Most SDRs I've seen are simply DVB (European digital TV) receiver USB dongles which some hackers at one point discovered they could write their own drivers for and use them for anything they wanted (not just TV reception). Of course those homebrew driver based SDRs are now the big thing in the SDR community, but none of them (as far as I know) can tune to frequencies as high as 2.2GHz. Is the Ettus B100 that you talked about some new device invented by radio hobbyists? Like is this some dedicated SDR device (not DVB reciever with alternate drivers) created by and for the SDR community?

author: tkuhmone
author_rank: Regular Contributor
timestamp: January 29, 2017, 12:21:04 pm
content: Quote from: Ben321 on January 29, 2017, 05:52:24 amI have been using both Ettus SDR radios and cheap TV/USB dongles for SDR experiments. The last DVB stick was "LV5TDeluxe". Some experiments done with Icom & Yaesu wideband receivers. Ettus B100 SDR is desktop unit with USB2 interface.https://www.ettus.com/content/files/Ettus_B100_DS_FINAL_1.27.12_4.pdfEttus Research as a company, has been working already some time with SDR technology radios. Company was part of National Instruments from 2010. The B100 radio that I own, is not on production anymore. There is still RF boards available. Coverage is up to 6GHz (with proper RF-board), all the boards using the same "base-unit". This is the card I have on my Ettus (ie WBX).https://www.ettus.com/product/details/WBX

author: cdev
author_rank: Super Contributor
timestamp: January 29, 2017, 03:06:31 pm
content: The early e4000 RTL2832U dongles can tune to slightly above 2200 MHz and there is a satellite band there with many dead older satellites that still transmit various beacon signals. The web site uhf-satcom.com has lists of them.A way to recognize if your receiver is receiving sats is to graph out a known satellite band and look for the Doppler curves.I would highly recommend the ultra cheap dongles for this kind of thing because it's a well-established path to successful RA and OP can get numeric quantitative output easily. Also not much money is lost if it turns out QTH is unsuitable for RA as many perhaps even most are.Can't beat $6.50 each in quantity 1 with free shipping.He should get something that is compatible with the gnuradio libraries. There are maybe a half dozen or so decent choices.

author: Ben321
author_rank: Frequent Contributor
timestamp: February 02, 2017, 06:37:13 am
content: Quote from: cdev on January 29, 2017, 03:06:31 pmAccording tohttp://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/the RTL2832U chip (which is the chip that all of these RTL-SDR dongles use, just that they all use different cases on the devices, because they are all made by a bunch of different generic Chinese electronics companies that rip-off each other circuit designs) has a frequency range of 24 – 1766 MHz, which is VERY far from 2.2GHz. Where did you find a dongle that can go up to 2.2GHz? You say it's called e4000 RTL2832U? I doubt though that it was using an actual RTL2832U chip though, simply because those don't have the range needed to get up to 2.2GHz.

author: borjam
author_rank: Unknown
timestamp: February 02, 2017, 07:36:43 am
content: SDRPlay covers 10 KHz - 2 GHz.As a self contained receiver, the Yaesu VR5000 goes up to 2,4 GHz. I don't think SSB is disabled past some frequency, but I will check this evening.It's not a bad receiver provided you use it properly. A good filter is more than recommendable to avoid overloads.

author: David Hess
author_rank: Super Contributor
timestamp: February 02, 2017, 11:56:14 am
content: Quote from: borjam on February 02, 2017, 07:36:43 amOverload is a problem with all wideband receivers. Without RF preselection, the first mixer stage gets hammered by the entire input frequency range. Good scanners use varactor tuned RF preselection and even this is not enough.

author: borjam
author_rank: Unknown
timestamp: February 02, 2017, 03:09:52 pm
content: Quote from: David Hess on February 02, 2017, 11:56:14 amOf courseThe VR5000 (I own one) has even some antenna coupling circuitry that you can use to help with intermodulation, but depending on the application you better add decent front end filtering.

author: steve_tech
author_rank: Newbie
timestamp: February 02, 2017, 09:10:45 pm
content: ICOM R7000 went to 2 Gig. I have one and it is extremely well made.

author: cdev
author_rank: Super Contributor
timestamp: February 02, 2017, 11:41:54 pm
content: The elonics e4000 tuner chip is the one that goes up a little bit above 2.2 GHz,The Rafael Micro R820T (or "R820T2") tops out at 1766 MHz and goes down to 24 MHz.I'm sorry I didn't make that clearer. Neither tuner is that great, when compared to dedicated hardware with real bandpass filters.. but for the money (these days often under $10) they are great.Its a big advantage of being an SDR making extraction of numerical data fairly easy. For something like radio astronomy thats a big advantage. I dont know how you could get that kind of data from conventional receivers without tapping into their receive chain. There is a whole family of software which lets you do innumerable things with the signals.They were the first of a whole cluster of cheaper SDRs.. Now there are likely a whole bunch of slightly more expensive, sort of middle of the pack SDRs now (anything thats compatible with the osmocom libraries for gnuradio ) that would be a better choice if you are willing to spend from around a hundred to a few hundred bucks. That will also get you the ability to do math on the data, like the RTLSDR.The RTLSDRs are sensitive enough to do poor mans radio astronomy..Quote from: Ben321 onTodayat 01:37:13>Quote from: cdev on 2017-01-29, 10:06:31

author: tkuhmone
author_rank: Regular Contributor
timestamp: February 07, 2017, 02:29:26 pm
content: Quote from: cdev on January 28, 2017, 03:24:06 pmI will try to search suitable contact points.... Next week on southern Finland, there is public presentation of radio astronomy activities in local observatory (Metsähovi). Although I suspect that presentation is mostly about the professional radio observing - I try to absorb as much info as I can, as a hobbyist :-)