Carl Reade

It is for the current setup which is not portable. It is a continuum addon. I should be able to work out beam width etc. I should be able to add a two way splitter and read continuum, spectrum at the same time using SDR Sharp and an ADC program.

Yep nail on the head!

Basically the same as what you do with a satellite meter and LNB.

My next step on the project is to add a total power element to the scope. I have an old RA project from years ago which has a simple diode detector and a DC amplifier circuit. My plan is to bypass the dongle and connect the dish/ amp chain to this and and an ADC to measure the voltage and see what results I get. I could be way off the method. If it works it will add a bit more capability. Carl

Hi I have the 1300/1700 one. It incorporates the OH line band at 1.6Ghz. the other incorporates the amateur band at 23cm for moon bounce communication at 1.2Ghz. that's the only real difference.

Hi the filter I'm using is quite a few years old from RAS. It is the three rod design. I suspect that the new one is probably improved and now etched on a circuit board. Both do the same thing. RAS have been around for a long time designing and building equipment for the RA sector I would say their noise figures are accurate. They are also filtered for the band which is a big plus. The cheaper LNAs on eBay will work but they are mass produced and basic so their noise figures would not be accurate especially as they are not filtered and wideband. They would depend on your local RF environment. The cheaper one I recommended a post or two above I have seen working. Here is the link to the one I am using at the dish. These are designed, built and tested by a professional company and supply to the RA community, again I would trust their figures and you can see my results here with it. http://g8fek.com/index.html So the two routes are either purchase a more expensive one designed for the job or go for the cheaper type which you will need a filter for and need to screen. Both will work. What I have learned in this project is software processing is half the job as well. You will be detecting the H line but not even realising it. The better the LNA and antenna the easier it is to discern from the noise. Hope this helps Carl

You could make one. It is just an RF choke and a capacitor. Nothing to them really.

Hi the dementions of the can stay the same no matter what dish size, however I use a biquad feed there is a link to it's calculator in earlier post. http://www.setileague.org/hardware/feedchok.htm The bias fee was from eBay as long as it's within the frequency range any will do. This one is 0.5 - 2000Mhz.

Hi here is a diagram and pic of what I put together. There are a lot of different cable connectors at play due to components being different. Most LNAs are SMA connectors and for the coax (WF100) F type connectors. So plan what adapters you will need to put whatever components you use together. I.E SMA male to female F etc. For example the dongle will need a male SMB to female F connector tail lead. Carl

Yes it's the same one should be fine. The satellite shop should have 20db line amps. Have you thought about a feed for the dish?

Hi you cannot use a LNB for hydrogen line. The LNB is receiving 12 GHz however the H line is 1.4 GHz. So you will need the can made to receive 1.4 GHz. In the link he is using a very good LNA on the dish with a noise figure of 0.3 dB as well. Half the work is in the software using smaller dishes. For a minimum start I would go for, 1m dish, 20db LNA, 20 dB line amp, dongle and you should be able to detect hydrogen. This LNA has been used successfully, it's 20db gain and ( important noise figure of 0.6db) https://www.ebay.co.uk/itm/LNA-50-4000MHz-SPF5189-RF-Amplifier-Signal-Receiver-For-FM-HF-VHF-UHF-0-6dB-UK/263793459193?epid=19021137313&hash=item3d6b50bff9:g:ss4AAOSwiNxbO2sL&redirect=mobile You will need to put a dish feed together as well. Happy to help will have a diagram up soon. Carl

Hi on this site there is a link to a spreadsheet for the calculations for a can feed horn. http://www.setileague.org/hardware/feedchok.htm Carl

Hi no boring questions at all, Here is a link for filters at a reasonable price I would use one at least to start with and next to the LNA. https://redirect.viglink.com/?format=go&jsonp=vglnk_154137269185016&key=e6d017f13f6a6e8cc619287ca1b92ca3&libId=jo3hfox701013trd000TA1f6l0dvz&loc=https%3A%2F%2Fstargazerslounge.com%2Ftopic%2F319651-anyone-doing-hydrogen-line-observing%2F%3Fpage%3D2&v=1&out=http%3A%2F%2Fadsbfilter.blogspot.com%2F2015%2F06%2Fhydrogen-line-1420-mhz-filter.html&ref=https%3A%2F%2Fstargazerslounge.com%2Fforum%2F75-radio-astronomy-and-spectroscopy%2F&title=Anyone doing hydrogen line observing%3F - Page 3 - Radio Astronomy and Spectroscopy - Stargazers Lounge&txt=http%3A%2F%2Fadsbfilter.blogspot.com%2F2015%2F06%2Fhydrogen-line-1420-mhz-filter.html Your looking a noise figure of 1db or less on the LNA not sure if that one is. If you can get one screened on the board that is also ideal. Wideband LNAs amplify everything. SDR is fine Line amps fine You will also need various connectors, SMA etc I will put up what I put together soon which should help. Here is a link which is excellent and helped me a lot with software http://parac.eu/projectmk3.htm Carl

Hi, I would think the can type would be better as it would reject interference better but I have not seen a comparison between the two. I decide on the biquad as I had the materials at hand. Yes LNA it's amplification. As someone once put it, you are making an impossibly weak signal into a rediculisly weak one. The aim is to get the hydrogen line out of the noise. The inline amps are to eliminate gain loss in the coax and filters and multiple connectors used. The difference between these and LNAs is probably the noise figure which is around 4 dB so no good at the dish but fine for second stage amplifiers. yes bandpass filters you may get away with one as long as you don't have local interference. The LNA I use is filtered then I have one just before the dongle. I use the Egoo cheap SDR dongle. From reading they all are around the same noise figure 6db but that is irrelevant to the system noise figure. Would definitely cool it with a heatsink as they get very hot and heat is bad.

Ok best advice i would say is, Get the biggest dish you can! You will likely have to make the dish feed yourself either the the one on this thread or the can type (measurements online). Next is a good low noise amplifier (LNA). Around 30db gain and the lowest noise figure you can get. This noise figure will be the benchmark for the system. You will need probably two 20db satellite line amplifiers these are cheap and work fine. You will need filters in line as well to keep out interference. You can get these on the LNA4ALL site. You will need a power supply 12V and a DC inserter to power the amplifiers. You will need a receiver, a SDR dongle is fine A computer and software. Once you have a working scope then you can improve it as you go along. Carl

Hi what sort of observations are you wanting to do, Hydrogen line, sun moon? You can make a basic radio telescope from the following, A small dish 50cm. A universal LNB An analogue satellite meter A 12 Volt power supply This would enable you to take readings from the sun and moon to start with.

Yea I know I don't have the test gear to make them even. Haven't been on the air myself in a while. I'm guessing there is a build in the pipeline? Carl

Hi Robin, it's a specific one made by Radio Astronomy Supplies. I think it was +/- 15Mhz. The label has came off over time. (Photo) I should also mention the LNA is the SBA1300-1700 from RF Design (G8FEK). The guy Adam who sells LNA4ALL also now makes H line filters at 20 Euro I have ordered before with him and good to deal with. http://adsbfilter.blogspot.com/2015/06/hydrogen-line-1420-mhz-filter.html. Carl

More playing with data and contour graphs the green areas and all within is hydrogen. Even between the two arm sweeps hydrogen is present. The centre Freq should read 1.420410Ghz. Carl

Hi all let the scope run from around 17:30 through to 09:30 this morning. This would pick up two sweeps of the galaxy. Excel seems to struggle with 3d graphs but managed to put one together. There are two interference bands and in-between them the milkyway peeks. The rear peek is the strongest I have seen so I will check where it passed later. The gragh is 2.4 MHz wide spectrum over the time period.

Finally the scope is mounted. I knew the concrete pier would be multiple use. Now I can get some proper settings done. LNA now boxed and single 40mm pipe used for the feed.

Thanks for that Robin. I am pushing my luck with a single dish this size in the garden ? Yes Taurus is another to look at. I can leave the scope recording 24hrs with the FFT program. Currently I need to get it on a mount so it's easier to set Alt/Az. But its producing good results and lots of data. Carl

Hi all turned the scope towards Cassiopia for a drift scan not sure if Cas a is in there somewhere but was certainly within the beam. Below is an animation and a still in Cassiopia. Carl

Hi I am averaging in FFT this link should help http://parac.eu/projectmk4.htm Yes it's the Milky Way. A drift scan of the arms. It's a 1.2m dish therefore 1.2m in diameter. Beamwidth 10-12 deg. I am currently still fine tuning the system and have not tried to receive anything beyond the galaxy at this time. All the stronger sources outside the galaxy are in the southern hemisphere. If you mean other galaxies I would doubt a dish of this size would be capable, possibly pulsar observations could be achieved. You also have to take into account that radio sources are brighter at other frequencies than 1.4Ghz. Carl

Hi all here is an animation made from Excel data from last night from 6 pm to around 12am. its a bit crude as the graph auto fits as the signal gets larger. Its around 60x 5min chunks of data. Will need a better way of displaying but work in progress. The system I think is working beyond what I expected for a 1.2 m dish.