dspira-lessons/forum/electronics/

[utterances-bot]

Electronics Forum – Digital Signal Processing in Radio Astronomy - Lessons Portal

Lots of lessons

https://wvurail.org//dspira-lessons/forum/electronics/

[ZL4DK]

So I went the hard way and got the components together to build the DSPIRA LNA (I actually built two). I found the cover shield was ridiculously expensive in small quantities but solved this by milling a small aluminium case for the LNA that internally approximately matches the dimensions of the shield. Testing so far shows that these LNAs are working but I have yet to put them on an antenna. I am using a HackRF One clone as the receiver. This seems to be working OK also. I must admit I am struggling with Linux. My old laptop seems to be overflowing with the data coming in from the HackRF (strings of zeros printed in the bottom left window) but that doesn't seem to be stopping the software. I have a SDRPlay receiver also, but haven't managed to get this working with GNUradio.

Regards David

[GlenLangston]

Hi David

It is absolutely great that you’ve got two working amplifiers that you’ve built!

There is a way of testing the performance without an horn antenna that you should try first.

This requires only a very inexpensive termination, available from Amazon. (Two for $6 or 5 for $10)

See: http://wvurail.org/lightwork/memos/LightWorkMemo028-r7-NoiseTemp.pdf

You should be getting an effective temperature of between 80 to 100 Kelvins. Your telescope will work with an effective temperature under 300 Kelvins.

Best regards

Glen

https://www.amazon.com/YOTENKO-coaxial-Terminator-Termination-Connector/dp/B07TQ5J5C2/ref=sr_1_4?crid=2JQHA2A6NDD4O&dchild=1&keywords=50+ohm+terminator+sma&qid=1632421417&sprefix=50+ohm+ter%2Caps%2C152&sr=8-4

On Sep 23, 2021, at 1:24 AM, ZL4DK @.***> wrote:

So I went the hard way and got the components together to build the DSPIRA LNA (I actually built two). I found the cover shield was ridiculously expensive in small quantities but solved this by milling a small aluminium case for the LNA that internally approximately matches the dimensions of the shield. Testing so far shows that these LNAs are working but I have yet to put them on an antenna. I am using a HackRF One clone as the receiver. This seems to be working OK also. I must admit I am struggling with Linux. My old laptop seems to be overflowing with the data coming in from the HackRF (strings of zeros printed in the bottom left window) but that doesn't seem to be stopping the software. I have a SDRPlay receiver also, but haven't managed to get this working with GNUradio.

Regards David

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[ZL4DK]

Thanks Glen, yes I did try this last night. Initially I had no success and on investigating I found almost no voltage across the SAV-541. I found I had a 27k Ohm resistor in R2 instead of 27 Ohm. I had been following https://github.com/WVURAIL/dspira/blob/master/labs/06/2018_06_22.pdf and this error is in the parts list (the schematic is correct). I changed this resistor for a 30 ohm one (I didn't have a 27 Ohm) and it seems to be good now, although I haven't done the full test to work out the effective temperature yet. I'm running the GNUradio spectrometer software on a laptop rather than the NSFintergrate on a RPi. I assume they are roughly the same thing. I might look at getting a RPi they seem pretty good. Is there a recommended RAM size?

[glangsto]

Hi Dave,

Glad you’re making progress.

Hopefully Pranav or Kevin will update the parts list value for that resister. I’m wondering if the amplifiers ordered recently have that part error!

I’m not sure which spectrometer you mean by GNUradio spectrometer. However that will probably work, but you need to average for about a minute on the “hot” and “cold” measurements (code is just no load attached), so you’ll need to figure out how to do averaging.

The NsfIntegrate programs do that and also do the “Y” factor to compute the effective noise temperature. (This is a simple calculation, but is a little unusual). (See online documents like: https://www.osti.gov/servlets/purl/1562649)

Concerning the raspberry PI, a 4B with 4 GBytes of memory is plenty. The newer, PI 400, is actually slightly better, but does not fit in the box I use. I’ve got one running at a horn, but just in a plastic bag, not a sturdier, weather tight box. So far it has not gotten soaked with rain, after about 6 months outside.

Good Luck!

Glen

The code for the Pi is all completely on-line and in one single, very big (3.3 GByte), download. The same code works for both the Pi 4B and Pi 400.

On Sep 23, 2021, at 4:05 PM, ZL4DK @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Thanks Glen, yes I did try this last night. Initially I had no success and on investigating I found almost no voltage across the SAV-541. I found I had a 27k Ohm resistor in R2 instead of 27 Ohm. I had been following https://github.com/WVURAIL/dspira/blob/master/labs/06/2018_06_22.pdf and this error is in the parts list (the schematic is correct). I changed this resistor for a 30 ohm one (I didn't have a 27 Ohm) and it seems to be good now, although I haven't done the full test to work out the effective temperature yet. I'm running the GNUradio spectrometer software on a laptop rather than the NSFintergrate on a RPi. I assume they are roughly the same thing. I might look at getting a RPi they seem pretty good. Is there a recommended RAM size?

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[PranavSanghavi]

Hi @ZL4DK, good spotting the error in the parts list. you were referring to an outdated document on a outdated website that we have since updated to reflect new and corrected stuff.

you might want to refer to this: https://wvurail.org/dspira-lessons/DetailedLNAInstructions I shall work to clear out stuff from the old webpage or have a more obvious redirected,

a distro image for raspberry pi and a general document is also here https://wvurail.org//dspira-lessons/RaspberryPi if you want to add more to this as you experiment do let me know

[ZL4DK]

OK so if a have understood correctly Y = Hot_Output/Cold_Output and T = (Hot_Temp - Y * Cold_Temp)/(Y-1) After a bit of integration, for cold I get a signal level of 115 and for Hot I get a signal level of 830 If I assume Hot is 300K and cold is 0K this gives me a Temperature of 48K, this seems a little too good.

[ZL4DK]

And just to try it again I reduced the gain on my HackRF One receiver and now have a Hot signal of 130 and a cold signal of 19. this gives a Temperature of 51K.

[GlenLangston]

Hi Dave,

Well that is a great number for the Rx Effective temperature. Kevin Bandura’s design has given me the best measure Tsys on an antenna that I’ve gotten.

I’ve not directly measured the Trx on my copy of his amplifier, as it has been so reliable that I’ve always had it on a telescope. (Currently 5 are running).

So, I’d say that 51K is lower than I’ve measured, but is still physically possible. I actually use T hot = 290K and T cold = 10K, for my measurements, but there is not too much justification for my T cold.

It would be great if you’d write up your measurements as a LightWork Memo. It seems like you’ve done a careful job.

Maybe add a couple pictures and repeat your measurements 3 times to see if the gain is change with time. That’s the only effect that I’m aware of that might be an issue. That is, I’ve found that for some amplifiers the gain decreases as they warm up, so doing hot first, then cold second shows a lower Trx. But if you Cycle through 3 measurements you can see any trends.

Thanks for your measurements!

Glen

On Sep 23, 2021, at 8:17 PM, ZL4DK @.***> wrote:

And just to try it again I reduced the gain on my HackRF One receiver and now have a Hot signal of 130 and a cold signal of 19. this gives a Temperature of 51K.

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[ZL4DK]

I tested my second LNA and this isn't so good. Cold gave a reading of 52 and hot a reading of 160 which equates to a temperature of 140K. Yes I repeated the readings a few times cycling between hot and cold and there is a slight drift as things warm up but not excessive. I set up my antenna (a 1200mm dish) and can easily see the Hydrogen bump with either LNA. After calibrating (hot point at Ground and cold pointing at cold sky) the system temperature chart showed a line at 160K for the good LNA and 300K for the not so good one. However some of that might be my antenna. The mount I have only allows me to swing it a limited amount and I had trouble pointing it completely at the ground and trouble pointing it completely away from any hydrogen when cold. It probably has a few bad sidelobes also.

[GlenLangston]

Hi ZL4DK (aka Dave?),

Well, you’ve made great progress! Actually having lower than 150K LNA effective temp is better than most commercial amplifier boards will give.

Glad to hear the amplifier gain is not changing too much during your tests.

Since galactic hydrogen is really remarkably bright, peak > 50 K, both your amplifiers will enable you to easily see our galaxy.

So is your 50K amplifier measurement repeatable? That is a great number! The GBT has amplifiers, cryogenically cooled, that have an effective temp of 19 Kelvins.

As I said I’ve got 5 horns, with different combinations of amplifiers. I have a range of Tsys values from 140 to 240 K, by hot-cold measurements. This includes a foam insulation top of all the horns, to keep them from collecting too many leaves and too much snow and rain. The “lid” seems to add about 25 Kelvin. The horns have been outside for several years now. (See: https://www.gb.nrao.edu/~glangsto/Glen+4Horns.jpg)

The hot-cold load test actually measures the ratio of Tsys/(gain efficiency), so a higher reading likely indicates the gain is a little low.
(ie not all the signal is making it to the first LNA). A parabolic antenna with feed probe at focus has a gain efficiency between 0.5 and 0.7.

Horns can be more efficient, gain = 0.8 to 0.95, but are difficult to make very large.
My larger horns are about 32 inches in diameter, which is about 80cm.

It would be great if someone would write up measurements of hot-cold temperature using the WVURAIL horn design.

My horns are all cylinders, and I got a professional to calculate the optimum feed probe position and length, to improve gain.

Congratulations on your success!

Glen

PS I’m working on a memo showing how to measure the properties of our galaxy: 1) our speed of rotation 2) number of arms 3) mass of the disk near the Sun

On Sep 24, 2021, at 6:47 AM, ZL4DK @.***> wrote:

I tested my second LNA and this isn't so good. Cold gave a reading of 52 and hot a reading of 160 which equates to a temperature of 140K. Yes I repeated the readings a few times cycling between hot and cold and there is a slight drift as things warm up but not excessive. I set up my antenna (a 1200mm dish) and can easily see the Hydrogen bump with either LNA. After calibrating (hot point at Ground and cold pointing at cold sky) the system temperature chart showed a line at 160K for the good LNA and 300K for the not so good one. However some of that might be my antenna. The mount I have only allows me to swing it a limited amount and I had trouble pointing it completely at the ground and trouble pointing it completely away from any hydrogen when cold. It probably has a few bad sidelobes also.

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[GlenLangston]

HI ZL4DK,

I confirm your calculations. According to the references (eg https://www.osti.gov/servlets/purl/1562649, equations 59, 60 and 61),

Y = N_hot/N_cold

where The Ns are measurements, in counts, from your SDR.

Then the Receiver temperature is

T_rx = (T_hot - (Y * T_cold))/(Y - 1)

So for your case

Y = 130/19 = 6.8

You (and I) assume T_hot = 290K and you assume T_cold = 0K, then

T_rx = (290K - (6.8 * 0K))/5.8 = 50 K, which is about what you reported.

Now let’s consider the error estimate for the measurements

The uncertainty appears to be +/- 1 in for both measurements.
The cold measurement dominates, so

Y’ = 130/(19 +/- 1) = 6.5 to 7.2, then estimate the Y uncertainty as 0.7/2 => 6.8+/-0.35

So T_rx could be between 47K and 53K, so a fairly tight range.

Now I use Tcold = 10K (not zero)

This tweaks the results to

T_rx = (290 - (6.8 *10))/5.8 = 38 K. Which is even lower. So maybe your number is better.

So, I confirm your calculations.

Best regards

Glen

On Sep 23, 2021, at 8:17 PM, ZL4DK @.***> wrote:

And just to try it again I reduced the gain on my HackRF One receiver and now have a Hot signal of 130 and a cold signal of 19. this gives a Temperature of 51K.

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[ZL4DK]

OK this is cool. The sky is full of interesting signals. At noon today while pointing straight up I got a very large single peak. I think this is from the direction of the Southern Cross. (I'm at 170.386 E and 45.889 S) Time zone is currently UTC +13. Earlier this morning I got a smaller but more interesting double humped red shifted signal from I think the direction of Vela. My dish is fixed pointing approximately north but I can swing it in elevation. It would be good to change the mount so I can move it more easily and this would make calibration easier. I also need to learn a bit more about astronomy to know where I am pointing. Thanks for your help and comments Glen. Your array of horns looks fun.

Regards David

[ZL4DK]

OK Just for news I have an update on my LNA construction and testing efforts. I had purchased 3 circuit boards so finally got the components together and got the third one going. Initially this looked faulty and I finally found a bit of solder shorting the top of R16 to ground. Clearing this fixed the problem and the LNA performed as good as the first one with a noise temp of actually slightly less than 50K. This made me look harder at the second one that didn't seem to be doing as well as it should. I decided to try changing the SAV-541 thinking maybe I had a poor performing one. In the process of removing it I got a blob of solder on C2 and when removing this C2 fell off the board revealing that I hadn't soldered it properly on one side. I figured this was probably the source of my problem. I re-soldered C2 and installed the new SAV-541 (I figured I'd close to cooked the old one by now) and now have a third LNA working with a noise temp of 50K so am very happy. I plan to keep two of the LNAs but will look for a local school or other worthy recipient for the third. Thanks again for the help.

Regards David

[glangsto]

Dear David,

That’s fantastic news. Would you mind writing up a very short LightWork Memo on that topic? It would be very valuable to others to hear of your good success both making ant testing Kevin’s amplifier.

They would appreciate some documentation of your measurements. (https://github.com/WVURAIL/lightwork)

Everyone should really do the noise measurement test before starting their observations, as it provides an easy, and pretty accurate, check that the whole system is working.

Best regards

Glen

Glen I Langston, Ph. D. Galactic Astronomy Program Director National Science Foundation 304-456-3032

On Oct 9, 2021, at 8:07 PM, ZL4DK @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

OK Just for news I have an update on my LNA construction and testing efforts. I had purchased 3 circuit boards so finally got the components together and got the third one going. Initially this looked faulty and I finally found a bit of solder shorting the top of R16 to ground. Clearing this fixed the problem and the LNA performed as good as the first one with a noise temp of actually slightly less than 50K. This made me look harder at the second one that didn't seem to be doing as well as it should. I decided to try changing the SAV-541 thinking maybe I had a poor performing one. In the process of removing it I got a blob of solder on C2 and when removing this C2 fell off the board revealing that I hadn't soldered it properly on one side. I figured this was probably the source of my problem. I re-soldered C2 and installed the new SAV-541 (I figured I'd close to cooked the old one by now) and now have a third LNA working with a noise temp of 50K so am very happy. I plan to keep two of the LNAs but will look for a local school or other worthy recipient for the third. Thanks again for the help.

Regards David

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[GlenLangston]

Hi DSPIRA and all Aficionados,

Hope everyone is doing well.

I’m working on providing example “experiments" and data for folks wanting to do some radio astronomy on their own.

Jupyter notebooks are the currently fashionable way of mixing programming and executing of example programs. There’s a huge amount of online documentation.

The code is starting to come together. Get a version by typing (on a linix/mac system): cd ~ git clone https://github.com/glangsto/jupyter https://github.com/glangsto/jupyter cd jupyter jupyter-lab

Then you’re in and can run the programs.
(You may need to install jupyter-lab) (See https://jupyterlab.readthedocs.io/en/stable/getting_started/installation.html https://jupyterlab.readthedocs.io/en/stable/getting_started/installation.html)

The lesson goals are: 1) Have a few simple goals for people to try with Horn Radio Telescope Data already available 2) Make it possible to use either the NSF series of Gnuradio programs or spectrometer_w_cal.grc to use the software tools. i) I’ve started conversion programs, toCsv to convert the NSF .ast and .hot files to the type of files that are compatible with spreadsheets see: https://github.com/glangsto/jupyter/blob/master/ConvertObsToCsv.ipynb https://github.com/glangsto/jupyter/blob/master/ConvertObsToCsv.ipynb 3) Have a basic understanding of the Milky Way structure. See: https://github.com/glangsto/jupyter/blob/master/MilkyWay1Intensity.ipynb https://github.com/glangsto/jupyter/blob/master/MilkyWay1Intensity.ipynb You might start with this notebook as it models the Milky Way without data.

4) To Be done: Compare observations to the Model

Please give these a try and let me know what you think.

Thanks!

Glen

FYI I’m having a good bit of trouble getting spectrometer_w_cal.grc to write files. We might want to have the “prefix” displayed in the interface and allow it to be changed.

For a beginners guide to Jupyter notebooks look at

https://www.dataquest.io/blog/jupyter-notebook-tutorial/ https://www.dataquest.io/blog/jupyter-notebook-tutorial/

On Sep 17, 2021, at 11:32 AM, Joe Wise @. @.>> wrote:

Awesome. We are looking forward to getting some data from your site.

We were able to get two telescopes to serve as an interferometer last summer.

If you are interested, I can send you information. Further work will be required. It is a tricky proposition.

Joe Wise

[ZL4DK]

Hi Glen, I've written some notes about buiding and testing my LNAs and have had a look at the Lightworks memos. I'm new to Github and am not really sure about how I would submit this. Can you point me in the direction of how to ga about this?

Regards David

[GlenLangston]

Hi David,

That’s great that you’ve written up your experience!

I think you just try to push an update on the GitHub website, then if there is any problem, probably Pranav or Kevin will have to sort it out.

Certainly I’d like you to be able to push any (constructive) changes you’d like to make.

We’ve not added as many contributors as we should have.

Kevin and Pranav, any suggestions for David on adding a new memo?

Thanks

Glen

On Oct 21, 2021, at 3:38 PM, ZL4DK @.***> wrote:

Hi Glen, I've written some notes about buiding and testing my LNAs and have had a look at the Lightworks memos. I'm new to Github and am not really sure about how I would submit this. Can you point me in the direction of how to ga about this?

Regards David

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

[kbandura]

The sites themselves are git repositories, if you are familiar with that.

Using the web interface, you can go here:

https://github.com/WVURAIL/lightwork/tree/master/memos

then say ‘add file’ to add a new file.

And then here:

https://github.com/WVURAIL/lightwork/blob/master/README.md

and edit that to include the new file in the list.

You can also email me and I can put it up! @.***

From: Glen Langston @.> Sent: Thursday, October 21, 2021 3:43 PM To: WVURAIL/dspira-lessons @.> Cc: Subscribed @.***> Subject: Re: [WVURAIL/dspira-lessons] dspira-lessons/forum/electronics/ (#8)

Hi David,

That’s great that you’ve written up your experience!

I think you just try to push an update on the GitHub website, then if there is any problem, probably Pranav or Kevin will have to sort it out.

Certainly I’d like you to be able to push any (constructive) changes you’d like to make.

We’ve not added as many contributors as we should have.

Kevin and Pranav, any suggestions for David on adding a new memo?

Thanks

Glen

On Oct 21, 2021, at 3:38 PM, ZL4DK @. <mailto:@.> > wrote:

Hi Glen, I've written some notes about buiding and testing my LNAs and have had a look at the Lightworks memos. I'm new to Github and am not really sure about how I would submit this. Can you point me in the direction of how to ga about this?

Regards David

— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-948947137 , or unsubscribe https://github.com/notifications/unsubscribe-auth/AADL4WJXZL34CDW6R4ASDTTUIBUMLANCNFSM5ES3FZEQ . Triage notifications on the go with GitHub Mobile for iOS https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675 or Android https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub . https://github.com/notifications/beacon/AADL4WKXALF777N3K7M4SELUIBUMLA5CNFSM5ES3FZE2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOHCH4RQI.gif

[Kimmo1]

Hi

This project is very professional, many thanks to all of you.

I have some comments and questions, but first of all, I would like clarify one thing. I have RTL-SDR dongle and Nooelec LNA for the 21cm hydrogen line, but no antenna yet for 21cm wavelength. I am running Gnuradio and the spectrometer_w_cal.grc program from a bootable flash drive.

I can turn the bias tee on RTL-SDR on and off with the command 'rtl_biast -b 1/0' However, it seems to me that the program spectrometer_w_cal.grc automatically turns the bias tee on. Am I correct ?

This may be problematic if someone has connected the dongle directly to a DC short circuited antenna. For example, I was testing the system by connecting the dongle directly to an antenna, and tuned to FM frequencies (the antenna was not DC short circuited).

I think it would be better that one should turn the bias tee on and off in the spectrometer_w_cal.grc program. Is that possible ?

Cheers, Kimmo

[kbandura]

Spectrometer with cal does indeed set the bias to on by default. To change this, in gnuradio-companion, the Osmocom Source block has a 'Device arguments' box, change the bias=0/1 to disable/enable the bias tee, or just remove that entirely to leave as defaults.

On Fri, Oct 22, 2021 at 6:43 PM Kimmo1 @.***> wrote:

Hi

This project is very professional, many thanks to all of you.

I have some comments and questions, but first of all, I would like clarify one thing. I have RTL-SDR dongle and Nooelec LNA for the 21cm hydrogen line, but no antenna yet for 21cm wavelength. I am running Gnuradio and the spectrometer_w_cal.grc program from a bootable flash drive.

I can turn the bias tee on RTL-SDR on and off with the command 'rtl_biast -b 1/0' However, it seems to me that the program spectrometer_w_cal.grc automatically turns the bias tee on. Am I correct ?

This may be problematic if someone has connected the dongle directly to a DC short circuited antenna. For example, I was testing the system by connecting the dongle directly to an antenna, and tuned to FM frequencies (the antenna was not DC short circuited).

I think it would be better that one should turn the bias tee on and off in the spectrometer_w_cal.grc program. Is that possible ?

Cheers, Kimmo

— You are receiving this because you commented. Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-949998778, or unsubscribe https://github.com/notifications/unsubscribe-auth/AADL4WMSWEW27ANAWUX2JSLUIHSKXANCNFSM5ES3FZEQ . Triage notifications on the go with GitHub Mobile for iOS https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675 or Android https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub.

[whrzg]

I would like to build the DSPIRA Radio Telescope and have begun ordering the parts to build the DSPIRA LNA. The voltage regulator (Digikey part number LM2937IMPX-5.0/NOPBTR-ND) is not available. Both Digikey and Mouser are out of stock and I have been unable to locate another supplier for the part. Are there any suggestions as to other suppliers or substitute voltage regulators? Thank you very much for any help you can provide.

[rbaker314]

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=LM2937IMPX-5.0%2FNOPBTR-ND%29&_sacat=0

On Wed, May 11, 2022 at 11:03 AM whrzg @.***> wrote:

I would like to build the DSPIRA Radio Telescope and have begun ordering the parts to build the DSPIRA LNA. The voltage regulator (Digikey part number LM2937IMPX-5.0/NOPBTR-ND) is not available. Both Digikey and Mouser are out of stock and I have been unable to locate another supplier for the part. Are there any suggestions as to other suppliers or substitute voltage regulators? Thank you very much for any help you can provide.

— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1124105443, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABZERAIPXFYZSHCY5UREBNTVJPY6FANCNFSM5ES3FZEQ . You are receiving this because you are subscribed to this thread.Message ID: @.***>

[kbandura]

This is a drop in replacement for that part:

https://www.digikey.com/en/products/detail/microchip-technology/MCP1825S-5002E-DB/1636099

Good luck!

[whrzg]

Thank you very much for the ebay link!

[whrzg]

Thank you very much Professor Bandura for the digikey link to the drop in replacement part!

[GiaCet]

Hallo Professor Bandura, the sav-541+ amplifier from minicircuits website is of out of stock. The most similar amplifier is the sav-581+. Could be ok? Best Regards Gianni Cetrulo

[kbandura]

Should also be available on digikey:

https://www.digikey.com/en/products/detail/mini-circuits/SAV-541-/13929660

[GiaCet]

Ok, Thanks a lot.

Regards Gianni

[skywise-8]

Hi

I'm trying a system with a Airspy-Mini SDR and a Nooelec HI Sawbird LNA. Computer is a laptop running Ubuntu. In Gnuradio I run the spectrometer_w_cal.grc program.

In LightworkMemo028 (p. 11) it says that compared to using a GPIOLabs Amplifier, the Nooelec Amplifier would require about 4 times the observing time of GPIO.

I don't quite understand what is meant by observing time, using the spectrometer_w_cal.grc program. Is the integration time the same as observing time? So instead of a long integration over 10 sec, I should try integrating over 40 sec?

Best regards, Morten, Copenhagen

[GlenLangston]

Hi Morten,

Very good hearing from you. The sensitivity of a telescope is inversely proportional to the system temperature.

However you can make up for lower sensitivity by averaging longer.

If the optimum system temperature for the Horn Radio Telescope is 120 K, with the GPIO Labs amplifier, and with the NooElec HI amplifier the system temperer ins 240 K, then the telescope with the GPIO Labs amplifier is twice is sensitive.

However if you observer longer, with a less sensitive telescope you can still do better.

The noise of an observation, Delta T, reduces as the square root of bandwidth and time.

Since T is twice as great for NooElec as for GPIOLabs amplifier Observing 4 times longer gives the same noise (Delta T)

Since I average for an hour, you can get an excellent observation with the NooElec amplifier, by averaging longer.

Hope that helps.

Best regards

Glen

On Jun 15, 2022, at 10:24 AM, skywise-8 @.***> wrote:

Hi

I'm trying a system with a Airspy-Mini SDR and a Nooelec HI Sawbird LNA. Computer is a laptop running Ubuntu. In Gnuradio I run the spectrometer_w_cal.grc program.

In LightworkMemo028 (p. 11) it says that compared to using a GPIOLabs Amplifier, the Nooelec Amplifier would require about 4 times the observing time of GPIO.

I don't quite understand what is meant by observing time, using the spectrometer_w_cal.grc program. Is the integration time the same as observing time? So instead of a long integration over 10 sec, I should try integrating over 40 sec?

Best regards, Morten, Copenhagen

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[glangsto]

This text was in the message for Morten, included as an image.
I forgot that images are taken out of email in GitHub:

Sensitivity of a Single Dish

We can take advantage of the fact that the signal will be correlated from one sample to the next, while the noise will not be, and "beat down the noise" by making many sample measurements and adding them up.

According to the Nyquist theorem, a time series of measurements of signal of bandwidth Delta v, of duration “t", will contain (2 Delta v t) independent samples, so the noise should go down by the square-root of the number of samples, or

Delta T = T / sqrt(2 Delta V t)

where T is the equivalent temperature of the signal plus noise.

Glen

On Jun 15, 2022, at 4:58 PM, Glen Langston @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Hi Morten,

Very good hearing from you. The sensitivity of a telescope is inversely proportional to the system temperature.

However you can make up for lower sensitivity by averaging longer.

If the optimum system temperature for the Horn Radio Telescope is 120 K, with the GPIO Labs amplifier, and with the NooElec HI amplifier the system temperer ins 240 K, then the telescope with the GPIO Labs amplifier is twice is sensitive.

However if you observer longer, with a less sensitive telescope you can still do better.

The noise of an observation, Delta T, reduces as the square root of bandwidth and time.

Since T is twice as great for NooElec as for GPIOLabs amplifier Observing 4 times longer gives the same noise (Delta T)

Since I average for an hour, you can get an excellent observation with the NooElec amplifier, by averaging longer.

Hope that helps.

Best regards

Glen

On Jun 15, 2022, at 10:24 AM, skywise-8 @.***> wrote:

Hi

I'm trying a system with a Airspy-Mini SDR and a Nooelec HI Sawbird LNA. Computer is a laptop running Ubuntu. In Gnuradio I run the spectrometer_w_cal.grc program.

In LightworkMemo028 (p. 11) it says that compared to using a GPIOLabs Amplifier, the Nooelec Amplifier would require about 4 times the observing time of GPIO.

I don't quite understand what is meant by observing time, using the spectrometer_w_cal.grc program. Is the integration time the same as observing time? So instead of a long integration over 10 sec, I should try integrating over 40 sec?

Best regards, Morten, Copenhagen

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[glangsto]

Hi Morten,

Hope your observations are going well. Did you build a horn telescope?

Is the software running as you expect?

Note the signal is pretty week, especially if you are not looking exactly at the disk of our Milky Way Galaxy.

The expected “raw” signal is a weak bump in the spectrum

This youtube video shows what you might expect to see:

https://www.youtube.com/watch?v=qXBN_0yWl-o&t=78s

Good luck!

Glen

Maybe post a picture of the plots you’re seeing.

Glen I Langston, Ph. D. Galactic Astronomy Program Director National Science Foundation 304-456-3032

On Jun 15, 2022, at 10:24 AM, skywise-8 @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Hi

I'm trying a system with a Airspy-Mini SDR and a Nooelec HI Sawbird LNA. Computer is a laptop running Ubuntu. In Gnuradio I run the spectrometer_w_cal.grc program.

In LightworkMemo028 (p. 11) it says that compared to using a GPIOLabs Amplifier, the Nooelec Amplifier would require about 4 times the observing time of GPIO.

I don't quite understand what is meant by observing time, using the spectrometer_w_cal.grc program. Is the integration time the same as observing time? So instead of a long integration over 10 sec, I should try integrating over 40 sec?

Best regards, Morten, Copenhagen

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[skywise-8]

Hi Glen, and thanks for your quick reply!

I built a horn telescope in the autumn, and then had to pause the project during winter. Anyway, now I'm resuming the project, and is in a test phase. I have done only a few short observations. I'll try to post a screenshot later.

The spectrometer_w_cal program is running fine, I think, though I certainly don't understand all the settings. For instance I'm still trying various gain settings.

Regarding the time duration of observations: If I want to average over 4 hours, (compensating for the higher noise from the Nooelec amplifier), can I set spectrometer_w_cal settings for this duration? I could change integration_time1 and integration_time2, maybe set the short time to 10 sec, and the long time to 3600 sec? Then I would get 4 csv-files of 1 hour each, and these I could add in a spreadsheet for a combined 4 hour measurement? Is this the way to do a 4 hour averaging, or am I missing something? When calibrating, will 10 sec integration times be enough? I don’t want to calibrate for an hour or so, if it can be helped :-)

Best regards, Morten

[glangsto]

Hello Morten,

Thanks for your explanation, I understand a bit better.

You probably want to only observe for a few minutes, then average the data later, as needed.

I’ve used spectrometer_w_cal a few times and it works fine, but I’m not an expert. Perhaps others can chime in?

My experience is more with NsfIntegrateXX, NsfDetectXX and NsfWatchXX, where the XX corresponds to the bandwidth of the device you’re using. For an inexpensive dongle use “24” for 2.4 MHz, for the Airspy mini XX=60 for 6 MHz bandwidth. If and SDRPlay RSP1A, I’d use NsfIntegrate80 for 8 MHz bandwidth.

Concerning some of your questions, yes you’d average for a shorter time, like a few minutes. If you’re looking at the ground to calibrate you need to observe the ground as long as the longest average of sky you want to make. I think 1 hour is about max, because the sky rotates a telescope beam width in about an hour.

Glen

Glen I Langston, Ph. D. Galactic Astronomy Program Director National Science Foundation 304-456-3032

On Jun 16, 2022, at 10:26 AM, skywise-8 @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Hi Glen, and thanks for your quick reply!

I built a horn telescope in the autumn, and then had to pause the project during winter. Anyway, now I'm resuming the project, and is in a test phase. I have done only a few short observations. I'll try to post a screenshot later.

The spectrometer_w_cal program is running fine, I think, though I certainly don't understand all the settings. For instance I'm still trying various gain settings.

Regarding the time duration of observations: If I want to average over 4 hours, (compensating for the higher noise from the Nooelec amplifier), can I set spectrometer_w_cal settings for this duration? I could change integration_time1 and integration_time2, maybe set the short time to 10 sec, and the long time to 3600 sec? Then I would get 4 csv-files of 1 hour each, and these I could add in a spreadsheet for a combined 4 hour measurement? Is this the way to do a 4 hour averaging, or am I missing something? When calibrating, will 10 sec integration times be enough? I don’t want to calibrate for an hour or so, if it can be helped :-)

Best regards, Morten

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[kbandura]

When you are getting started looking for the galaxy, any of these amplifiers will be enough to see the galaxy in less than a second, and ~10s should give results with only a little noise. Calibrating on the ~10s integration should work fine when the system is working. Longer integration always lowers the noise, and this can be done by averaging the output files after the fact or while recording.

[skywise-8]

Thank you, both Glen and Kevin

I tried integrating over several 60sec periods and then averaged them, this definitely decreased the noise! Though I'm still unsure about the best Gain setting.

Though I managed to attach images to a comment I made last year, I've forgotten how to do so - so for now I can't show you a graph :-(

I wanted to try NsfIntegrate60, so I could test my LNA like it is done in LightworkMemo028. Unfortunately I was unable to run the program:

Warning: failed to XInitThreads() Traceback (most recent call last): File "/home/mc/gr-radio_astro/examples/nsf/NsfIntegrate60.py", line 39, in import ConfigParser ModuleNotFoundError: No module named 'ConfigParser'

Best regards, Morten

[dave290]

I have also had this same difficulty with the nsfintegratexx, for any versions not equal to 24 or 100. (I’d like to run the Airspy r2 with a bandwidth of 25 or 30 MHz, instead of 10 MHz) Dave Schultz

On Fri, Jun 17, 2022 at 9:41 AM skywise-8 @.***> wrote:

Thank you, both Glen and Kevin

I tried integrating over several 60sec periods and then averaged them, this definitely decreased the noise! Though I'm still unsure about the best Gain setting.

Though I managed to attach images to a comment I made last year, I've forgotten how to do so - so for now I can't show you a graph :-(

I wanted to try NsfIntegrate60, so I could test my LNA like it is done in LightworkMemo028. Unfortunately I was unable to run the program:

Warning: failed to XInitThreads() Traceback (most recent call last): File "/home/mc/gr-radio_astro/examples/nsf/NsfIntegrate60.py", line 39, in import ConfigParser ModuleNotFoundError: No module named 'ConfigParser'

Best regards, Morten

— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1158940037, or unsubscribe https://github.com/notifications/unsubscribe-auth/AP25FZ2GP5IBQJ75KJFGM4DVPSFBHANCNFSM5ES3FZEQ . You are receiving this because you are subscribed to this thread.Message ID: @.***>

[GlenLangston]

Hi Morten,

Which Gnuradio version are you using? The code assumes gnuradio 3.10. I’m not seeing the error you identify, but I’ve not tried this under ubuntu lately.

I’ll try to give that a test this weekend.

If I remember correctly you’re using Ubuntu on an Intel PC.

Best regards

Glen

On Jun 17, 2022, at 10:41 AM, skywise-8 @.***> wrote:

Thank you, both Glen and Kevin

I tried integrating over several 60sec periods and then averaged them, this definitely decreased the noise! Though I'm still unsure about the best Gain setting.

Though I managed to attach images to a comment I made last year, I've forgotten how to do so - so for now I can't show you a graph :-(

I wanted to try NsfIntegrate60, so I could test my LNA like it is done in LightworkMemo028. Unfortunately I was unable to run the program:

Warning: failed to XInitThreads() Traceback (most recent call last): File "/home/mc/gr-radio_astro/examples/nsf/NsfIntegrate60.py", line 39, in import ConfigParser ModuleNotFoundError: No module named 'ConfigParser'

Best regards, Morten

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[dave290]

I realize I’m jumping in here, but this may be helpful. I get the same error messages as Morten using Glen’s OS image that contains nsfintegrate codes. I saw these with nsf25 and 30.

On Fri, Jun 17, 2022 at 2:52 PM Glen Langston @.***> wrote:

Hi Morten,

Which Gnuradio version are you using? The code assumes gnuradio 3.10. I’m not seeing the error you identify, but I’ve not tried this under ubuntu lately.

I’ll try to give that a test this weekend.

If I remember correctly you’re using Ubuntu on an Intel PC.

Best regards

Glen

On Jun 17, 2022, at 10:41 AM, skywise-8 @.***> wrote:

Thank you, both Glen and Kevin

I tried integrating over several 60sec periods and then averaged them, this definitely decreased the noise! Though I'm still unsure about the best Gain setting.

Though I managed to attach images to a comment I made last year, I've forgotten how to do so - so for now I can't show you a graph :-(

I wanted to try NsfIntegrate60, so I could test my LNA like it is done in LightworkMemo028. Unfortunately I was unable to run the program:

Warning: failed to XInitThreads() Traceback (most recent call last): File "/home/mc/gr-radio_astro/examples/nsf/NsfIntegrate60.py", line 39, in import ConfigParser ModuleNotFoundError: No module named 'ConfigParser'

Best regards, Morten

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1159184941, or unsubscribe https://github.com/notifications/unsubscribe-auth/AP25FZ6LHD4T4JRTJBXAJI3VPTJOBANCNFSM5ES3FZEQ . You are receiving this because you commented.Message ID: @.***>

[dave290]

…I last grabbed the image in March and run it on a R-pi 4.

On Fri, Jun 17, 2022 at 3:44 PM David Schultz @.***> wrote:

I realize I’m jumping in here, but this may be helpful. I get the same error messages as Morten using Glen’s OS image that contains nsfintegrate codes. I saw these with nsf25 and 30.

On Fri, Jun 17, 2022 at 2:52 PM Glen Langston @.***> wrote:

Hi Morten,

Which Gnuradio version are you using? The code assumes gnuradio 3.10. I’m not seeing the error you identify, but I’ve not tried this under ubuntu lately.

I’ll try to give that a test this weekend.

If I remember correctly you’re using Ubuntu on an Intel PC.

Best regards

Glen

On Jun 17, 2022, at 10:41 AM, skywise-8 @.***> wrote:

Thank you, both Glen and Kevin

I tried integrating over several 60sec periods and then averaged them, this definitely decreased the noise! Though I'm still unsure about the best Gain setting.

Though I managed to attach images to a comment I made last year, I've forgotten how to do so - so for now I can't show you a graph :-(

I wanted to try NsfIntegrate60, so I could test my LNA like it is done in LightworkMemo028. Unfortunately I was unable to run the program:

Warning: failed to XInitThreads() Traceback (most recent call last): File "/home/mc/gr-radio_astro/examples/nsf/NsfIntegrate60.py", line 39, in import ConfigParser ModuleNotFoundError: No module named 'ConfigParser'

Best regards, Morten

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1159184941, or unsubscribe https://github.com/notifications/unsubscribe-auth/AP25FZ6LHD4T4JRTJBXAJI3VPTJOBANCNFSM5ES3FZEQ . You are receiving this because you commented.Message ID: @.***>

[whrzg]

I contacted Digi-Key to request help identifying the Panel mount 4 hole male bulkhead SMA connector that attaches to the antenna can. They gave me a part number and I ordered that part but it is missing the solder point that goes on the inside of the antenna can. Does anyone have a part number for the Panel mount 4 hole male bulkhead SMA connector? Thank you.

[skywise-8]

Hello again :-)

In the hope of being able to run NsfIntegrate60.grc I upgraded Gnuradio to 3.10. Still, it wouldn't run.

What's worse, spectrometer_w_cal.grc was unable to run in Gnuradio 3.10! Long story short, I had to reinstall Gnuradio exactly like explained on the Dspira-lessons site to make it work again.
In the process I've learnt a bit more about Linux, though I'm still very much a novice. It's tempting to just never try to update Gnuradio again ;-) At least I can now get back to scanning the Milky Way, hopefully soon with a better amplifier: I have now ordered the GPIO Labs LNA :-)

Best regards, Morten

[glangsto]

Hi

I’ve been running the NsfIntegrate60.py on a Raspberry PI 400 with an AIRSPY mini. I’ve not seen the error you’re describing.

Are you running on a Raspberry PI?

I’ll setup a computer for you to VNC into to.

please email me directly at glen.i.langston -at- gmail.com

And I’ll send you the IP address.

Glen

Glen I Langston, Ph. D. Galactic Astronomy Program Director National Science Foundation 304-456-3032

On Jun 30, 2022, at 2:22 PM, skywise-8 @.***> wrote:

This email originated from outside of the National Science Foundation. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Hello again :-)

In the hope of being able to run NsfIntegrate60.grc I upgraded Gnuradio to 3.10. Still, it wouldn't run.

What's worse, spectrometer_w_cal.grc was unable to run in Gnuradio 3.10! Long story short, I had to reinstall Gnuradio exactly like explained on the Dspira-lessons site to make it work again. In the process I've learnt a bit more about Linux, though I'm still very much a novice. It's tempting to just never try to update Gnuradio again ;-) At least I can now get back to scanning the Milky Way, hopefully soon with a better amplifier: I have now ordered the GPIO Labs LNA :-)

Best regards, Morten

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you commented.

[GiaCet]

Hallo Prof. Bandura I have two questions for you:

1) The DSPIRA LNA schema (pdf file) report that the resistive attenuator between sav-541+ and the band-pass filter BFCN-1445+ use R6: 5.8ohm and R9-R10: 870Ohm 1dB attenuation, while the order part list report R6: 17.4Ohm and R9-R10: 287Ohm for 3dB attenuation. What is the best choise?

2) C15 on schema (pdf file) report 27pF, order part list report 6.8pF. What is the bset choise?

Best Regards Gianni

[kbandura]

27 pf will work perfectly. I recommend the 3db attenuation resistor set. (17.4 and 287)

[GiaCet]

Thank's prof. Bandura for your answer. One more question, I want to use DSPIRA LNA with a 3m parabolic dish. The cable connecting LNA to the receiver is about 30m (about 98ft) long. Is it a problem if I use 12 Volts to power supply? In general LM2973 should theoretically support this power supply. In my tests, the LM2937 output is 5V and I found a sharp rise in temperature throughout the PCB, especially in the area between SAV-541 + to the first GALI-39 +. This happens if I feed LNA with voltages higher than about 5.5V. At 12V the pcb is untouchable.

Best Regards Gianni

[ZL4DK]

Hi Gianna,

yes the LNA runs fairly hot. The regulator is probably the biggest heat source, as it carries all the current of the LNA and drops about 7 volts (12-5) across it. Heat (Watts) = current x Voltage. You can reduce this heat if you run the LNA from a lower voltage, I would recommend 7 or 8 volts which drops the heat produced by the regulator significantly. But Yes the LM2973 is a low dropout regulator and could go as low as 5.5 volts on the input before it starts to struggle to maintain a regulated 5 Volt output.
The rest of the heat production is spread throughout the LNA with the 1st stage producing slightly more than the other two. This heat won't change with changing the supply voltage between 12 and 5.5 volts. But dropping the heat produced by the regulator will help reduce the temperature of the whole board. Your long cable shouldn't be a great problem, as long as the voltage feeding the LNA is still above 5.5 Volts

[whrzg]

I completed my DSPIRA LNA and tested it using a Raspberry Pi 4 and an Airspy R2 according to the instructions here: http://wvurail.org/lightwork/memos/LightWorkMemo028-r7-NoiseTemp.pdf. I connected everything together according to the instructions here: https://www.youtube.com/watch?v=Oo28QCEZe_g. There was no change in the display of intensity vs frequency when I used the 50 ohm load on the LNA and when I didn't. I investigated using the instructions contained on the last page of this document: https://github.com/WVURAIL/lightwork/blob/master/memos/LightWork0030-r1-ATaleOfThreeLNAs.pdf. I don't have a power supply so I connected everything as I did during the test of the LNA. Since I didn't have a power supply I connected the negative probe of the multimeter to the outside of the metal case for the Raspberry Pi 4. When I checked, there was no voltage on the input or the output of the voltage regulator 1C1. I tested the voltage on 1C1 with the 50 ohm load both connected to and disconnected from the input to the LNA. I know nothing about electronics but I'm assuming the power for the LNA comes from the Airspy R2 and the Airspy R2 gets it's power from the Raspberry Pi 4. I'm wondering if one of those two devices has a problem that prevents the LNA from getting the power it needs but I don't know how to check them. I've tried checking the various parts of the Airspy SMA plugs for voltage but can't detect any. I would be very grateful for any recommendations anyone has about how to make further checks to identify the source of the problem with the LNA. Thank you. Bill

[ZL4DK]

Hi Bill. Yes you are correct the RPi powers the Airspy via the USB cable and the Airspy then powers the LNA via DC feed up the coax cable. If the software is talking to the airspy (as it appears to be from your description) then the airspy must be powered up fine. The DC feed out of the SMA of the Airspy is switched on or off via software and I wonder if This is not enabled in the software you are using. I don't have an Airspy but I read that the Airspy R2 only has a 4.5V output on this socket which is not ideal but should do something. The LNA ideally requires around 7-12Volts. If you investigate the GNU radio blocks in your software you should find the block the reads and configures your Airspy and you may be able to find the section that turns on the Bias for the LNA. If it is already set to on then you may have a short or open circuit somewhere. I was pulling out what little hair I had left recently until I found a SMA cable I hadn't crimped properly fall apart in my hands. It no doubt was open circuit for a long time. If you did have a short circuit, it is unlikely you would have permanently damaged this output, they are usually safely current limited.

Regards David

[whrzg]

Hi David

Thank you very much for the information. It helps me a lot. I didn’t know the software had to be active for the Airspy to power the LNA. I’ll follow your recommendation and see if the LNA works. If not, I’ll investigate shorts and open circuits in the pcb.

Thanks again very much.

Bill

On Oct 11, 2022, at 6:24 AM, ZL4DK @.***> wrote:

Hi Bill. Yes you are correct the RPi powers the Airspy via the USB cable and the Airspy then powers the LNA via DC feed up the coax cable. If the software is talking to the airspy (as it appears to be from your description) then the airspy must be powered up fine. The DC feed out of the SMA of the Airspy is switched on or off via software and I wonder if This is not enabled in the software you are using. I don't have an Airspy but I read that the Airspy R2 only has a 4.5V output on this socket which is not ideal but should do something. The LNA ideally requires around 7-12Volts. If you investigate the GNU radio blocks in your software you should find the block the reads and configures your Airspy and you may be able to find the section that turns on the Bias for the LNA. If it is already set to on then you may have a short or open circuit somewhere. I was pulling out what little hair I had left recently until I found a SMA cable I hadn't crimped properly fall apart in my hands. It no doubt was open circuit for a long time. If you did have a short circuit, it is unlikely you would have permanently damaged this output, they are usually safely current limited.

Regards David

— Reply to this email directly, view it on GitHub https://github.com/WVURAIL/dspira-lessons/issues/8#issuecomment-1274468877, or unsubscribe https://github.com/notifications/unsubscribe-auth/ARWUO3TIVVFIPHG63QLLJJ3WCU56HANCNFSM5ES3FZEQ. You are receiving this because you commented.