Power Supply requirement for a Local LNA

[Vinay Bharambe]

Hi Everyone,

I have a couple questions that I'd really appreciate some help with.

I am a newbie with Radio instrumentation and trying Hydrogen line detection with a horn antenna. I recently bought a LNA for the setup. It has few things written in foreign language and says it requires 12V of Shielded DC power supply. Below is the image.

 I would like to know where can I get one such power supply. Also, what should be precautions using it with LNA.

Thanks,

Vinay

[jan Lustrup-LA3EQ]

This Chinese LNA is very noisy and has too much gain..

Go for a “Sawbird+ H1” LNA.

It has band pass built in filter for hydrogen line and you can feed it via the coax cable.

Jan Lustrup

 

https://www.amazon.com/Nooelec-SAWbird-H1-Applications-Frequency/dp/B07XPV9RX2

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[Alex P]

Alex P

May 30, 2023, 11:07:31 AM (18 hours ago) 

to Society of Amateur Radio Astronomers

I agree with the SawBird H1 ..

If you use this nooelec SDR it has an internal 'Bias T' that will power the SawBird H1 over the interconnecting SMA coaxial cable .

( also available on Amazon )

NESDR SMArTee XTR SDR - Premium RTL-SDR w/Extended Tuning Range, Aluminum Enclosure, Bias Tee, 0.5PPM TCXO, SMA Input.

$ 43.95

Alex

[Vinay Bharambe]

Hello all,

 Thank you very much for the responses.

 Yes. I am using NOOELEC SMArt SDR, the exact one. I understand that noise is a problem with these Chinese LNAs and SAWBird is better option. Sadly, I've invested in buying 5-6 of them. I have both 32dB and 64dB versions. Can I get detection with these , may be slight noisy ? or it is practically impossible. Can I use them as gain stage rather than frond end LNA ?

 I do have some of these evaluation boards. Can I use one of them as LNA ? and how good are these ?

Thanks,

Vinay

[Vinay Bharambe]

P.S. : I do have minicircuits BPF - Model VBFZ 1400 (1350-1450MHz), also a specialized GPIO Labs H1 line filter.

[b alex pettit jr]

Hello Vinay,

Try them ... 

What is the antenna system on which this will be used ?

Regards,

Alex KK4VB

==========================================

[b alex pettit jr]

And to answer your Original Question :

For a 12V power source : use either a rechargeable battery or a Linear power supply

Alex

[Vinay Bharambe]

Hii,

 I'll be using a Pyramidal Horn antenna with a good 93x75cm aperture. Yeah I am going big :) Rest is rectangular waveguide for the 1420 MHz frequency and 2mm think copper wire monopole probe. The designed gain of the system is 20dB.

 Will the Minicircuits LNAs / Evaluation Board be better than Chinese boards ? I have seen some comparisons on Astropeiler.de website. https://astropeiler.de/wp-content/uploads/2020/01/Hydrogen_2.pdf Though the manufacturer is different.

 Yeah I've solved the Power supply problem. I've got a SMPS for it. I think I should create a topic with LNAs as title in the discussion.

Thanks,

Vinay

[Mathew George]

Please make a measurement and show? 

I don't think you will be able to H21 without much trouble.

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[Mathew George]

Sorry.

I think you will be successful in making H21 measurement, without much difficulties.

[b alex pettit jr]

For the LNA, try ones with the Lowest  Noise Figure .. 

After that, you can pass the signal through a Band-Pass Filter and

 then a second Wide Band Amplifier ( noise figure not as critical )

Alex

[b alex pettit jr]

Switching Mode Power Supplies   may radiate noise .... 

You should compare it  to a simple 12V battery ( 8 ea AA cells  etc ) to ensure the SMPS is not adding noise.

[Vinay Bharambe]

Thank you very much for the LNA suggestion. I'll definitely try it.

Yeah. Make sense. I'll try comparing with 12 V battery. How about 12V Laptop chargers ?

[b alex pettit jr]

No  .. Laptop Chargers are also  SMPS !

The Mini Circuit components you showed in the photo are only evaluation Test Boards = they do not have any electronics installed ???

[Vinay Bharambe]

I did not understand your question. Electronics installed as in internal components or external components?

It does have internal components as shown in the datasheet figure and according to its datasheet 12V power supply is enough for it.

[b alex pettit jr]

Hi Vinay,

Here is the pdf for WTB-517+

It is an Evaluation Test Board (TB)  for a Device Under Test  DUT, 

It is intended to allow someone to mount and test a component but Nothing is installed ....

Open one up .. is there an amplifier installed ??

There should be frequency response / gain / noise factor data if it had an operational low noise amplifier

the WTB 409  and WTB 678 seem  the same ... evaluation boards, but Not functional LNAs 

Here is a Data Sheet for an actual LNA   ( it requires 5  volts power )

https://www.minicircuits.com/pdfs/ZX60-P33ULN+.pdf

Alex

[Vinay Bharambe]

Hii Alex,

 I opened it up. I think I exactly have it, the components. Please see the image below.


Thanks,
Vinay

[b alex pettit jr]

Okay.

So the TB-517    contains the SYBP-1420 Band Pass Filter centered on 1420 MHz .. that's good for H1

https://www.minicircuits.com/pdfs/SYBP-1420+.pdf

What are the part  numbers on the  SMT amplifier chips the other units ?

Thanks,

Alex

===========================================================================

[Vinay Bharambe]

Hii,

 Please see the image below. I have annotated the part numbers on the image.

Vinay

[b alex pettit jr]

=================================================================

TB 678

The P103 =  a low noise LNA

https://www.minicircuits.com/pdfs/PGA-103+.pdf

>>>>   Max Voltage  5V not 12V <<<<

The " TC07" is a Bias T  =  the P103 could be powered via the "RF out" coax.

========================================================================================

Band Pass Filter

TB-517  

  SYBP-1420 Band Pass Filter centered on 1420 MHz .. that's good for H1

https://www.minicircuits.com/pdfs/SYBP-1420+.pdf

=======================================================================================

 TB 409

" 52 " = the Gali 52

https://www.minicircuits.com/WebStore/dashboard.html?model=GALI-52%2B

And, on the .pdf you posted,  that does show 12V power is correct.

=============================================================================================

So, you have a system 

Antenna > PGA103 ( 5V power )  > 1420MHz Band Pass Filter > Gali52 ( 12V power ) > SDR

Alex

[Vinay Bharambe]

Hi Alex,

 Yeah. I think I can work with this one. 

 Thanks a lot. Will definitely post about the results here.

 About the "TC07" , so powering via RF out is an option. But, normally one can power by connecting 5V across "Vs" and "GND" , right ?

Vinay

[b alex pettit jr]

Hi Vinay,

Yes, just use the external  Vs/Gnd terminals  5V .

From the specs, the system may have a lower system noise than the nooelec SAWBird H1 ..

And as a reference, I'd power all by batteries .. and then try power supplies .. especially the 5V power.

I'd like to see your results ..  mount the first LNA right at the feed point.

Alex

===========================================================

[Vinay Bharambe]

Hii,

 That's great. 

 Yeah. I'll definitely power them all by battery first. Also, 5V I think can be done with a normal Li-ion battery. 

 Yeah. Exactly first LNA right at the feed point and everything else later.

 

Vinay

[Cameron Moore]

Hi Vinay,

One thing I have found is that any type of switch mode power supply is very noisy and generally and isn't suitable for radio astronomy equipment. I have had the most success with linear power supplies i.e. those that use a transformer, bridge rectifier, and a 7805 (for 5 volts) or a 7812 (for 12 volts).

https://www.sparkfun.com/datasheets/Components/LM7805.pdf

You can search for 7805 on eBay for examples.

By all means, try using a 5 Volt battery pack first.

Cameron

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[Vinay Bharambe]

Hi all,

 Just to continue with that. Detection can be done on a normal SDR software or one can use rtl_power, etc. I was curious about how one can make contour maps of the observations??

Thanks,

Vinay

[tedcl...@gmail.com]

Not sure I understand your "contour map" question.

Short-time analysis or long-time ?

Does this help ?

     "ezRA - Simple Overview" 13-minute video,

      https://youtu.be/kHgwEbWKhzs
from

      ezRA - Easy Radio Astronomy
      1420 MHz Galactic hydrogen data collection and analysis
      https://github.com/tedcline/ezRA

---
Ted Cline   N0RQV

On Friday, June 16, 2023 at 12:43:58 AM UTC-6 Vinay Bharambe wrote:

Hi all,

 Just to continue with that. Detection can be done on a normal SDR software or one can use rtl_power, etc. I was curious about how one can make contour maps of the observations??

...

 

[Vinay Bharambe]

Hii I was talking about "Galaxy maps" as seen in this image of your video.

So, while recording I can record Frequency against voltage (I'm using rtl_power). So, how to make such maps from it ? Yeah one can get the Galactic Lat and Long from Altitude and Azimuth of Antenna direction.

You can read about my setup from above thread.

Thanks,

Vinay

[Vinay Bharambe]

Hi Alex,

 I tried connecting P103 Evaluation board. But for some strange reason I'm seeing no change in output. I tried connecting it with a USB 5V connection, a 9V battery and also a voltage divider connection from 12 V power supply.

Please let me know, If you have an idea about it. I am thinking of giving it a try today.

Vinay

[Vinay Bharambe]

The Gali 52 is working perfectly and showing amplification.

[Vinay Bharambe]

I connected connections to Vs and Ground by soldering on the ends.

[b alex pettit jr]

Hello Vinay,

I am sorry the PGA-103+ is not operating .. the normal Power should be  5V        6V MAXIMUM

TCBT-14+ Bias Tee

Alex

====================================================

[Vinay Bharambe]

Hiii,

 Do i need to connect an external C1 ??? Of 0.1 uF ?? I had just directly connected Vs and Ground.

Vinay

[b alex pettit jr]

No, that cap is on the test board

It should have worked with 5V as you connected ..

Alex

On Monday, June 19, 2023 at 08:44:29 AM EDT, Vinay Bharambe <bharambe....@gmail.com> wrote:

Hiii,

 Do i need to connect an external C1 ??? Of 0.1 uF ?? I had just directly connected Vs and Ground.

Vinay

.

[Vinay Bharambe]

Ok Thanks.

I'll have a look at it again.

Which sources one can use for calibration purpose?? I know S8 but other than that ?

Vinay

[b alex pettit jr]

For Starters, see what the dB difference is between pointing the antenna at  290K Earth and  'overhead' ~ RA 12 Hrs 10k Cold Sky.

Alex

[tedcl...@gmail.com]

Hi Vinay,

You asked about creating Galactic sky maps using

      ezRA - Easy Radio Astronomy
      1420 MHz Galactic hydrogen data collection and analysis
      https://github.com/tedcline/ezRA

Most ezRA programs expect data in the ezRA .txt format.

There are many ways to collect 1420 MHz antenna data into computer files.
Here are some popular data collector programs:

    SDR# & IFAvg plugin

    ezCol, ezRA astro on gitHub

    MIT Haystack SRT

    CCERA BAA GNU Radio,
        "GNU II" on YT @britishAstronomical

    CFRAD2.exe on parac.eu

    H-Line on gitHub

    astro-virgo on pypi.org

    DSPIRA on WVURail.org

I think data conversion to the ezRA .txt format is possible for each of these.
Some data converter programs are already in ezRA.

ezCol does not need data file conversion.

Also available for data collection is
    rtl_power
    rtl_power_fftw (binary output)
    rtl_power_fftw (ASCII output)
I have just created ezRA .txt format data conversion programs for the first 2.
If wanted, please contact me.

---
Ted Cline

tedCl...@gmail.com

[Vinay Bharambe]

Hi Ted,

 I tried ezCol.py. It is an excellent collector program. Excellent interface and options. I ran the Collector for a few minutes yesterday but I'm unclear whether I received a detection or not.  I do have .txt files. I saw the central hump while observing. The power too was about one-two units higher than the other two humps but the hump was a bit less pointy. For example, this picture has somewhat pointy central peak. In my observations, the peak was shaped more like other two peaks (but yes one-two units of power higher).

 Here is the link for the observation dataset. Mostly try for later files for better results. If you can find something out of it or tell me commands to run for analysis, it will be great.

Thank You,

Vinay

[b alex pettit jr]

Vinay,

Can you use AirSpy SDR# Studio with IF_Ave plug in and capture and save one 3 min to 5 min long file and send it to me ?

( for a reference Background, point the antenna at the ground , or  away from a strong Hi region and acquire a sample for the same duration of time )

Alex

[b alex pettit jr]

Hello Vinay,

I was looking through your data files .. it appears you were acquiring samples at 10 and 30 second intervals .. too fast.

Try 2 - 4 Minutes for better S/N.   300,000 to 600,000 averages or so

2023-06-19T17:21:31

2023-06-19T17:22:00

2023-06-19T17:22:30

2023-06-19T17:22:59

2023-06-19T17:23:28

2023-06-19T17:28:36

2023-06-19T17:28:46

2023-06-19T17:28:56

2023-06-19T17:29:05

2023-06-19T17:29:15

===========================================================

I plotted one file .. I do not understand the Units associated with Vertical Scale

" Relative RMS Power  "  referenced to what ?.               Ted ????

Alex

[Vinay Bharambe]

Hi Alex,

 I did tried Airspy earlier, but I don't know why my Nooelec SMART SDR is not connecting to it. I have CubicSDR, RTL_pan, rtl_power and ezRA now.

 Now, let's come to my mistakes from Day 1 observations. 1st is I used very short durations. I'll use longer exposure and for longer total time. My second mistake I was expecting instantaneous detection or peak on 256 K sample rate, the way we receive on tuning to FM bands. 3rd I should point it in proper direction as in post processing I'm seeing power difference (as time passes the object is out of my antennas front lobe). 

 Alex, you can find plots similar to yours for my entire observation set below. You can also see .gif file in each folder. So it's easy to just view it. The earlier folders /sets are very random and many times without antenna. So, please focus on datasets with default_14.txt onwards. If you're familiar with Ted's ezRA ezCon.py plots, can you comment on 17g dataset ? 

 Also, If you can comment about my electronics ?? is it working or it's the problem here. 

Thanks everyone,

Vinay

[b alex pettit jr]

Hello Vinay,

I don't understand the vertical units scaling on the EZ software ,

Thus, I can not discern if your system is operating or not.

Point your antenna at the Ground and take a sample ..

That will show a  plot with no H1 data.

17G

 I have calibrated and verified my AirSpy mini SDR and saved IF_Ave data sets using a fixed RF noise source and SMA attenuators

and generally plot my data in dB relative to Cold Sky ..

Date referenced to some fixed value is needed in order to test and compare configurations.

Alex

=============================================================================

[b alex pettit jr]

17G DataSet

Vinay,

Provide either Celestial ( Dec RA) or Galactic ( Long Lat ) Coordinates of that data

and if I have also have data from that region, I will compare with my measurements.

Alex

[Vinay Bharambe]

Hiii Alex,

 Yeah. I will also like to know about the RMS units and how they are obtained. While, I can assure about the shape of the observation as I've checked it with RTL_pan (a rtl_power based gui for windows). Ted, please if you can help us here.

 I did pointed the antenna towards zenith (the galactic plane was at 30 degree altitude) and there was no signature. 

 I'm sorry, I was not very particular with directions. I do not have information about it.

Thanks,

Vinay 

[b alex pettit jr]

Vinay,

Use Stellarium to find the coordinates ...

https://stellarium.org/

And this  chart to identify regions of bright H1 emission.

Thanks to Marcus,  CCERA   et.al.

Alex

[Vinay Bharambe]

Hii,

 Yeah yeah. I'm using stellarium. But actually to point Antenna in that direction without a proper mount is difficult and the Pyramidal horn is huge in size 130cm in length and about 1 meter square in area. 

 Thanks for the map. It will be very useful.

Vinay

[b alex pettit jr]

Vinay,

With Stellarium and date/time/direction of the antenna, estimate the Dec/RA of your 17G data.

As the beam-width is large, great precision is not required.

Alex

[Vinay Bharambe]

Hiii,

 It is approximately RA/DEC: 20h45m52s / 25deg21min12sec . Just below the galactic plane. My horn angle is about 15-20degree.

Vinay

[b alex pettit jr]

Hi Vinay,

I don't have any data from this location  and that is at an area of rapidly changing intensity.

Try again for something closer to Dec +40  RA 20:30  ??

BUT, to give you some comparison, Here is a sample I acquired at ~  Dec +30  RA 21:30

( somewhat close in intensity to your data )

02 May 2023

Alex

[Vinay Bharambe]

Hii Alex,

 Thank you. I'll definitely try to observe in this region.

 I would like to have your suggestion about software. Will rtl_power be any good ??? It has directly access to dB and I know how to set parameters in it.

Vinay

[tedcl...@gmail.com]

On Wednesday, June 21, 2023 at 4:10:15 AM UTC-6 b alex pettit jr wrote:

Hello Vinay,

...

===========================================================

I plotted one file .. I do not understand the Units associated with Vertical Scale

" Relative RMS Power  "  referenced to what ?.               Ted ????

 

Hi Alex,

ezCol collects samples of spectra power data.

ezCol (currently) has no absolute power calibration.

ezCon analysis compares sample data to other recent sample data, a relative comparison.

ezCon analysis presents plots of relative power.  No absolute value calibration.

This is helpful because system gain varies significantly, due to ambient temperature changes.

SDR# with IFAvg plugin over short-time periods, is helpful to compare antenna changes (ignoring any system gain temperature variation).

ezCon analysis is helpful for long-duration drift-scan data study, comparing sample data to its neighbors.

ezCon often compares Galactic hydrogen data to non-hydrogen data (such as from 1423 MHz, or a resistor).

Thanks !

---
Ted Cline
tedCl...@gmail.com

[tedcl...@gmail.com]

On Wednesday, June 21, 2023 at 11:16:31 AM UTC-6 Vinay Bharambe wrote:
Hii Alex,
...

Will rtl_power be any good ??? It has directly access to dB and I know how to set parameters in it.

Beware.

rtl_power provides _relative_ measurements, in dB.   Not absolute dB.

Essentially same as ezRA's ezCol.

http://kmkeen.com/rtl-power/
says

Unfortunately the dB values are mostly meaningless in an absolute sense. But they do have relative value, when compared between multiple runs. Make a change to the hardware, run the scan again and overlap the two sets of data. Did the change actually cause an improvement? Little experiments like this will help you separate the snake oil from the science.

I assume the same is true for  rtl_power_fftw.

I expect the same is true for  SDR# with IFAvg plugin.

Absolute measurements are difficult to achieve (hence “hot-cold” measurements, and “y-factor”).

---
Ted Cline
tedCl...@gmail.com

[b alex pettit jr]

Hello Vinay,

If you wish to use other software, you need to verify it is Calibrated  by introducing a few rf attenuators  .

A 3 dB atten should shift the data down 3 dB,  10dB atten = -10 dB etc.

And, its nice to be able to shift the baseline to make cold sky == 0 dB.  (   Excel or other )

Have you reviewed all the info on this website ??

Cheap and Easy Hydrogen Line Radio Astronomy with an RTL-SDR, WiFi Parabolic Grid Dish, LNA and SDRSharp

Cheap and Easy Hydrogen Line Radio Astronomy with an RTL-SDR, WiFi Parab... We've recently been testing methods to help budding amateur radio astronomers get into the hobby cheaply and eas...

The ideal solution would be to use  SDR# & IF_Ave .. I know it works .

Alex

[b alex pettit jr]

Hello Ted,

I implement a similar drift correction process for the contour plots, but I set an off freq from any H1 influence

in each sample.to the same value and That to " 0 dB "  It is not a gain shift but an additive noise that needs

to be subtracted from the samples .. I set all to the lowest ..  It keeps the dB scaling of the data valid.

It seems to be  more variations in atmospheric transparency or reflectivity.  vs hardware temp / gain variations.

I've tested my LNA over 73F <> 120F with a variation of ~ 0.1 dB  ( built a small oven )

Alex

ezCon analysis compares sample data to other recent sample data, a relative comparison.

ezCon analysis presents plots of relative power.  No absolute value calibration.

This is helpful because system gain varies significantly, due to ambient temperature changes.

ezCon analysis is helpful for long-duration drift-scan data study, comparing sample data to its neighbors.

[Vinay Bharambe]

Hi Alex,

 I'm onto SDR# with IF_Avg plugin. Looks like a good setup. Specially it is continuously averaging so that the Graph on IF_Avg windows is cumulative of last "xyz" seconds.

 Please help me with few questions.

What should be sample rate ??? I know we are setting dynamic averaging. But still, whats ideal ? AGC ??? both off for Galactic observation ?

Out of these options. Let me know best settings.

FFT ? 256 enough ??

Intermediate average ?? 100 for 256 FFT ?

Level ?? Is it just a scroll bar or changing it changes the observation ?

Gain ???

Dynamic averaging ?? 2-4 mins, right ??

Thanks,

Vinay

[Vinay Bharambe]

Hii,

 I'll be doing observations today. So, what are the post processing methods ? I mean, I save the file as .txt or .csv. SDR# will give me let's say dB. I can plot it as function of frequency. 

 And then I can compare it with your  ~  Dec +30  RA 21:30 plot, right ?

Vinay

[b alex pettit jr]

QUICK Reply

AGC OFF  always

Once you turn AGC OFF, adjust the RF Gain slider to MAX

512 Freqs

Gain & Level influence Only the IF_ Ave Display not the saved data

It might be easier to set the Intermediate Avg to 100 as it is a multiplier for the Dynamic Average slider

Yes,  try for 4 mins .. that = 1 degree in sky drift.  you can try shorter for comparison.

I began using 5 minutes and have kept such..

Alex

On Friday, June 23, 2023 at 04:16:27 AM EDT, Vinay Bharambe <bharambe....@gmail.com> wrote:

Hi Alex,

 I'm onto SDR# with IF_Avg plugin. Looks like a good setup. Specially it is continuously averaging so that the Graph on IF_Avg windows is cumulative of last "xyz" seconds.

 Please help me with few questions.

What should be sample rate ??? I know we are setting dynamic averaging. But still, whats ideal ? AGC ??? both off for Galactic observation ?

Out of these options. Let me know best settings.

FFT ? 256 enough ??

Intermediate average ?? 100 for 256 FFT ?

Level ?? Is it just a scroll bar or changing it changes the observation ?

Gain ???

Dynamic averaging ?? 2-4 mins, right ??

Thanks,

Vinay

.

[Vinay Bharambe]

Yeah Thanks.

Any idea to convert dynamic average to minutes or just count it ?

Vinay

[b alex pettit jr]

 Dec +40 Dg     RA  20:30 Hrs

On Friday, June 23, 2023 at 04:19:34 AM EDT, Vinay Bharambe <bharambe....@gmail.com> wrote:

Hii,

 I'll be doing observations today. So, what are the post processing methods ? I mean, I save the file as .txt or .csv. SDR# will give me let's say dB. I can plot it as function of frequency. 

 And then I can compare it with your  ~  Dec +30  RA 21:30 plot, right ?  NO

Vinay

[b alex pettit jr]

Yes :  Count the # avg/min for your SDR

and then you can determine what's needed