First Light on LRO-H5 140cm Communications Dish 16/6/2026 @ 04:45 am

[Andrew Thornett]

Hi All,

I am currently outside with the dawn chorus (bird song at dawn), as the Milky Way is (sort of) overhead at this time of the day. I don’t normally get up at this time to do astronomy – usually dreaming away in bed – but sometimes sacrifices are needed for our hobby!

 

I have just spent last 30-45 minutes testing the new LRO-H5 radio telescope – 140cm communications dish with Discovery hydrogen line feed.

 

Firstly, it was not working at all, just like it was with the solar cooker dish – I then discovered that the computer it was on said that the SDR was connected even when it wasn’t! That does not make sense, so I changed to another mini-PC and Voila! Hydrogen peak immediately appeared. [As I was using that computer for the solar cooker dish this suggests the computer might have been the problem there – either way, my wife prefers this dish and feed when she looks out of the window to the solar cooker one and such things are VERY important.]

 

The wonderful thing about the Discovery feed is that it is so easy to adjust the focal position just by pulling the stalk up and down – no fiddly adjustments – I could do that whilst looking at computer screen to find best point. The screenshot below is from best focus point.

 

Andy

 

 

 

[Alex P]

Hello Andrew,

In what Units are the Y-Axis Values ?

How do these compare to your other antennas ?

If the signal changes 6 dB ( doubling in linear amplitude )

    What is the corresponding change in the Y values shown ?

Alex Pettit

 

[Andrew Thornett]

I know - as on ezRA they are just relative values and I will need to do the testing you have mentioned in past. At moment, all I wanted to get some hydrogen line data so that I confirmed that the telescope was working.

Next step is to change cover to SDR Sharp and do proper cold and hold calibration and see exactly what I am getting.

Clear from conversations with my wife that the periphery extension with mosquito netting was NOT liked wheb I out it on LRO-H2. Maybe you have a very understanding spouse - personally I have one who tolerates well my hobby but anything I can do to keep her happy is worthwhile!

I also think she nuch prefers the small Discovery feed to a cantenna or dual feed so I am probably limited with what I have got.

I have discovered that the Discovery feed is certainly a great way to find the focus point as so easy to change the length of the stalk and watch the trace on the laptop in real time.

Andy

Sent from Outlook for Android

---

From: 'Alex P' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: Thursday, 18 June 2026 11:22:37
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: [SARA] Re: First Light on LRO-H5 140cm Communications Dish 16/6/2026 @ 04:45 am

 

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[b alex pettit jr]

It  is not difficult to optionally have the Y axes scaled in dB .

An extra ClickBox would allow data to be scaled in units which can be useful for Quantification of performance

suggestion : Mount the Disco Feed on your WiFi Dish and compare the numbers to the 1.5m 

Here are the performance values & measurement for proper positioning I obtained.

Alex

On Thursday, June 18, 2026 at 06:28:23 AM EDT, 'Andrew Thornett' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:

I know - as on ezRA they are just relative values and I will need to do the testing you have mentioned in past. At moment, all I wanted to get some hydrogen line data so that I confirmed that the telescope was working.

Next step is to change cover to SDR Sharp and do proper cold and hold calibration and see exactly what I am getting.

Andy

[b alex pettit jr]

I have an Idea :

If you can install the DiscoFeed on the 1m WiFi,

we 'should' be able to calibrate the Y axis units on the EZra plots.

Do you have any SMA attenuators ?

( such as )

Get back with you this afternoon ( my afternoon )

Alex

[b alex pettit jr]

Andrew,

If you were taking data @ 3AM, you would have been acquiring data ~ RA2030.

At a Declination of  40 degrees, your data should have had two distinctive Doppler shift regions, 

not just one  ..??

[b alex pettit jr]

    Here's the plan :

If you can install the DiscoFeed on a 1m WiFi Dish,
we 'should' be able to calibrate the Y axis units on the ezRA plots.

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

Using the same celestial coords  Dec+40  @ RA2030

Duplicate this test series and record the values from the ezRA  Relative RMS Power scale.

Setting the averaging for 30 seconds should be sufficient .. position at a spacing, wait

30-60 secs for the plot to stabilize, read the Cold_Sky and pk H Line values and write them down 

Record these 2 measurements for spacings of 24 to 40 cm in 2 cm steps.  &  REPEAT

Send the results & I'll try to determine a scaling factor and conversion to dB.

Alex

[Stephen Arbogast]

Andrew, congratulations on  success, looks very cool.  My  Discovery Dish is not as large as yours... just  the minimum needed.   I  am very happy with it...   not  calibrated  using ezRA.   I'm  expecting my  Discovery  Drive sometime this  late summer so  I can try   SDRAngel  with  some hot/cold  calibration curves.  

[andrew....@googlemail.com]

I don’t know yet what maximum is but it is now 02:20 BST (01:20 UTC) on 19/6/2026 & plot is looking very impressive as per below =

 

 

From: 'Stephen Arbogast' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: 19 June 2026 01:51
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: [SARA] Re: First Light on LRO-H5 140cm Communications Dish 16/6/2026 @ 04:45 am

 

Andrew, congratulations on  success, looks very cool.  My  Discovery Dish is not as large as yours... just  the minimum needed.   I  am very happy with it...   not  calibrated  using ezRA.   I'm  expecting my  Discovery  Drive sometime this  late summer so  I can try   SDRAngel  with  some hot/cold  calibration curves.  

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[b alex pettit jr]

Andrew,

Use this link to find what the spectra should look like .. 

Argelander Institut für Astronomie - HI Profile Search

Argelander Institut für Astronomie - HI Profile Search

Realize the X scale is in Red Shift Velocity ( & 'backwards' from Freq ) 

That narrow sharp peak in the spectra below is .. 'unusual'  .....

Alex 

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

[b alex pettit jr]

Andrew,

Do you have a plot like this from ~ 6 hrs ago, @ RA 12:00 ?

Alex

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

[b alex pettit jr]

Dec +40 Deg

RA  12:30 Hrs

( ~ 19:00 - 20:00 Local Time )

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

If  you do not get a nearly flat line around this sky region, the system has a problem

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

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

Plot from one of my antennas

-ap

[b alex pettit jr]

DEC +40

RA 11:30 - 12:30

System : Pettit  1m Circular Patch Feed Disk Yagi Enhanced Rel

HLine Signal 1.2K above Cold_Sky !

-ap

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

On Friday, June 19, 2026 at 05:10:00 AM EDT, 'b alex pettit jr' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:

Dec +40 Deg

RA  12:30 Hrs

( ~ 19:00 - 20:00 Local Time )

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

If  you do not get a nearly flat line around this sky region, the system has a problem

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

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

-ap