Chicken & Egg on New Installation

Discussions about the Ryde "Set-top Box" Style Digital ATV Receiver. See https://wiki.batc.org.uk/Ryde_Receiver
G0LJF
Posts: 106
Joined: Wed Dec 25, 2019 5:28 pm

Re: Chicken & Egg on New Installation

Post by G0LJF » Fri Apr 29, 2022 1:36 pm

Thanks for that, but with a straight [low loss / rigid] coax feed, or Mini N-Type, those Bullseye LNB just don't fit.

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Yes, I agree that a 3-D printer is getting to be a mandatory tool.

Do you have any recommendations, they seem cheap enough at £200 or so+.

Mike

EA7KIR
Posts: 86
Joined: Tue Feb 09, 2021 3:38 pm

Re: Chicken & Egg on New Installation

Post by EA7KIR » Fri Apr 29, 2022 2:02 pm

I’m thinking of extending the arm by an inch or two, instead of buying a printer.
Michael EA7KIR

G0LJF
Posts: 106
Joined: Wed Dec 25, 2019 5:28 pm

Re: Chicken & Egg on New Installation

Post by G0LJF » Fri Apr 29, 2022 2:23 pm

Well I have no printer so I made an offset (oval) mount from a 22mm straight copper solder connector (knock the middle insert stop pins off first).
Then I mounted that, off centre, in a piece of 40mm plumbing pipe.

Then filled the gap with Polyester resin. And finally milled the surfaces flat.

Worked for me. I tapped a 3 mm hole for a locking screw straight into the lot.

But with an N-type socket (use the min SMA footprint/1mm pin ones only) it is even worse - less clearance, and again worse with Heliax or 1/2 corrugated coax.

Mike

g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Chicken & Egg on New Installation

Post by g0mjw » Fri Apr 29, 2022 6:44 pm

There is no magic to the length of the copper pipe behind the patch feed, it is low loss so make it longer if you need more clearance. Polarisation rotation may be an issue if more than a few metres long or if you try to bend it. Unlikely situation in practice.

Don't neglect wood as a material for making things with if you don't have a 3D printer (Prusa Mini, Flashforge Dreamer NX, Creality are all OK). Wood is easy to get, easy to machine, cheap, sustainable and if treated will last longer than the transponder.

Don't extend the arm. Just raise the height a bit so it fits. It won't make a significant difference to the gain within reason. what is important is the focal plane.

Mike

g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Chicken & Egg on New Installation

Post by g0mjw » Fri Apr 29, 2022 6:45 pm

G0LJF wrote:
Fri Apr 29, 2022 2:23 pm
Well I have no printer so I made an offset (oval) mount from a 22mm straight copper solder connector (knock the middle insert stop pins off first).
Then I mounted that, off centre, in a piece of 40mm plumbing pipe.

Then filled the gap with Polyester resin. And finally milled the surfaces flat.

Worked for me. I tapped a 3 mm hole for a locking screw straight into the lot.

But with an N-type socket (use the min SMA footprint/1mm pin ones only) it is even worse - less clearance, and again worse with Heliax or 1/2 corrugated coax.

Mike
mike - if you arrange for the connector to be at the top the clearance should be better with the offset mount.

EA7KIR
Posts: 86
Joined: Tue Feb 09, 2021 3:38 pm

Re: Chicken & Egg on New Installation

Post by EA7KIR » Mon Jun 27, 2022 12:06 pm

g0mjw wrote:
Sat Apr 16, 2022 8:00 pm
It should be over 10 with that dish so there is some tweaking still to be done, but a lot better. Is it as far back as it can go? You will probably need to tweak the elevation a little.

Mike
Here's how I ended up lengthening the feed arm, whilst maintaining the axis. GREEN=Original,RED=Modified.
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Feed_Arm_Modification.png
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Feed_Arm_Modified.jpg
Feed_Arm_Modified.jpg (1.23 MiB) Viewed 3225 times
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NB Mike G0MJW - SMA pigtail as you suggested.

BUT - I'm still only getting 7.3 MER., using a Gibertini OP 125 L 1.3m Dish, AND after aligning everything to the NB CW Beacon. The signal level drops by 10db on wrong polarisation.

1) Is a 10db drop enough ?
2) Is this the correct lens for FD 0.66 ?
3) Could it be misaligned to a radiation lobe ?
Michael EA7KIR

g0mjw
Posts: 2330
Joined: Sat Sep 20, 2014 9:15 am

Re: Chicken & Egg on New Installation

Post by g0mjw » Mon Jun 27, 2022 3:16 pm

I would suggest a proper lens, not that one, but it will sort of work. The HB9PZK design is a lot better. Make sure it is at the focus. 10dB difference is not good though, nothing like. Should be 20dB at least. You need to get the polarisation rotation correct. Also this can be impacted by not being at the focus, but not by that much. I assume you tweaked it by rotating the LNB looking for a null in the opposite polarisation?

Edit - in the photo the edge of the pipe at the front looks very rough? I assume that's just the photo?
Edit 2 - are you sure you rotated the polarisation offset the right way?

EA7KIR
Posts: 86
Joined: Tue Feb 09, 2021 3:38 pm

Re: Chicken & Egg on New Installation

Post by EA7KIR » Mon Jun 27, 2022 4:26 pm

g0mjw wrote:
Mon Jun 27, 2022 3:16 pm
I would suggest a proper lens, etc...
* The HB9PZK looks nice, but I haven't got a 3D printer. Is anyone selling these?

* I focused and rotated for max NB CW, but my wife, who was watching the laptop below, became bored before I could tweak for a null.

* The pipe edge is fine, I think it's a reflection from the sun.

* I switched between 18v for NB and 12v for WB, using a Lab PSU. The LNB is normally supplied with 12v from the NIM.

An OM from the UK is over here this week and agreed to help with another go.

Do you have an ideas on my other recent post at viewtopic.php?f=86&t=7993 ?
Michael EA7KIR

radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Chicken & Egg on New Installation

Post by radiogareth » Mon Jun 27, 2022 4:41 pm

I found the Portsdown4 'Beacon MER' (QO-100 menu (RX, QO-100 selected, bottom right corner) far easier to use than the NB beacon signal strength. I took my portsdown outside on battery power. Very quick to tweak the dish & LNB. Or you could use Chrome remote desktop to view your PC on your phone if your wife has gone....
Gareth

EA7KIR
Posts: 86
Joined: Tue Feb 09, 2021 3:38 pm

Re: Chicken & Egg on New Installation

Post by EA7KIR » Sun Jul 10, 2022 2:13 pm

g0mjw wrote:
Mon Jun 27, 2022 3:16 pm
I would suggest a proper lens, not that one, but it will sort of work. The HB9PZK design is a lot better.
I have a friend in the UK who might be willing to 3D print one for me, if I can send the design. The original text at https://rfantennas.wordpress.com/author/hb9pzk/ appears to have gone, so no clues there.

Google is my friend, but not on this occasion, so I'm asking if anyone can tell me where I can download the files.
Michael EA7KIR

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