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Re: Which rocket lens ?

Posted: Fri May 03, 2019 6:50 pm
by PH2M
g4hiz wrote:
Fri May 03, 2019 5:24 am
Hi Frank,

Interesting. As I said previously, I have not tried the LNB as a functional unit, only the lens, which seems to work ok on a couple of dishes. The statement concerning being a 'PLL type' was based on a Single output version that I opened, please see photos below.

73
Jen
Hello Jen,

Yes I did see You bought the Single output version, I took the gamble buying the Twin version (was even doubting about the Quad version), but sadly the Twin version = DRO :evil:
I have decided to stay with my present Inverto (Single)Longneck before going to any Twin or Quad (I finally want to use at least 2 ports for simultaneous NB + WB QO-100 RX

73 de Frank PH2M
Inverto-Longneck-LNB-3.jpg
Inverto-Longneck-LNB-3.jpg (32.15 KiB) Viewed 858 times
Visiosat_Bisat_QO-100.jpg
Visiosat_Bisat_QO-100.jpg (105.13 KiB) Viewed 858 times

Re: Which rocket lens ?

Posted: Sat May 04, 2019 6:44 am
by G8PEF
G4FRE wrote:
Wed May 01, 2019 8:27 am
thats the way that also worked for me

Dave
g4fre
Yay! Success.... I now have a 'lovely' red lens which came off intact.
Incidentally, the reason it wasn't gunked onto the w/g with silicone is that it has a nice o-ring seal trapped between the face of the w/g and a small lip on the inside of the lens.

I'm curious about the internal construction of the lens, and I can get hold of another one of these lnbs, so I might sacrifice a lens - saw it in half, nose to tail - to see its insides.

Now looking for materials for the feed - any thoughts on whether copper or brass is better for the sheet/tube ?

Re: Which rocket lens ?

Posted: Sat May 04, 2019 7:21 am
by g4hiz
Hi Frank,

Sorry to hear that you didn't get what you were expecting with your Dual o/p AB LNB. One thing that crossed my mind was whether it was from 'old stock'. Looking at the serial number of your unit, it starts with 2016... whereas my Single unit starts with 2017....I took a look at the AB website and all models appear to have the same Phase Noise spec and imply PLL type.

Not wishing to get drawn into LNB discussions on the 'Lens thread' but I looked at a Single o/p device that I have. It looks pretty straightforward, with no apparent filtering and so I checked the RF output on the spectrum analyzer. The noise shape seemed pretty flat from about 600MHz upwards until about 1.4GHz (where it dipped a bit), this with the 9750MHz LO. Using test signals in a rough radiated environment, 10494MHz (744MHz at IF) was in the 'flat' part of the spectrum, similarly with 10368MHz (618MHz at IF). This was of course, a PLL type as pictured previously. If I get time, I shall check its performance on QO-100.

Good luck with your dual output system !

73
Jen

Re: Which rocket lens ?

Posted: Wed May 15, 2019 9:58 am
by G8PEF
g0mjw wrote:
Tue Apr 30, 2019 5:41 am
That's the one you want, with the flat end and in two pieces that slot together. The pointy thing it for cases where you cannot get a rocket lens, and there is a newer design by HB9PZK of that which is better that will be published soon.

Mike
Ok, now I’m confused. Both Mike and Noel (who has seen the actual lens I have) have both have said that what I have is ‘the one I need’...
However, on re-reading Mike’s post (above), it mentions “two pieces that slot together” - mine is a ‘single’ piece (well, ok it’s a red outer shell with white insides, but they seem to be bonded together).
I’ll try to attach a couple of pics of one slightly damaged one so you can see what I mean.

The other thing is that it doesn’t fit on the end of 22mm pipe - the internal diameter of the red bit is too big. It is, however a reasonably good fit into 28mm copper pipe.

All comments and suggestions welcome.

73
John M
E157E1CE-DB42-43E8-B431-6294F9FCD0A5.jpeg
Rear view
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Front view
C1877C37-A362-4E9F-9305-BA03121AEC21.jpeg (1.86 MiB) Viewed 767 times

Re: Which rocket lens ?

Posted: Wed May 15, 2019 10:05 am
by G8PEF
Ah! I have just managed to get the white bit out of the red shell. The inner appears to be just a cylindrical white block (polyethylene?) apart from the single machined/moulded ring on the end facing the waveguide, visible in the photos above.

Comments welcomed.
J

Re: Which rocket lens ?

Posted: Wed May 15, 2019 10:10 am
by g0mjw
Never seen one of those - but its still a lens so stick it on the end of the waveguide as best you can and see if it works.

Re: Which rocket lens ?

Posted: Mon May 20, 2019 8:31 am
by g7ntg
I tried various lenses and horns with my POTY patch antenna on a 1.2 metre dish with a f/d of 0.4 but everything I tried caused either a drop in received signal strength or transmit power. I ended up with the waveguide projecting 7mm in front of the patch (1/4 wave at 10.4 GHz) which seems to give the best results for transmit and receive.
I used a rocket lens on my 80cm sky dish which gave a few dB improvement on receive on narrowband.

Re: Which rocket lens ?

Posted: Mon May 20, 2019 6:22 pm
by PA3FYM
Some experiments with several lenses were performed here.

Using a 10 GHz beacon and measuring the received sig strength with
a HP-435 (m)Wattmeter it was possible to reach 0.1 dB accuracy
and also determine the -10 dB opening angle(s).

More information to be published soon. Hint: it seems that
90° opening angle (ca 10.5 - 11 dBi) for a f/D = 0.6 dish is
suboptimal. A smaller angle seems to deliver more SNR.

Re: Which rocket lens ?

Posted: Tue May 21, 2019 5:37 pm
by g0mjw
g7ntg wrote:
Mon May 20, 2019 8:31 am
I tried various lenses and horns with my POTY patch antenna on a 1.2 metre dish with a f/d of 0.4 but everything I tried caused either a drop in received signal strength or transmit power. I ended up with the waveguide projecting 7mm in front of the patch (1/4 wave at 10.4 GHz) which seems to give the best results for transmit and receive.
I used a rocket lens on my 80cm sky dish which gave a few dB improvement on receive on narrowband.
That is as expected. The lens is for dishes with F/D of 0.6 to 0.7. It is not for 0.4 f/D - look at this web page https://rfantennas.wordpress.com/author/hb9pzk/

Willi indicates the open waveguide is good for 0.3 so you might benefit from a small lens but not a rocket and probably not much.

Re: Which rocket lens ?

Posted: Mon Jun 03, 2019 9:09 am
by g8lce
I bought a poty kit that comes with a PTFE lens. I found the lens I took off the original LNB worked better than the kit one in my situation. So it may be worth trying the original lens if you have bought a poty kit. I put the original 'waterproofing cover back on with some sealer over the top of it. I may remove that when I make a waterproof cover for the whole poty.