Which rocket lens ?

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
g4hiz
Posts: 38
Joined: Thu Oct 18, 2018 6:40 am

Re: Which rocket lens ?

Post by g4hiz » Tue Apr 30, 2019 8:51 pm

Hi Tim,

I've not tried the AB LNB 01 itself, only the lens, so perhaps I will try it given your test. What was the dish size to achieve the MER that you did ?

Previously I had reduced the Octagon diameter to make a snug fit into the pipe, but the AB LNB 01 has the benefit of plenty of length to play with after cutting off the lens mount.

The AB LNB 01 is a PLL type with a 25MHz crystal. The one that I investigated was not easy to open though, as the sealant had seeped inside to stick tracks to the case, resulting in some pulling-up on opening, although repairable.

73
Jen

G8PEF
Posts: 115
Joined: Mon Oct 30, 2017 6:42 pm

Re: Which rocket lens ?

Post by G8PEF » Tue Apr 30, 2019 10:44 pm

Hi, Mike...
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.
Thanks for that info - now, any idea how to get it off the LNB without busting it? The ones above seem to be siliconed on to the LNB - this one seems to be 'snapped on' with a sort of barbed ridge on the inside of the plastic resting behind a small step in the outer diameter of the casting.
I guess I could saw off the w/g and then go to work on the remaining bit of w/g(carefully) with the Dremel?

radiogareth
Posts: 287
Joined: Wed Jan 06, 2016 9:46 am

Re: Which rocket lens ?

Post by radiogareth » Wed May 01, 2019 6:58 am

Place JUST the plastic part, right up as far as you can without letting water into the WG part, in a jug of boiling water for a minute. Quickly dry and twist/pull with a towel or rag. Worked for me.
Gareth

G4FRE
Posts: 85
Joined: Fri May 26, 2017 6:57 am

Re: Which rocket lens ?

Post by G4FRE » Wed May 01, 2019 8:27 am

thats the way that also worked for me

Dave
g4fre

G4WIM
Posts: 202
Joined: Thu Jan 29, 2015 8:36 pm

Re: Which rocket lens ?

Post by G4WIM » Wed May 01, 2019 3:45 pm

Jen,

I'm using a 1.2M channel master and with my Octagon LNB at the optimum position I got an MER of 9 to 9.5dB from the beacon.

With the AB LNB and dual feed it's about 1dB worse but this could be due to the LNB being about 50mm too close to the dish due to the dual feed.

Later this week I'll be installing some longer dish arms like Noel has done and fingers crossed I'll be back around the 9dB mark again.

Regards Tim

g4hiz
Posts: 38
Joined: Thu Oct 18, 2018 6:40 am

Re: Which rocket lens ?

Post by g4hiz » Wed May 01, 2019 7:22 pm

Hi Tim,

I've been experimenting myself today with an old 1.2m offset dish that had no feed system whatsoever. Anyway, having built a feed support structure and got everything optimised as far as I could determine, the beacon MER was 9dB, with zero bit errors. The LNB was an Octagon and it used the AB LNB 01 lens on the G0MJW dual band feed. The Rx was a Mk 1 Minitiouner (Sharp type) running version 0.8 software.

The were a couple of factors that I found critical to setting up the feed position. Positioning of the feed at the focus was very important. After having optimised things, I found that the point of the lens cone was positioned at the focal length. With the feed positioned either way, dBs were lost very easily.

The other important point was where on the dish that the feed was pointing. I found this to be optimal just below the centre of the dish, which was confirmed also by the angle of elevation being about right.

Anyway, good luck with your antenna experiments !

73
Jen
Last edited by g4hiz on Wed May 01, 2019 9:00 pm, edited 2 times in total.

G8PEF
Posts: 115
Joined: Mon Oct 30, 2017 6:42 pm

Re: Which rocket lens ?

Post by G8PEF » Wed May 01, 2019 7:46 pm

radiogareth wrote:
Wed May 01, 2019 6:58 am
Place JUST the plastic part, right up as far as you can without letting water into the WG part, in a jug of boiling water for a minute. Quickly dry and twist/pull with a towel or rag. Worked for me.
Gareth
Thanks Gareth (and Dave :) ) - I'll give that a go at weekend.

John

G4WIM
Posts: 202
Joined: Thu Jan 29, 2015 8:36 pm

Re: Which rocket lens ?

Post by G4WIM » Wed May 01, 2019 9:16 pm

Hi Jen,

thanks for the tips - fingers crossed I'll recoup the lost dB's due to the feed being too close to the dish.
I'll report back in due course.

Regards Tim

PH2M
Posts: 9
Joined: Thu Mar 07, 2019 10:56 am

Re: Which rocket lens ?

Post by PH2M » Thu May 02, 2019 7:31 pm

g4hiz wrote:
Sat Apr 20, 2019 8:15 am
It is a PLL type. The crystal is 25MHz.
Be careful not ordering the AB LNB 01 MTwin ! I bought one this week for a nice price from Estonia on eBay, arrived in 4 days! But found it is a DRO version :oops: (Nice for the lens if You need it, but not good for QO-100 :(
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73 de Frank PH2M

g4hiz
Posts: 38
Joined: Thu Oct 18, 2018 6:40 am

Re: Which rocket lens ?

Post by g4hiz » 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
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AB LNB 01 Single Obverse.jpg
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AB LNB 01 Single Inside.jpg
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