80-90cm dish in the west london area (closed)

[Channel Hopper]

If it is Channel Master 90cm you have than I do not see any reason to change it to 80sm made of tin antenna. Channel Master (Raven) is the best option ever made. I wold not change CM dish to any other , moreover if it is smaller in size.

The Raven Jeallen speaks of is not constructed like the earlier CM dishes, it is metal reflector.

 

[Channel Hopper]

"Adjusted" the LNB for 10E "to death" but with no success

With a true VSat (sometimes called elliptical) dish, the whole dish assembly needs to be adjusted to match the geostationary arc for a reasonable signal to be detected off the focal point. The Raven was not designed with anything other than a single LNB at the end of the feed arms.

Examples of the backplate alignment that allows this can be found in the Prodelin 195X series and all of the toroidal antenna designs.

Fly Away Antenna Prodelin .95 Meter Elliptical - New Era Systems

https://gdmissionsystems.com/-/medi...hash=98D0097A9EF7D4D3DCB12B3F8CD38A86C15C0941

 

[Captain Jack]

Will be in London in couple of weeks but surely will not have time to tune antennas

When and where are you in London? Would be good to meet up - I can show you the rains....

 

[jeallen01]

.... The Raven was not designed with anything other than a single LNB at the end of the feed arms. ..

That's not quite correct as the Gemini 90 was designed to use multiple LNBs using a dedicated bracket (which I have) - per the attached pic (taken from the Raven Gemini 90 brochure of around 2000). When I first installed it (much nearer the house than it is now), I extended that bracket in both directions to widen the reception arc (and thus did get 1W - not 5W as previously stated - to 28E).

Also attaching a pic (from 2016) of the Gemini 90 with 3 LNBs on the supplied multi-LNB bracket - but have now removed part of that and substituted an LNB rail from another multi-LNB kit because that allows more lateral adjustment for the LNBs.

Edited:
PS: it's rather obtrusive, and difficult to adjust, in that location, so that's why I'd like another 80-90cm dish.

 

[Captain Jack]

I remember these dishes, however, I only ever saw one of them hanging on the side of a house not far from my parents' place. Not sure if it's still there now.

 

[jeallen01]

PS: there were also 70cm and 120cm versions of the Gemini - 120 brochure is attached

 

[RimaNTSS]

Independent tests in harsh conditions prove that the Gemini 120 can out perform
certain 1.8m antennas.

Here they already had Jonsa in mind.

 

[Channel Hopper]

You might be reading too much into the information

https://www.satellites.co.uk/forums/attachments/raven-gemini-90-jpg.119236/

And the LNB bracket shown in the image looks somewhat different to the one you have.

Take some pictures from above (or below) as it could be you have not got one that brings LNBs on each side to the correct focal distance determined by the parabola specified by Raven.

 

[jeallen01]

You might be reading too much into the information

https://www.satellites.co.uk/forums/attachments/raven-gemini-90-jpg.119236/

And the LNB bracket shown in the image looks somewhat different to the one you have.

Take some pictures from above (or below) as it could be you have not got one that brings LNBs on each side to the correct focal distance determined by the parabola specified by Raven.

The angled multi-LNB bracket on the dish is what was supplied with it when I bought it in around 1999-2000 (can't remember from where, but both items were brand new), and it works out quite well for 19E on the centre line, and for 28E to the left (as seen looking at the dish face from the LNBs) as that is higher than the 19E LNB. The problems seem to arise with the LNBs to the right of the 19E one when looking for sats to the West of 19E - even 13E is problematic, which it should not be!

The 13E LNB height is (as you would expect) lower than the 19E one, but finding "anything" is very difficult (even when removing the LNB from the bracket and moving it around above/below/behind/in front of the bracket - as you sometimes do to get a "sniff" of a satellite!).

NB: The Gemini is shallower than the average 90cm dish, and that means the optimum reflection points are more difficult to pin down.

Frankly, as I said early on, I need something a little more "predictable" than this dish as I am running out of patience with it!

 

[Channel Hopper]

Again from the manufacturer's promotion, I cannot recall Raven ever supplying a dedicated multi LNB holder for their dish designs, though there were plenty of dealers peddling items to go in the same box.
There will always be a loss off beam on any dish, though the offset is better suited to allow bracketry in front of the reflector.

 

[jeallen01]

@CH
Can't remember the details either - was 18 yrs or so since I bought the Gemini

 

[jeallen01]

Update:

Further dish acquisition now on hold due possible planning issues - but not our house!

Next door had some large extensions at the side and rear in 2015, but now workmen are erecting a wide and long single storey "something or other" behind the rear extension. Not especially happy about this, and so reported the issue to the Council Planning Dept, and it will be investigated over the next few days.

Also spotted a possible "bed in a shed " situation a few doors away over a couple of fences - whoever, puts a TV mast/antenna AND and an aircon unit on the shed at the end of the garden otherwise?

OTOH, that risks my dish "situation" being "investigated" so have taken down all the fixed ones at the end of the garden, and the TD110 will follow later this evening - leaving just the TD88 there and a Zone 2 dish on the conservatory roof = pretty much "legal".

Hopefully, will re-erect the taken-down dishes after any "furore" has died down - and probably move the TD110 to the taller pole to get a bit wider arc,

 

[Ghostleader]

Update:

Further dish acquisition now on hold due possible planning issues - but not our house!

Next door had some large extensions at the side and rear in 2015, but now workmen are erecting a wide and long single storey "something or other" behind the rear extension. Not especially happy about this, and so reported the issue to the Council Planning Dept, and it will be investigated over the next few days.

Also spotted a possible "bed in a shed " situation a few doors away over a couple of fences - whoever, puts a TV mast/antenna AND and an aircon unit on the shed at the end of the garden otherwise?

OTOH, that risks my dish "situation" being "investigated" so have taken down all the fixed ones at the end of the garden, and the TD110 will follow later this evening - leaving just the TD88 there and a Zone 2 dish on the conservatory roof = pretty much "legal".

Hopefully, will re-erect the taken-down dishes after any "furore" has died down - and probably move the TD110 to the taller pole to get a bit wider arc,

Ooft, what a hassle, no luck mate, hopefully this gets sorted sooner rather than later.

 

[jeallen01]

Ooft, what a hassle, no luck mate, hopefully this gets sorted sooner rather than later.

Well, 3 months on and all's gone quiet, and so most of the dishes are now back up and running.

I then put up the old 60cm offset (was used for Sky until a couple of years ago) to get a shot at the sats around 52-53E, and whilst I can get some signal and pictures with the TM down the garden, the extra cables and switches in the route to the lounge result in too much signal loss (and I think I also have a problem with a house blocking some of the signal).

Therefore I'm back in the market for a half-decent 80cm (90 would be too big for where it will be located) offset at a knockdown price (say around £25) if anyone has one around our area!
PS: also looking around on Gumtree and Sphock - but not found anything decent yet)

 

[Captain Jack]

I have an unused Viasat dish. I think it's more 70cm than 80cm but I can measure more accurately, if needed. You'd have to collect though!

 

[jeallen01]

I have an unused Viasat dish. I think it's more 70cm than 80cm but I can measure more accurately, if needed. You'd have to collect though!

Thanks for the offer but I think I'll pass on that - you are "not quite" in our area. OTOH, if we are ever in "your area" in the future (could happen, I have relatives & friends in the South West that we should have visited but haven't) I'll drop you a PM to see if you still have it.

BTW: I think I've found an 80cm dish, with TM LNB, on Gumtree a few miles away in Feltham - They want £30, but just waiting to see if my offer of £23 will be accepted!

 

[jeallen01]

Update: couldn't bargain the price of that local 80cm & LNB down, and so bought one of these 80cm for £30 delivered - and, whilst it obviously not a "precision" piece of kit, it is well-built. Now has 3x LNB's on it - centred on 46W with the outlyers on 42W & 52W - and works fairly well on the main transponders on the sats.

So this Ad can be deleted/archived when one of the staff has the time.