Triax dish arms - weird question on dimensions!

[jallen01]

A few years ago I acquired (can't remember from where, but it could have been my next door neighbour or the local recycling centre!) what turns out to be GT-Sat 80cm dish which looks very like this one, and I'm just getting around to installing it but I want to fit a multi-LNB bracket.

Problem is that the arm is rectangular in cross-section, and the only commercially-available brackets that I can find for arms that shape seem to be for Triax dishes - so could anyone with Triax knowledge tell me the internal & external dimensions of the arms they generally use as maybe one of those would fit the G-Sat dish arm?

Thanks in advance.

[RimaNTSS]

Go to nearest store and buy some cheap galvanized stuff and then construct something like that. Pretty easy
easyfeed (Custom).JPG

[echelon]

plenty of different lnb racks of varying kinds on a well know a**tion site !!

some fit the rectangular slot where the lnb holder normally goes, with up to 4 lnb holders

some circle the current lnb and lock tight , with one or two extra holders for more lnb,s

some good be bolted onto the arm itself and then adjusted accordingly

some details and pictures in this lnb thread https://www.satpimps.co.uk/showthrea...60102-Twin-lnb

[jallen01]

Go to nearest store and buy some cheap galvanized stuff and then construct something like that. Pretty easy
easyfeed (Custom).JPG

Looks interesting! However, where did you get those clamping pieces used around the arm and the LNBs as I have never seen them anywhere?

PS: still interested in any answers to my original question as, if that looks a possible solution as it could also provide the LNB clamps.

[jallen01]

plenty of different lnb racks of varying kinds on a well know a**tion site !!

some fit the rectangular slot where the lnb holder normally goes, with up to 4 lnb holders

some circle the current lnb and lock tight , with one or two extra holders for more lnb,s

some good be bolted onto the arm itself and then adjusted accordingly

some details and pictures in this lnb thread https://www.satpimps.co.uk/showthrea...60102-Twin-lnb

I've had a very good look at that site and many others, but I could not work out which have the correct dimensions to able to fit the arm on this dish, which is why asked the question.

Also, I'd like to try to fit up to 2x LNBs on either side, and that also limits the possible choices - especially as I would not want to have to buy 2x of "whatever" to get the extra LNB holders.

[echelon]

I've had a very good look at that site and many others, but I could not work out which have the correct dimensions to able to fit the arm on this dish, which is why asked the question.

Also, I'd like to try to fit up to 2x LNBs on either side, and that also limits the possible choices - especially as I would not want to have to buy 2x of "whatever" to get the extra LNB holders.

triax dish lnb socket on the arm itself is

outer is 50mm wide by 20mm height

inner is 46mm by 16mm

[RimaNTSS]

However, where did you get those clamping pieces used around the arm and the LNBs as I have never seen them anywhere?

Have you been in the shop where they sell plumbing stuff and different nuts&bolts? It is LEGO for *****s.

[jallen01]

triax dish lnb socket on the arm itself is

outer is 50mm wide by 20mm height

inner is 46mm by 16mm

Thank you VERY much, and I will check those dimensions against the arm on the GT-Sat dish tomorrow!

[echelon]

this is the one on my 80cm triax dish

https://www.satpimps.co.uk/showthrea...l=1#post420787

4 lnb holders, been there a long time

[jallen01]

Have you been in the shop where they sell plumbing stuff and different nuts&bolts? It is LEGO for *****s.

This may be a "national" issue because I am in the UK and I have been into a few of those shops over the years and seen nothing, and nor would I know what to ask for; and most plumbers' merchants only have a small proportion of their stock on display and so asking for the right thing would generally be necessary. The only things I have seen that remotely resemble those clamps are the brackets use to support copper pipe runs, but they have standoffs with flanges that you then use to screw the brackets to the wall (and since most LNBs have 40mm collar dimensions, then probably only those for plastic waste pipes would have the right dimension at the LNB ends).

[TheBadger]

Don't know if these are any good to you

 _http://www.jtmplumbing.co.uk/pipe-fittings-c433/rubber-lined-unlined-brackets-c244/jtm-rubber-lined-clamp-m10-m8-pp7502?utm_source=google&utm_medium=***&utm_term=jtm-rubber-lined-steel-pipe-clamp-clips-35mm-1-quot-32-36mm-clips-35-clips-35mm-1-32-36mm-rlc004&utm_campaign=product%2Blisting%2Bads&gclid=CjwKEAiA3Ou1BRDso5XyhduuwFASJABP3PEDWudp6ViX6GTgVsaHmpiTEnGvkucN5GxblaKv0RT9hRoCfevw_wcB

[Mobley2]

Trying to fit the arm from another dish is not really a practical solution. While you may be able to get the arm to fit at the dish surface
you have absolutely no way ( unless you are acquainted with complex mathematics) of working out the Focal point for the Lnb.
On most arms the bend at the front of the arm would be matched to the angle that the Lnb holder enters the arm tube this,is to achieve maximum gain, fitting a different arm, could
mean that the Lnb focus might be beamed at the top of the dish and consequently the practical gain from the dish could be severely diminished. In order to have maximum gain the focus needs
to be more or less at the centre of the dish. I have some experience of trying this on an 80Cm dish with a Triax multi Lnb holder, but the focus was way off and it was not a success
If you are tempted to try using metal plates and threaded rod with stand off clamps, then I would suggest you do your experiments at ground level, as small adjustments could mean the difference between getting a signal
and nothing. My apologies for such a long winded reply.

regards mobley 2

[jallen01]

Mobley2
I think you slightly misunderstood my question about the arm as I was not intending to change that - but "simply" the LNB holder at the focus point end, and thus needed to know if TRIAX-type parts might fit, and, in turn, that meant knowing the dimensions that Triax normally use..

As for trying things out at ground level - my dishes are or will be all at ground level (actually about 5-6ft above it on poles or mounted on very firm fence posts) so that would be a given anyway
regards

John

[jallen01]

Don't know if these are any good to you

The 42mm version looks as if it might fit the 40mm neck LNBs, and the 22mm version would probably work for the LNBs with smaller necks - so that looks a very good lead (and could well be helpful to others looking for extra LNB holders for their modding projects.

Many thanks for that.

It also got me to thinking back about some rubber-lined P-Clips that I bought for another job last year as some of the sizes could accommodate LNBs as well, and some of those might be useful to or others - see

_http://www.eb*y.co.uk/itm/Rubber-Lined-Hose-P-Clamps-Pipe-Clips-Fastenings-/190886523214?var=&hash=item7220c8785e

[jallen01]

triax dish lnb socket on the arm itself is

outer is 50mm wide by 20mm height

inner is 46mm by 16mm

I've just measured the GT-Sat arm, and the external dimensions are 30mm wide x 15mm high - so it's a lot smaller than that Triax arm. Thus any Triax-type parts to be used would have be designed to fit over the end of a Triax arm, and not inside it - and then they would need quite a bit of shimming to take up the differences in dimensions. Might be worth a shot though if other avenues don't work out.

Anyway, many thanks again for making the measurements.

[echelon]

agreed, I suppose it could be adapted but its a long shot, so I would recommend one of the other lnb racks like the UNIVERSAL metal ones (gilbertini ?) and adapt one of those

or the INVERTO or KONIG ones that clamp onto the existing lnb with one collar and have one or two spare collars that are adjustable along slots in the metal

so it seems that you would need to experiment or build your own rack anyway

at first I did think you were going to change the arm, which gives the problems mobley mentioned earlier, then I realised you wanted to know about the triax arm dimensions of the box section at the lnb end, so as I have a spare arm (in the garage) with a single lnb holder mounted in it I disconnected the lnb holder and then measured the slot and the holder itself, for accuracy

so with some ingenuity I am sure you can manage it, especially with such easy access

another trick I do is wind sticky black tape around the lnb necks themselves if they are too narrow, to enhance the thickness

[Mobley2]

Mobley2
I think you slightly misunderstood my question about the arm as I was not intending to change that - but "simply" the LNB holder at the focus point end, and thus needed to know if TRIAX-type parts might fit, and, in turn, that meant knowing the dimensions that Triax normally use..

As for trying things out at ground level - my dishes are or will be all at ground level (actually about 5-6ft above it on poles or mounted on very firm fence posts) so that would be a given anyway
regards

John

Ahh! understood, I would still advise you to note my comment re the Triax multi bracket, when I bought mine, thinking similar to yourself, that it might fit, I had to mount it over the arm tube, not inside it, because of internal dimensions
however that was not my problem, I found the angle of the Lnb holder to be quite different to the original Lnb holder, and it was pointing much too high, pretty much on the dish rim, and consequently more noise than signal. If you are able to
compare them to check this then maybe it will be a runner, in my case I could not as I bought it online. Good luck in your endeavors

regards mobley2

[jallen01]

Echelon

I've decided to order a couple of these • after finding the image shown here as I could not previously see how to fit them to the existing LNB arm - might need to put some quick/cheap bracing struts to the ends of the brackets like I did many years ago to the Raven Gemini 90 and old NEC 80cm dishes (pics available if anyone is interested!)

Mobley2

I take your point about the LNB holder angle - hopefully the brackets that I bought should put the new LNBs at the same angle as the existing LNB holder on the arm, but I can probably twist them in the vice to change that if I have to.

The main reason I bought some new brackets was to get the LNB holders as cheaply/quickly as possible - but, FWIW, extension brackets can often be fabricated from the perforated strips sold for securing car exhausts and the like (or even a piece of perforated dexion!)

[johnhenry]

I have a 80 cm dish with 3 LNB'S fitted. I set up on 13e as my primary to align the dish, then i fitted my secondaries 19e and Thor 0.8w all connected to 4 to 1 down switch fitted to the frame of my dish. I scanned each satelite on to my receiver first starting in with position 1 Hotbird 13e, position 2 Astra 19e, position 3 Thor 0.8w, As for my Astra 28e i ran this from my sky mini dish (Sky LNB with 4 connections 2 of which went to HD Skybox for Sky+ the third connection on the Sky LNB is a spare) the 4th Sky LNB connection is then connected to the 4 position on the down switch and scanned to position 4 on the receiver. By using the Sky dish for 28e this gives room on the 80cm dish to easily fit the 3 LNB'S for 13e, 19e AND 0.8w. Do hope this all make sense

[echelon]

it makes sense to me and is similar to mine

as for the pic in post #18 , I was looking at similar ones like the INVERTO or KONIG versions, but yes I think you will be fine with them , providing you can fit the centre one around the neck of your existing lnb as well as its current holder too (a long neck lnb would be ideal for that centre one, like the smart shown in the pic)

so for clarity, it clamps around the existing lnb neck , not the dish arm

if you can somehow brace it as well, even better

otherwise its try those UNIVERSAL 4 WAY ones and bolt the rack to the dish arm