How heavy are these large satellite dishes? (and tips on taking them down?)

[XOIIO]

Alright, got it unloaded, not precise but I had guessed the weight at 180, after weighing the pieces, the middle was 25.25 pounds, and each section was 27.5, so it came to 190.25 pounds, sure felt like a lot more though. It was indeed a 10 foot dish (or possibly 10.5, maybe 11) with the center in place)

I've got a few more pics of all the sections, the condition of a few of them, and the receiver if you guys are interested. We did only put a small hole in it. There were 3 other small tears but they were stitched up with wire a long time ago. The pole for mounting needs to be a shade under 3.5 inches.

The receiver is surprisingly small, I don't know why the dome on the outside was so massively over sized. Should be fun to crack open though, wish I had an oscilloscope to hook up to it and see if I could grab any signals.

[tom66]

What type of signal is that for? Satellite TV? Even the first IF of satellite TV is in the GHz band; you're going to need a pretty fancy scope to see it.

[XOIIO]

What type of signal is that for? Satellite TV? Even the first IF of satellite TV is in the GHz band; you're going to need a pretty fancy scope to see it.

Ah, didn't think of that, I figured I'd keep my eye out for a cheap or free old analog scope, but you are right, it's for 3.4-4.2 GHZ, though the output frequency is 950-1750 mhz.

I know dick all about scopes, I would know more but I left an old techtronicks (if that's the right spelling) scope in the garage over winter, come spring, it was totally dead :/

edit: just popped open the lid on it, under the screw cover there's a circuit board. probably some RF voodoo, but under the round cover I was expecting some fancy stuff, it's basically just empty with a couple little wires sticking in from the sides spaced apart a bit. Quite the anti climactic result lol.

edit 2: oh yeah it's a twin output C band LNBF (I'm guessing the LNFB stands for the type of receiver).

I'm curious, how much did these big dishes cost new? I imagine they were something only people with a decent bit of money could have.

[tom66]

LNB = low noise buffer, I think. Possibly F is frontend. There will be more. There should be a mixer, local oscillator and IF filter, at the very least.

It's Tektronix.

[XOIIO]

LNB = low noise buffer, I think. Possibly F is frontend. There will be more. There should be a mixer, local oscillator and IF filter, at the very least.

It's Tektronix.

Ah, alright, thanks.

Oh yeah here is another shot of them all unloaded, they are quite nice little things to have sitting around, someone artsy could probably make interesting stuff with them.

[Rory]

Now for some reminiscing about BUD technology...

LNBF = Low Noise Block (Downconverter) Feedhorn.  In the early days you could get the LNA (Low noise amplifier), usually a GaAsFET or HEMT, Downconverter (a combination mixer/local oscillator), and feedhorn mixed and matched depending on the receiver you used not to mention how much money you were willing to spend.

In the first couple of generations the receivers used a fixed 70 MHz IF (which was great for FM TV with a Gunnplexer) with a tunable oscillator in the downconverter that drifted all over the place with temperature changes.  There were actually a pair of wires that ran up along the cable to tune the oscillator. Cheap receivers had no or crappy AFC so you had to occasionally tweak the fine tuning when the channel drifted too far off frequency.  Then somebody, either Drake or Scientific Atlanta, I think, came up with using low loss RG6 coax and a tunable higher IF in the receiver, with a fixed LO in the downconverter, hence the 950-1750 MHz IF.  The satellite box next to the TV is basically a wideband tunable FM video receiver, connected to a descrambler device.  Early units had a separate control box for the linear actuator that had presets for each of the satellites. Later receivers have the control circuitry built into the set top box.

If you look in the feedhorn you may find a little servo motor that rotates the feed probe to adjust for horizontal or vertical polarization... satellites had channels with odd channel numbers in one polarization, even channels in the other. Adjacent satellites sometimes had opposite polarization on channels so smaller dishes with broader beams could separate them apart.  More expensive LNBFs had dual feedpoints so both polarizations could be received simultaneously, like in CATV headends and commercial installations like lodging establishments.  Essentially the idea was to line up the feed probe with the antennas on the satellite.

BTW, I did most of my installations in the wilderness of SE Alaska in the 80's, then later had my own BUD living in the country until DISH network got affordable.

[XOIIO]

I haven't taken the circuit out of the feedhorn (I'm guessing that's the antenna bit I'm talking about, and have a picture of on the table?), there is a little box on the board but I think it's one of those older style adjustable resistors (or perhaps a potentiometer, never looked into the on board ones) but the antenna wires inside it look like they are through metal holes, I don't think there will be a motor in there.

I bet putting up those dishes was a fairly nice job, it was hard taking it down, but still fun, nice view at the top, and was outdoors.

As to putting them up, did you do it this way? (I'm just guessing but it seems to make sense). I figured you would put the bottom 3 sections on the frame/mount for the pole, hooking them together, then the metal ring at the center, securing it into place to the 3 sections, then proceeded to put the last 3 top sections up one at a time? That's how I'd do it, unless you guys had a flatbed with a crane to lift it up in one piece.

Interestingly I can't find much if any info on pricing of those things but I found a forum for satellite dish fanatics it seems, I can probably find some more obscure info there. Something I would like to find is an adapter from full sized coax to the small one used on desktop wireless card external antennas, then it would be easy to stick one up there and have it reach a decent distance.

[Rory]

You're going to have to come up with your own feedhorn if you're going to try sniffing distant wifi,  C-Band is above 3 GHz while wifi is around 2.4 GHz.  I was wondering if a USB wifi dongle on the end of a USB extension cord would be sufficient, maybe mount it 1/4 wavelength in front of a reflector, facing the dish.  Not real sensitive but maybe the gain of the dish will make up the difference.
 
In the USA using a high gain antenna on Wifi is technically verboten, unless you are using it strictly as an amateur radio link with no encryption, and only using it to link with other hams.  Not being from the Great White North, couldn't tell you about your case.  Just don't get caught and annoy your neighbors.

[XOIIO]

You're going to have to come up with your own feedhorn if you're going to try sniffing distant wifi,  C-Band is above 3 GHz while wifi is around 2.4 GHz.  I was wondering if a USB wifi dongle on the end of a USB extension cord would be sufficient, maybe mount it 1/4 wavelength in front of a reflector, facing the dish.  Not real sensitive but maybe the gain of the dish will make up the difference.
 
In the USA using a high gain antenna on Wifi is technically verboten, unless you are using it strictly as an amateur radio link with no encryption, and only using it to link with other hams.  Not being from the Great White North, couldn't tell you about your case.  Just don't get caught and annoy your neighbors.

Well, I have one of those extended antennas on the small coax cable, I think its a 5db gain one, with a magnetic base, I could just whack it in the middle where the old feedhorn used to be (maybe even inside it with the antenna sticking out)  and it should work fine, I imagine the dish will bounce 2.4ghz fine as well.

I did use a USB dongle on the small dish but the extended antenna worked much better, I just need a USB dongle that I can plug one into to hook a laptop up to it.

[Rory]

The mesh dishes were light enough that they could be preassembled on the ground then lifted up into place by a small team. The trick was to use a drift pin/marlinspike in the axis boltholes to hold the dish in place on the mount before slipping in the bolts - it's a lot easier than fiddling around with bolts in misaligned holes. Especially in 40F rainy weather.

The fiberglass dishes were a lot heavier and if we couldn't get access to a bucket truck, sometimes we built a tripod or a-frame out of wood poles and hoisted the dishes up with a come-along or a chain hoist and fabric strap harness. I helped put up a couple of 5-meter Anixter dishes this way, took a couple of days to assemble and erect. 

Part of my full-time job at that time was to build and maintain LPTV stations for the Alaska Satellite Television Project, 2 channels per site usually, one for educational TV and the other for, as we joked about, soap operas.  At that time HBO transmitted their downlink signal in the clear (unencrypted) on the same bird as our channels, and several times we would have to go out to the village by float plane, retune the receiver back to the educational channel so the kids could get their Sesame Street, then fix the lock on the shack door.  After that, sit at the dock with a fishing pole trying to catch salmon while waiting for the flight back.

I also occasionally moonlighted putting in home dish systems for a friend of mine, usually doing the hookup/dish alignment/test phase, following a crew of construction types... ran lots of dual RG6 with control wires from the dish into the house. 

[XOIIO]

Man those fiberglass ones do sound like a pain. Interesting that you guys put the others up in one piece though, that's pretty neat.

Oh yeah, I have eyes on a new target if the Canadian government ever dies and this becomes un owned property (the one here is actually on a tower sort of building.)



lol.

[BTO]

Your in Luck
i do this all the time for a living

OK,  this is what you need

1. Make sure you car has a Tow Bar
2. a Small Trailer and some rope
3. Yourself and a Freind or two  (don't do it on your own,  Unless you've taken down at least 20 or so of these things and you know how to do it yourself...... I still use 2 Guys to take
Down C Band Dishes)


now, you have 2 ways to go about this

You can
1. Disassemble the entire dish and Support Post
or
2. You can Seperate the Dish itself from the support post

if you choose Number 2,
then.. Load the dish (Assebled) in the back of your trailer and secure it with the ropes

the rest of the stuff you can just throw in the trailer as well

if you choose to disassemble the whole thing

MAKE SURE YOU KNOW HOW TO RE-ASSEMBLE IT

to Disassemble it,  You'll need 2 Large Shift Spanners
Some Power Tools, Phillips Head bits etc

the first thing you do is take the dish down from the support stand, Cut the RG6 Cable that runs from the LNB to the Set Tob Box, before you take down the dish (or Just disconnect it from the LNB)
next.. on the ground disassemble it.
take off the LNB cover first (3 screws , Phillips head)
take off the LNB (3 Screws Phillips Head)
this will make the Dish Arms go Loose  , Now remove them from the Dish
if it has it.. Remove the Centre Plate in the middle of the dish
Now remove the metal bit that holds the dish onto the pole from the back,  You'll need 2 big Adjustable wrenches
Next.. Disconnect the Wedges from Each other You'll have about 6 or 8 wedges total
normally you need your cordless drill for this, it takes some time

and.. that's pretty much it


re -assemble in reverse


Depending on Size, Let's assume it's a 1.8Metre Dish,   You could be looking at about 50Kg or so

NOW .. CONSIDER THIS
if you take it down in high winds, Your going to have a problem...  BE REALLY REALLY CARFEULL

if you drop it, and bend it, You can't just bend it back into shape and expect it to be ok (doesn't always work that way)

Use 2 or 3 guys, work Slowly and BE SAFE

the hardest part is..
1. When you first remove it from the pole, and you get that free fall feeling from the dish, of having no support.............. you need to control that with a few guys
2. Getting it to the ground  (thankfully your not taking from a roof, therefore you don't need to worry about your footing on roof tiles)

PM me if you need help with this



NOW. REGARDING RETUNING

You need to know what your doing
You need a Spectrum Analyzer (A Good One, not a shit one) that does DVB-S/DVB-S2
You need to know what satellite you want to point to
You need to know it's geostationary orbital postion in the sky
you can look the satellite up on   LYNGSAT
you need to know you LNB L.O. Frequency,   Most Likely  5150
You need to know what Frequency you want to scan IN
you need to know Your Forward Error correction (FEC)
You need to know your symbol Rate
You need to know your Polarisation
You need to know how the spectrum looks in Vertical 13 Volts  and in Horizontal 18 Volts , otherwise you'll be crossed Polarised and wont know why you can't get a signal


there's a lot to it
and if you don't have a spectrum analyzer,   Your pretty much , shit out of luck

anyway,  i hope this info helps you

if you have questions... AND I KNOW YOU WILL HAVE

PM Me

i'm happy to help
i have tonnes of experience in this field,
and unlike many others in this industry , i am one of the few who actually knows what to do , How to do it properly and i can explain anything to you,

good Luck

[XOIIO]

Well, lots of good tips in the post above, but I already have it in my back yard  .

A hand socket wrench and electrical conduit as a breaker bar worked fine for getting it down lol. No spectrum analyzer, but I'm not going to use this for satellite TV. I also only did it with one other guy. I pretty much did what you said, but half of it XD.

[XOIIO]

Here's the circuit board from inside, I figured a scan might work better but it's not great. Do you think there is a way to tweak a scanner for a larger depth of field? That would be awesome.

Anyways, single sided, the back is metal stuck onto the circuit board somehow, the metal case was where the square shielding pattern was, it was just a plastic screw to hold the board down. The metal case seems to be magnesium. The two antenna "sticks" are soldered in put also have a very fine wire connecting them to what seems to be a small magnetic device from what I am guessing.

[XOIIO]

Hmm, wouldn't want to do this to my own printer/scanner (as its a fairly nice one though it only does 600 dpi max) is to remove the glass and maybe rig a thin grid of wires or some way to lay the board so that the actual board part is where the glass would be, then it would be in focus and the larger components would be too close. Depends on the clearance though but that might work.

[BTO]

Cool,  You took it down yourself,   Good Work

regarding that Sexy piece of hardware in Canada

if they ever die, give me a PM and i might just join you in taking it down  LOL

that' would definitely be an experience