Home made diseqc positioner

Channel Hopper said:
Dont forget there is still a requirement for skew on a number of satellites
Click to expand...

I still have somewhere the magnetic polarizer back from the analog times and a pace mss1000. When I switched to digital I didn't want to spend the outrageous amount for the few digital receiver with integrated positioner, I didn't want the clumsiness of an external vbox, so I took another route: a dedicated pc with vdr and a homemade positioner (why hack the hardware when I could more easily hack the software). Edit: and I also forgot about the polarizer and just put an universal lnb in place.
 
The ferrite polariser was a flawed design from the beginning, no need to revisit the horror.
 
in the past i used magnetic polariser !! i had tested a few ! one is good (an IRTE) but i saw that the voltage had to be ajust according to the frequency , i made a special firmware to do that (in analogic)
but today i am using inverto pll LNB (universal model) with c120 flange .
in 99.9% case no need to ajust polarisation
i use also chaparal mecanic polariser in C band.
 
I'm not sure (it's been ~25 years ago) but I think mine was an IRTE too. But since I switched to digital I'm just using an universal lnb. Not that much satellite hopping these days though.
 
dreambox1959 said:
in the past i used magnetic polariser !! i had tested a few ! one is good (an IRTE) but i saw that the voltage had to be ajust according to the frequency , i made a special firmware to do that (in analogic)
but today i am using inverto pll LNB (universal model) with c120 flange .
in 99.9% case no need to ajust polarisation
i use also chaparal mecanic polariser in C band.
Click to expand...


Yes, current required changes with frequency, many receivers had only two ferrite settings for each satellite.

The formula for the change is not just impacted by frequency though, but type of dielectric inside the polariser, the internal diameter, the ferrit core diameter and the length of the polariser itself.
The main issue was a continuous voltage provided to an external device, via a bespoke cable run, where the impedance of the wire would change with seasonal and daily temperature fluctuation, plus the atmospheric humidity around the connectors and feedhorn.

I think there were also satellite slots with both linear and circular transmissions, requiring further adjustments of the overall bore settings when a dielectric plate was in the feed throat.

Their demise could not have come too soon.
 
Ref those magnetic polarizers: in 1991, the NEC-branded LNB on the dish of my very first (NEC 5000) sat system was mag polarized, and the Rx (NEC 3000, IIRC) had full sat-by-sat polarization adjustment that proved quite useful in those days of relatively low signal strengths as even 10 deg of adjustment off the nominal H or V settings could make a substantial difference to the signal strength - and I rather missed that when I later moved "onwards & upwards" to a Echostar Rx and a "Universal" LNB.
 
I had the 'joy' of testing the Racal 4502.....
 
Ha! I knew it was there somewhere! Definitely my searching skills have deteriorated :p
 
After reading the old post and answer , i saw this newer design .
Also very impressive !
 
dreambox1959 said:
i have bought 5 printed-board in china , it s remain only one i can launch a new order !
who wants a pack ?
components are very common !
i give you one programmed µp 89s52 , relays , but you have to find and build it all !!!

View attachment 128301


here is my device :
View attachment 128298

the other pictures in another post are the Cardiff's device.
Click to expand...
I want one !!!!!!!!
 
Impressive:Y
 
Excellent! Many thanks! Sorry, I didn't get around to doing the measurements still. Hopefully this week.
 
john !
are you able to build your own positioner with PCB and some components ?
or do you want i build it for you ? with a few money !!
 
I think that if you build them in a few dozen pieces here there would be a line to buy it, and I would be one of them, so if you want to start a limited production go ahead I could be a customer, congratulations yours is a great job
what is the value of the output voltage?
if it were 40 Volt cc it would be fantastic, in this case even with cables with an important length they do not suffer from the voltage drop, and even the motors that consume a little more current are always delivered in an optimal way
 
Dreambox1959, will this be a pure positioner or would it be possible to control the skew with it as well?
 
hi every one

i use a 2x18V Ac transformer , we get about 40-45V DC .i created a pwm stage for start and stop move.
my own dish is a 2m PF.
there is 4 relays :2 for azimuth 2 for elevation.
a special feature for LNB Changer (see in this forum) + skew control for each sat.
a large LCD screen 13x5 cms + keyboard + IR remote + Diseqc control.
i m just an electronic hobbyist , i bought components for building about five positioner (it s some money) if someone want an unit , it cost about 250euros + Shipping fees , so i need some guarantee before sending a functionnal unit.
a big part of price come from box : a nice alu front face costs about 60 euros , a simple box costs 40 euros , a strong transformer about 40 euros ....
 

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