Another Logistics nightmare solved :- Hughes KA lnb

[Vipersan]

From what I see from the scans it does look like you are achieving the switching action...
It is difficult I know ..as you have little to reference but the fact that you have at least one lockable signal which disappears would indicate this is happening ..
Sadly the footprints you receive at your location I cannot emulate here ..so difficult for me to compare..
Do remember you are for the most part switching circular polarised signals with that one exception so these would appear in both H and V to varying degrees..
If it helps I will swing the SL3 over to 9E and post my scans of the 'almost' H and V carriers I receive..
them this morning..
Well done Llew ...at first glance you look to have switched H V ok..
To prove this is relatively easy..
remove the screws holding the LNB to the OMT ..
take a small piece of thin aluminium tape of foil..
slide over each opening in turn then reattach the lnb ..
Rescan ..
In theory if the orifice is covered when the scan is done and the switching is active or not active ..
You will see or 'not' see a result..
rgds
VS

 

[Llew]

Good idea VS. I'll try that.

AFAIK there's no other receivable satellites for me within this Ka band to check the different polarities, I checked Hylas 2 31W, but I can only see one data stream (L or R, can't remember which).

 

[Vipersan]

Ok Llew ..
This is what I get scanning 19700 to 20200 ..
The gain does drop off a little at the high end ..this is the fault of the modded SL3.
As you can see the same peaks are present in both scans but then this would be expected if they are circular polarised..
There is also a slight diffence in gain the Blue scan being V the red being H ..and this is due to the SL3 largely as it is set to have the main probe in the resonance chamber angled for Horizontal ..the probe for V bing in the annexed chamber of the SL3 ..thus a little lower in gain.
But as close to H and V as I can get with this lnb...and is reliable.
rgds
VS

 

[Vipersan]

Here is my Hylas scan ..
Note the similarities or variances with 9E ..
Also Circular so the same humps in both scans.
rgds

 

[Llew]

Yes, I remember now you can check H and V with the SL3. The difference seems to be that I get the two carriers at the end of the scan in different positions on 9E.

 

[Vipersan]

Yes that is odd llew ..
Perhaps an oddity due to the coupling of the 27mhz signal ?
Perhaps just a variation within the Hughes LNB..?
But more likely due to the depolariser being in the system ..
Isolating RHCP then trying to port it to V rather than H through the OMT...and then to the opposite active port of the Hughes lnb..
Chances are if you switched the Hughes lnb ..then rotated the depolariser into it's other notched position ...the lockable carrier would appear on the opposite linear polarity..of the scan

 

[Llew]

Food for thought there VS. I'll try the various options in due course. Cheers.

 

[Vipersan]

You are going to find it difficult to test H/V in Ka band B ..simply because there aren't any linear broadcasts up there..
All appear to be circular ..
Maybe this area of the KA spectrum isn't good for linear propagation ?
..or maybe it was just a _standards_ choice made by the techies..
Ka A has linear as does Ka D & Ka C ..but not Ka B

The best way to test if your switcher actually works correctly is the port cover up method I suggested earlier..

 

[Llew]

OK, here's my results using port blanking on Hughes LNB as suggested.

H port blanked :-

No carrier detected at 20185 with 27MHz switch off.
16APSK (data?) carrier with switch on.

V Port blanked :-

Locks the 'jamming' carrier (20185L 25000 1/2)
No carrier detected with 27MHz switch on.

It appears the H/V switching is working, but I have no idea what the 16APSK carrier is in the V mode.

The 27MHz source is a simple on/off crystal oscillator circuit sending a 1V p/p sine wave to the LNB through the power block port of a 2-way splitter, with the receiver (my DVB PC card) connected to the power pass port.

 

[Vipersan]

Nice one Llew ..
Looks like you switcher works just fine..
Perhaps you should upload the schematic ?
As to the 16APSK I assume it's the one you see when using an inverto dual in RHCP mode (H switched) ..as V switched would give LHCP (RTE) in Ireland..
Sadly I couldn't confirm anything in LHCP as I no longer get anything at all ..not even a jamming carrier..
the 16APSK is however present here.
I hate spot beams ..it's set do destroy my hobby and frustrate the hell out of me...lol
I acquired another inverto dual cheap so can post up 2 scans one of each polarity if it helps ...?
rgds
VS

 

[Llew]

Yes, put your scan up VS, for comparison. I didn't save the scans of the LNB port checks, it was getting late, so it was just a visual check. I can always repeat the experiment though.

Here's the circuit I made. Farnell does the oscillator, just needs a common enough +5V regulator plus a couple of capacitors.
I used a mains adaptor to power the circuit, happened to be +12V one, but anything say +9V upwards would do. I think +5V regulators can be supplied with up to +36V if I remember, but anything too high and you might need a heat sink.

Oscillator switching off is simply pull the mains plug out!

Edit - removed an unwanted Vcc symbol from pic.

 

[Vipersan]

Is that the full part ident Llew HG-215 ?
just entered that part number at farnells site ..and nothing returned ?
actually 2 hits ..
1mghz osc package and a 20mghz package ..
where did you get yours buddy ?

 

[Llew]

Oscillator in box. Crystal is a SMT device, I just placed it on its back beetle-wise on a bit of copper foil and soldered wires to the pads.

 

[Llew]

Is that the full part ident Llew HG-215 ?
just entered that part number at farnells site ..and nothing returned ?
actually 2 hits ..
1mghz osc package and a 20mghz package ..
where did you get yours buddy ?

Dammit, they're not available from Farnell UK now, must have sold out.

The German site appears to still stock them, but haven't checked P&P from there.

http://de.farnell.com/epson/hg-2150ca-27-00mhz-svh/oszi-high-stability-27-00mhz-5v/dp/1907492

 

[Llew]

VS, Try RS online. They have them in stock now (didn't when I wanted mine).

http://uk.rs-online.com/web/p/crystal-oscillators/6676701/

 

[Vipersan]

Dammit, they're not available from Farnell UK now, must have sold out.

The German site appears to still stock them, but haven't checked P&P from there.

http://de.farnell.com/epson/hg-2150ca-27-00mhz-svh/oszi-high-stability-27-00mhz-5v/dp/1907492

Not to worry Llew there are other manufacturers ...
I am wondering though ...if the convention of standard H/V switching could be utilised ..
13v/18v ..
The difference being 5v ...
presumably it would be possible using a simple resistive ladder or op amp to produce the vcc needed only when 18v is present ?
such that only switched on when 18v present ...and since it is such a low current needed..the supply could be generated in line by the lnb switched voltage ?
so in theory it could be constructed inside a simple die cast box with only in/out F connections ....

 

[Llew]

That was how I originally made it, there's a schematic I uploaded in the KA section somewhere.

I tried it out, but the high-pass filter at the receiver input to the circuit I used wasn't adequate, there were a lot of spikes coming back to the receiver, spread across the Crazyscan spectrum.

(As I've mentioned above, RS-Online now have the oscillator).