EuropaSat/Hellas Sat 3 & GSat 17 VA-238,

[John]

... after thinking on a bit about this polarity mod for the XMW cone feed i can use my 1.2 CM test dish at ground level with a spare 18GHz lnb. Iv'e made a start on the plate by copying a shape off the net .... will be very much trial and error using the Promax but should be interesting, especially if it stops raining.
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[John]

... This little fella has turned up this morning at very low level on my Horizontal lnb at 18721.50. The normal beacon is on the right.
@Llew .... have you anything on your Vertical lnb Llew ?.
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[Llew]

Yes 19721V, at good strength John -

 

[Llew]

Same strength on Horizontal by the way.

 

[John]

.. Yep, the little fella has grown slow but sure over the last half hour or so and as we speak seems to be up at the same level as the other freq.

 

[Llew]

Now the weather's more promising, I'll do some further polarity investigation with a plate tailored to the XMW feed.

 

[John]

Now the weather's more promising, I'll do some further polarity investigation with a plate tailored to the XMW feed.

Yep, weather improved dramatically here today as well so will drag the test dish out. That new freq has gone into overdrive now

 

[Marcus_21]

Tests carrier this morning.. frequencies 11471 H and 11553 H (should be on the Middle East beam).

 

[Llew]

Got the random burst up at around the 19146 area John. Don't think its internally generated, goes when feed mouth covered.

 

[John]

Got the random burst up at around the 19146 area John. Don't think its internally generated, goes when feed mouth covered.

View attachment 108737

.... struggling at the moment trying to optomise a bit of old credit card material to act as a dielectric plate. I can gain nearly an extra dB on the signal as opposed with out it but i can not null it out as i should be able to .... assuming it's a circular signal and it's also very critical to get the slab position just right. I'm just having a think now as to what other method i can use ie: the Hughes polorizer section.

 

[John]

... favourite saying again, "where there's a will there's a way". I'll see if i can get this to null in the right place, if so , i can think on about grafting the feed onto it.
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[Llew]

Yes, I didn't null it out when I tried yesterday. Maybe they have two transponders working V and H on the same frequency

 

[John]

Yes, I didn't null it out when I tried yesterday. Maybe they have two transponders working V and H on the same frequency

.. Could well be Llew. This Hughes polorizer works pretty well on this bit of a lash up lol.

 

[Llew]

That's what I'm using John. Cap with plate. Nulls out to just above noise level, barely visible.

Plate at 45° gives maximum (more than without plate), plate at 315° nulls it out (almost).

 

[Llew]

Had the plate angular positions wrongly typed. 315° and 45° results corrected.

 

[John]

Nice one, i do like that cap idea Llew. On my lash up the lnb remained in the Vertical probe position and just the Hughes polorizer position was changed. For a lash-up this has been quite successful , with a bit of skew applied it totally nulled. Change the poloriser through 90° and the signal is there at full strength. Now need to make a propper job of it and treat it to a feed lol. Taking observations from my Cband poloriser positions i'm 99.9% that the signal is being received in RHCP..
** The first picture shows the setup in LHCP.
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[Llew]

That's a good way you've done that John. I'll try that myself sometime. We did a lot of stuff with the Hughes parts when we started Ka experiments.

Yes the cap/plate idea makes it easy to adjust the setting by simply turning the cap round, knowing the plate stays central in the mouth.

 

[John]

That's a good way you've done that John. I'll try that myself sometime. We did a lott of stuff with the Hughes parts when we started Ka experiments.

Yes the cap/plate idea makes it easy to adjust the setting by simply turning the cap round, knowing the plate stays central in the mouth.

.. I was getting nowhere fast when i tried using card so had to go onto the Hughes. Just need to do a proper job on the mating of the two surfaces. I could do with trying to find a decent Ka rotating joint to really make it versatile. Another job to put on the list.

 

[Marcus_21]

At this time a 12495 V carrier is active



Previously it was active full transponder (12475,50 V)

 

[John]

.. just thinking out of the box a bit re: the 18GHz program output of this satellite when it gets into full service, the beacons would seem to be RHCP, will the programming be circular or linear though ?. I can't at the moment think of any 18GHz Ka lnb linear or circular for domestic use that's available so will be interesting to see what is going to be the recommended lnb / lnbf to use. Will it be a bit of a special thing newly produced like the Inverto Ka / Ka lnbf of recent ? . So until that info is known i'm going to hold back a bit with any further development on my lash-up