Newsnet on Ka Band A

[s-band]

Hi Tony, Sorry, I lost the plot there, the frequency should have been 18894.75H (not 17894 as my post) with its V neighbour 6kHz above. My LO is at 18.25GHz giving an IF of 644.75MHz (and 306MHz IF for ITN Newsnet) as my LNB is a modified band B.

The feed is here Ka with Prodelin/Viasat 1.2m Band B I'm not using the main body or the circular polariser. I also have a feed, for higher frequencies, which does not have the teeth around the WG.

 

[tony smith]

Hi s-band
Yes that's better, understand your downconvertor, and why no filter, OK but I cannot see this carrier, but will change my
front end during the coming week to get at better look at H, one of my other feeds has less other pol rejection, one we made.

 

[Channel Hopper]

Hi Tony, Sorry, I lost the plot there, the frequency should have been 18894.75H (not 17894 as my post) with its V neighbour 6kHz above. My LO is at 18.25GHz giving an IF of 644.75MHz (and 306MHz IF for ITN Newsnet) as my LNB is a modified band B.

The feed is here Ka with Prodelin/Viasat 1.2m Band B I'm not using the main body or the circular polariser. I also have a feed, for higher frequencies, which does not have the teeth around the WG.

That is a different front end system to the one I thought you had, but no matter.

Skyware do a feed system that is compatible with the Prodelin offset antennas, and they use a non elliptical feedhorn, presumably since the antennas are in the normal plane with larger dimention in the vertical.

http://www.skywareglobal.com/wp-content/uploads/2015/09/Ka-Circular-RXTX-Feed-Spec.pdf

Circular polarity aside, it is interesting they have the option of an 'extended' feed system, which extends into the lower band for Astra 1L reception. If it not filtered differently along the waveguide then conceivably it might have a different dimension in part of the waveguide, and yet still retain the WR42 transfer at the important end.

 

[s-band]

Skyware do a feed system that is compatible with the Prodelin offset antennas, and they use a non elliptical feedhorn, presumably since the antennas are in the normal plane with larger dimension in the vertical.

http://www.skywareglobal.com/wp-content/uploads/2015/09/Ka-Circular-RXTX-Feed-Spec.pdf

Very interesting, thanks. The circular polariser and feed look the same as the ones I have but with mine the OMT is within the ODU body. There is no filter to keep TX out of RX apart from a choke at the OMT/LNB transition and anything that may be inside the OMT. I have 2 different banded feeds, one for 19.2-20.2 (which I use down to 18.5) and the other 21.4-22. The only visible difference is that the lower frequency one has teeth around the inside of the circular WG to the feed horn. None of them have standard WG sized apertures nor to the guides within the ODU

 

[Channel Hopper]

In this business you quickly find coincidences with product specification turns out to be down to a third party supplier.

NC (a radius of 200miles from Smithfield) is awash with employees and ex staff from a number of famous names in the industry

 

[tony smith]

Hi s-band
Had a look today ref any carriers around the 18.894 Ghz mark nothing that I can see at my site, even on the lowest threshold
of the R&S, on any linear polarity. all looks very clear.

In fact this section of the sky at 19.2 east looking K band has very little active.

K band (18.2 - 19.2 Ghz) was always at one time very busy, when it was used by North American, the bread and butter
Andrews 3.7 metre ESA King post antennas, which we installed a few, would cover from Ku (K band under) up to K band with
the same dual reflector optics and wave guides, although we did at times use the TX port on the OMT.

 

[John]

.. Any Star Wars fans, some 18GHz coverage at the moment.
...................................................................................................................................................................................................................................................................................................................................................................................

 

[Llew]

The Force isn't with me too well tonight John - some break up

 

[Llew]

Odd feed today (main Newsnet frequency) - is there a balmy microclimate region in the UK somewhere ? Not an overcoat in sight

 

[scopus]

Odd feed today (main Newsnet frequency) - is there a balmy microclimate region in the UK somewhere ? Not an overcoat in sight

View attachment 114974

Not so warm in Brighton now.....

 

[Llew]

That's better...

 

[Llew]

18527V 3629 2/3

SIS101 guys working hard

 

[Llew]

...Gone for tea?

 

[scopus]

...Gone for tea?


View attachment 116091

More like a crafty beer,

 

[s-band]

Today's scan & test cards

 

[John]

Today's scan & test cards

View attachment 116199View attachment 116200View attachment 116201

Is that using the XMW pll Graham ?.

 

[s-band]

Is that using the XMW pll?.

No, that's in bits, it's a much modified Gilat B

 

[s-band]

Busy today
XMW LNB, skew not optimised, 1.2m
Plenty of SIS test cards

 

[John]

Busy today
XMW LNB, skew not optimised, 1.2m
Plenty of SIS test cards
View attachment 116259View attachment 116260

XMW ...... youv'e cracked one of them then ?. Good work.
Edit:
Saw the post before i read the email doh. Nice one

 

[mikeisyou]

Has anyone got any spare time tonight for a ka-band scan on Astra 1, I will be forever grateful. Thanks