Everyone loves to skew ..but not everyone needs to

[Vipersan]

Whilst experimenting with the feed I recently constructed ...as a side project ...I decided to see just how many circular L/R polarised channels would actually lock _without_ any form of dielectric plate or depolarizing mechanism in place ..
So an open throat ESX421 lnb with scalar feed on a 1.8 pf dish ...thus polarisation is irrelevant ...so left off the list.
The lnb is therefore Skewless and could be placed at the focus in any rotation ..and H or V selected ..it matters not
The DB values are those provided by the F15 ..the receiver used ....and should only be used as relative comparison levels..
What I can guarantee is that these channels listed are lockable without depolarisation on a 1.8 ...around Manchester UK
This may be useful info for anyone thinking of experimenting ..or getting involved in C band ...and there are precious few of us in Blighty..
All the best for 2012 and good hunting
;)
VS

..a final note worth adding I think ..
This list was made and checked in thick cloud and drizzly rain conditions ...so more may be possible on a clear day..




Express AM1 at 40.0°E
3675
tp 6 RSCC DVB-S 33483-7/8
(7.1 db)
---------------------------------------

Arabsat 5A at 30.5°E
4176
tp 16 Arabsat DVB-S 27500-3/4
(5.7 db)
----------------------------------------

Arabsat 5C at 20.0°E
3707
tp 1 TV Oromiyaa DVB-S 2200-3/4
(7.9 db)

3913
tp 7 TV de Mauritanie DVB-S 8150-3/4
(8.0 db)

4054
tp 14 Qatari mux DVB-S 27500-3/4
(6.0 db)
-----------------------------------------------

Intelsat 10-02 at 1.0°W
4025
tp 24 BBC Arabic DVB-S 7324-2/3
(6.3 db)
-----------------------------------------------

Atlantic Bird 3 at 5.0°W
3633
tp C6 Tele Congo DVB-S 2018-7/8
(6.3 db)

4114
tp C4 Télé Africa DVB-S 2143-5/6
(7.5 db)

4117
tp C4 1 Music DVB-S 2222-3/4
(6.0 db)

4120
tp C4 (Optima Sports feeds) if active of course... DVB-S 2222-3/4
(8.0db)
-----------------------------------------------------------------

Express AM44 at 11.0°W
3662
tp 6 RSCC DVB-S 10808-1/2
(4.5 db)
----------------------------------------------------------------

NSS 7 at 22.0°W
4115
tp 35 American Forces Network DVB-S 3680-2/3 (encrypted power Vu)
(9.5 db)

4179
tp 18 Arabsat/ASBU Bouquet DVB-S 27500-7/8
(6.8 db)
----------------------------------------------------------------

Intelsat 905 at 24.5°W
4111
tp 86 ORTM DVB-S 5750-1/2
(2.3 db requires a wait of about 10 seconds to lock but always does)
----------------------------------------------------------------

Intelsat 907 at 27.5°W
3838
tp 22 RTP Internacional DVB-S 7235-3/4
(5.2 db)

4048 R
tp 25 Record Internacional Europa DVB-S 7000-3/4
(6.1 db)
----------------------------------------------------------------

NSS 806 at 40.5°W
3630
tp 20 ERT World DVB-S 3333-2/3
(7.5 db)

3830
tp 12B Global Media Telecomunicaciones DVB-S 6142-7/8 (Encrypted)
(6.5 db)

3889
tp 23A Época TV DVB-S2 MPEG-4 1050-5/6 (time of day dependent but will lock sometimes)
(5.5 db)

4059
tp 15 Hipodromo de San Isidro DVB-SMPEG-4 1700-2/3 (wait a few seconds)
(7.5 db)

4088
tp 16 Canal 39 DVB-S MPEG-4 1476-7/8
(8.3 db)

4094
tp 16 Atel TV DVB-S 2963-3/4
(5.9 db)

4100
tp 16 Televen DVB-S 6111-3/4
(8.7 db)
-----------------------------------------------------

Intelsat 707 at 53.0°W
3808
tp 22 Africable DVB-S 3906-1/2 (requires a few seconds wait to lock)
(2.5 db)

 

[Huevos]

It would be interesting to see the results with the plate in and out. My guess is 3dB difference.

Also, the opposite should be possible, i.e. receiving a linear signal with the delay plate in the LNB. Not 100% sure that that will work in both polarities. It does with a yagi, but in that case the delay is created by having one radiator 1/4 wave further forward than the other, or by having a harness that does the same, the big difference though with a yagi for circular is there is an active element in each polarity.

 

[Vipersan]

Hi Huevos ...
I'll run a test on the few linear birds I can access in the near future ...
Feeling too rough today ...
after a small amount of alcohol and a very late night ..new years eve..
;)