s-band
Member
- Joined
- Feb 7, 2016
- Messages
- 1,251
- Reaction score
- 2,002
- Points
- 113
- My Satellite Setup
-
1.5m IRTE PF, Invacom SNF-031, TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El (being refurbished), 1.8m Precision PF with Bullseye Ku LNB or various C & X bits
- My Location
- Essex
Provoked by John's thread Just Sharing This - 1.2 Precision / Octagon lnbf mod I got around to fitting an Octagon PLL LNB to an Invacom C120 flange. The id of the Octagon is within 0.2mm of the id of the IRTE feed but I think there's an extra error of the same order due the LNB not being quite concentric with the flange. It is only force fitted at the moment and I may try to re-do it.
I did comparisons on 1W which is probably not the best option due to the 0.5 degree spread but the dish was not moved between tests carried out at the same time. Two tests (SMW vs. Invacom and Invacom vs. Octagon) were done at different times. At about 14dB SNR, QPSK, a 2dB change in SNR is equivalent to about 2.8dB in RF level using the TBS6983.
The table gives the averages for all transponders. It masks the fact that, on some TPs, the Octagon was ~2dB down on the Invacom. The SMW and Invacom were more consistent. XML files for the Octagon & Invacom are attached as .txt.
Concluding, the SMW 1dB max NF was a bit better than the Invacom 0.3dB which was 0 to 2dB better than the butchered Octagon 0.1dB.
SMW LNA and IRTE Feed https://www.satellites.co.uk/forums/attachments/smw_lna-bdc_dsc1067-jpg.94158/
I did comparisons on 1W which is probably not the best option due to the 0.5 degree spread but the dish was not moved between tests carried out at the same time. Two tests (SMW vs. Invacom and Invacom vs. Octagon) were done at different times. At about 14dB SNR, QPSK, a 2dB change in SNR is equivalent to about 2.8dB in RF level using the TBS6983.
The table gives the averages for all transponders. It masks the fact that, on some TPs, the Octagon was ~2dB down on the Invacom. The SMW and Invacom were more consistent. XML files for the Octagon & Invacom are attached as .txt.
Code:
SNR Average
4/6/16
Skew peaked at mid frequency, horizontal
Invacom H (same time as SMW) 14.35dB
SMW H (with above) 14.83dB
31/7/16
Skew peaked on lowest frequency Horizontal only
Invacom V & H 14.28dB
Octagon V & H 13.57dB
Invacom H 14.60dB
Octagon H 14.00dB
Concluding, the SMW 1dB max NF was a bit better than the Invacom 0.3dB which was 0 to 2dB better than the butchered Octagon 0.1dB.
SMW LNA and IRTE Feed https://www.satellites.co.uk/forums/attachments/smw_lna-bdc_dsc1067-jpg.94158/
Attachments
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