s-band
Specialist Contributor
- Joined
- Feb 7, 2016
- Messages
- 1,188
- Reaction score
- 1,846
- Points
- 113
- My Satellite Setup
-
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El (being refurbished)
- My Location
- Essex
The actuator drives the 1.2 OK but at its limit even the 1.2 is not easy to shift manually. The only flop is caused by the fixed joint slop mentioned above, the moving mount isn't too bad. I've only ever used big PF dishes in the past and hadn't quite realised how out of balance the offset is - obvious if I'd thought about it more. Even the old 3m was easier to handle than this thing. The inclined drive is fine and very smooth, the vertical load is taken by the mount. The current drawn by the Linak is quite low indicating it's not straining too much. Looking at the mount and it's full range of movement, the pic below is the only way I can see to add a counterbalance easily. In plan view it will be an H frame with 2 weights. However, it's going to increase the dead weight by 50kg, at a guess, although that will be vertical if balanced. Does this make sense?
I did a quick test using a Sharp PLL BS1K2EL LNBF. It took about a minute to align to 1W (benefit of inclined tracking). I compared it to the 1.5PF (Inverto black) and the results suggest that the PF is not aligned. Using 30W, the average SNRs were:
The detail suggests that the PF feed or LNB falls off a bit at the bottom end. It is quite likely that the PF is mis-aligned as it has not been tweaked for >10 years. EBSPro files attached.
Another observation was that the cross polar rejection was only 16-18dB on the CM but is 20-24 on the PF. Also, the position of the feed on the CM holder did not seem very critical. The sharp has a long neck and moving it 25mm only made fractions of a dB difference. There are too many variables in this comparison but it was done mainly to play with the mount.
I did a quick test using a Sharp PLL BS1K2EL LNBF. It took about a minute to align to 1W (benefit of inclined tracking). I compared it to the 1.5PF (Inverto black) and the results suggest that the PF is not aligned. Using 30W, the average SNRs were:
Code:
1.5PF 1.2CM
H 14.2 14.4
V 14.2 13.9
Tps 71 73
The detail suggests that the PF feed or LNB falls off a bit at the bottom end. It is quite likely that the PF is mis-aligned as it has not been tweaked for >10 years. EBSPro files attached.
Another observation was that the cross polar rejection was only 16-18dB on the CM but is 20-24 on the PF. Also, the position of the feed on the CM holder did not seem very critical. The sharp has a long neck and moving it 25mm only made fractions of a dB difference. There are too many variables in this comparison but it was done mainly to play with the mount.
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