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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
Titanium PLL C Band LNBs
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<blockquote data-quote="s-band" data-source="post: 968135" data-attributes="member: 407744"><p><strong>Mods to C1W-PLL (not-Lite)</strong></p><p></p><p><strong>Polarisation</strong></p><p>As received this switched at 15V to H and 14.5 to V. Curiously, there is an intermediate state when dropping from 14.7 to 14.6V. The level dropped by ~10dB before switching fully. That may be yet another reason why random changes in performance are seen. I didn’t investigate but maybe it’s when both front ends are on at the same time? It’s probably not needed but I changed the switching voltages to 15.9/15.2V by changing the circled resistor to 8k2 (was 10k)</p><p></p><p><strong>TCXO</strong></p><p>This was fitted in a different way, compared to the lite, on another piece of PCB with track hacked to suit. The PCB is grounded via a copper strap with some Kapton tape to prevent shorting to the main PCB tracks. As per Osmocom, the level is not really that critical. When doing the lite I hadn’t noticed that the duty cycle of the Rakon output changes dramatically if loaded resistively. That must have messed up the bias in the downconverter. For this one I put a 47p in series and then a 100p to ground to form a capacitive divider to drop the level. The supply was fed from the 6V line via a 220R decoupled with 100n. The voltage is still a bit high but it works.</p><p></p><p>The point marked “TP” can be used to probe with a counter without upsetting the TCXO.</p><p></p><p><strong>Sealing</strong></p><p>I also put some screws in the empty fixing holes and the holes for which I didn’t have short enough screws, I filled with sealant.</p><p></p><p>I don’t know why I spent so long on this but once I started….</p><p></p><p>[ATTACH]92312[/ATTACH]</p></blockquote><p></p>
[QUOTE="s-band, post: 968135, member: 407744"] [B]Mods to C1W-PLL (not-Lite)[/B] [B]Polarisation[/B] As received this switched at 15V to H and 14.5 to V. Curiously, there is an intermediate state when dropping from 14.7 to 14.6V. The level dropped by ~10dB before switching fully. That may be yet another reason why random changes in performance are seen. I didn’t investigate but maybe it’s when both front ends are on at the same time? It’s probably not needed but I changed the switching voltages to 15.9/15.2V by changing the circled resistor to 8k2 (was 10k) [B]TCXO[/B] This was fitted in a different way, compared to the lite, on another piece of PCB with track hacked to suit. The PCB is grounded via a copper strap with some Kapton tape to prevent shorting to the main PCB tracks. As per Osmocom, the level is not really that critical. When doing the lite I hadn’t noticed that the duty cycle of the Rakon output changes dramatically if loaded resistively. That must have messed up the bias in the downconverter. For this one I put a 47p in series and then a 100p to ground to form a capacitive divider to drop the level. The supply was fed from the 6V line via a 220R decoupled with 100n. The voltage is still a bit high but it works. The point marked “TP” can be used to probe with a counter without upsetting the TCXO. [B]Sealing[/B] I also put some screws in the empty fixing holes and the holes for which I didn’t have short enough screws, I filled with sealant. I don’t know why I spent so long on this but once I started…. [ATTACH]92312[/ATTACH] [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
Titanium PLL C Band LNBs
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