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DISH SETUP: Single sat, Multi-Sat & Motorised
KA Band section
Ka B/C overlap (Hughes) Thread
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<blockquote data-quote="Vipersan" data-source="post: 893545" data-attributes="member: 325666"><p>So this is where it gets tricky ..</p><p>I have simply cap coupled the output of the osillator to the IF line ..</p><p>I did an unterminated scan at 42 E ..and one with the SL3 connected ..</p><p>You can see that it crushes the IF making the previously 10db turksat signal unusable ...</p><p>and standing or travelling waves evident in the unterminated scan.</p><p>this is simply loading the IF line via a 15pf capacitor to the osc and NOT entirely related to the 27mhz signal as a similar result can be seen in both Vertical and Horizontal scans ..</p><p>As I suspected ..a better method of injecting the 27mhz signal is needed ..</p><p>cap coupling is inadequate..</p><p>I am hoping a PIN diode might be the answer but may simply make it worse ..or not work at all..</p><p>As I have already said ..RF is a tricky unpredicatable beast..</p><p></p><p>Tomorrow I will try a smaller capacitor ...as there is already some capacitance between the IF line and the osc output as these 2 lines lie side by side on the verro board ..</p><p>I'd estimate in the order of 1 to 2pf ....and this does not crush the signal but it is doubtful sufficent 27mhz signal is coupled to the IF at this level of capacitance.</p><p>rgds</p><p>VS</p></blockquote><p></p>
[QUOTE="Vipersan, post: 893545, member: 325666"] So this is where it gets tricky .. I have simply cap coupled the output of the osillator to the IF line .. I did an unterminated scan at 42 E ..and one with the SL3 connected .. You can see that it crushes the IF making the previously 10db turksat signal unusable ... and standing or travelling waves evident in the unterminated scan. this is simply loading the IF line via a 15pf capacitor to the osc and NOT entirely related to the 27mhz signal as a similar result can be seen in both Vertical and Horizontal scans .. As I suspected ..a better method of injecting the 27mhz signal is needed .. cap coupling is inadequate.. I am hoping a PIN diode might be the answer but may simply make it worse ..or not work at all.. As I have already said ..RF is a tricky unpredicatable beast.. Tomorrow I will try a smaller capacitor ...as there is already some capacitance between the IF line and the osc output as these 2 lines lie side by side on the verro board .. I'd estimate in the order of 1 to 2pf ....and this does not crush the signal but it is doubtful sufficent 27mhz signal is coupled to the IF at this level of capacitance. rgds VS [/QUOTE]
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DISH SETUP: Single sat, Multi-Sat & Motorised
KA Band section
Ka B/C overlap (Hughes) Thread
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