As I see it, we have a few options for getting the 110 MHz LO to both the POP110 and AS110 demod boards.
The current situation is described by Kiwamu in elog 5746. The 55 MHz signal comes into the box, and is split 4 ways, with each path having 19.7 dBm. One of these 4 is for 110. It has a 2dB attenuator (giving us ~17.7 dBm), and then it goes to an MK-2 frequency multiplier. I'm a little lost on why we're giving the MK-2 17 dBm, since it says that it can handle an input power between 1 - 15 dBm. It has ~16 dB conversion loss, so the 110 output of the distribution board has (according to the drawing) 1.9 dBm. The demod boards have a 10 dB attenuator as the first element on the LO path, so we're giving the ERA-5 -8 dBm.
We can either amplify the 110 leaving the distribution box, split it, and then attenuate it to the appropriate level for the demod boards, or we can change the attenuators on the POP110 and AS110 demod boards.
Since we seem to be over driving the 2x frequency multiplier, I think I should change the 2dB attenuator to a 5dB attenuator, so we're giving the 2x multiplier ~15 dBm. The conversion loss of ~16 dB means we'll have -1 dBm of 110 MHz. I want to amplify that by ~10 dB, to give 9 dBm. Attenuate by 5 dB to get to 4 dBm, then split into 2, giving me 2 110 MHz spigots, each of ~1 dBm. Since the demod boards expect between 0-2 dBm for the LO's, this should be just fine.
Thoughts, before I start scrounging parts, and pulling the RF distribution box? |