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Message ID: 10849     Entry time: Tue Dec 30 20:35:59 2014
Author: rana 
Type: Summary 
Category: PSL 
Subject: PMC Tune Up 
  1. Calibrated the Phase Adjust slider for the PMC RF Modulation; did this by putting the LO and RF Mod out on the TDS 3034 oscope and triggering on the LO. This scope has a differential phase measurement feature for periodic signals.
  2. Calibrated the RF Amp Adj slider for the PMC RF Modulation (on the phase shifter screen)
  3. The PMC 35.5 MHz Frequency reference card is now in our 40m DCC Tree.
  4.  The LO and RF signals both look fairly sinusoidal !
  5. Took photos of our Osc board - they are on the DCC page. Our board is D980353-B-C, but there are no such modern version in any DCC.
  6. The PMC board's Mixer Out shows a few mV of RF at multiples of the 35.5 MHz mod freq. This comes in via the LO, and can't be gotten rid of by using a BALUN or BP filters.
  7. In installed the LARK 35.5 MHz BP filter that Valera sent us awhile ago (Steve has the datasheet to scan and upload to this entry). It is narrow and has a 2 dB insertion loss.

For tuning the phase and amplitude of the mod. drive:

- since we don't have access to both RF phases, I just maximized the gain using the RF phase slider. First, I flipped the sign using the 'phase flip' button so that we would be near the linear range of the slider. Then I put the servo close to oscillation and adjusted the phase to maximize the height of the ~13 kHz body mode. For the amplitude, I just cranked the modulation depth until it started to show up as a reduction in the transmission by ~0.2%, then reduced it by a factor of ~3. That makes it ~5x larger than before.

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