- 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.
- Calibrated the RF Amp Adj slider for the PMC RF Modulation (on the phase shifter screen)
- The PMC 35.5 MHz Frequency reference card is now in our 40m DCC Tree.
- The LO and RF signals both look fairly sinusoidal !
- 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.
- 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.
- 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. |