Band 3 cartridge: For cartridge #1, a scan of the noise every 1 GHz was obtained for each LO point, power and Mixer bias. The SSB noise for the four channels is between 40K and 50K. With the mixers heated to 4K, the system noise has increased (earlier results from Jan 05 were TSSB ~40K). A final calibration of the hot load and the cold load was done in order to make sure results are compatible with the NRAO Integration Centre. The Control software for the Cartridge Test Set is now integrated with the LO and mixer bias module, resulting in a semi-automatic mode which will be upgraded towards the end of the year with a more complex fully automatic mode. Two mixers have been identified for a Cartridge #2 2SB unit. Wafer # 4 was qualified by measuring three mixers. Testing of SIS wafer #8 has begun, and the first chip tested is good. A new lot of preamps from ACC failed to meet the output return loss specification, and the cause is being investigated. The preamp test system entered into regular production use. • Band 7 cartridge: Verification testing of cartridge New hire (from Socorro into the FE LO group) Jim Muehlberg began design of the digital PLL circuit. • Tests of revised LO Photonics Line Length Corrector with a prototype cable wrap show that the phase correction is no longer susceptible to low level acoustic vibrations. (Tucson) • Recommended CAN and AMBSI- All slots in all bins of the first quadrant have now had an initial functional verification. • The Station Card firmware now provides full support for the TFB Card, and we are ready to test TFB cards. An ALMA Digitizer has been connected to drive one TFB card. The first basic spectral analysis seems correct (line detected and moved around; no conspicuous spurious features throughout the band) Marson appointed as CIPT coordinator of ATF activities. First in-kind NAOJ staff member has started work in Socorro. The move of the prototype LO sub-system from the NRAO Tucson lab to Socorro will begin June 20. Combined lab integration will begin the next week. ATF: investigated. System testing will resume week of May 9. the Sunday barbecue at the OSF:  outsourced catering does it again! The 12 M at Kitt Peak used to do lots of detection experiments in beam-switched mode. With only 4 nutators, that's not going to be a very sensitive mode on ALMA. However, for a detection experiment on extended objects, frequency switching may be the only mode possible. If any source is sufficiently extended (i.e. more than a primary beam width) than it won't be visible on any interferometric baseline. The most sensitive prospect of detecting a weak signal under these circumstances is to average the power spectra from 64 single dishes. You have to be switching something for observations like that, and frequency switching is going to be the only thing that may be fast enough. Position switching, slewing the entire antenna back and forth, may simply not be fast enough to take out the atmosphere and still allow good spectral baselines. Frequency switching, since we can't nutate the S/R on 64 antennas, is likely to be the only way to go. So, weak detections of extended sources will require frequency switching. Cheer Yes, frequency switching is only a total power only activity, and yes it is necessary for every telescope. Apart from atmospheric studies, it is the only mode ALMA will have for detection of weak extended line emission. Supposing there is line emission from a weak but extended source, which is resolved out on most, possibly all, interferometer baselines; interferometric observations simply won't see it. The only hope then is to average total power spectra from 64 (or N) antennas. We'll need to switch against something, and as most antennas will not have a nutator, that leaves antenna position switching or frequency switching. Besides being more efficient (you see the source 100% of the time) frequency switching will be much more rapid, and is likely to give superior results. It's true you could average, say, data from 4 frequency-switched antennas for 16 times as long, but I don't think that's a reasonable option. If you can frequency switch one antenna, you can switch 64 without any significant further effort. ALMA has been advertised to the community as providing better capability than any of the existing (or now closed) single dish instruments, in both total power (i.e. extended emission) and interferometric observations. Without frequency switching this won't be true. I really don't understand why this is even in question. It's not a major expense, and has been in the design from the beginning. It's a different issue from supplying nutating mechanisms, because the cost is much lower (close to zero if not actually zero, since it'll be the same design of LO on all antennas, and if you can do it on one, you can do it on all of them.) So far, as I understand it, although we've agreed that only 4 antennas are likely to be used for total power continuum, I think it's still the case that total power spectral line observations are to be supported by all 64 (well, N) antennas. FS is an important part of spectral line TP observing. There isn't much widget space above the receivers for something like a chopping mirror, so I suspect that if we're to do beam switching at all, it has to be with the secondary.