Older PHI surface analysis systems use an A number for all the various power supplies that are part of a particular system. I have no idea what the A stands for. Below is a list of the A numbers for some of the PHI units. I plan on expanding this list as more information becomes available.
The A numbers can be useful if you find a cable but do not know where it connects to. If there is a label on the cable the A number can at least get you to the right unit.
| Model number | Description | A number |
| 96 A | V/F preamp | A76 |
| ABS select | ABS/Heater select box | A114 |
| AVC | Auto valve control | A118 |
| Boostivac | Ion pump control | A218 |
| Bulk Head | Bulk head panel | A112 |
| CMA/MCD | Deflection Divider | A277 |
| DCGIII | Ion gauge control | A47 |
| DIGITEL 500 | Ion Pump Control | A137 |
| E.C.L. PS | Amp disc power supply | A259 |
| Filter Bias | SIMS multiplier filter | A139 |
| Power Dist. | Fuse strip | A143-2 |
| Neut. Defl. | Neutralizer deflection box | A223 |
| Oven/Pneumatic | Air and power distribution | A117 |
| SPEC PS | Specialty power supply | A143-1 |
| RF PS | RF Generator power supply | A284 |
| Vid Mon | Video monitor | A152 |
| 1182 | Amplifier discriminator | A236 |
| 11-065 | Ion Gun Control | A4 |
| 16-020 | Heat exchanger | A78 |
| 16-050 | Heat exchanger | A282 |
| 18-180 | Electron gun control | A268 |
| 20-020 | Heater control | A183 |
| 20-028A | Heater control | A114 |
| 20-320 | Electron gun control | A159 |
| 20-327 | Electron gun control | A210 |
| 20-610 | Bertan HV supply | A71 |
| 20-622 | Electron gun control | A193 |
| 22-040 | X-ray source HV supply | A160 |
| 250 | MCD preamp | A250 |
| 257 | Interface board | A258 |
| 32-096 | X-ray source control | A79 |
| 32-096 | X-ray source control | A79 |
| 45-300 | Electronic console | A194 |
| 71-205 | Motor control board | A127 |
| 72-030 | Neutralizer control | A191 |
| 74-062 | Digital Storage Monitor | A188 |
| 72-250 | PSD supply | A141 |
| 74-500 | DASH electronics | A252 |
| 72-100 | Electron multiplier supply | A123 |
| 72-150 | AES analyzer control | A128 |
| 72-360 | Small area lens board | A167 |
| 72-700 | SIMS Quad Control | A283 |
| 73-057 | SIMS analyzer control | A139 |
| 77-067 | Ion Gun Control | A125 |
| 77-072 | DP scanning control | A230 |
| 79-170 | Scanning Electronics | A186 |
| 81-175 | Scanning Electronics | A187 |
| 80-360 | Analyzer Control | A124 |