| Electronics > Repair |
| Aeroflex IFR-2398 / calibration / repair help |
| << < (12/16) > >> |
| vk2cow:
Thanks George, this looks like the circuit in my analyser indeed. I am guessing this is from the service manual of the LG version of the same instrument? |
| vk2cow:
For the benefit of future generations troubleshooting an IFR 2398. Initially: 0) All self cal pass exept the Level cal 1) I got SWR 4:1 or worse (antenna analyser looking into spec an input, spec an switched on, SWR the same regardless of attenuation selection (0 to 50 db, 10 dB step). 2) I see the spec an built in cal 40 MHz signal at -42 dBm (should be -30 dBm) and any signal provided to the input of the spec an was over 20 dB less than what it should be. My thinking: 3) I focused to the circuit directly at the input of the spec an (as indicated by the SWR behaviour). Thanks to George for the schematic. My actions (so far): 4) I supplied -12 volts to the board, then measured the voltage on each of the two control pins of every AH002R2 RF switches. All of them had ~-8.8V and 0V but the first one had -1V and 0V. 5) I removed the first AH002R2 switch 6) I connected directly with a short jumper to connect the N-type input to the rest of the attenuator chain (pin1 to pin7 from memory). 7) Re-installed the RF module. All self CAL failes exept the YIG - expected as there's no connection to the 40 MHz internal cal signal. SWR is now 1:1 (yey!!!) 8) Just for fun, added an external 40 MHz about -30 dBm signal to the input of the analyser and rebooted it. It passed all tests! Under these conditions, it behaves as you would expect but the amplitude seems to be out by ~3 dB. Given the dodgyness of the calibration, that's hardly a surprise. I have ordered a AH002R2 from eBay (fingers crossed) and will report what happens when I install it. cheers Dimitris |
| doarmin:
Bonjour rien depuis fevrier dernier y a t il du nouveau depuis le remplacement du circuit?? Personnellement je recherche le schemas de la carte vidéo detecteur IFR2398 ref 513-648A.car comportement bizarre autour des capas chimiques C175 à C177. |
| George Edmonds:
Hi These electrolytic capacitors and a none electrolytic capacitor, plus a number of resistors and an inductor appear to be form just an input filter for the +15VDC supply to the board. G Edmonds |
| George Edmonds:
Hi Please note that I cannot and will not provide full schematics, here is a partial scan showing the +15VDC input filter. G Edmonds |
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