![]() |
| If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|||||||
|
|
Thread Tools | Display Modes |
|
#19
|
|||
|
|||
|
Experts, correct me where I'm wrong.
1. An operating transponder, not being interrogated, is simply a receiver with a low current drain. 2. When interrogated by a ground radar or TCAS, a transponder transmits a short "squitter" at 175 or 250 watts which is a BIG current drain. 3. Flying in an area with many interrogations per minute is likely to be a congested area where the transponder is needed and a wise pilot would keep it on despite the current draw. 4. Flying away from a congested area toward a remote area with few interrogations, the transponder automatically cuts back on its current draw by operating less and less as a transmitter and more as a receiver. So, where is the need to turn it off? Doesn't the transponder effectively manage its own current draw to match the level of congestion? Move away from congested areas and the current draw is minimal. I haven't read of a case where the transponder is sucking batteries flat and if that happened, how much additional battery capacity is needed to keep it running for the whole flight? (I can remember pilots carrying car starting batteries to run a vacuum tube radio. No imaginable suite of avionics would draw that much current today.) So, aside from the cost of a transponder installation, what is the concern? Bill Daniels p.s. Having suffered a couple of alternator failures at night in hard IFR with single engine airplanes, I became very interested in the current draw of each bit of avionics. My calculations showed is that if the aircraft battery is in good condition and fully charged at the point where the alternator failed, and the pilot swiftly switches off the alternator field with the split master, the battery will run a full IFR panel longer than the fuel will last. I tested that calculation and it proved true with good safety margins. |
| Thread Tools | |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| VHF & Transponder antenna | Steve | Home Built | 1 | December 6th 04 05:29 PM |
| Operation without a transponder | flyer | Piloting | 11 | September 14th 04 09:48 AM |
| Transponder test after static system opened? | Jack I | Owning | 6 | March 14th 04 04:09 PM |
| Fixing the Transponder with Duct Tape and Aluminum Foil | Ron Wanttaja | Home Built | 45 | March 14th 04 01:18 AM |
| transponder codes | Guy Elden Jr. | Piloting | 1 | December 2nd 03 06:21 PM |