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 |
#1
|
|||
|
|||
For Jim Weir: Transponder Installation
Hey, Jim, I've bought a Microair T2000 to replace the bum transponder in my
Fly Baby. A couple of questions: 1. The instructions say not to install the antenna within one meter of the unit. What's the limiting factor here? I always prefer short cable runs, and had a nice spot picked out 15 or so inches away. What problems is a near-by antenna introducing? The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. 2. The Microair uses a DB-25 connector. I haven't soldered onto a connector like this for about eighteen years. I'm presuming the best approach would be to tin the wires, slide them into their locations, and solder them in place? Should I be using shrink tubing on each connection, too? (the connector itself has a strain relief). 3. I'm about 99.99999% sure about this, but with $1500 on the line, I'd appreciate confirmation: When the installation manual shows the pin assignments for the DB-25 connector, the assignments are as if I am looking directly at the connector on the transponder...right? In other words, the connector itself will be a mirror of this diagram. That seems to be confirmed by the teeny teeny numbering on the DB-25 supplied with the unit. A couple of questions to RAH in general: Considering that I operate in an ATC environment next to never (Excluding the temporary tower at Arlington, I've been into a controlled field three times in the past seventeen years, and two of those were NORDO), is there any real need to install an external Ident button? The one on the unit itself is tiny, but I figure I can pull off a glove to press it if needed. Adding a button complicates my connector arrangements (the unit is being installed in a removable box). Second, my existing encoder is a Terra AT3000. It was working at the last check, but is anyone aware of any specific issues with this model? As long as I'm digging things up anyway, I could just as well pay another $150 for a new encoder, but am loath to do that without a specific reason. (Loath, adj.: Already in trouble with the wife for spending $1500 for a new electronics gadget.) Ron Wanttaja |
#2
|
|||
|
|||
I figured since you posted it in the newsgroup it was open to others
throwing out their 2 cents... Ron Wanttaja wrote in message . .. 1. The instructions say not to install the antenna within one meter of the unit. What's the limiting factor here? I always prefer short cable runs, and had a nice spot picked out 15 or so inches away. What problems is a near-by antenna introducing? I'd follow their advice, apparently they have concern that some of that 200W on Tx will make it back inside the box. The field strength falls off quickly with range so moving the antenna away from the rest of your gear makes a big difference. The short antenna cable runs will give you slightly more power I suppose radiated but I don't think anyone is going to notice, especially if you're using the right coax for your antenna feed. The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. The jury is still out on what effects microwave radiation has on the body (besides the obvious burns warned about in the HAM regs). I think your intuition is correct and don't put the antenna right next to your "junk" even though there is a null in the field moving out from each end of the whip. 2. The Microair uses a DB-25 connector. I haven't soldered onto a connector like this for about eighteen years. I'm presuming the best approach would be to tin the wires, slide them into their locations, and solder them in place? Should I be using shrink tubing on each connection, too? (the connector itself has a strain relief). The best way to do these is use the good quality crimping machined pins (not stamped) that insert into the connector one at a time. The crimp tool is not cheap but maybe your EAA chapter has one in its tool crib you can use. 3. I'm about 99.99999% sure about this, but with $1500 on the line, I'd appreciate confirmation: When the installation manual shows the pin assignments for the DB-25 connector, the assignments are as if I am looking directly at the connector on the transponder...right? In other words, the connector itself will be a mirror of this diagram. That seems to be confirmed by the teeny teeny numbering on the DB-25 supplied with the unit. Follow the numbering on the connector, you won't go wrong. Doing this will prevent the ineveitable reversals caused by confusion of front/back view and male/female definitions. Ron Wanttaja BTW, I just bought a copy of your book on Amazon. |
#3
|
|||
|
|||
"Ron Wanttaja" wrote:
The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. Hazard to human tissues is related also to time, which for an xponder means duty cycle also. They xmit for 21 microseconds each time reply light blinks. Even at 250W and at that distance, should be less effect than a cell phone next to your head. See http://n5xu.ae.utexas.edu/rfsafety/ for an RF Safety Calculator and links to tech discussions. I'm presuming the best approach would be to tin the wires, slide them into their locations, and solder them in place? Should I be using shrink tubing on each connection, too? (the connector itself has a strain relief). If the DB-25 pins are "solder cup" type, they work by merely by inserting wire, heating pin cup, and let solder wick itself in. If crimp-type, crimper is better, though for thin wires and if properly secured, soldering I think is OK. Shrink tubing is good if solder cup and thin wires for a little added anti-flexing of the wire. If soldering to tabs with a hole in them, definitely shrink tubing if connections are exposed to shorting by metallic FOD, which can find its way there under Murphy's Law. When the installation manual shows the pin assignments for the DB-25 connector, the assignments are as if I am looking directly at the connector on the transponder...right? Any ambiguity here is easily checked with an ohmmeter set for at least 2K. Grounds of course will be common to the box. Ohmmeter between +14V-in and ground will show a reaction between infinity and some resistance when switched off/on. Usually see increasing resistance as the ohmmeter charges a capacitor. Fred F. |
#4
|
|||
|
|||
"Ron Wanttaja" wrote:
The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. Haven't I heard you complain about the lack of a heater in that plane? Just think - you could have the first "Frybaby". Rich "Can't hurt a dead man" S. |
#5
|
|||
|
|||
|
#6
|
|||
|
|||
On Fri, 30 Jan 2004 12:53:21 -0800, "Rich S."
wrote: "Ron Wanttaja" wrote: The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. Haven't I heard you complain about the lack of a heater in that plane? Just think - you could have the first "Frybaby". But Rich, the end that sits in the bottom of the end is usually warm anyway. I need more heat higher up. Maybe a helmet-mounted transponder antenna? :-) Ron "Bender" Wanttaja |
#7
|
|||
|
|||
On Fri, 30 Jan 2004 09:56:58 -0800, Jay wrote:
Ron Wanttaja wrote in message . .. 2. The Microair uses a DB-25 connector. I haven't soldered onto a connector like this for about eighteen years. I'm presuming the best approach would be to tin the wires, slide them into their locations, and solder them in place? Should I be using shrink tubing on each connection, too? (the connector itself has a strain relief). The best way to do these is use the good quality crimping machined pins (not stamped) that insert into the connector one at a time. The crimp tool is not cheap but maybe your EAA chapter has one in its tool crib you can use. It's not cheap ($44), but I really like the pin crimping tool that B&C Specialties sells. Bob Nuckolls recommends this tool. B&C sells good quality machined pins too. I much prefer machined pins over soldering, as I am much better at squeezing a set of handles than I am at trying to solder small things. http://www.bandc.biz/cgi-bin/ez-cata...9X358218#RCT-3 http://www.bandc.biz/cgi-bin/ez-cata...4X358218#s604p -- Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://go.phpwebhosting.com/~khorton/rv8/ e-mail: khorton02(_at_)rogers(_dot_)com |
#8
|
|||
|
|||
On Sat, 31 Jan 2004 08:07:01 GMT, Ron Wanttaja
wrote: Follow the numbering on the connector, you won't go wrong. Easy for you youngsters to say...I could tell there were numbers there, but wasn't completely sure what each one said. Amazing how a computer will go down to 4 point text, yet they're able to put 2-point on a piece of physical hardware. Guess I'll have to set up my solder station next to my big magnifier/lamp combo. Your only issue is identifying one pin on one end. They run 1-13 on the "long" row, then 14-25 on the short row, with 1 and 14 on the same end; 14 "between" 1 and 2. Mark the pin 1 end with your wife's fingernail polish (not on the pin itselfg) and all you have is a counting exercise. You might want your magnifying glass to solder ... even with a good iron, it is awfully easy to melt the ones you have completed ... excersize care. A remelted joint has a nasty habit of becoming a "cold" joint. Yes, heat shrink each one ... and not shrinking while you are working is a problem. George |
#9
|
|||
|
|||
Ron Wanttaja wrote:
Hey, Jim, I've bought a Microair T2000 to replace the bum transponder in my Fly Baby. A couple of questions: 1. The instructions say not to install the antenna within one meter of the unit. What's the limiting factor here? I always prefer short cable runs, and had a nice spot picked out 15 or so inches away. What problems is a near-by antenna introducing? The current antenna location is precisely 4 inches below my heinie, and I'd just as soon get it further away, thank'ee. 2. The Microair uses a DB-25 connector. I haven't soldered onto a connector like this for about eighteen years. I'm presuming the best approach would be to tin the wires, slide them into their locations, and solder them in place? Should I be using shrink tubing on each connection, too? (the connector itself has a strain relief). 3. I'm about 99.99999% sure about this, but with $1500 on the line, I'd appreciate confirmation: When the installation manual shows the pin assignments for the DB-25 connector, the assignments are as if I am looking directly at the connector on the transponder...right? In other words, the connector itself will be a mirror of this diagram. That seems to be confirmed by the teeny teeny numbering on the DB-25 supplied with the unit. A couple of questions to RAH in general: Considering that I operate in an ATC environment next to never (Excluding the temporary tower at Arlington, I've been into a controlled field three times in the past seventeen years, and two of those were NORDO), is there any real need to install an external Ident button? The one on the unit itself is tiny, but I figure I can pull off a glove to press it if needed. Adding a button complicates my connector arrangements (the unit is being installed in a removable box). Second, my existing encoder is a Terra AT3000. It was working at the last check, but is anyone aware of any specific issues with this model? As long as I'm digging things up anyway, I could just as well pay another $150 for a new encoder, but am loath to do that without a specific reason. (Loath, adj.: Already in trouble with the wife for spending $1500 for a new electronics gadget.) Ron Wanttaja If you don't play well with soldering irons and you can get past some folks' aversion to using 'non-certified' stuff in their experimental airplanes, try using a 'true bidirectional' parallel printer cable made for your windows PC. http://www.pacificcable.com/Picture_...ataNAme=PM1-6T shows the pinout for this cable (IEEE 1284A) on page 7. Order the length you need, cut off the printer connector (don't cut off the db25 connector;-))& split the wires to each destination as needed. ID the pins & number the wires to match using your ohm meter. Several folks have put the xp ant. under the engine inside the cowl, & Iknow of at least one person that's used one in a wheel pant successfully. If you don't fly IFR, you won't likely need to reach the radar with it from further than 40 miles anyway so perfect ground plane mounting isn't that big an issue. Charlie |
#10
|
|||
|
|||
Ron Wanttaja
shared these priceless pearls of wisdom: -Hey, Jim, I've bought a Microair T2000 to replace the bum transponder in my -Fly Baby. A couple of questions: - -1. The instructions say not to install the antenna within one meter of the -unit. What's the limiting factor here? I always prefer short cable runs, -and had a nice spot picked out 15 or so inches away. What problems is a -near-by antenna introducing? I'll be darned if I know. The unit is hogged out of a solid aluminum block and is about as well shielded as anything I've ever seen. Perhaps they are relying on the loss of the cable to mitigate any reflections from the antenna? I just don't know. Me? I wouldn't worry about it. Put it where you will and we'll solve any problems through experimentation. - -The current antenna location is precisely 4 inches below my heinie, and I'd -just as soon get it further away, thank'ee. You mean you are planning on having more kids? - -2. The Microair uses a DB-25 connector. I haven't soldered onto a -connector like this for about eighteen years. I'm presuming the best -approach would be to tin the wires, slide them into their locations, and -solder them in place? Should I be using shrink tubing on each connection, -too? (the connector itself has a strain relief). That's how I did it. Yes, tiny shrink on each one just is belt-and-suspenders protection. - -3. I'm about 99.99999% sure about this, but with $1500 on the line, I'd -appreciate confirmation: When the installation manual shows the pin -assignments for the DB-25 connector, the assignments are as if I am looking -directly at the connector on the transponder...right? In other words, the -connector itself will be a mirror of this diagram. That seems to be -confirmed by the teeny teeny numbering on the DB-25 supplied with the unit. PROBABLY so, but I don't have a copy of the final manual. Microair manuals leave as whole LOT to be desired. The preliminary manual I have supports your contention, but ... Jim Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Transponder Question | log | Home Built | 2 | December 2nd 03 06:08 PM |
transponder check? | Russell Duffy | Home Built | 10 | August 14th 03 11:36 PM |