Terra TRT 250D Transponder

tonycondon

tonycondon

Gastons CRO (Chief Dinner Reservation Officer)
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Tony
Anyone have one, or know a good place to find one? I got sniped with a last second (literally) bid on ebay today on one. This seems like a good candidate for going in my glider. low profile, low power draw, solid state electronics. Thanks!
 
Don't know anything about the transponder, but did you get your radio installed!? Maybe you posted pictures and a thread and I missed it...
 
no not yet Troy. Im going to start working on shaping up the new instrument panel this week. Gotta figure out what all is going to be in the new instrument panel first though!
 
spike - exactly what im looking for. thanks!
 
Two cautions WRT this transponder:

1) AFaIK there is no one that can repair one if it fails.

2) There's an AD against some serial numbers:

Applicability: Model TRT 250 transponders, part number (P/N) 0900-0250-00, with serial numbers (S/N) 4194 and below, Modification Level (Mod Level) 4 and below; 3-inch ATI-mounted TRT 250 pushbutton transponders, P/N 0900-0250-20, with S/N 5324 and below, Mod Level 4 and below; and TRT 250 D digital display transponders, P/N 0900-0250-30, with S/N 1155 and below, Mod Level 1 and below.
 
thanks lance. i was aware of the AD. i was going to call and check on the serial numbers.
 
DANGER, WILL ROBINSON!!!!!!

I had one of these installed in my Pitts. Crap, crap, crap. DO NOT waste your money on it. Do yourself a favor and just spring for a Garmin 320A.

Did I mention the Terra was crap? Always in and out of tolerance, which seemed to be temperature or humidity related or something, so the one shop I found willing to try repairing it couldn't replicate on the ground the errors ATC was reporting to me. YUCK!
 
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Tony, you might wanna ask Ken Ibold what he thinks about these, as he has some experience with them.
 
interesting Ken. ive talked with some other glider guys who used them and liked them. the 320A just draws too much power for my taste, unless i can get one cheap. anything over an amp is excessive for my battery situation. the more i look into this issue the more it seems that i just need to accept the fact that the only really good solution is going to cost big $$$. might as well get used to it i guess. for some reason i think i need to buy an airplane...it'll only get worse.
 
Just get an airplane with the radios in it that you like. Then find someone to build a slide in-out mounting tray and wiring harness. Then you can pull the radios out of the plane and put them in the glider when you want. :)
 
tonycondon said:
anything over an amp is excessive for my battery situation.
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What am I missing? The specs call for 12 watts max power input on the 320A. There's your 1 amp.

Looking back at what records from my Pitts I still have, I see four factory repairs of the unit before I bought the plane, totalling $2600. Plus the 200+ the shop spent when I sent it in but could not get it fixed. A new 320A is, what, $1200 or so.
 
CJones said:
Just get an airplane with the radios in it that you like. Then find someone to build a slide in-out mounting tray and wiring harness. Then you can pull the radios out of the plane and put them in the glider when you want. :)
Click to expand...

Aside from the other practical issues with this, it's not legal for a pilot (sans A&P cert) to put a transponder into a certified airplane even if it's tray mounted. And technically AFaIK a transponder check is required each time this is done although I know that's almost never complied with.
 
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Tony, it's very likely that the actual average current draw of either a 327 or a 320 Garmin transponder is considerably less than the specs call out. Typically the number given is a worst case value which could easily be two or three times the normal current. If I get a chance I'll try to measure the actual current my GTX327 uses and let you know the result. Assuming the power consumption is sufficiently low and you can find a place to fit it, I think you'd be a lot happier with one of them than a Terra or Narco unit.

-lance
 
gismo said:
Aside from the other practical issues with this, it's not legal for a pilot (sans A&P cert) to put a transponder into a certified airplane even if it's tray mounted. And technically AFaIK a transponder check is required each time this is done although I know that's almost never complied with.
Click to expand...
Fixed it for ya ...
 
Ken Ibold said:
Fixed it for ya ...
Click to expand...

right, but technically the transponder has to be rechecked anytime its removed, whether certified or experimental. as lance said, not that that really happens in the real world, but just sayin...
 
gismo said:
Tony, it's very likely that the actual average current draw of either a 327 or a 320 Garmin transponder is considerably less than the specs call out. Typically the number given is a worst case value which could easily be two or three times the normal current. If I get a chance I'll try to measure the actual current my GTX327 uses and let you know the result. Assuming the power consumption is sufficiently low and you can find a place to fit it, I think you'd be a lot happier with one of them than a Terra or Narco unit.

-lance
Click to expand...

OK the electircally stupid needs help. i know ohms law. does that still apply to something like a transponder, even though it isnt consistently drawing power? so if it draws .5 amps at 28 volts would it draw 1 amp at 14 volts and more at 12 volts?
 
tonycondon said:
OK the electircally stupid needs help. i know ohms law. does that still apply to something like a transponder, even though it isnt consistently drawing power? so if it draws .5 amps at 28 volts would it draw 1 amp at 14 volts and more at 12 volts?
Click to expand...

It depends on the design but generally there are two common cases depending on the method used to regulate the internal voltages. In one case (linear regulator) the current is relatively constant regardless of the applied voltage which means the power required will be proportional to the voltage. In the other case (switching regulator) the power required will be relatively independent of the applied voltage so the current will be inversely proportional to the voltage. A product can also be designed with a combination of the two so you can see it's kinda hard to guess without a schematic or at least a comprehensive spec.

I suspect that any transponder that can run on any input voltage from 10-30 volts is using a switching supply and would expect the current to be approximately proportional to the inverse of the voltage.

And there are other issues. A transponder's power consumption is likely affected by how often it transmits (it's receiving all the time it's on). If you're near a busy major airport your transponder will probably get interrogated almost constantly between the approach radar, nearby center radar, and multiple active TCAS and TAS equipped aircraft in the vicinity. Out in the toolies and away from any major airline traffic corridors you might only get hit a few times per minute. Then there's the encoder which typically gets it's power from the transponder and if it's connected by parallel gray code signaling there's a small amount of power wasted "pulling up" the encoder signals and that will vary with altitude in a most peculiar fashion. Illumination also consumes power although this is typically supplied on a separate pin of the connectors. Sometimes though, the illumination power is derived from the main power and only controlled by the illumination (dimming) input.
 
I'm sorry to hear of some bad experiences with Terra products. At one time they were the equipment of choice for a yearly give away aircraft for either AOPA or some other well know operation. Terra built nice stuff. Those that want to trash it have obviously had bad experiences as I have with many products. And there are a lot of good manufacturers that have gone away for a lot of reasons other than a bad product.
I have ALL Terra radios in my plane and have 500 hours on it now with 780 hours total time on the plane. The Terra products were used when installed and I had one problem that was repaired for a reasonable cost by one of a couple great repair stations that still service them, contrary to some mean and uninformed posters here.
My point is, if you had bad experiences with Terra equipment, just say so and don't get obnoxious about it. Those of us with positive experiences will do the same and those interested in them can make up their own mind. I don't think the nasty slams are neither justified nor indicative of an intelligent assessment. Vicious criticism should be taken as indicative of the angry mind that wrote them. And that's just sad......:sad:
 
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Tony,
Shoot me a PM and I will explain how I am installing a TXT250 in my
Non- electric Vagabond. There is a place for Terra repairs.
To many grey area's to try to explain here.
Dave
 
Dave,

thanks for the offer, but I never did find a Terra.
 
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