Bubblehead

Bubblehead

Well Known Member
Moderators may want to move this to another place. Do we need an ELT forum?

On my 8 the ELT antenna is mounted on the right rear armrest and bends up and around the rear seat. It's protected but probably worthless because it is in the aluminum "bath tub" of the fuselage.

I want to move the antenna to the empennage area but the current antenna is bent and the base is at an angle, intended for the bottom of the fuselage. Does anyone have a design for a home made 121.5 MHz antenna? I intend to mount a BNC on the bulkhead and Plug the antenna into it.
 
I am going to arc up some debates here for sure, but why the heck do folk persist in hard mounted old 121.5 ELT's when all the evidence points to them failing. They are not satellite monitored (only VHF a/c) and in any kind of crash be it a forced landing that gets ugly or a genuine crash, they fail to operate.

If you do something really stupid and spear in, you are dead anyway.

If you have some kind of problem and are going to land/crash off airport, your best bet is a GPS driven 406MHZ personal EPIRB. Activate it on the way down. Even if it fails after impact enough data will have been logged.

Not sure how well you can register them in the USA but here we can with full aircraft/boat details, next of kin details etc.

Whats more they are a few hunderd buck. Cheap insurance if you are injured in a remote place.....or even a big farm and nobody knows where to send the paramedics.

Yes I sound a bit hard nosed about it........if you don't agree, ask your wife and kids, unless they hate you they will agree with me. :)

DB:cool:
 
RV10inOz said:
I am going to arc up some debates here for sure, but why the heck do folk persist in hard mounted old 121.5 ELT's when all the evidence points to them failing. They are not satellite monitored (only VHF a/c) and in any kind of crash be it a forced landing that gets ugly or a genuine crash, they fail to operate.

If you do something really stupid and spear in, you are dead anyway.

If you have some kind of problem and are going to land/crash off airport, your best bet is a GPS driven 406MHZ personal EPIRB. Activate it on the way down. Even if it fails after impact enough data will have been logged.

Not sure how well you can register them in the USA but here we can with full aircraft/boat details, next of kin details etc.

Whats more they are a few hunderd buck. Cheap insurance if you are injured in a remote place.....or even a big farm and nobody knows where to send the paramedics.

Yes I sound a bit hard nosed about it........if you don't agree, ask your wife and kids, unless they hate you they will agree with me. :)

DB:cool:
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I agree!! You can buy a nice PLB with GPS for around $500, the same thing in a "certified ELT" will cost you over $2000. Seems like a no brainer to me :D
 
Bubblehead said:
...On my 8 the ELT antenna is mounted on the right rear armrest and bends up and around the rear seat. It's protected but probably worthless because it is in the aluminum "bath tub" of the fuselage...
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Mine was there as well, but I removed it for exactly that reason - It has almost no chance of radiating any kind of signal.



Bubblehead said:
I want to move the antenna to the empennage area but the current antenna is bent and the base is at an angle, intended for the bottom of the fuselage...
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...And that is where I put it - on the bottom. Of all the possible locations on the -8 (all of them bad), I came to the conclusion that the bottom of the fuselage is the least bad. Based on crash photos, it seems that there is a 50/50 chance the airplane is going to come to rest inverted anyyway, so why not mount it where it will do the most good in a crash.
 
I have an ELT because I have to according to FAA rules. And I do my best to abide by those rules.

But I have ZERO confidence in my 121.5 MHz ELT working and have seen no evidence that the 406 MHz units are any more reliable. The ELT is nothing more than mandated dead weight in my opinion.

I do carry a Fastfind GPS integrated PLB and have for several years. Yes they get registered (See note above about following rules) and you can add appropriate info.
 
PLB as an ELT?

The PLB idea does make lots of sense, esp considering the low cost.

However, just taking a quick look at FAR91.207, it seems that a hard mounted ELT is required to be on board the airplane. (??)

So, would it satisfy 91.207 requirement to just carry the PLB in the airplane?

Sounds like an opportune time to make the change, while my 8's still in the shop.
 
Bill Wightman said:
The PLB idea does make lots of sense, esp considering the low cost.

However, just taking a quick look at FAR91.207, it seems that a hard mounted ELT is required to be on board the airplane. (??)

So, would it satisfy 91.207 requirement to just carry the PLB in the airplane?

Sounds like an opportune time to make the change, while my 8's still in the shop.
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You still need to have the "certified" ELT installed the airplane.

Personally I don't plan on spending big bucks on 406 ELT unit I see some advantage over a PLB .... or I'm mandated to do so.
 
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RV10inOz said:
... why the heck do folk persist in hard mounted old 121.5 ELT's when all the evidence points to them failing...

If you do something really stupid and spear in, you are dead anyway.

If you have some kind of problem and are going to land/crash off airport, your best bet is a GPS driven 406MHZ personal EPIRB. Activate it on the way down. Even if it fails after impact enough data will have been logged.

DB:cool:
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Yo, DB - I appreciate your sharing your thoughts but you have made some assumptions about me and my plane that are not true.

I have a PLB AND use APRS to let my loved ones track me and so I can 911 when stuff starts hitting the fan. I also use flight following almost all the time when traveling cross country, which is 80% of my flying.

If I have to have an ELT I'd like to at least minimize the obstructiveness of the antenna by getting it out of the cockpit and maximize the likelihood that the antenna will survive and radiate when needed.

I also have the telescoping antenna mounted next to the ELT in the rear baggage area so even if the tail gets torn up, if I am ambulatory I can hook in the telescoping antenna and maybe get some help.

I've given some thought to my original question and can answer it myself (KC9PR, Advanced class license.) I will make a simple whip with a length appropriate to 121.5 and mount it to the bulkhead.

Mel, Walt, Bill and others - good information, thanks.
 
Bubblehead said:
....
I've given some thought to my original question and can answer it myself (KC9PR, Advanced class license.) I will make a simple whip with a length appropriate to 121.5 and mount it to the bulkhead.
......
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Is it really a simple whip?

The ELTs also transmit on 243.0 MHz
 
can't here elt 'womp-womp' on 121.5

As I'm about finished with my 7A, I picked up a used ameriking 450 for a 'good' price. Transmitting through a belly mounted elt antenna, I can't here anything on 121.5. Removed the elt and held it in my hand (in the cockpit) with the telescope antenna. Again, I couldn't here anything on 121.5, BUT when I keyed (and held the key) on the sl-40, I could here the 'womp' from the elt.-This doesn't make any sense to me. Shouldn't I clearly here the 'womp' on 121.5 in the recceive mode? Yes, I pulled the plane out of the garage and into the lawn to minimize any RF interference. Comments welcome!

Jim Diehl
7A N891DD
Williamsport, pa
 
Bubblehead

Maybe you missed my subtle point........ I said
but why the heck do folk persist in hard mounted old 121.5 ELT's when all the evidence points to them failing.
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That was not aimed specifically at you. More the FAA in fact.

There are not many times where CASA actually lead the way over the FAA, many times they take your perfectly sound regs and make them worse, but with ELT's the facts have proven they are not worth a pinch of horse dung. PLB's have been approved and recomended for ages.

You need to convince the FAA they are wrong on this stance.
 
Sam Buchanan said:
243.0 is a multiple of 121.5 so the same antenna will work for both frequencies.
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Yes... but the 1/4 wave whip becomes a 1/2 wave whip at 243.0 MHz with a way different matching impedance.

It looks like some of the commercial ELT antennae have loading coils at the base or in the middle. A trap in the middle could certainly turn a 1/2 wave into a 1/4 wave whip at 243.0 MHz...:)
 
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