Craig
Well Known Member
I decided to convert from the 121.5 based AK-450 to the 406 based AK-451.
I guessed that it will be inevitable (of course that may not be true).
I'm still in the construction phase, so I figured it would be better to do it now than later.
I had some questions that couldn't be answered before I started. Maybe I can pass along some information that might be useful to anyone else thinking about converting.
The AK-451 is advertised to be a direct, drop-in replacement for the AK-450. That is generally true.
The main unit is the same size, and can go in the existing holder.
The remote unit is the same size (That's one of the things that I couldn't verify until I had it in hand). I was worried about that because I had a nice hole cut in the fixed instrument panel that is finish painted. I would have had to cut it up if the remote control unit was a different size. In the rear of the remote control unit, they use a telephone 2 for 1 splitter to power the required and provided buzzer. That takes up a little extra space on the back side of the remote control unit.
The coax should be replaced with RG 400/U coax.
The antenna must be replaced. It is a little shorter than the -450 antenna. Removing the old antenna turned out to be trouble for me. I had my antenna mounted aft, between the horizontal and vertical stabilizers, like about half of you. I know this is one of the never ending debates, but that's where I decided to put it. It was no problem putting it in. Now, however, I have the empennage permanently (I hope) mounted. The forward spar of the horizontal stabilize blocks access to the hole that your hand has to go through to get to the BNC connector and the nut on the antenna. Several choices went through my mind to get the antenna off:
1. Make some special tools.
2. Remove the empennage
3. Remove the elevator push-pull tube and crawl back through the fuselage.
I chose option 3. If your airplane is more complete, or finished, you'll have to decide. I decided to mount the new ELT antenna where about the other half of you have it - by the passengers right elbow.
The instructions for the conversion state that you can use the same telephone cord between the main unit and the remote control unit. I didn't find that to be true. When I did the post installation test, I could activate the
ELT from the remote, but I couldn't shut it off. When I substituted the new telephone cable that they supplied, the remote control unit works as advertised.
I guessed that it will be inevitable (of course that may not be true).
I'm still in the construction phase, so I figured it would be better to do it now than later.
I had some questions that couldn't be answered before I started. Maybe I can pass along some information that might be useful to anyone else thinking about converting.
The AK-451 is advertised to be a direct, drop-in replacement for the AK-450. That is generally true.
The main unit is the same size, and can go in the existing holder.
The remote unit is the same size (That's one of the things that I couldn't verify until I had it in hand). I was worried about that because I had a nice hole cut in the fixed instrument panel that is finish painted. I would have had to cut it up if the remote control unit was a different size. In the rear of the remote control unit, they use a telephone 2 for 1 splitter to power the required and provided buzzer. That takes up a little extra space on the back side of the remote control unit.
The coax should be replaced with RG 400/U coax.
The antenna must be replaced. It is a little shorter than the -450 antenna. Removing the old antenna turned out to be trouble for me. I had my antenna mounted aft, between the horizontal and vertical stabilizers, like about half of you. I know this is one of the never ending debates, but that's where I decided to put it. It was no problem putting it in. Now, however, I have the empennage permanently (I hope) mounted. The forward spar of the horizontal stabilize blocks access to the hole that your hand has to go through to get to the BNC connector and the nut on the antenna. Several choices went through my mind to get the antenna off:
1. Make some special tools.
2. Remove the empennage
3. Remove the elevator push-pull tube and crawl back through the fuselage.
I chose option 3. If your airplane is more complete, or finished, you'll have to decide. I decided to mount the new ELT antenna where about the other half of you have it - by the passengers right elbow.
The instructions for the conversion state that you can use the same telephone cord between the main unit and the remote control unit. I didn't find that to be true. When I did the post installation test, I could activate the
ELT from the remote, but I couldn't shut it off. When I substituted the new telephone cable that they supplied, the remote control unit works as advertised.
