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Learning things the hard way: SL-40 to SL-30 conversion

Jesse

Well Known Member
So I'm working on a panel upgrade, part of which involves removing an SL-40 and installing an SL-30. For those who know these two radios (but not too well), you would think just what I thought, "add the Nav Connector and Nav Antenna connector to he back of the SL-40 tray and voila." Of course, there are holes in the back of the tray that fit those parts perfectly. But you, as I did, would try to slide in the SL-30 and would find that it slides in about 1/4" shy of all the way. After and hour or two of head-scratching and wondering what it was hanging up on, you would, as I did, realize that the SL-30 tray has both antenna connectors at the same depth on the back shell, while the SL-40 tray has the COM antenna connector at the "right" depth, but the place where the Nav antenna connector would go about 1/4" shallower. I am not really well versed in other SL instruments, so I assume some other instrument uses the right half of the SL-40 tray for something else. So I tried to save about 3 minutes and ended up losing 3 hours in the process. Chalk up one more for ole Murphy!
 
So I'm working on a panel upgrade, part of which involves removing an SL-40 and installing an SL-30. For those who know these two radios (but not too well), you would think just what I thought, "add the Nav Connector and Nav Antenna connector to he back of the SL-40 tray and voila." Of course, there are holes in the back of the tray that fit those parts perfectly. But you, as I did, would try to slide in the SL-30 and would find that it slides in about 1/4" shy of all the way. After and hour or two of head-scratching and wondering what it was hanging up on, you would, as I did, realize that the SL-30 tray has both antenna connectors at the same depth on the back shell, while the SL-40 tray has the COM antenna connector at the "right" depth, but the place where the Nav antenna connector would go about 1/4" shallower. I am not really well versed in other SL instruments, so I assume some other instrument uses the right half of the SL-40 tray for something else. So I tried to save about 3 minutes and ended up losing 3 hours in the process. Chalk up one more for ole Murphy!

Are you saying that in the end you needed to remove the SL40 tray and replace it with an SL30 tray.
 
I had to chuckle over this, I made the same calculations and decisions when I swapped out my SL40 for an SL 30. Don't forget you have to add an additional power source now for the nav section also.
 
I knew all that. I did the wiring on the bench. I just never tried to fit the instrument in the tray on the bench.
 
As you have discovered with first hand re-invention of the wheel, again there are always little details we might not have thought about. For those building this is a good post. If you have designs for future upgrades after the build make sure you do all of your due diligence for evaluating what is needed to make it happen. I had this same idea in my head when I was building. I would fly a while with an SL40 then upgrade to an SL30 just as you have described. Knowing this in the build I called the one man I KNEW would understand what would be needed to make it happen.

If you want answers to instrument questions you might not even know you have:
BETTER CALL STEIN!
 
Here's my 40/30 story. I was having intermittent problems with my SL40. A friend was doing a panel upgrade and had a SL30 he let me borrow. I looked up the COM side wiring and all was identical, so I took it along on my flight.

So flying along, my intermittent problem appeared. I popped out the SL40, inserted the SL30 (which fit because I must have a 30 tray)- and nothing!!

Turns out the SL30 must have the COM, AND the NAV sections powered in order for it to operate.

Slid the 40 back in and continued the flight without any other problems.

The things that make you go hmmnn.
 
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