I am planning to relocate an EDM700 from the current RHS location to the RMI location in the bottom right of the LH panel.
Firstly I would go for the 3" version of the EDM, to fill the RMI hole, but it's not clear whether it is the same instrument in a bigger box, or a larger display etc.
Secondly I wonder if they offer a version with more data storage. The manuals on their website are just the same ancient ones I already have, which describe the existing product which holds only about 10hrs of data at 1 sample every 6 secs or so. It would be great to extend this because on most long trips I lose some data, and also as soon as the buffer "wraps around" it corrupts the old data and the standard JPI software can't read it anymore. Only their newest software can extract anything from it, but it can't export to CSV, only to XLS (a slight hassle for me).
I will also need to extend the thermocouple cables by 2-3ft. These all converge on one DB25 connector. Obviously one could make an extender cable, and the CJC aspect should not matter because the temp difference between the hot and cold junctions is so huge. But is there a good reason to rewire all 13 probes?
Surely what you need is an EDM 730 which holds 100 hours of data and an improved presentation. Obviously it needs to fit the panel, not always easy on a TB, but it seems to be possble to install it in 4 different orientations so there might be a chance.
I think there is an exchange scheme with the EDM700 and it is pin compatible.
The 730 is too big to go in anywhere near the same space.
Also, the EDM700 is certified as primary CHT/EGT instrument on the TB20 Type Cert, so any deviation from that would be a problem.
What about the EDM 830? I installed that instrument and it is fantastic. STC wise it is just a variant of the 700 and there were no problems installing it in my EASA registered plane. I think for primary instrumentation you'd need the 930 variant.
If there isn't room for a 730 there certainly isn't room for an 830 or 930. Shame but there is always a finite amount of panel space.
In the long run I want to re-work the RHS panel to be a full "pilot" panel i.e. with another SN3500 EHSI, which needs "something" removed from it, and that will be the EDM, because once I have two EHSIs the KI229 RMI will be redundant.
I have come across this
which shows the 3" EDM is actually a bigger instrument.
In the long run I want to re-work the RHS panel to be a full "pilot" panel i.e. with another SN3500 EHSI
Why would you want to invest in an outdated instrument? EHSIs are really a thing of the past. They're something in between a steam gauge and a glass cockpit. A glass cockpit gives you much more at roughly the same cost. I'd move the Sandel to the right and install an Aspen on the left side or a G500 if you want to spend a lot of money and completely reorganize your panel. The Aspen actually frees up a 3" hole as you can remove the VSI.
Just because Aspen was plagued by reliability issues in the past, doesn't mean they still have those. So far, the Aspen is about the only new avionics component in my airplane that hasn't failed on me (GNS430W has twice already). They offer 4 years warranty nowadays.
Peter, I think it is possible to swap the display for a bigger one. Contact Ingo Fuhrmeister at [email protected]
Why would you want to invest in an outdated instrument?
I like separate instruments, which I can install myself (obviously in a "certified" process) and if necessary pull out and replace myself, and calibrate myself.
Most "glass" stuff today is locked-down, with codes that are available to installers (official dealers) only. I have managed to get installation and maintenance manuals using various "interesting" means but the installer codes are all but impossible to get.
So any issue = flight to the dealer.
The Sandel stuff is still selling well, into the helicopter and military markets, because it's well built. I am really pleased with my EHSI. A superb display, in sunlight and everything below.
There is no argument that an EFIS presentation is the best going, but I am not willing to pay the price in risk. If I get a failure when away from base, it could be a very long way away, and sod's law is that it will be... Currently, everything in my plane is "field-serviceable". Well, maybe the engine is a 2-man job 
But even the engine can be swapped over, by any A&P.
The Aspen installer menus are easy to get to and I would argue that I know my way around this internal menu better than my installer by now!
There is very little in my airplane that would stop me if it failed during a trip. Certainly not the Aspen EFIS. The Aspens are simply swapped with the configuration applied to the new device. Same for the GNS430 by the way. I have photos of all internal configuration pages of my devices. My dealer has mailed me loaner devices several times in the past, knowing that I am capable of applying the correct configuration.
