Originally posted by kpack05 on the RailPro Users Yahoo! Group on Sep 7, 2015Jacob,
I'm glad you have access to get some recordings!  I for one would love a great recording of a GP7/9....I have one planned to build right now, just gathering parts.  
Tascam makes a great recorder and should be adequate for what we need.  I had a Tascam DR-04 but it was stolen along with a bunch of other stuff.  I still have my mic though, a Sennheiser e815s.  I never could find any opportunities to record so I'm debating getting another Tascam or not.
Watch this video as a guide to getting good recordings: 
 As noted in the video it sould be handy to get a shock mount and extension pole in order to isolate the mic from vibration and to place it near the exhaust.  A wind sock(dead cat type) is a must.  All these things can be found on Amazon for decent prices.
If you're able you can get a much better recording by recording the locomotive under load (hence the video of Jason from Rapido taping the recorder on the roof of the locomotive).  You'll need to get all 8 notches with all transitions, startup and shutdown.  Also get the compressor, air blasts, and any other sounds a locomotive may make.  Bonus if you can get the engine spooling from notch 1 all the way up to notch 8.
-Kevin