When I started to build my Lancair in 1989 it clearly "needed" an ADF (Automatic Direction Finder) in a small Package (Terra).  The antenna was top mounted on an aluminum ground plane in the ceiling of the baggage compartment.  Although the total unit only worked for a year or two after I started flying the Lancair, at least I could continue to listen to the AM radio as I traveled across the country.  Recently, even that failed.  So.....

 

Modern times forced a reconsideration for in-flight amusement.  Listening to HIWAS wasn't working for me since I avoid bad weather.  Forced conversations with FSS, like issuing another dull PIREP, "Smooth a glass at 9500," had lost it's luster.  With the AOA silent, the BOSE headsets filtering out disturbing noises (except at night) and the Traffic Monitor, set to "FAR", occasionally blurting "Traffic" over some remote airport,  it was time to occupy my auditory sensor with something of more bandwidth than the local AWOS info.  So...   

 

I said to myself, "Self, let's skip all that old junk."  That meant no stink'n 8-track, no tape deck, no CD spinner and no IPOD.  The highly portable, recently released XM Satellite Radio, My-Fi, fit the bill beautifully.  There was just one small problem, the unit's "line-out" function was never meant to be fed into my audio system, something designed to accommodate carbon mike input - an impedance of about 600 ohms - an aviation standard developed in the 30s/40s to match the telephone equipment then extant.  

 

Quick research indicated it was foolhardy to try and match the impedance - better to just amplify the input a bit.  A Google search found a simple mono pre-amp kit powered by 10-30 VDC:

 

http://www.hobbytron.com/vk1803.html  

                                                               

 

 Now, where to locate this "bulge in the cable?"  Hmmmmmm...... Well, the wee Terra radio box could be used along with available power inside the box and output to the Terra monaural audio panel.  So, I pulled out the radio guts, stuffed the pre-amp in and made a new face plate with a volume control, mono input and a 12 VDC power plug.

 

Another problem soon appeared, what should I do with the circuit breaker and audio panel switch labeled "ADF?".  Easy enough, I labeled the new face plate: "Audio Data Fortifier."

 

Why keep monaural?  'Cause that's how everything is currently wired - maybe stereo is in the future.  Maybe 5.1 Dolby surround-sound when ATC can broadcast effects along with something like, "a B7E7 is overtaking you from the rear, keep your speed up or else. Vrooooooom."

 

The real benefit is that the plane is 4 pounds lighter, the empty weight CG moved forward by .1 inch and I can select from 120 channels of audio source - Country, Rock, Disco, Right America, FNC, etc. - anywhere in the country and that's whether I am flying, driving, boating, motorcycling, running, walking or crawling.