Oscilloscope Project


12 June 2012

Greetings from Nairobi, Kenya. My name is Joe Wagnell and I’m a missionary working with Africa Inland Mission as an avionics technician and mechanic. We have a special need that I would like to share with you.

Aircraft transponders transmit a beacon and an identifying code to the Air Traffic Control tower and other aircraft. They are used for identification, traffic control, and to alert other aircraft of their presence (collision avoidance). Most small aircraft only have one transponder, and if this unit fails, the aircraft is grounded and not allowed to fly.

AIMAir’s Radio Base (also known as an avionics shop) in Nairobi, Kenya needs a (relatively) high bandwidth oscilloscope. Currently, the Radio Base has a two channel 300Mhz scope. However, transponders transmit and receive in the 900Mhz to 1100Mhz range. To adequately work on the aircraft’s transponders, test equipment is needed that will allow the capture and monitoring of these signals.

Joe, Esther, Benjamin, and Ezri Wagnell in the hangar.
The front of the hangar at Wilson Airport, Nairobi, Kenya
Joe’s work bench/desk. Working on a MD200 Navigation Indicator.

A used four channel, 1,500Mhz scope (HP 54845A ) can be purchased for about $4500 - $5500. Not only would this allow for troubleshooting and fixing the transponders, but it would quickly become the primary oscilloscope for the Radio Base


You can make a tax deductible donation towards this project. All of the monies donated will be used for the purchase of the oscilloscope. You can give:

Online: At http://oscope.73scout.com

By Check : Make a check payable to AIM and put OSCOPE Project on the info line and send to


PO Box 3611

Peachtree City, GA 30269

December, 2012

In June of 2012, I sent out a request asking for funds to be donated for the purchase of an oscilloscope. The Radio Base had a 300Mhz oscilloscope, but it was not sufficient for troubleshooting some of the avionics in the aircraft, specifically the transponder, which operates at frequencies greater than 1,000Mhz. I had originally presented a need of $4,500 to $5,500 and a little under $5,900 was donated for this project. Due to your readiness to give, we were able to purchase several needed accessories for the oscilloscope and pay for shipping expenses. Thank you all for your generosity and for partnering with us on this project. The oscilloscope arrived in Nairobi in November and has already been put to good use fixing transponders. May the Lord bless you for your generosity.

Merry Christmas and have a Happy New Year

New oscilloscope on the work bench

Joe Wagnell

Measuring a 960 Mhz signal

Fixing a KT76A transponder with the new oscilloscope