Field Test of the Beeping 108 MHz tracking transmitter (FM108K & FM108KS)
 with the 
VHF tracking & Aircraft Band super-regenerative receiver (VHF1K)

Ground - to - Ground Test ..Date: 9/28/02
Transmitter antenna:  12 inches
Transmitter battery:   small 33mAh 12volt battery included with kit
Transmitter mounting: mounted vertically four foot above ground with component side facing the  testing area 
Terrain: Flat farm land, "line of sight" 1/2 mile in all directions
Receiver antenna 19 inch telescoping vertical antenna included with kit
Receiver mounting Hand held, chest high approximately 4 foot above ground

Range test Ground-to-Ground

transmitter and receiver 4 feet above ground
100 yards loud and clear signal
200 yards moderately loud and clear signal
300 yards Clear easy to hear
400 yards clear and weak signal
450 yards clear and weak signal
500 yards weak but still discernable
550 yards very weak hard to discern
Direction locating Good direction determination using body as shield while holding receiver at chest level.  It helps to lower the antenna when working inside of 150 yards.  (see signal pattern below)
Flight test July 19 2002 
Rocket Paper tube, balsa wood fins, length = 16.5" fuselage diameter = 1", single stage - parachute recovery
Engine D12-3 Estes Industries
Transmitter FM108 small with 12 volt 33ma battery
Receiver VHF1 - 12 inch telescoping monopole antenna
Transmitter/rocket configuration Option 1 (see below). signal remained stable before, during and after launch.  No frequency drift was noted.  Full deployment of parachute with full extension of antenna.
special test item - polyurethane coating of Printed circuit board (PCB) Successful test - no heat related damage or corrosion noted on PCB - (One previous test flight failed due to suspected corrosion of the PCB which caused a short between the foil tracings on the PCB).-  This transmitter had two coats of polyurethane covering the entire circuit board and all components except for the battery and battery connections.
special test item - triple wrapping battery to PCB using rubber electrician tape, stretched and wrapped 3 times Successful test - (One previous launch had a transmitter failure when the battery disconnected during parachute deployment. Rubber banding battery to PCB has worked on several occasions and has failed on one occasion.)  
Report Loud and clear signal received throughout flight.  Rocket drifted approximately1/2 mile east of launch site and over a small hill into a heavily wooded area.  Signal was weak but clear at launch site after rocket landed.  Because of the distance that the rocket drifted from the launch site it was necessary to conduct the preliminary search by automobile.  Once the strongest signal was located from the roadway a foot search was initiated which resulted in the recovery of the rocket from a black oak tree (approximately 20 ft above ground).   Radio location using the VHF1 receiver was accurate to within 5 degrees using body shielding for location of the null point (null point is 180 degrees from direction of signal, see diagram below).

 

 The rocket and transmitter configurations used for flight testing are shown below:


FM108 small 0.5" x 1.75" 
shown with 12" antenna, 12 volt battery, shock cord and parachute connect

 

 

Signal strength diagram of VHF1 receiver

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Copyright 2002 Jerry Baumeister
Revised - 9-28-02