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
return to jerry's home page E-Mail to:
Copyright ©2002 Jerry Baumeister
Revised - 9-28-02