Are there any concerns regarding the battery?
YES: Lithium poly batteries can be destroyed if overcharged or over discharged.
Always use an appropriate charger. NEVER discharge below 3 volts. Even though
the BeeLine Transmitters have a low voltage shutdown feature, the battery can
still be over discharged. Always turn the transmitter off when not in use.
Why do I need an amateur (ham) radio license?
The radio spectrum used by the 2 meter and 70 cm BigRedBee transmitters is regulated by the
FCC in the United States. The FCC requires that you be a licensed amateur radio operator to transmit
on these frequencies.
These frequencies may or may not be regulated in other countries. YOU are
responsible for making you follow all applicable rules and regulations in your
The 900 Mhz transmitters do NOT require a license in the United States, Canada,
What frequency should I use?
As a licensed amateur radio operator, you are free to use any frequency in the
70cm band. Please consult the ARRL band plans for recommendations and
restrictions. You may want to avoid repeater inputs/outputs and the weak signal
areas, especially in populated areas.
Where should I put my BigRedBee?
The BigRedBee Transmitter should be treated like any other piece of sensitive
electronics. The circuit board can withstand very high G flights, but is not
potted. The best place to put your transmitter is in the nosecone or a payload
bay. Simply wrap in bubble wrap and jam it in! Close proximity to altimeters and
should be avoided due to concerns of RF from the transmitter adversely affecting
other electronics. Attaching directly to the shock cord is not recommended,
unless the transmitter is enclosed in some protective container.
What about composite airframes?
Carbon Fiber and metal will block RF signals. Phenolic, cardboard, fiberglass
and other composites are OK.
How long does the battery last?
That depends on the transmitting parameters programmed into the BeeLine. With a
10% duty cycle (.5 seconds on, 4.5 seconds off) and 10 minutes between call sign
transmissions, a new, fully charged battery will last for more than 48 hours.
Can I use my own battery?
Yes. Any battery providing at least 3.2V and not more than 9V can be used to
power the transmitter. The supplied lithium poly battery has a fully charged
voltage of 4.25V, and should not be discharged below 3.2V
Can I use my own battery charger?
Yes, but it must be specifically designed to charge single cell
lithium polymer batteries.
What's the range of this transmitter?
That depends on number of things such as quality of the receiver, gain of the
antenna, and terrain. This transmitter has been tracked from 10 miles out using
a handheld ham receiver, and 20 miles using a more sensitive mobile rig and
larger car mounted antenna. The signal was clearly hear for the duration of the
N2N flight to 40,000 feet. The most important variable is terrain. At 433 Mhz,
RF waves don't 'follow' the ground well, and are easily blocked by small hills.
What kind of serial cable should I use?
The serial adapter is designed to plug directly into a standard DB-9 serial
port. If you use a cable, make sure it is a straight through extension cable,
and not a 'null modem' cable, or other kind of cable that swaps pins. Using the
wrong cable will result in timeouts, and may damage the serial adapter.
Are kits available?
No. Only fully assembled boards are offered for sale.
Can the BeeLine transmit telemetry data?
No, you need a BeeLine GPS transmitter to transmit data packets.
How do I program my BeeLine Transmitter?
You need to download the BeeLine Communicator. The latest version is
My PC doesn't have
hyperterminal, what should I use to monitor the serial data stream?
I recommend Tera Term , others have
successfully used 'putty'.
What kind of antenna should I use?.
1) Build your own: http://old.bigredbee.com/docs/70cm_yagi.pdf
2) Buy one, I recommend this:
3) Or, for base operation, I have this one (not a directional yagi):
Does the programming software run under Linux?
No, but one customer has reported that it worked fine using a windows emulator,
WINE version 0.9.17.
What about that fancy helical antenna?.
These come in left and right hand circular polarization, but when dealing with a
linear transmit antenna, either will work. The come with an optional 18dB
LNA that can make huge difference for extreme flights.
How big is it?
The 16mw BeeLine Transmitter
The 100mw BeeLine Transmitter
(yes, the 100mw version is smaller)
Both weigh approx 6 grams without the antenna or battery.
How big is it?
The 100mw (version A62) u-blox (2021 version) 70cm BRB GPS is 26mmx60mm
The 850 mah battery
weighs 25 grams and is
approx 1.28" wide.
The original (Lassen IQ) 70cm BeeLine GPS is 1.225" wide
long and weighs 25 grams w/out the battery.
The 2M High power GPS is 1.255" wide x 3.635" long and weighs 56 grams
w/out battery or antenna
The 900 Mhz transmitter weighs 25 g without battery, and is 28mm wide x 67mm
Digikey part numbers:
Blue 3-pin battery connector:
White 3-pin power right angle connector:A19480-ND
White 3-pin power straight connector: A19470-ND
White 5-pin male data connector: A19432-ND