Frequently asked questions
Q. I have heard that I will have to buy new equipment for the 406 ELTs. Is this true?
A. No. All 406.025 MHz ELTs, EPIRBs, and PLBs in the US and most other countries are required to have a 25 mW 121.5 MHz homing transmitters on them. Tracking ranges of 10 miles or more are not unusual, despite the lower beacon power. All L-Tronics direction finding equipment, LL and LH Series Little L-Pers and LA Series Aircraft DF, will work just fine.
Q. Do you take trade ins?
A. Rarely. We sometimes have used receivers. Call if you are interested or monitor e-bay and similar sources. If you purchase a unit, we will be happy to check it out and/or repair it for you. Be sure that a used unit is for 121.5 MHz and has its antenna and mast as we no longer have replacement antennas (24 in. long wood) or masts available.
Q. Why cant you continue to build the old Little L-Per ?
A. Several key components of the original receiver are no longer in production. Replacing them with current production parts meant major changes and requalification for the old unit. Instead, we decided to completely redesign the L-Per. Similar problems have surfaced with the LL design. We kept supplies of most parts for our discontinued equipment and will continue to support waranty and repair service. We will also continue selling accesories for all units as long as inventory lasts.
Q. Our unit has been given an L-Per on 243 only. Can we add the 121.5 crystal?
A. No. These units were a special production for the Air Force and are restricted against modification. However, you can still use them to locate ELTs, as all non-406 MHz civilian beacons operate simultaneously on 121.5 and 243.0 MHz. Some military ELTs are on 243.0 only. Use of 243 will eventually be phased out with the implementation of the 406 beacons.
Q. My old (LH Series) DF has only 121.5 and 121.775. Can I order a 243 crystal for the empty slot?
A. It wont work. 243 requires a second tuner and a second antenna crossbar matched to the frequency. We are no longer doing modifications to LH or LA series equipment.
Q. What kind of batteries should I use in my Little L-Per ?
A. We recommend EverReady or Duracell alkaline batteries for their consistent high capacity, long shelf life, and good seals . Change batteries in pairs or sets, always of the same type. REMOVE BATTERIES WHEN UNIT IS NOT IN USE TO AVOID MAJOR CORROSION DAMAGE FROM LEAKING BETTERIES. Carry an extra set when going into the field, with terminals taped to prevent a "hot pocket." If your DF is used once a week or more, you might consider NiCd or NiMh rechargeable batteries. Otherwise, stay with alkalines because the rechargeable types have lower capacity and self-discharge fairly quickly, so they may be dead if they havent been charged in three or four months, particularly if it is hot. There are Lithium AA cells (Eveready L91, 1.6V) that have higher capacity, lower weight and supurb storage life but they are quite expensive. Do NOT use 3V Lithium cells as they will quickly discharge even when the receiver is off and may do internal damage.
Q. My older style L-Per doesnt work right. How can I tell whether the receiver or the antenna is bad?
A. Swap receivers with an L-Per that is known to work properly. If your receiver still doesnt work, its bad. Otherwise, your antenna is faulty.
Q. How can I check my antenna for proper operation.
A. You can check the antenna with an ohmmeter. See Antenna Checks on this site for details. This works on portable and magnetic antennas and those mounted on aircraft. Be sure to open up the elements on the hand held antennas before measuring. The test can be done at either the "blue box" or through the mast cable. The Antenna Checks also explain how to swap receivers to check antenna systems.
Q. My new LL Series DF shows a continuous left direction when no audible signal is present. Whats wrong?
A. There may be dirt in the antenna hinges. See Antenna Checks above. There is also a software-hardware mismatch in receivers with serial numbers below 30171. A free factory upgrade is now available. In the meantime, if this occurs, turn peak detection off (SET4, ITEM 5) when receiving weak signals.
Q. How do I send equipment to you for repairs?
A. Package equipment carefully (please do not ship in the carrying case. too many have come through with broken handles and latches). If you know the problem is with the receiver, you can send it by itself. However, we recommend that you send the antenna(s) and mast(s) as well for minor upgrades and cleaning. Our minimum charge, and we do repair many for the minimum, applies to the whole set. BE SURE you place a note INSIDE the box with a brief description of the problem as you see it, your name, shipping address, e-mail address, phone number, and method of payment. See section on Repairs and Modifications for details.
Q. Will the LL Series DF track beacons used to find missing medical patients (Project Lifesaver ) or other similar animal tracking transmitters?
A. No. The LL Series DF covers the frequencies used, but the present software does not work with these signals.
Q. Is the LL-16 available to customers in Europe?
A. Yes. A version with French notation on the LCD display is available.
Q. What does the new LL Series Little L-Per look like?
A. Check here or the home page for pictures. The speaker is behind the panel on the left. The LCD display is transflective so, unlike some cell phone displays, is clearly readable in direct sunlight. LEDs and fiber optics light both the display and the buttons for night use. The stainless steel antennas and the handle fold up so the receiver can be placed on the dashboard of a car or plane or packed easily. Batteries are replaced through a finger-operated plug on the right side. Jacks for left/right and fore/aft antennas are located on top, along with a jack for external power and audio. The case is sealed and designed for up to 15,000 feet altitude or 9 foot immersion in water and for a 20 to +60° C temperature range. It floats.