In late May 2006, a moderate software flaw was discovered in the microcomputer code that runs the PicoDopp DF. The flaw involves ONLY the eight AUXILIARY outputs on the MAIN board that drive the Economy Pelorus display. The Economy Pelorus display board is an optional "local" display board that a few customers have chosen to use, but most customers do not employ it. All the other PicoDopp outputs are unaffected, including those to drive the MultiDisplay board, which uses RS232 data instead of the AUX outputs.

The flaw apparently has been present since the first version of the PicoDopp was created, but was overlooked until a customer ( very carefully ) checked the sector boundaries for each of the 16 LEDs on the Economy Pelorus board, in May 2006. The installation of a new microcomputer chip is required, to fix the problem.

If you purchased a PicoDopp unit prior to May 25 2006, you are affected by this notice. If you do not own an Economy Pelorus display, and/or if you do not use the AUX outputs for a pelorus display, and/or if you have no intentions of using these outputs for a pelorus display, this problem can be ignored, with no consequences.

The Economy Pelorus display consists of 16 LEDs arranged in a circle. Therefore, each LED represents a "sector" that is 22.5 degrees wide. ( 22.5 x 16 = 360 ) Each LED indicates a detected DF bearing that lies within 11 degrees ( plus or minus ) of the LEDs "proper" bearing. For example, the EAST LED ( bearing = 090 ) will indicate for DF bearings anywhere from 079 to 101 degrees.

The problem is this : For DF bearings from 000 to 255, the display indicates the bearings properly. For DF bearings greater than 255, the display indicates on the wrong LED : It indicates one LED "clockwise" from the correct LED, for that bearing. Therefore, the indicated DF bearings ( only on the Economy Pelorus display ) can be "wrong" by as much as 22 degrees, rotated clockwise from the proper bearing.

Again, this is only true for DF bearings 256 and above. DF bearings below 256 degrees will indicate properly.

This error is not great enough to prevent success when used as a mobile DF for hunting. Errors can be as great as 90 degrees, and still the DF will ( eventually ) lead the hunter to the transmitter. This probably explains why the problem has not been reported until now, since very few PicoDopp users actually employ the Economy Pelorus display, and for those which do use the Economy Pelorus display, the errors are not large enough to be very obvious, when used for hunting.

The problem can only be fixed by replacing the PIC microcomputer installed on the PicoDopp MAIN board. For those who elect to do this, I offer two possible methods :

Option 1 : The PicoDopp DF MAIN board can be returned to me. ( you pay shipping ) I will install a new microcomputer, re-test and return the board via Priority Post, free of charge. Other shipping methods ( if desired ) will require payment for the return shipping. Repair and return will take 1 week of time, after arrival of the MAIN board.

Option 2 : I can provide a replacement microcomputer "chip" via Priority Post, free of charge. You can then install the new microcomputer yourself. Other shipping methods ( if desired ) will require payment for the shipping. if you feel your soldering skills are not adequate for this task, you are encouraged to select option 1. The old microcomputer must be ( carefully ) removed from the MAIN board, and the new one must be installed. This is probably the fastest way to effect repairs, I can ship a new microcomputer almost immediately.

This problem is also true for earlier models of PicoDopp which did not include the GPS input. If you have such a unit and elect to fix the problem, please be sure to indicate ( to me ) that your PicoDopp does not have the GPS input, since this will affect the version of code in the replacement chip.

My apologies to all for this ( fairly small ) error. My records indicate this probably affects less than a dozen PicoDopp users, worldwide.