Pointer Cadet Range

[Spaceman3750]

Does anyone know what the line-of-sight range of the Pointer Cadet training beacon is? I'm not even sure the power is indicated on it...

[a2capt]

Well, for purposes of distance, I've been at one end of testing where we were trying different antenna combinations with the Little L-Per, over a 22nm distance and turning on/off and doing carrier only were detectable for the most part.

[SarDragon]

From an ad:

The Model 6000 originally was assigned a 121.600 MHz frequency but going forward all newly built units will be retro fitted to the new frequency of 121.775MHz by the factory. Also, for home made battery packs, we suggest a maximum of 8 volts for supply. A battery pack consisting of 5 alkaline "C" cells would supply 7.5 volts. Typical output signals from trainer units are of 150mw range at 7.5 volts supply. To achieve a simulated ELT with a broken antenna or low power, don't extend telescopic antenna or use 4 "D" cells to produce a 6 volt supply voltage.

I've seen one used in a desert environment with a Yagi antenna that would get out about four miles off axis with a weak signal, and over six miles with a strong signal on axis.

[tribalelder]

121.XX will be line of sight, so curvature of the earth, from flat ground to flat ground is a 15-20 mile outer limit-terrain will usually reduce range -- unless you or the target are on a hill.

Receiver sensitivity is the other half -- gain antenna vs whip, RS scanner vs L'Per ...  Mileage WILL vary.

From a mid-80's exercise-scanner w/ rubber antenna-.5 miles, homebrew df using RS jetstream radio (the 'Bromstead Box) about 1 mile, Old l'Per 7+ miles against same Pointer. I never got to run the Tracker vs L'Per trials...

[sardak]

Here are the numbers from the Certificate of Compliance shipped from Pointer with two beacons:
Nominal output power per spec = 100 mW
As tested power:
S/N 6378, tested 3/19/85  100 mW at 121.6000 MHz
S/N 6719 tested 10/10/07 145 mW at 121.7764 MHz

As for reception range, as mentioned, it varies considerably based on many factors. Receiving these signals with L-Pers at a range of 20 or so miles is not uncommon.

Mike

[ol'fido]

Also, if it is near high tension lines, the signal may resonate for quite a distance regardless of the power on the unit.

[Spaceman3750]

Thanks for the help guys, I should be well within range on my exercises but I'm going to pull it out of the cabinet and test my scenario to make sure it will work since this is an urban environment where anything is possible (in retrospect, I guess that throws the whole line of sight thing out the window).

[lordmonar]

I have recived a hard hit on the Pointer with the Becker DF at 20+/- miles while at about 5K AGL.  That was as we rounded a mountain which blocked our LOS....so I would guess that you can get a good hit farther out then that.

A lot depends on the batteries in the Pointer Cadet, the Antenna and where it is actually placed.

[SABRE17]

what size antenna will give a similar range to the 406 beacons? I know that the 406's put out 121.5 id like to replicate a 406 beacon putting out 121.5.

[sardak]

what size antenna will give a similar range to the 406 beacons? I know that the 406's put out 121.5 id like to replicate a 406 beacon putting out 121.5.

Again, the antenna is just one factor in the equation. What you really need to know is that the power output of the 121.5 homing signal on on a 406 ELT is in the range of the output power of the Pointer 6000 practice beacon. Here are the specs for the homing signal on 406 beacons sold in the US:

ELT (RTCA Standard DO-204A)
50 mW to 400 mW (technically, per the document - EIRP shall not be less than -13 dBW or greater than -4 dBW)

PLB (RTCM Standard 11010.2)
25 mW to 100 mW (the technical requirement -  25 mW -0/+6dB PEIRP)

EPIRB (RTCM Standard 11000.2)
same as PLB

Mike