Description
Since some people built VHF/UHF beacons based on my keyer, this page describes how
to use IK0WRB Keyer this way.
First of all please note that no modifications are really necessary to all keyer
versions, because the beacon function is already built in.
You simply store your beacon message in memory, then enter beacon mode
(rotatory switch either on "6" or "B" position).
However, if you want to use this keyer as a beacon only, you can spare some
components, simplify the circuit and have more features.
You can also store the message to be broadcast directly in the chip programming phase,
without using a cw key. You can also save the rotatory switch, the
button and the two-colors LED (speaker is totally optional, unless you want to keep
awake someone you hate). In fact you need only a battery,
or power input, and the output plug. Perhaps you can restore a single color red LED,
just to monitor everything is working well.
Another possibility is to drive with pin 2 directly a crystal oscillator, which would
be the driver of the beacon transmitter. In this case the keyer could be part
of the beacon circuit itself.
The simplified circuit (for a beacon)
As you can see I added a voltage regulation, because a beacon
is supposed to work 24 hours a day with some form of steady power, not batteries.
The components list
- a Microchip PIC 16F84 (or 16F84A), in the 18 pins package
- a BC108 transistor, or NPN similar (LOOK at the voltage on your transmitter TX plug)
- a 78L05 regulator chip
- a crystal from 0.5 to 4 MHz (see below)
- 2 capacitors of 22 pF, 15 VL
- a capacitor of 330 nF, 50 VL
- a capacitor of 100 nF, 50 VL
- a resistor of 470 Ohm, 1/4 W
- a resistor of 100 kOhm, 1/4 W
- 2 resistors of 10 kOhm, 1/4 W
- a red LED
- a socket for output
- a switch
- a socket for power (DC from 6 to 35 V)
- (optional) a 200 mW speaker and a switch
The program
The program used for the beacon totally different from the keyer one.
Please use only the beacon program on the beacon circuit and keyer program
on the keyer circuit, or damages could result to the chip!
The parameters of the beacon are the following:
- Initial pause 1-15 (seconds) before the message begins
- The beacon message (up to several dozens CW characters)
- How many times the message is repeated (1-15)
- Final pause 1-15 (seconds) after the message ends
- Carrier duration 1-255 (seconds)
- CW speed 1-255 (wpm)
- CW weight 2.0 - 4.0 (step 0.5)
All these parameters are established before the chip programming phase,
but, how to compute all these parameters? You need only to use my bcnprom.exe
program, which is included in the ZIP distribution file. You specify the crystal you
are using and all other parameters as well as the beacon message and the program will
show you the content of the 64 bytes of the EEPROM and will also store these bytes
directly in the HEX file (currently beacon11.hex).
And of course, here is the package: beacon14.zip.
Version 1.4 of bcnprom expands the character set usable in the beacon message, adding
the following signs, some of which were introduced in 2004 in the international Morse code:
@ ! & ñ " $ æ. Moreover now the characters é and è
use two different Morse codes.
Links
This text is also available in Italian language (in italiano)
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