Five Two Beacon
146.520 Simplex is dead. Or, just not talked on
enough?
Background
Many call 6.52 a "wasteland" and indeed on
long trips I've taken over the years, I've heard nary a station
over hours of monitoring, scanning and calling. It turns out
though that many more ops may be listening but just like a open
band with no one talking, no one knows anyone else is there.
Something I've done for the past few years now is run a "6.52
beacon" when I'm on a long trip. It amounts to an MP3 player
connected to a Baofeng HT with VOX enabled. The MP3 player plays a
20 second CQ followed by a couple minutes of silence, and plays
the same file over in a loop. The HT only transmits with VOX
during the CQ so the net result is a 20 second CQ and a couple
minutes of receive. With APRS there's a beacon feature but
most hams aren't running APRS, and those that do may not be
listening for a voice call anyway. So the 6.52 Beacon was born,
and over the years has scared up a far greater number of contacts
than random "monitoring" calls ever have.
The theory is this- when you're mobile, your 2M simplex line of
sight might be 5 miles. If you're driving 70 miles an hour you'll
cover this distance in under 5 minutes. You could drive into and
out of the range of other stations countless times and neither of
you knew it, because no one is transmitting. With the "CQ beacon"
you're transmitting a call within every line of sight "window".
You also increase the odds of catching someone who just turned a
radio on or is scanning. If I hear a call come back I turn off the
HT and return the call using my mobile rig with more power and
better antenna to maximize the range.
The duty cycle is such that on low power (all you need) the HT
runs all day on a single battery charge and my MP3 player will
play over 24 hours on its' battery, so it becomes a simple toss in
the car addition to deploy. It has given me a "new" thing to do
while operating mobile on long trips and is a lot of fun to make
contacts this way.
Construction
Here's the hardware setup: UV5R radio, 3.5mm to 3.5mm audio
jumper, $10 MP3 player. Plug one end of the audio jumper into the
headphone jack of the player, and the other end into the mic input
of the UV5R. The UV5R mic input is 3.5mm and the player headphone
jack is 3.5mm, so you can't plug into the wrong one.
 |
6.52 Beacon - UV5R and MP3
Player
|
UV5R Setup
VOX needs to be turned on. This is found in menu item 4. Press
[MENU] and the up/down buttons to adjust the value from [OFF] to
[5], or whatever seems to work best for the audio drive level from
your audio player. Once the value is set, press [MENU] again to save
the value, then press [EXIT] to go back to regular operation.
 |
 |
Set UV5R Menu 4
VOX - ON
|
Set VOX value to
consistently key from MP3 player
|
MP3
Player Setup
The audio player volume sets both the transmit deviation level and
the audio used to trip the VOX, so some experimentation might be
required to strike a balance of VOX setting in the menu, adequate
deviation, the radio keying solidly during voice, and unkeying
during silence. For my setup, the player volume is fairly high
(almost max) and the radio VOX value is set to 5.
Beacon Audio
The audio file can be anything you want, whatever sound you play
will key the radio and be transmitted. For the 52 Beacon I used
about 20 seconds of "CQ 52 this is..." and then 2 minutes, 40
seconds of silence. This results in a file that sends out a 20
second CQ every 3 minutes. Below is a graphic from an audio editor
showing the audio and silence segments. You can use an audio editor
to record the message and add the silence after (I use Audacity). Or
just use a voice recorder app on a phone while sitting in a quiet
room, record the message and just sit quietly for a couple minutes
to add the silence.
 |
Audacity track showing audio and silent
period.
|
Beacon Operation
Set the audio player to play files in a continuous loop
and let your CQ file play. It's probably worth mentioning that for
best results, use an external antenna on the HT for best range,
whether it's mobile or stationary. If someone responds to the
beacon, you'll hear them through the HT speaker and you can either
pick it up and call back through that, or work them through a 2nd
radio. I usually just turn off the UV5R and call back with a
different radio. The stock battery on the UV5R is enough to power
the beacon continuously on low power (all you need) for 12 hours or
so, a solid day of driving during a trip. The MP3 player I use can
play the CQ file nonstop over 24 hours, so generally no external DC
supply will be required to operate this setup for typical daytime
trips, POTA, Field Day operation, or doing periodic QST
announcements at your radio event.
