of the most common issues at any flying field has been Frequency
control and we know that all AMA sanctioned fields are required
to have some type of frequency control system in place. Even
with these control systems in place you are never 100% sure
that no one is on your channel. This is where the new 72Mhz
Frequency Checker from Hobbico comes in.
Voltage: 4.5V DC
Scan Frequency: 15 seconds
Dimensions: 3.14 x 0.94 x 2.36 in
(80 x 24 x 60mm)
Weight: 2.05 oz (58g)
Requires: 3 AAA alkaline
Warranty: 1 year
HCAP0340 72MHz Radio Frequency Checker
HCAP0341 External Antenna for Frequency Checker
Hobbico frequency checker is inexpensive, street price of
$49.99 and very simple to use. All you have to do is take
it out of the box, add 3 AAA batteries and turn it on. As
it scans through each of the channels you will see the individual
LED's light up. If it finds the channel active it will leave
the LED light on as it continues to scan the rest of the channels.
It takes the checker about 15 seconds to scan all the channels
before cycling through them again.
checker has a scanning range of 300 feet but you can increase
its range to 1000 feet by buying the additional external antenna
($8.99). It is also small and light that you could carry it
around in your shirt pocket.
this sounds good but how well will this actual work out at
the field. I received the checker the day before a competition
that my club was hosting so I figured that this would be a
great time to try it out. Since we were going to have someone
controlling the transmitter impound and frequency board, I
though the checker would be a good double check to make sure
no stray transmitters were being turned on.
started out using the checker without the external antenna
to see how well it would work and it actual worked pretty
well. I could watch as the competitors checked out their transmitters
and see on the checker when they turned them on and off. I
didn't get any stray channels showing up during this time
so I was pretty impressed with it's performance.
I plugged in the external antenna and turned the checker back
on. During the first cycle the checker showed that channel
34 was active. This was a bit of a surprise since all the
transmitters where impounded and turned off. So I figured
that we were picking up a stray signal on that channel but
when it cycled through again it showed 34 off and now 35 on,
then it showed 35 off and 36 on. It cycled through this pattern
a couple of times before clearing. It would do this for about
a minute, then disappear for awhile and then start up again.
This pattern stopped once I removed the antenna but would
reappear as soon as I re-attached the antenna. Now I had no
real way of knowing if there was anything on these channels
or if it was some glitch with the checker and the antenna.
It would have been nice to have had a second checker with
me to see if both were doing the same thing at the time. No
one was flying on these channels which was probably a good
thing but if there was I could have used their receiver to
see if they were getting any glitches with their plane.
getting home from the competition I tried the checker and
had the same issue with the external antenna. I live over
20 miles from our flying field so I shouldn't be seeing the
same behavior as I did at the field if it was caused by some
type of stray signals.
used the checker a few more times at our field and at a few
other locations and had similar results with the external
antenna. I don't know if these are stray signals or a glitch
but from reading Hobbico's Tech Notice it seems possible that
this is more of a glitch with the system then it is from picking
up a signal.
May 13, 2005
The "Special Features" section of the
instruction sheet lists the range in meters instead
of feet. The correct descriptions are: "Range
is up to 300 feet w/o external antenna" and
"Range is up to 1000 feet with external antenna".
Elsewhere on the instruction sheet the proper ranges
in feet are listed. We apologize for any confusion
this may have caused.
Hobbico's Frequency Checker is designed to scan
all fifty R/C frequencies in the 72MHz band and
identify when another transmitter is operating on
any such channel. It's important to note that the
Frequency Checker is NOT well suited to show very
brief, intermittent Rf signals that could cause
interference which may be present in the environment
near or between R/C channels.
Do not point a Tx antenna directly at the Frequency
Checker. This will make it more difficult for the
checker to detect the signal being emitted from
For best reception do not lay the Frequency Checker
on the ground during operation. Resting the checker
on an elevated surface such as a table or flight
box is recommended.
When using the optional external antenna: it's best
to point the antenna skyward for best reception.
Also, extra channels might appear to be in use if
the checker is physically located very near a Tx
which is emitting a signal. Moving the checker several
feet away from the Tx will clear the problem. If
used inside buildings which have a lot of steel/metal
in the structure, extra channels might inadvertently
be shown, and NOT using the external antenna may
deliver the best results in this situation.
we contacted Hobbico about the glitch and they figured that
I had a bad unit so they sent me a new one with a new antenna.
When the new unit arrived I tested both while I was at home.
The new unit worked fine while the old one still had the
glitch. I switched the antennas between the two units to
make sure it wasn't a problem with the antenna but there
was no change. I had the same results when I tested the
units down at the field.
I really like the Hobbico frequency checker since its
inexpensive and its small size makes it easy to keep
in my flight box or carry it in a shirt pocket. This is a
great help to have at a competition as another way to monitor
the frequencies that should be in use.
you should run into the same problem that I had with the first
unit just contact Hobbico for a replacement one. They were
very helpful when I contacted them about the problem.
frequency checker is well worth it's $49.99 price tag and
nice addition to one's field box.