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This list is to serve as a handy reference for anyone getting a new radio or spare set of crystals. We believe that by using
this list we can avoid having any radio channel duplications here in our club. However, for the instances where some of us
might visit another club, or have visitors at our site, it is probably a good idea to have an extra set of crystals.
Club members be sure to notify Gary Watson if there are any changes or additions to be made to this list.
A new technology came out a few years ago that will eliminate the need for a list of frequencies. DSM is now available for
most radios. With DSM, your transmitter scans the area for available frequencies and chooses an open channel for you.
Excerpt from website:
"What is DSM?
DSM is Digital Spectrum Modulation - a purely digital RF link between transmitter and model that is based on Direct Sequencing
Spread Spectrum technology. It operates within the ultra-high 2.4GHz worldwide ISM band, provides unequaled signal resolution,
and is immune to the most common forms of RF interference. It will even allow your model to “talk” back to you.
It requires no crystals and completely frees you from ever having to monitor frequency usage again. Best of all, with Spektrum’s
DSM System you can literally plug this phenomenal technology into existing transmitters like the JR R-1 and Airtronics M-8."
Check out the Spektrum Website for more information.
| 2.4 GHz |
27 MHz |
75 MHz |
75 MHz |
75 MHz |
| CH |
Freq |
CH |
Freq |
CH |
Freq |
CH |
Freq |
CH |
Freq |
| All |
2.465 |
A1 |
26.995 |
61 |
75.410 |
71 |
75.610 |
81 |
75.810 |
|
A2 |
27.045 |
62 |
75.430 |
72 |
75.630 |
82 |
75.830 |
| A3 |
27.095 |
63 |
75.450 |
73 |
75.650 |
83 |
75.850 |
| A4 |
27.145 |
64 |
75.470 |
74 |
75.670 |
84 |
75.870 |
| A5 |
27.195 |
65 |
75.490 |
75 |
75.690 |
85 |
75.890 |
| A6 |
27.255 |
66 |
75.510 |
76 |
75.710 |
86 |
75.910 |
|
67 |
75.530 |
77 |
75.730 |
87 |
75.930 |
| 68 |
75.550 |
78 |
75.750 |
88 |
75.950 |
| 69 |
75.570 |
79 |
75.770 |
89 |
75.970 |
| 70 |
75.590 |
80 |
75.790 |
90 |
75.990 |
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| Skipper |
CH |
Skipper |
CH |
| open |
61 |
Philip |
76 |
| open |
62 |
open |
77 |
| *conflict (86) |
63 |
Steve |
78 |
| Pip |
64 |
open |
79 |
| open |
65 |
open |
80 |
| open |
66 |
open |
81 |
| open |
67 |
Bouy Boat |
82 |
| Sean |
68 |
open |
83 |
| open |
69 |
open |
84 |
| open |
70 |
open |
85 |
| open |
71 |
Gary |
86 |
| Steve |
72 |
*conflict (64) |
87 |
| open |
73 |
open |
88 |
| Cliff |
74 |
open |
89 |
| open |
75 |
open |
90 |
| open |
A1 |
open |
A4 |
| open |
A2 |
open |
A5 |
| open |
A3 |
used by CB-23 |
A6 |
| Bill |
DSM |
John |
DSM |
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23-Channel Conundrum*
by Chuck Winder
Readers of the CR 914 NEWS will know about the potential of 2IM radio
interference that is called 23-channel syndrome. The puzzle has been:
Why doesn’t it happen more often?:
1. A single group of Txs standing
together and having 23 channel separations will not cause 2IM
interference in their boats. This explains Hitec’s Tony
Ohm’s observation that it is not a problem in model car
racing. In car racing, drivers stand together.
2. However, if a skipper standing a
distance from the above group sails close to the group of Txs, he will
probably experience 2IM interference.
The reason there is no problem in #1 is
that the 2IM signal at 460 KHz is much weaker than the Tx primary
signal. But if in #2 the signal received at the boat is sufficiently
weakened by the distance of the Tx from the boat, the 460 KHz signal
generated by the grouped Txs can be large enough to cause lack of
control.
At some sailing venues (like at Shoreline),
skippers walk along the pond to be close to their boats. In this case,
if boats
are widely separated, the conditions
in #2 can occur and interference will be experienced. At the Cow Pond
Regatta (4/10/2004), there were three 23-channel
combinations for the 19 boats! No loss of boat control was reported. At
this regatta the skippers all stood the same distance from their boats.
Though it surprised me at the time, #1 above tells why there
shouldn’t have been interference.
Tentative Conclusions
1. At a regatta where skippers stand
close together, there should not be 23-channel interference. Regatta
management can consider permitting 23-channel separations.
2. At a place such as Shoreline Lake,
the conditions for 23-channel interference can be occur since boats and
skippers can be spread out over a long distance.
3. If at any regatta the skippers are
restricted to remain within a small control area, then 23-channel
interference should not be a problem.
* The above discussion is derived from information from Dave
Collings, D & M Electronics and appeared in The
CR914 News ,
Issue 41 pg. 10
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