2.4 in model subs

[itolond]

Hi forum,

anyone effectively used 2.4 RC in their boats?

[salmon]

Yes. There are caveats to that. The antenna must be above the water (once under it loses signal quickly). However, that is not a big deal. The guys I know that used to run in brackish water used to run antennas up the scopes to keep it running and had longer delays on the loss of signal for the safety devices. Never hampered them from running all day long (or until batteries got low). Currently, we have sub guys running 2.4 and love it - no channel clashing for them.

[itolond]

Yes. There are caveats to that. The antenna must be above the water (once under it loses signal quickly). However, that is not a big deal. The guys I know that used to run in brackish water used to run antennas up the scopes to keep it running and had longer delays on the loss of signal for the safety devices. Never hampered them from running all day long (or until batteries got low). Currently, we have sub guys running 2.4 and love it - no channel clashing for them.

OK understand -the same restrictions apply for penetrating water. I have a few Hitrec FM units but thinking longer term

[thor]

I am writing a series of articles for the SCR on the various radio options available to us, including 2.4 Ghz. I have been running a 1/96th Permit around with a 2.4 Ghz system in it. It certainly works and it has it pros but, personally, after having run my boats for so many years with the freedom to dive as deep as I care to go I find the antenna to be extremely limiting. That's just my opinion, and you may find having what is basically a slightly submerged surface runner perfectly satisfactory for you. It is, definitely, a personal choice. A couple of my sub buddies use 2.4 Ghz and are perfectly happy with it. Sub Ed loves it!

[cdivine]

Could someone clarify this. I thought there were FCC laws governing which frequencies could be used for certain types of RC? Did I misunderstand this Matt? Have I been locked unnecessarily in to 75mhz for no reason?

[Oldus Fartus]

Could someone clarify this. I thought there were FCC laws governing which frequencies could be used for certain types of RC? Did I misunderstand this Matt? Have I been locked unnecessarily in to 75mhz for no reason?

The only band you can't run in a sub is 72 MHz which is for aircraft.

[thor]

Chad,

433 mhz requires an amatuer HAM license. It works extremely well, but there is that small snag. The 915 mhz frequency radios require no license, but have limited range submerged. Ive had a tough time averaging 24" depth before my failsafe trips. I have found one local lake where I can get down to almost 4 feet, but every other body of water has been 24" or less.

75 mhz allows almost unlimited depth capability and is still my preference. There is still lots of gear available and even new gear.

2.4 Ghz works extremely well, but is depth limited by the antennae. Unfortunately just lengthening the antennae for more depth range doesn't work well. Weird stuff starts to happen if you go beyond a certain length of coax

75 mhz is a surface frequency only.

72 mhz is an aircraft frequency only. However, no one I know who flies uses the 72 mhz frequencies any longer. All of the aircraft guys have swapped over to 2.4 Ghz. There are a ton of new 72 mhz radio system still available through various sources. If you chose to use 72 mhz on the surface you are in violation of the FCC regulations. Use 72 mhz at your own risk.

[JWLaRue]

..... If you chose to use 72 mhz on the surface you are in violation of the FCC regulations. Use 72 mhz at your own risk.

Better yet.....buy that 72MHz crystal-based radio and have it re-tuned by an FCC-certified person/company to run on 75MHz.....

-Jeff

[SubtechRC]

Both Bob Martin of Nautilus Dry Docks and I(Subtech) have a good stock of 4 & 6 channel radios on 75 MHz and 72 Mhz. We can have pretty much any 72 MHz radio converted over for you if you would like to have that done. Plus, I just located a nice stash of Futaba 9Cs that are new in box. These are absolutely fantastic radios and we have plenty of 75 MHz FM Modules in stock, as well. There are enough of these new units around to last the hobby many years into the future.

I do plan to be carrying the 915 MHz gear in the very near future. The 915 mhz systems are very nice and powerful, but the arduino programming is a bit more numbing than the 433 MHz systems.

[marvin harten]

Hi Thor- I am planning a 2.4 Ghz system. What should an antennae system look like and how would it be connected to the two wire arms of the Rx? Would you use coax cable? Based on your note, there seems to be a limiting factor as to the length of the cable or extension wires. Do you have an estimate as to the correct length? I would appreciate any information that you would be willing to provide.
Thank you.
Marvin Harten

[SubtechRC]

Marvin,

I would refer you to the thread by Sub Ed (Quarter Master) on what he did. He opened up and modified his receiver to accept coax. Unless you are quite adept at soldering and electronics work, I would not recommend going this route. I would recommend that you purchase a receiver that is already set up with the coax antennae.

Every receiver is somewhat different in design so the antennae length may vary a bit. I played around with mine to get it to work best for me, but I started having receiver issues when the overall length was more than 20" long from receiver to exposed tip above the surface.

Im no RF engineer and don't claim to be, but that's what I ended up with. I have about 8" of antennae above the top of my sail. Not very scale-like but it works

[QuarterMaster]

Here now you have.......

Graupner Robbe NAVY F-14 TX 2.4ghz conversion using Corona 2.4Ghz DIY Module & RX (DSSS)

Links are in the description for further help.

Be advised you ARE limited to keeping that antenna (1-1/4" exposed center conductor) above water. Again, 99% of my time driving with the intent of NOT losing sight of my scopes due to running in open water, I'm fine with it.

Availability of RX/TX components, NEVER needing to beg for frequency flags, and rock solid performance (no glitching) makes it ++ in my book.
.
As soon as another RX arrives (in transit), I plan a follow up video with focus on actually soldering the COAX to the RX PCB and other tidbits I've since learned.

[SubtechRC]

Very interesting, Ed! I've purposely driven my boat under with the intent of experimenting with antennae limitations and I had the very same observation. More than an inch of antennae is required to stay above the surface or contact becomes very intermittent or non-existent.

The other thing to keep in mind here, folks is that Ed is a very experienced and seasoned Sub Modeler. Take his caveats very seriously.

[scott t]

In your experiments have you left enough antenna to float on the surface of the water to see if you get reception with say a dragged floating antenna?

[SubtechRC]

Scott,

As I said above, the reception gets wonky very quickly after the antennae exceeds 20" in length. The antennae must protrude above the surface at least 1 1/2" or it just doesn't work as far as I have found so far. Ed has had very similar experiences.