What's in the water? A "Groton Report"

[QuarterMaster]

Many RC SUBmariners who have ran their models at the North Lake at the Sub Base in Groton*have experienced the "mysterious and random" glitching that it's infamously known for.
I know I have, even if it's just that well known "dead zone" around that upright discharge pipe along the north shore.

We know it's chlorinated.
We know it has piping along the bottom.
We even know there are pumps possibly generating EMI.

But did we know this?
This is what I discovered on my rare earth magnet when using the "mooring ball" this past weekend at the 2017 Groton SubFunRun.
There seems to be quite a bit of ferrous material in the lake bed and I'm sure free floating particulates as well. Even the grains of quartz were sticking!!

Is it from the natural geology of the area? Decades of steel pipe used in the plumbing corroding away?
Is it the sole cause of these apparent RX woes? Or one of many?

I do know one thing, those of use who use mechanical pumps or pistons for ballast control, even wet side gear reduction do suffer mechanically from the "Groton Granite" (silt) just floating around in it.
By day two my drive train got noisy(er).

Any experts (or not) with opinions out there?

BTW, the SHARK now operating on 2.4GHz, ran flawlessly, at least with respect to command and control lol. No worries about this so called "Frequency Board" thing either that everyone else seemed worried about! (HA!!)

[thor]

Hi Ed,

I've been playing around with various new radio systems in my boats, and I just finished up with trying to use a 2.4Ghz system and, as expected, a radio antennae extension was needed the surface. To get a reliable signal I ended up going to an extendable coaxial antennae attached to a thin FRP whip. What have you done with your system to get reliable and consistent reception?

[QuarterMaster]

Matt,

Followed exactly what was done here....

How To Adapt The 'New' 2.4gHz Gear To R/C Submarines

I have NEVER been as rock solid as she was in Groton this past weekend.

I'll take more pic's of mine and post by this weekend

[thor]

The link fails for some reason. Thats ok, I'd really like to see what you did.

[salmon]

https://forum.sub-driver.com/forum/general-topics/2949-how-to-adapt-the-new-2-4ghz-gear-to-r-c-submarines

Does the above link work better?

[crueby]

Yes, thanks!

[thor]

Thanks Ed & Tom. I read through that thread. While I chose to go a slightly different route the end results were identical. 2.4 Ghz is, certainly, a viable option.

Very nice work, Ed!

[QuarterMaster]

Matt,

Sorry this is late, and hope it helps....

Some Engineering Notes for you, as well as links for the Coax Stripper for RG-178, and components:

The thru-hull Gland Detail, I'm sure you have your own thoughts here.


This is how I'm making by antenna's now. Using the Nylon plug at the end guarantees a seal, and itself looks like a real antenna on the model lol


In order to make it easier, and not have the RX permanently attached to the Antenna passing through a bulkhead. I decided to purchase these M/F Cable Assembly's in 4' Lengths.
SMB Female To SMB Male Connectors RG178 Cable Assembly
This way if the antenna gets damaged, you don't have to de-solder the coax from the RX. It's a tough area to solder and I'm always worried about lifting lands (Cu) off the board.
The following shows how I'm setting it up now in lieu of a single continuous coax. Pricey, but worth it for me. Just cut the male side used in the dry space to size, and you should have plenty left on the female side to exit the dry space and be made into the actual antenna.



Coax Stripper: Paladin PA1258 Coax Stripper, RG178/179/735A
Coax Antenna Plug: Wear-Resistant Nylon Rod, 1/16" Diameter, 4' Length McMaster Carr 8538K11
Coax Antenna Waterproofing: Moisture-Seal Heat-Shrink Tubing, 1/8" ID Before, 1/64" ID After, 48" L, Brown Coax Antenna McMaster Carr 73115K71
Coax Antenna Waterproofing: Moisture-Seal Heat-Shrink Tubing, 1/8" ID Before, 1/16" ID After, 6" L, Black, Packs of 5 McMaster Carr 74965K51
Coax Antenna Gland: High-Temperature Silicone Rubber Tubing, Semi-Clear White, Durometer 70A, 1/16" ID, 3/16" OD, 10 ft. Length McMaster Carr 51135K608

Also, not sure if you seen this on the TX side.
Graupner Robbe NAVY F-14 TX 2.4ghz conversion using Corona 2.4Ghz DIY Module & RX (DSSS)
My next antenna build I'll do a video of that side.

The biggest thing is to buzz the shield to center to conductor with an Ohmmeter after stripping/soldering to insure NO shorts. This RG178 has very thin inner/outer jacketing.
Practice, practice PRACTICE!!

I'm really digging this 2.4ghz, Despite the limitations of PD, I have never felt so comfortable with control of my boat, not to mention the lack of "Frequency Hog" worries at an event.
It's a relief.

In the end, I'm sure there are many ways to run this cable, I know I want to rethink the whole watertight fitting to make the wet side completely removable. For now just oversize, and trim if needed by repair.

If you have any trouble with the links, I'll send the actual URL's.

[thor]

Ed,

Thanks! and nice work. The only big drawback to 2.4 Ghz is the lack of true 3D capability. By that, I mean a very limited Z axis. You can only dive as deep as your antenna will allow. Other than that it is definitely an excellent option.

Hitec has a couple of very nice 2.4 Ghz receivers ready to go the heavy coax so you don't have to open up your receiver to replace the 'cats whiskers' antenna with coax. I really don't like modifying my radio gear.

But, as you show, to get it to the surface even that must be extended. I like your method of doing that. Very slick!