Welcome to your 900Mhz Dipole Antenna!

[Thorbrandr]

I am ruining a TBS Crossfire Diversity with two dipoles on SMA connectors n my 212. I have space in the upper half of the WTC to run them crossed at about 30 degrees and at an angle up toward the bow. I had to work around the remote control, and the lower half of the WTC is taken up by a rather large battery. I figured that most of my running the side of the boat is presented to the radio, so this geometry seemed ok. it worked on the green water first run. I would need to do some moving of components and desoldering to get a more vertical orientation on the antennas.

I did lose telemetry below 4 feet or so. I was able to run the sub out at 50-60' submerged. I did have a few geometries where responsiveness dropped. Seeing this thread I will have to go back and test that some.

Sometimes if the connection gets spotty, try rotating your radio about the line between you and the sub to cut polarization mismatch losses. It can help. It does not help if you are in the receiving antenna null.

Note, as an RF systems engineer (not quite the same as an RF engineer or an antenna engineer) this thread makes sense.

[QuarterMaster]

Nice! I will take some pics and post it over there, but I am going to work on the USS Nautilus first. One project at a time. The biggest problem with the Krick model will be getting the wtc out of the boat. I glued the heck out of it into the hull!

Oooooooo...571...sweeeeet!

[billyd]

Awesome!

Start a new thread under the sub-form "Builders Thread" called "Billy's TYPE VII Krick" or some $#*! and let's start a refit log! No worries about putting it out there, NO one is judgemental (well except maybe HWMNBN, but that's only tough love, the man would give you the shirt off his back to see you succeed).

Start with some photos as she is.

Everyone is here to help, and really, just like the US Submarine Service "there is no such thing as a dumb question".

BTW, I refitted a KRICK U25, now using LiPO, Brushless Motors, new shafts, clear lid, and above all, 900Mhz!!.

Before...



After...



.Here's a video snippet of her by Bob himself at a previous run we did together. It starts at the Krick, but be sure to watch the whole thing.

More Seaview progress, an RC boat battle and more - Update from the Nautilus Drydocks - 12-16-23

Nice! I will take some pics and post it over there, but I am going to work on the USS Nautilus first. One project at a time. The biggest problem with the Krick model will be getting the wtc out of the boat. I glued the heck out of it into the hull!

[QuarterMaster]

Thanks for the response. After writing it all I figured it had been looked at but I left it up just to see what the general consensus is. I do have a crossfire, along with a lot of other rc stuff. I actually built a submarine (Krick Type V11) about 14 years ago. It worked well for awhile but then the water tight compartment ceased being water tight. I looked at trying to fix it but decided maybe someday to get a cylinder for it. It's now mounted on a wall (still functional I believe). That used an old 72mhz radio, and would cut out at about 4 feet deep or so. I just ordered stl's from Bob for the nuclear uss nautilus as I do a lot of 3d printing and have a very large printer (500mm^3) so I thought it would be a fun project for the next several months at least (I build slowly), and was thinking about what rc system to use and found this thread.

Awesome!

Start a new thread under the sub-form "Builders Thread" called "Billy's TYPE VII Krick" or some $#*! and let's start a refit log! No worries about putting it out there, NO one is judgemental (well except maybe HWMNBN, but that's only tough love, the man would give you the shirt off his back to see you succeed).

Start with some photos as she is.

Everyone is here to help, and really, just like the US Submarine Service "there is no such thing as a dumb question".

BTW, I refitted a KRICK U25, now using LiPO, Brushless Motors, new shafts, clear lid, and above all, 900Mhz!!.

Before...



After...



.Here's a video snippet of her by Bob himself at a previous run we did together. It starts at the Krick, but be sure to watch the whole thing.

More Seaview progress, an RC boat battle and more - Update from the Nautilus Drydocks - 12-16-23

[billyd]

Thanks for speaking out!

The short answer is that it's been already looked at.

We actually do have a member playing with it. But the general consensus is TBS Crossfire not worth it, price or power as a new purchase.

1-The Tandem units we employ now are don't need additional hardware. Most people are quite satisfied without the care and feeding of an extra mouth.

2-We don't "fly" miles away, no need to push envelopes. we can run happily @ 500mw 90% of the time.

3-While additional power might be great, 99% of use of an RC Sub is LOS, usually within 10m of ones location. Anything further is a blob under water, and periscopes are difficult to track, much less to spot beyond 100m. I know as that's my common distance to run at to avoid surface a$$clowns, maybe 5% of users have an environment to dive deeper than 1m.

4-Forget POV, not worth it. Back to the common, not clear environment. People have done FPV through a scope, great if you enjoy bouncing video.

The bottom line, if Crossfire was worth it to exclusively run submarines, it'd be the thing now.

Don't get me wrong, I'm a tech guy, and love pushing envelopes, but as an Engineer, requirements are are what's useful to me, and there is no specific requirement for ownership of Crossfire. So I wouldn't recommend it to 80-90% here. Maybe if you want to dive beyond 1-2meters, but why? To say you did? THAT is a personal choice and not a requirement for this pastime. Then I do encourage the user to review their needs for the additional expenditure.

Of course, if you do have it already as a drone pilot or other endeavor, rock on dude!

Again, thanks for the discussion, and stepping forward!!

Thanks for the response. After writing it all I figured it had been looked at but I left it up just to see what the general consensus is. I do have a crossfire, along with a lot of other rc stuff. I actually built a submarine (Krick Type V11) about 14 years ago. It worked well for awhile but then the water tight compartment ceased being water tight. I looked at trying to fix it but decided maybe someday to get a cylinder for it. It's now mounted on a wall (still functional I believe). That used an old 72mhz radio, and would cut out at about 4 feet deep or so. I just ordered stl's from Bob for the nuclear uss nautilus as I do a lot of 3d printing and have a very large printer (500mm^3) so I thought it would be a fun project for the next several months at least (I build slowly), and was thinking about what rc system to use and found this thread.

[QuarterMaster]

Thanks for speaking out!

The short answer is that it's been already looked at.

We actually do have a member playing with it. But the general consensus is TBS Crossfire not worth it, price or power as a new purchase.

1-The Tandem units we employ now are don't need additional hardware. Most people are quite satisfied without the care and feeding of an extra mouth.

2-We don't "fly" miles away, no need to push envelopes. we can run happily @ 500mw 90% of the time.

3-While additional power might be great, 99% of use of an RC Sub is LOS, usually within 10m of ones location. Anything further is a blob under water, and periscopes are difficult to track, much less to spot beyond 100m. I know as that's my common distance to run at to avoid surface a$$clowns, maybe 5% of users have an environment to dive deeper than 1m.

4-Forget POV, not worth it. Back to the common, not clear environment. People have done FPV through a scope, great if you enjoy bouncing video.

The bottom line, if Crossfire was worth it to exclusively run submarines, it'd be the thing now.

Don't get me wrong, I'm a tech guy, and love pushing envelopes, but as an Engineer, requirements are are what's useful to me, and there is no specific requirement for ownership of Crossfire. So I wouldn't recommend it to 80-90% here. Maybe if you want to dive beyond 1-2meters, but why? To say you did? THAT is a personal choice and not a requirement for this pastime. Then I do encourage the user to review their needs for the additional expenditure.

Of course, if you do have it already as a drone pilot or other endeavor, rock on dude!

Again, thanks for the discussion, and stepping forward!!

[billyd]

Hi everyone this is my first post to the forums, but I am not new to rc controlled vehicles. Has anyone tried TBS crossfire in a submarine? It operates at 915 Mhz and will also automatically increase transmitter power based on the signal connection, up to 2000mw. They have receivers with diversity antennae, allowing for the antennae to be placed at a different orientations to handle relative positional changes between the model and the Tx avoiding null spots. Another cool feature is telemetry allowing for all sorts of data to be sent back the transmitter for display. The antennae are not large (easily fit inside a cylinder) and the receivers can be standard size or as small as a quarter, depending on how many physical outputs you need to use. This equipment is usually used in model aircraft for flight beyond visual range with the pilot using live video to fly the aircraft, commonly referred to as FPV (first person view). Aircraft using this setup can fly miles away and the pilot can still maintain rc control. It would be interesting to see how it would work under water. Also you can use any transmitter with it as it piggybacks on any radio with a trainer port or ppm out. Unless you all already know about this in which I've wasted everyone's time and sorry lol!

[rwtdiver]

For me, its 75 Mhz, if I can find them, and if not, 2.4 all the way. Just do not need all that tech stuff to run submarines. But, if that is your cup of tea, coffee, coke, or what ever. Go for it!

Rob
"Firemen can stand the heat."

[QuarterMaster]

That is exactly what I was contemplating

GFL making it reach! Boy I wanna see that!

Now REREAD Bobs analysis!

But feel free to make extra work for yourself with an additional point of failure for 5-10% increase!

FWIW. no worries on anymore comments from me, I'm done here. Moving away from this subject at A/A Flank. Ping away boys!!

[Nathan]

How about disguising the antennae as one of the mast?

That is exactly what I was contemplating

[redboat219]

How about disguising the antennae as one of the mast?

[Nathan]

I definitely get what you are saying, Ed, and you are right that most of the time alignment within the cylinder will be just fine. The angle within the cylinder idea is very good, but still not always possible. And then the sail and periscopes just sit there staring at you... And as you said, people may have a requirement for a vertical placement - a search on "IPEX 4" got me some results on Amazon, if anyone needs to go that route.

Nathan

[QuarterMaster]

Sounds like we need a way to extend the antenna outside the WTC with a waterproof connector. Any ideas on where to start to source such a thing? What are these connectors and cables called?

Nathan, I think your missing the point of Bob's test. Depending on your needs, there may be NO NEED to do anything like that. If you spend 90% of your time at PD in our Texas mud, which I suspect you do, "GOOD" will work for you. Read Takeaway #4. Even at that beautiful Sylvan Rodriguez Park, you really can only run at depth 20-30 ft out before feeling "concerned".

So unless you have ALVIN and like to explore the depths of your swimming pool, or local quarry, or Cohutta/Carmel (1 weekend a year). OR you run below PD > 80' away (GFLWT) you need not penetrate the hull with 900Mhz. 2.4 is a different story.

Who out here wants another hull penetration to "feed"?

Look, it's about performance, what you need vs what you want. In my not so humble opinion, in a WTC you need to mount the RX near a BH anyway unless you purchase a custom IPx connector. Why do that unless you REALLY need to. I have a paycheck that states 80% of the users out there either don't care, or their needs don't warrant that.

I've been repeating the above long enough now (what are YOUR requirements??), so for those who care, read this....

In fact BOOK MARK it.

How to Mount/Position Transmitter and Receiver Antenna on FPV Drone

That being read, my recommendations are (for 80% of you).
Or go ahead and pop a hole offering another potential leak point.



I have spoken.

[Nathan]

Sounds like we need a way to extend the antenna outside the WTC with a waterproof connector. Any ideas on where to start to source such a thing? What are these connectors and cables called?

[RCSubGuy]

Video will post up later today as part of my weekly update, but here are the results. Really interesting results.

Our testing methodology involved the creation of a watertight enclosure that would allow for orientation of the dipole antenna underwater in relation to the transmitter. Testing equipment included a FrSky X18 Tandem radio paired to a TDR10 Tandem receiver. Output power was set at 250mW of a possible 1W (25%).

Two test series were conducted, one with the watertight box in about 18" of water behind a concrete lip in my pool spa. Interested in seeing how much the concrete affected signal strength, we conducted a second series with clear line of sight between the RX and TX. Due to constraints of my yard, the first tests were conducted at a distance of approximately 80ft from the receiver, and the second set was at about 40ft. We used the relative signal strength telemetry read at the transmitter (a built in feature of these radios), which is a value between 0 (no signal) and 100 (full signal strength) to get the following data:


RX in spa behind a 16" thick concrete/stone berm - 18" water depth - 80ft distance:

Description	Antenna aligned to TX	Antenna 90deg to TX	Antenna 45deg to TX	Antenna Vertically aligned
RX in open air	90	95	100	100
RX submerged	40	38	37	43
TX facing 90deg to RX	0	0	0	36

RX in pool with clear line of sight to TX - 24" water depth - 40ft distance:

Description	Antenna aligned to TX	Antenna 90deg to TX	Antenna 45deg to TX	Antenna Vertically aligned
RX in open air	95	100	100	100
RX submerged	40	45	46	50
TX facing 90deg to RX	0	39	37	40

Takeaways:

1. I don't see a significant difference in signal strength based upon the orientation of the receiver dipole antenna and the transmitter
2. There is a significant reduction in signal strength when the transmitter is not operated facing directly toward the receiver
3. There may be a large difference in signal strength when the distance between the TX and RX is increased far beyond the constraints of my test environment for this experiment, however, in my experience, most RC sub skippers operate their subs at a distance within 80ft from themselves. Any further out, and submerged operation becomes problematic and/or foolhardy. Operation while surfaced means that the built in 2.4ghz antennas are in play, and vast distances are achievable with high signal strength
   
   SO
4. When setting up the antenna in your sub, align the 900mhz dipole antenna vertically if you can.
5. If you cannot align the antenna vertically, avoid operation of your sub with the antenna aligned with your position

BEST:



GOOD:


NOT IDEAL: