75mhz radios, Condition Red!

[RCSubGuy]

Well, I was hoping that the supply of 75mhz gear would last longer than it has, but it appears that the supply of our needed radios it's getting close to drying up.

I have now nearly exhausted my inventory Sombra receivers. I have a few of the SL 8 units left but after that, nothing left. I was also hoping that they Vex Robotics transmitters would remain on the market for years to come, as there was a massive amount of those units in stock with the supplier. I just learned that they wrote the whole selection off, and scrapped everything that was remaining.

What is on the market now is what we have to play with.

Of course, we can always make do with sticking antennas above the surface and running gigahertz gear, but that is certainly not and ideal state. If we are to make this hobby something that appeals to the masses and provides the highest degree of enjoyment, we will need to source radio gear to make it all happen. I'm standing by to help in whatever way I can. If anyone has any ideas, suggestions, or comments, I would certainly be very happy to facilitate in any way that I can. I may have stumbled upon a source for receivers, but without transmitters they are next to useless.

[He Who Shall Not Be Named]

The thought of all those transmitters being unceremoniously dumped into a land-fill is awful! Likely done because of liability concerns (the Boston bombs employed commercially available r/c gear).

Here's another fork to stick into our situation: Little appreciated, but always the case, is the fact that the 27, 72, and 75 MHz bands were assured hobby use because of the lobbying clout of the Academy of Model Aeronautics. For decades the AMA insured that the Federal Communications Commission (FCC) would keep those bands assigned to the r/c vehicle hobbyist. Not anymore. That blanket congressional voice we enjoyed no longer is concerned about those bands. Other than us (the submarine drivers) no one has a vital need for the lower frequencies to operate their r/c vehicles. 2.4gHz works for all r/c vehicle drivers but us.

Without the support of the AMA in this regard; without their political clout, we can be assured that some day soon those lower bands will be auctioned off to other users by the FCC -- and the instant that happens, all our transmitters become illegal!

With one band (2.4gHz) -- and the ability of frequency hopping within the confines of that band -- there no longer is a need to support (lobby) for multiple bands and the discrete frequencies within each of those bands. No one but us sub-drivers needs RF to punch through water to enjoy our hobby.

Soon the only r/c gear available to us will (surprise!) be right at the resonate frequency of water!

We're screwed!

David

[He Who Shall Not Be Named]

I see a need for a source of supply that provides 2.4gHz receivers with an installed coax cable terminating in a full-wave 2.4gHz antenna.

It's the only option for the future of this hobby I can see at this time.



And a look at the album dedicated to use of 2.4gHz receivers in submarines:

http://s262.photobucket.com/user/dmeriman/slideshow/radio%20control%20gear

David

[greenman407]

I thought I had something for you Bob. The Robot Marketplace had Tons of 75mhz stuff......................Not Anymore.

[greenman407]

Its a pain in the BUTT, but you can take one receiver out of one boat and put it in another. But that doesn't do anything about advancing the Hobby.

[Albion]

I just found a shop over here with a pile of 29mhz 4channel rx and Tx complete with batteries are chargers, roughly $30 a set. No one enforces frequencies here and everyone else is on 2.4 ghz

[greenman407]

These people still have some:

[greenman407]

Dollar Hobby has nine(9) of them on Ebay:

[silentrunner777]

I don't know how long these will last, but they do have a 7 channel Rx. http://www.harbormodels.com/4yf-fm.html

[tsenecal]

for those of you that own 75mhz transmitters, and wish to stick with 75mhz receivers, there are tons of available 72mhz equipment that is available on ebay for under $30. any 72mhz receiver will run fine with a 75mhz crystal.

for those of you shopping to get a transmitter or complete radio setup, don't bother getting a 75mhz....

with the latest generation of equipment that is available, there is no soldering, no programming, no hacking about...

unless you want to

my laundry list for all that you need to get started in 433mhz, circa 2017:

one of these $105:

http://alofthobbies.com/frsky-taranis-q-x7.html

one of these $80:
http://www.hobbiesfly.com/transmitte...ompatible.html
or these:
http://www.hobbiesfly.com/transmitte...mitter-v2.html

and an antenna for it $25:
http://www.hobbiesfly.com/transmitte...f-antenna.html

as many of these as you need $30-$40:
http://www.hobbiesfly.com/transmitte...-receiver.html
or
http://www.hobbiesfly.com/transmitte...-receiver.html

and antennas for them $5:
http://www.hobbiesfly.com/transmitte...na-90-sma.html


you can second source 433mhz antennas almost anywhere, for example, if you need a tiny antenna to fit inside a tiny sub:
http://www.ebay.com/itm/433Mhz-GSM-a...8AAMXQBPpR5P-~

put batteries in the transmitter, put module in transmitter, figure out how to activate external TX module instead of internal, set radio up to output sticks and switches the way you want, swap receivers, attach antennas, power on, bind, and you are done. - please note that all the steps about setting up the transmitter are steps you do ON the transmitter, ie "setup a new model", like you would on any computerized radio.

study for a week to take your Ham TECHNICIANS test (35 multiple guess questions), take the test, pay your $10, you are good to go.

for the USA market, keep your HAM license handy, and respect the learning you had to do to get that license, and simply be a good HAM operator.... don't step on primary users of those frequencies, and you won't need to worry about ****ing anybody off.


for those of you in Canada, who cant legally use 433mhz, there may still be hope... give me some time, there are other frequencies i haven't yet tested in submarines.

[greenman407]

The one at Aloft hobbies says that its 120mhz

[george]

Hi tsenecal
Could you please confirm your first line in post #10 above? If I read that correctly, you said that one can buy a 72mhz receiver and put in a 75mhz FM Crystal and it will work for 75Mhz FM radio set in subs. I always thought that you had to have the 72mhz receiver retuned by radio south or others to 75mhz for the receiver to work with a 75Mhz FM radio and a dual conversion RX crystal.
Is that right?
George

[tsenecal]

The one at Aloft hobbies says that its 120mhz

No, "the one at Aloft hobbies" lists in its description that its "ARM Cortex M3 32-bit" cpu runs at 120MHz. which has nothing to do with its RF deck.

by default, this is a 2.4ghz system. it has a SECOND available, open, empty socket, where a second module can be put. that module could be another 2.4ghz module for FrSky, or any other RF module that fits in that socket.... like a 433mhz module as the second and third links are.

[tsenecal]

Hi tsenecal
Could you please confirm your first line in post #10 above? If I read that correctly, you said that one can buy a 72mhz receiver and put in a 75mhz FM Crystal and it will work for 75Mhz FM radio set in subs. I always thought that you had to have the 72mhz receiver retuned by radio south or others to 75mhz for the receiver to work with a 75Mhz FM radio and a dual conversion RX crystal.
Is that right?
George

A transmitter must be retuned so that it is guaranteed that it is transmitting on the correct frequency, and not blasting bad data somewhere it doesn't belong.

A receiver only needs to be capable of "hearing" the "correct" transmitter, and ignoring all others. You can spend the money and have it re-tuned if you want to, but if if works by just swapping the crystals (which it has for me EVERY SINGLE TIME) then why bother? when i say EVERY SINGLE TIME, i mean EVERY SINGLE TIME. not just swapping 75mhz from 72, but from 35, 40 and 50mhz as well.

PLEASE be warned... there are caveats: You must be absolutely certain that the 75mhz crystal you have is the correct type of crystal for your receiver. you can not mix and match. if you have a dual conversion futaba receiver, you need a dual conversion futaba crystal. very few crystals can be swapped, and you are guaranteed to fail if you try to stick an AM single conversion crystal into an FM dual conversion receiver, or a JR crystal into a Hitec receiver. you do need to know what you are doing if you are trying to do anything across brands or makes

[george]

Hello Again tsenecal

Thanks for the fast reply and THANK YOU VERY MUCH!!!! for the info. I think you have helped to save me quite a bit of money. I like / use Futaba 75mhz FM radios with dual conversion FM FPR127DF receivers. I have picked up a few in 72mhz with plans for conversion of them to 75mhz. I can`t express how much your post has saved me money in the future. I ONLY use the Futaba FM dual conversion receivers and now ALL I have to buy is the 75mhz FM Dual Conversion Crystals to match my TX.

Thanks AGAIN, IF I was near you I`d buy you a COLD BEER OR TWO!!!!!!!!!!!

George Tonkovic