75mHz RFI issues

[vasily]

Re: 75mHz RFI issues

Yep, putting a non-dual conversion crystal in a dual conversion receiver could cause some significant glitching. A dual conversion crystal is your next step.
Your F14 Transmitter is PPM. (which is FM, by the way). A transmitter that can use PCM mode will be labeled PCM, PCM 512, PCM 1024 or PCM 2048. All the PCM transmitters I've ever seen will also be able to switch modes from PCM to PPM via an external setting (usually a digital setting in a menu).
I'm pretty sure the Futaba 168 receiver is PPM only. The futaba website may tell you somewhere.

[Guest]

Re: 75mHz RFI issues

Not quite sure what the numbers mean you have quoted. Over here we use 40mhz rather than 75mhz, and the sets are generally FM based, but Futaba did produce a 40mhz AM system with two or three channels. This was a budget system and the crystals are not cross compatible with the FM system.

[southern or]

Re: 75mHz RFI issues

FUTL97 and FMC872 are the model numbers for the series of FM crystal sets I think. The 3PM X is a cheap ground controller. I'l be getting a set of FMC872 crystals (CH 71) hopefully Monday or Tuesday. I know the channel is probably arbitrary, but CH 69 is their out of box stock channel and I figured I'd go for the middle of the range.

Fun little side note about my F-14-It's made out of two F-14s. The top cover housing, throttles, antenna, and joystick are from a new 40mHz F-14 with a new three stage switch and module made up of three stage switches and knobs. The heart of it is a rescued 75mHz board and the back cover is from the old board's controller (it has all the FCC stuff on it). The 75's case was gone. The antenna was broke, it's antenna housing was broke, and when I opened it the antenna wire was close to being no more. Other then that it was good so I got the new 40mHz controller and just swapped boards. I felt that the battery the 75 came with looked sketchy so I'm using the AA battery module the 40 came with but it does work. Funny thing, Engel carries the batteries I need, but getting them to me is beyond cost prohibitive.

I also have a Futaba T9CAP controller with a FP-PK-FM 75mHz module that came in it. Does the module work as a reroute as well for the built in antenna? I ask because people have been removing the 2.4gHz modules with built in antenna out of the WFLY controllers and replacing them with FM ones. I have to say that Futaba doesn't make crystal changes easy. The crystal is located on the board itself facing the back on the F-14 so you have to take it apart to change, and the crystal housing on the module faces the controller so have to take it out to change them. The T9CAP has a built in stand which makes removing the module more difficult then it otherwise would have been-but the menu does say "PPM" when I power it up despite the "PCM 1024" (what is 1024?) printed on it. I still need to scour the Futaba site for the instruction manual to it.

Is it just me or is the F-14 just a lot of money for the privilege of having a modular transmitter? Having taken two apart and built a new one, I would't call it advanced or digital. It is really easy to setup and use however since it's well marked for plug n' play with no unending menus to go through.

[Guest]

Re: 75mHz RFI issues

It's not an overly expensive set herein the UK. I guess it's looking a little pricey when compared with some of the cheap offering from China, but compared with other Japanese sets it's not overpriced.

Inside it's nothing special although you have the flexibility of re-routing controls etc. Not so easy to do with standard radios.

i actually use my own battery packs in the FC16. three cell Lithium pack (old computer batteries). Runs fine and lightens the unit.

Certainly wouldn't pay through the nose for Futaba original batteries.

Crystal location is a bit of pig on that set, but generally not as bad as having to change the crystals on the receiver inside a sub.

[southern or]

Re: 75mHz RFI issues

Here in the USA, Futaba quit production on almost all of their FM and AM transmitters and switched to 2.4gHz. That has had a drastic spike in the cost of working F-14s because everyone has been long sold out and finding a used one for sale typically turns into a bidding war. I quit bidding on a perfectly good one after the price went past $400. It sold for $690. That's well over three times the original real value. I paid a lot, but I also had to buy two. After that, I've started hoarding 75 FM gear for "when that day comes."

[Guest]

Re: 75mHz RFI issues

I guess one of the problems for the USA, is that aside from 27mhz which seems to be universal, they differed from most of the rest of the world by having their bands significantly higher.

Here in the UK we've been very lucky really in that we have a very wide range of frequencies to use. Some countries got a very raw deal.

It is getting harder to find the older equipment now, although there is the 433mhz (459mhz here in the UK) modules that Tim has done some very good research on, and that appears to work more than adequately enough and comes with some major advantages- e.g. shorter aerials, no crystals etc.

The only downside appears to be that it does still require a bit of setting up on behalf of the user, and there seems to be a fairly narrow choice of receivers, which may hamper installation in very small models.

Mated with inexpensive modular sets like Turnigy 9x/9xr or a Taranis if you want huge flexibility, you have a capable set.

[southern or]

Re: 75mHz RFI issues

I'm not so sure about 27mhz, I think that's Citizen Band Radio (CB) here and in Canada as well but maybe some of the 40 channels except channel except 9 (27.065 MHz) might still be open for R/C. I doubt it however since ch. 9 is specifically allocated for emergencies. Same goes with VHF ch16 @ 156.8mhz, but that's an internationally allocated frequency. I know VHF 16 by heart because I grew up on the coast.

[Guest]

Re: 75mHz RFI issues

The main issue with 27mhz is that they will generally be getting on a bit if they're multi-channel. Once the higher frequencies were made available the manufacturers stopped production of 27mhz sets for anything other than 2-channel.

Here in the UK, if you can ferret out a 27mhz set with lots of channels (e.g. four or more) then you will find it'll probably be about 30 years old or more.

The old Futaba M-series was highly revered in its day, not least because it was FM based and had a very hot output. But to be honest I've never had range issues with normal 40mhz FM based equipment, and the fact that a lot of more modern kit has niceties like DSP added onto receivers helps iron out little glitches when underwater.

[chips]

Re: 75mHz RFI issues

The UK Radio Control Council has a nice table that shows world wide r/c frequencies

In the US and Canada the 27 MHz channels and frequencies are:
A1 - 26.995 MHz
A2 - 27.045
A3 - 27.095
A4 - 27.145
A5 - 27.195
A6 - 27.255

CB radio frequencies are 10 KHz higher or lower than the r/c frequencies listed above.
3 - 26.985 MHz
4 - 27.005
7 - 27.035
8 - 27.055
11 - 27.085
12 - 27.105

[southern or]

Re: 75mHz RFI issues

Okay, new crystals and the receiver works great now. Receiver channels 1-5 work flawlessly, but decoder channels k1-k8 have some major problems. I'm using Robbe multi switch decoders No. 8369 set to PPM. The problem the decoder is having is well, decoding. The module it's receiving the channels from has four three stage switches and 4 dials. CH5 on the receiver has a three stage switch and it works flawlessly, full left, center, full right for servos. On the decoder the three stage switches don't work properly. They go full left, and full right and the third stage doesn't work at all. The dials are hit and miss and have a very poor range of movement. The decoder also seems to be suffering from lag which is weird and if I move the dials to fast the decoder sometimes misses the command entirely. I have 2 decoders (same model) and they both do it. I tried 2 different batteries on the decoder so the batteries aren't to blame because they both provided ample power to the receiver and I know both are fully charged.

Any thoughts? I'm planning on assigning the ballast tanks to the dials, but in their current running state I could send the sub into an uncontrolled dive. Upside though is that my frankenmitter works great.

[southern or]

Re: 75mHz RFI issues

I um, plugged the module into the receiver channel rather then the module adapter channel . The three stage switches work now as do the dials, but it still lags and I'm not entirely happy with the range of motion on the servos. I still need to make wiring harnesses for the dive system (they are getting their own 6V batteries) but I'm hoping that the range on the dials will be enough to get the tanks trimmed, full, and empty.

Also, just out of curiosity, WHY don't the marked channels on the transmitter correspond to the marked channels on the receiver? transmitter CH1 is CH3 on the receiver, CH2 is CH4, CH3 is CH1, CH4 is CH2, but CH5 is still CH5. The module is reversed too, but it transmits on CH7 for some reason.

[southern or]

Re: 75mHz RFI issues

I um, plugged the module into the receiver channel rather then the module adapter channel . The three stage switches work now as do the dials, but it still lags and I'm not entirely happy with the range of motion on the servos. I still need to make wiring harnesses for the dive system (they are getting their own 6V batteries) but I'm hoping that the range on the dials will be enough to get the tanks trimmed, full, and empty.

Also, just out of curiosity, WHY don't the marked channels on the transmitter correspond to the marked channels on the receiver? transmitter CH1 is CH3 on the receiver, CH2 is CH4, CH3 is CH1, CH4 is CH2, but CH5 is still CH5. The module is reversed too, but it transmits on CH7 for some reason.

I almost forgot, I'm not using a multi adapter f1561 because I only have one module.

[Guest]

Re: 75mHz RFI issues

Re channel order, are you using a Futaba receiver?

[southern or]

Re: 75mHz RFI issues

Futaba R168DF receivers

[KevinMC]

Re: 75mHz RFI issues

I um, plugged the module into the receiver channel rather then the module adapter channel . The three stage switches work now as do the dials, but it still lags and I'm not entirely happy with the range of motion on the servos. I still need to make wiring harnesses for the dive system (they are getting their own 6V batteries) but I'm hoping that the range on the dials will be enough to get the tanks trimmed, full, and empty.

Also, just out of curiosity, WHY don't the marked channels on the transmitter correspond to the marked channels on the receiver? transmitter CH1 is CH3 on the receiver, CH2 is CH4, CH3 is CH1, CH4 is CH2, but CH5 is still CH5. The module is reversed too, but it transmits on CH7 for some reason.

Is this on a Robbe F-14? The control-to-channel assignment is all up to you and where you plug each of the sticks/input devices into the main board.