PCM radios - comments?

[anonymous]

I have just been trying out a PCM radio in my sub and I wondered if many/any others have been trying these. (I have seen a few comments posted - equally balanced for and against.)

My experience was positive with good range and interference rejection. The biggest bonus was many less glitches, presumably from internal interference (lots of electronics in a small space.)

One thing I don't like is that you lose your fail safe settings for 2 minutes if you temporarily lose receiver power.

Are they worth the extra money?

[anonymous]

Who's using PCM (Pulse code

Who's using PCM (Pulse code modulation) receivers?
Any problems/advantages?

[Guest]

I use one in my

I use one in my Seehund.

However I wouldn't recommend them, chiefly because any radio glitch activates the failsafe immediately, which is great for an aircraft, but a pain with a submarine.

Andy

[petn7]

Doesn't the use of a

Doesn't the use of a PCM radio on a submarine negate the need for an external failsafe device in the WTC?

[anonymous]

Yes - with limitations.

The failsafe

Yes - with limitations.

The failsafe settings are sent from the transmitter every minute or so and loss of power to the receiver will lose these settings until the next contact with the transmitter i.e your sub could be on the bottom having lost the failsafe settings!

Also as Andy says the failsafe will trigger after only 1 or 2 seconds. A long time for airplanes but not for submarines.

May be as in lots of things the needs of R/C airplanes are better catered for than submariners!

One other thing I do like is if you have a freqency clash at the pond - an ordinary FM transmitter will not start to control your model.

David

[anonymous]

Many thanks for your comments.

On

Many thanks for your comments.

On reflection I think I am going to give up on PCM. The failsafe is a real problem because it does the wrong thing too quickly!

Submarines need failsafes that are self contained in the sub and only cut in many seconds or minutes after there is a problem.

PCM was clearly developed only with airplanes in mind - I suspect that it may not be good for helicopters either.

[anonymous]

Note to self ( and

Note to self ( and anyone else searching on PCM in the future!)

On reflection , I will continue to use PCM but will probably incorporate a backup battery(just plugged into a spare servo socket on the receiver) to maintain the failsafe settings.

[anonymous]

Further observation. (Sorry I seem

Further observation. (Sorry I seem to be talking to myself but hopefully it's useful to others!)
I have been using my PCM receiver a few times now and it is good. Less interference and the failsafe defaults are useful. I have programmed in a few seconds delay into submerge and surface to slow the failsafe cutting in.
I have not used a backup battery. Even using a BEC you would have to be very unlucky to have a power failure in the 1 minute between the defaullts being updated by the transmitter.

[KevinMC]

Davy,

What radio are you using

Davy,

What radio are you using that offers a programmable failsafe delay? (I'm guessing it's a JR. Certainly not Futaba.)

KMc

[wingtip]

anything like the JR 8103

anything like the JR 8103 on up will have failsafes and the 10x has the delay features of "slowing" the servo/function down that was programmed as a failsafe.... futaba radios from the 9c on up all have the same features as well....
i think a failsafe setting of turning on a pump for a rcabs bladder would take long enough for signal to return and then open the valve back up and you would see minimal depth change... however, in a gas/air system this would be much more noticeable as the gas/air would enter much much more quickly than the little 6volt pumps for the rcabs....
I just bought my spare 8103 (150 bucks, cant beat that) that i plan on converting to 75mhz. and i plan on using the failsafes as well... this will also be the test bed for the antenna length testing i will be conducting as mentioned in the other thread....

[anonymous]

I am using a Futaba

I am using a Futaba 9C but the delay is programmed into my own software that controls the dive/ surface pump etc on the submarine.

I must admit I was not aware of eny servo slow function on the transmitter failsafe. I am going to have a 'delve' into the many pages of the manual! It would be useful because otherwise the defaults cut in very quickly - less than a second.

Thanks for the suggestion and i will let you know what I find.

Dave

[anonymous]

You are right, Wingtip! Only

You are right, Wingtip! Only page 59 of the 9C manual!

There is a throttle slow function on the 9C "to emulate a gas turbine" - now that is really useful on submarines

Joking aside it does look to have potential since "it can slow the servo traverse down to 8 seconds."

I will say how well I get on.

[anonymous]

I have tried the slow

I have tried the slow function and it works nicely when the transmitter is turned on.
Unfortunately the failsafe still cuts in almost instantly - sensible for aircraft but less good for submarines where some delay would be helpful in responding to any loss of signal.
Thanks for the info Wingtip and maybe one day a transmitter will be designed for submarines
Having said this I'm pleased with PCM and the failsafes are useful with the mods I described earlier.

Dave

[KevinMC]

Davy- I was afraid that

Davy- I was afraid that the slow feature would be ignored during failsafe. This is because the "slow" is artifically generated at the transmitter, so the RX won't know anything about it. When the failsafe kicks in it just jumps into its "failsafe" position.

But you're not sunk yet! <Groan> If you've got any room for extra electronics there is another option. I've seen several DIY in-line servo slowers that could be plugged in between the Rx and your ballast servo. (Here's one]http://www.rc-cam.com/ldtastic.htm)[/url] This would accomplish the same thing as the servo slow feature in your transmitter but will continue to work during "failsafe" operation.

[wingtip]

mcdaniel rc, if they're still

mcdaniel rc, if they're still around, had a servo slower i used at one time on a 182 cessna for the flap functions so it just didnt pop them down causing it to balloon upwards... it was a nice feature and was adjustable...
but i think it didnt slow untill you triggered or initialized it correctly once turned on so during failsafe it might be useless as well... they were in little orange boxes...