# Futaba 4pk



## ScottH (Nov 24, 2005)

Is anyone out there running one?

Just curious if it is that much better than the 3pk.


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## ovalrcr (Sep 9, 2007)

Im curious too...and I thought my 3pk was my last radio for a long time...i guess we'll see huh?


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## pancartom (Feb 26, 2002)

I just got mine last week. We got rained out Wednesday, so I still haven't raced with it yet. I replaced a 3PK that was a couple of years old. The 4PK seems to have all of the same functions as the 3PK, I just wanted to upgrade to the FASS system from the Spektrum I was using with the 3PK.


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## hobbyten (Apr 5, 2004)

they've been having a bad time with the fassst system in 1/4 scale this yr. the reciever gets a little warm and shuts down in the wide open position. most of them have went back to spektrum to avoid this. this may not be a problem with the 4 pk especially where there's not a lot of heat involved. good luck my first love in radios has been futaba but i also went to spektrum and love it.


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## OvalmanPA (Mar 21, 2000)

Maybe I'm missing something here? How would the receiver be getting to warm unless you are running it by the engine?  If that's the case move it away from the engine. :lol: I've seen to many problems still with the Spektrum system to want one. I have a 3PM 2.4 system that works great, never a glitch yet.

Sorry, doesn't have anything to do with the 4PK but the comment about the receiver "overheating" has me curious.


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## ScottH (Nov 24, 2005)

There is a thread discussing these issues in the QSAC forum.


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## hankster (Jan 1, 1998)

The receiver provides the voltage/current to drive the servos. QS use two steering servos and a throttle servo and the extra current draw can cause overheating.


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## ovalrcr (Sep 9, 2007)

hankster said:


> The receiver provides the voltage/current to drive the servos. QS use two steering servos and a throttle servo and the extra current draw can cause overheating.


Not familiar with 1/4 scale but this would make sense!


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## ovalrcr (Sep 9, 2007)

hobbyten said:


> good luck my first love in radios has been futaba but i also went to spektrum and love it.


I always use futaba too but Im gonna get a spektrum module for my 3pk instead of the fasst system because of problems with low voltage when running 4 cells.


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## hobbyten (Apr 5, 2004)

hankster said:


> The receiver provides the voltage/current to drive the servos. QS use two steering servos and a throttle servo and the extra current draw can cause overheating.


they also are inclosed in a box to keep them away from fuel and such which holds the heat in.


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## ovalrcr (Sep 9, 2007)

pancartom said:


> I just got mine last week. We got rained out Wednesday, so I still haven't raced with it yet. I replaced a 3PK that was a couple of years old. The 4PK seems to have all of the same functions as the 3PK, I just wanted to upgrade to the FASS system from the Spektrum I was using with the 3PK.


Be sure to let us know how you like it. :thumbsup:


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## OvalmanPA (Mar 21, 2000)

I'll have to check out that thread because I had no idea an issue like that could even exist. I know guys were concerned about issues with 4 cell when these systems first came out but I haven't experienced any problems using 4 cell in Spec truck and a Trinity 4 cell spec pack sure isn't a power demon. :lol:


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## VA.RACER (May 5, 2003)

*fasst system*



ovalrcr said:


> I always use futaba too but Im gonna get a spektrum module for my 3pk instead of the fasst system because of problems with low voltage when running 4 cells.


I had just the opposite problem at the Snowbirds.
I was using the pro receiver. I understand the micro receiver helps stop that with the spektrum system.


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## Mike Clark (Apr 28, 2007)

OvalmanPA said:


> Maybe I'm missing something here? How would the receiver be getting to warm unless you are running it by the engine?  If that's the case move it away from the engine. :lol: I've seen to many problems still with the Spektrum system to want one. I have a 3PM 2.4 system that works great, never a glitch yet.
> 
> Sorry, doesn't have anything to do with the 4PK but the comment about the receiver "overheating" has me curious.


Well lets see if I can offer some additional information.
All 1/4 scale cars have the following, two high torque steering servos, most use a 1/4 scale hi torque for throttle control, depending on you available location for the receiver you'll need a Y connector cable for the steering servos and at least a 12" extension for the thottle servo.
Now couple that with the fact the throttle servo is almost never off except for a burp entering into a turn and the steering servos while in tandem are used extensivly all the time. 
The voltage drop across all servo cables and the voltage across the receiver is what's heating up the receiver and as the receiver gets hotter the voltage drop goes even higher pushing the receiver into the thermal limit and shut down.

I'll give you a for instance: Racing at LPR in Montgomery, Alabama last weekend I ran my car and finally got to the point of predicting when my receiver would trip off. 
For this test I removed the 2 ram air intakes that I installed to provide external cooling for the receiver. 
I filled my gas tank 1/2 full and went out and ran 55 to 60 laps. Brought my car down pit road and parked it with the engine running and in 5 to 6 seconds while sitting still the receiver connection led would go from green to red and lock me out of operation. I could go back to the pits and cool the receiver down with nitrogen and go right back out.

I performed this exact action 3 times with the same result.
That's predictability! Most time my receiver was hotter than my tires and that's hot, at least 160 degrees. Futaba has two of my receivers and hopefully the problem will be resolved.

Problems: Either the receiver is to small for an efficent thermal exchange or the traces & components are on the PCB are borderline of being to small for this application.


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## AJS (Mar 21, 2002)

I have the Faast system and I have never had a glitch, 3 different cars, three different receivers and always on 4 cells, never a problem. I was at the BRL finals last year and I know of 2 racers that purchased the FAAST System because they were having problems with their spectrums getting hits, replaced with the Faast and no problems. And this was all 4-cell racing.


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## jake86 (Jan 3, 2003)

AJS said:


> I have the Faast system and I have never had a glitch, 3 different cars, three different receivers and always on 4 cells, never a problem. I was at the BRL finals last year and I know of 2 racers that purchased the FAAST System because they were having problems with their spectrums getting hits, replaced with the Faast and no problems. And this was all 4-cell racing.


 Make that 3 racers. I switched to a 3pk and a faast system because of the problems I was have with my spektrum systems. No problems since the switch. 

How is going AJ?


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## OvalmanPA (Mar 21, 2000)

Mike Clark said:


> Well lets see if I can offer some additional information.
> All 1/4 scale cars have the following, two high torque steering servos, most use a 1/4 scale hi torque for throttle control, depending on you available location for the receiver you'll need a Y connector cable for the steering servos and at least a 12" extension for the thottle servo.
> Now couple that with the fact the throttle servo is almost never off except for a burp entering into a turn and the steering servos while in tandem are used extensivly all the time.
> The voltage drop across all servo cables and the voltage across the receiver is what's heating up the receiver and as the receiver gets hotter the voltage drop goes even higher pushing the receiver into the thermal limit and shut down.
> ...


So you haven't had any problems with the "air ducts" you made for cooling then? I would say this shows with the receiver being so small that it can't dissipate the heat quick enough with you guys running it in a box with all the strain they are experiencing in 1/4 scale. I would think with more airflow there wouldn't be as many problems. I hope Futaba can get something figured out for you because they really are a nice unit (FASST). Thanks for the information and it was a good read in the QSAC area as I had no idea something like would/could happen.


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## ScottH (Nov 24, 2005)

Mike -- Do you think that it is the traces in the reciever or the length of the Y-Harness and extension.

If it is a WIRE ISSUE, we should be able to slove that with some larger wiring. Maybe even going away from the cheap copper wire with some higher quality wire.

Hmmmmm... got me thinking now.


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## AJS (Mar 21, 2002)

I'm doing fine Jason, won't be long till carpet racing!!!!!!!!


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## Mike Clark (Apr 28, 2007)

ScottH said:


> Mike -- Do you think that it is the traces in the reciever or the length of the Y-Harness and extension.
> 
> If it is a WIRE ISSUE, we should be able to slove that with some larger wiring. Maybe even going away from the cheap copper wire with some higher quality wire.
> 
> Hmmmmm... got me thinking now.


Hi Scott,
I've got the largest wire available on the Y plug and the extension and the servos also. I have purchased new servos, a volt watch and I've gone as far to put ferrite beads along the cable runs to cut down on any capacitive action. 
Like I told Futaba Tech Support today in a one hour conversation, I reproduced the problem three time last Saturday and all I had to do is remove any external cooling means for the receiver. Right now I can either use the ram air system that's in place or use some thermistors, place them inside the receiver and use them to turn on a processor type cooling fan placed over the receiver. No matter one receiver will be opened tommorow no matter what, here's hoping.


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## DOUGHBOY (May 7, 2008)

I Run The 3pk With The Spektrum 2.4 Module And Love It I Have Looked At The The 4pk And Dont Really Like The Way Its Laid Out But I Am Sure That I Wil Grow To Love It As Much As My 3pk If Not More


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## Toxic2 (Oct 1, 2005)

I also changed from spektrum to fast system. Inside, my spektrum would send my car full throttle into the money wall.:drunk: Changed to fast and have had no problems. Have had no problems running futaba in 4 cell spec. class. Run spektrum in my losi late model outside with no problem.


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## JOHN B (Apr 17, 2006)

the 4pk is a great radio it is lighter and has more bells and wistles than you could ever use!!!!!!!!!!!


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## ScottH (Nov 24, 2005)

JOHN B said:


> the 4pk is a great radio it is lighter and has more bells and wistles than you could ever use!!!!!!!!!!!


Besides weight, what makes it superior to the 3pk? Having "more bells and whistles than you could ever use", is not a plus in my eyes. The 3pk has lots of things that I will never use. But the ergonomics, reliability, features I WILL use and precision of the 3pk is what sold me on it.


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