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-   -   Futaba 3PK - Crystals for PCM (https://www.rctech.net/forum/electric-road/39678-futaba-3pk-crystals-pcm.html)

RichO 05-02-2004 07:23 AM

Futaba 3PK - Crystals for PCM
 
I currently have an HRS receiver, and find it great indoors. I am having some really bad glitches outdoors and thinking about using the PCM receiver to see if that clears it up.

I looked onto the Futaba website and Tower Hobbies, and both mentioned that you need crystals FUTL52** versus FUTL64**for HRs.

What is the difference between these two crystals?

BTW: I am looking forward to the new synth stuff coming out for the 3PK... about time...

RichO 05-02-2004 07:49 PM

What? No one has ever done this?

vassago 05-03-2004 05:28 AM

PCM and HRS both utilize the FM band so the crystals are the same.
If you buy a PCM reciever on the same band (27, 35, 40 or 75mhz) you will be fine.

If you experience glitching with HRS, you will experience it with PCM. Your car wil be slower to respond to commands and such.
Try to solve the glitching, PCM is not a magical cure.

sedanaddict 05-03-2004 06:10 AM

pcm crystals
 
whether or not pcm will stop glitching depends on the source of the glitches. if it is from something wrong with your car or exposed wire or bad servo/ speedo, it won't make any difference. if it is from another radio "bleeding" on your freq. it might help. the crystals are the same. the modulation of the radio waves is different.

RichO 05-03-2004 06:14 AM

Yeah, this is just some analysis to see what my options are. I am remounting all of the electronics in the car this week to see if I can sort out the problem. Hopefully there will not be a need to go to PCM.

BTW: Not sure if its the car or something else... others experience similar issues but it only happens to certain cars. Two of us with XXX-s have had a similar issue.

vassago 05-03-2004 06:17 AM

Which car do you run?

Check for motor shunts connecting to a graphite chassis, use a plastic antenna holder instead of an aluminium one.
Check for frayed antenna wire, loose connectors, try a different servo and motor.

Does the radio glitch when it is far away or when it is close?

Sleighty 05-03-2004 07:26 AM

sorry to go a little off topic but i didnt really want to create a new topic for my question.

with the 3pk, do you have to run digital servos? or can you run standard servos e.g S3003? or doesnt it allow you to do that. If it does, what adjustments do you loose by running a lower spec servo?

thanks in advance

disaster999 05-03-2004 07:39 AM


Originally posted by Sleighty
sorry to go a little off topic but i didnt really want to create a new topic for my question.

with the 3pk, do you have to run digital servos? or can you run standard servos e.g S3003? or doesnt it allow you to do that. If it does, what adjustments do you loose by running a lower spec servo?

thanks in advance

if your running with HRS, you have to use digital servo. analog servos would just go up in flames. if your using PCM, you could use any servo.

vassago 05-03-2004 07:40 AM

With the HRS reciever you need a digital servo, with the PCM or other receiver you can use any servo you want.

MR JOLLY 05-03-2004 07:45 AM

i have a 3pk
you don`t need special x-tals, You can only use HRS mode on tranny with the HRS reciever, when you go to a normal reciever you tell the tranny to use pcm, I can use anybodys else`s car by telling my tranny to go to PCM then i can use novak,ko recievers, this is with ko & futaba X-TALS aswell. Even with using HRS mode on my car i can still use ko X-TALS with no bother indoors or out,
(but i would recommend the futaba x-tals) :)

RichO 05-03-2004 07:45 AM


Originally posted by vassago
Which car do you run?

Check for motor shunts connecting to a graphite chassis, use a plastic antenna holder instead of an aluminium one.
Check for frayed antenna wire, loose connectors, try a different servo and motor.

Does the radio glitch when it is far away or when it is close?

It happens both when its a moderate distance from the driver stand, as well on the far back straight. However, this isn't the biggest track in the country, so I don't think its a distance thing.

The car is a XXX-S.

I have gone to a different receiver, with the same consequences. I have changed the position of the ESC. The receiver wire did use to be close to the motor wire and chassis, but I have looped it over so its atleast 3-4 mm away from both. The receiver wire doesn't loop back on itself any more either. I have thought about adding some additional insulation on the wire, but have not done it yet. I have also thought about changing the antenna mount so that the wire goes into the tube and not up through the mount where it could come into contact with the chassis. The mount is the standard plastic one. The only frayed bit of the wire is at the very end, and that happened last weekend during a glitch crash.

MaxSpeed 05-03-2004 09:08 AM

RichO,

I drive for Futaba and had the same problem once. Changed motor, reciver, esc but still glitched. The problem, bad servo! Are you running a digital servo? If so, swap it out with a different one and try again. If a digital servo takes a hard hit, it can cause glitch city!! Just my two cents.

Oh yea, run your antenna wire directly through the antenna tube. That eliminates the wire touching anything. Good luck.

RichO 05-03-2004 09:13 AM

I am running a JR digital servo in the car at the moment. Also, the receiver has been recently mounted on top of the servo to move weight around in the car.

I will move to my backup servo and see if there are still any issues. I do notice that the digital servo twitches ever since I put in the HRS, does this happen with all of the digital servos or is it unique to this combination?

Any thoughts on how to stop it? It happens in both the Losi and my NTC3 with the same combination but two sets of receivers and servos.

RichO 05-03-2004 09:14 AM

BTW: This issue occurred long before the receiver was moved. I never have an issue on carpet, it seems to be strictly an asphalt thing.

MaxSpeed 05-03-2004 09:30 AM

Personally, I would not put the receiver on top of the servo, one less thing to cause interference. The combination of JR/Futaba should not be an issue. The only "movement" you should get with a digital servo is around center. Digital servos are always trying to "find center".

Double check your crystals. Make sure they are nice and snug. Outdoors they tend to bounce around a bit more. You may want to put a piece of tape over the crystal to make sure it doesn't work loose.


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