CoastieTX

I have a new Futaba R168DF receiver (http://www2.towerhobbies.com/cgi-bin...?&I=LXLSX4&P=V) that I am using on channel 51 with this crystal (http://www2.towerhobbies.com/cgi-bin...1P?&I=LXBFK851). This equipment is being used in my second plane and I am having terrible glitching/interference problems.

Originally, I bought this 7CAP PCM radio system (http://www2.towerhobbies.com/cgi-bin...1P?&I=LXGAF151) and the included receiver (R138DP) and servos have worked perfectly.

I have examined both crytals in both receivers and they are identical. They both appear to be undamaged and in good condition. Swapping crystals between the receivers results in the original R138DP receiver working correctly and the R168DF receiver displaying the same glitching/interference problems. 95% of the time, the R168DF functions normally but experiences quick, intermittent "hits" causing the servos and control surfaces to deflect and then return to neutral.

This problem persists at all times during the day, both inside my residence and outside. I do not think the problem is an isolated source of interference. Of course, when using the R168DF receiver, I ensure my transmitter is in PPM mode, as opposed to the PCM mode used with the R138DP receiver. There is nothing abnormal about the radio installation in the second plane which would account for the glitching - the receiver antenna cleanly exits the bottom of the fuselage and is routed to the tail. It is not wrapped around anything and the receiver displayed the problem even before final installation.

At this point, my problem shooting has led me to believe that either:
1. I am not using the correct crystal in the R168DF receiver
2. I have a faulty receiver

This is the first time I have purchased a separate airborne radio flight pack to be used with my original transmitter. Am I missing something obvious here or do I need to return my receiver?

Thanks.

Coastie

davewallace

My Feedback: (29)

CoastieTX,
Is anyone else in your area having trouble with CH 51? The R138DP will ignore interferrence, because it only responses to coded transmissions. The FM RX will respond to this interferrence. Chances are that either your RX is bad, or there is interference in the area. You should ground the plane, until you get an answer.

Dave

pilotpete2

Hi Coastie,
I really suspect that you have a bad receiver there, your troubleshooting seems to bear this out.
One thing I would check out is to make sure that the receiver is designated as "high band", as being on ch 51 is definitly towards the high end of the band, if it were a low band unit 11-35, it may not work well that high on the band and range would be reduced.
Keep us posted on your outcome, good luck,
Pete

CoastieTX

First, my apologies that the links in my original post don't work. I tried to fix them but no luck - funny, they worked fine before I submitted the post.

According to the specs, the R168DF receiver is a dual conversion receiver and accepts both high and low band crystals. This is from Tower's description of the product:

FEATURES: Strong interference free reception for all 4+ channel Futaba FM
systems
Narrow band spacing and dual conversion signal filtering
Accepts high or low band crystals
One year limited warranty


INCLUDES: 72MHz (ch 11-60) Futaba R168DF 8-Channel FM Receiver


REQUIRES: One 72MHz Receiver Crystal, (ch 11-35) FUTL57** Low Band,
OR (ch 36-60) FUTL58** High band

This leads me to believe I am using the correct equipment. davewallace, if you are correct, then this example is solid proof, at least in my eyes, that using a PCM receiver is worth the extra price.

pilotpete2

Hi Coastie,
Ouch, got egg on my face, your new receiver is one of the new Futaba line that breaks with the high/low band tradition.
I would try a replacement from Tower before I gave up on PPM receivers, if the interference in your area was that bad, I would expect to see fail safe engage on your PCM receiver.
Have you performed a range test? if so what were the results?, if the range test is not good, then you have a defective receiver, as your troubleshooting proved that the crystal is good.
Pete

mygs

hello! CoastieTX, I recent buy the same Receiver and I have exactly the same problem, I'm from Mexico and change the crystal too, and again the same problem in the field and my home, I prefer ground my plane and I will ask for help to towerhobbies.

airbusdrvr

Just a thought about an area you could examine. If you have a faulty servo or connection to the servo(servo extension), this can also cause what appears to be a glitch. Just a thought. I feel you pain as I am going through a similar scenario with one my Spektrum/JR setups. What a pain tracking down the problem.