JSF-TC

My Feedback: (2)

Danny,

Based upon a number of posts here on RCU, I have installed a Revolution Whip antenna on my turbine Rafale, and also on my new gas powered Katana. The Rafale checked out OK and I have been flying that for a the last 6 months. I'm using a PCM10X for all my models.

Attempting to range test the Katana, before it's first flight, I could only get 50-60 paces engine off, without the antenna fitted and less than 30 paces engine running. In both cases, the PCM fail-safe did not kick in, but I started to get spurious control surface movements instead.

It's hard to describe, but I am running separate channels on each elevator half and each aileron, and as I increased the range, I would start to get different movements on each elevator half, and on the ailerons. They weren't following the commands smoothly.

We replaced the Rx with a 945 Dual Conversion RX and got 120+ paces engine off, so it's either the 649 Rx, or the Tx or Rx crystal. I have a spare 649 which I'll try next to isolate the Rx or crystals. However, it got me thinking about the antenna. I'll also try replacing the antenna of the suspect Rx and try it again, asuming the spare Rx cures the problem.

I just spoke with a tech at Horizon Hobby regarding the recommendation for fitting a whip antenna and was told NOT to fit a whip antenna, but to use the standard wire. Could this be a cause for the reduced range.

If I get better range with the standard wire compared to the whip, I'll recheck my turbine.

Your advice and recommendation is appreciated.


Thanks

Paul

JSF-TC

My Feedback: (2)

I carried out some engine off range tests last night. Please see the second post below for the details.

http://www.rcuniverse.com/forum/Revo...2090733/tm.htm

What really surprises me is the difference in range achieved between the 945 Dual Conversion Rx and the 649 Rx, over double the range of the 649. Is this usual?

Thanks

Paul

dsnyder

It is unusual to increase the range like that with the 945 over the 649, but not impossible. It is possible that one or the other may be better in some installations and areas than others. There are numerous factors including equipment used, equipment installation, noise in the area, etc that can cause one receiver to work better than another. The only way to find out which is better in your area and installtion is to test.

The whip antenna is also similar, in that in some installtions it may improve range, while in others not improve range. It all depends on the installation, proximity to extensions, leads, servos, batteries, ECU's, engines, etc. In jet models in particular whip antennas can provide a increase in range due to the complexity of the model, and the amount of electronic equipment on board. Prop driven aerobatic aircraft generally speaking however may not benifit from the whip antenna in the same mannor.

If your range increased with the 945 it is doubtful that the TX is suspect.

JSF-TC

My Feedback: (2)

Danny,

Thanks. I'll try an engine running test with the best 649 Rx and see what I get.

I always thought that with PCM, you either got a perfect response, or it went into failsafe, but what I'm seeing as I approach the point where it goes into failsafe (5 or so paces before the failsafe activates) is that the servo response starts to become erratic. I get the same general response with all 3 Rx.

It really looks like the master servo (Channel #2 for R aileron or Channel #3 for R elevator) responds correctly, but the slave channel (Channels 6 and 8) seem to be either delayed, or just not immediately following the master. I have full up elevator set for failsafe indication, plus hold on the ailerons. I get the impression that some channels may be jumping into and out of failsafe at different times and rates, thus giving the impression of erratic response. Is this what may be happening?

Thanks again for your help.

Paul

dsnyder

Yes, that is likely what is happening. It is going in and out of fail safe quickly showing up as erratic movement. This can at times affect one channel and not another.