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Archive for March, 2013
Posted by 7oneWo1f | Mar 12, 2013 @ 06:19 PM | 33,543 Views
The hitec HPP-21 programmer is pretty neat. It allows one to program end points center for a servo. Programming the center of your servo helps when the splines don't provide the 90 degree servo arm orientation at center. You can do this with programmable radios with sub-trim, but doing so results in losing throw in the direction you subtrim.

Based on my measurements of my HPP-21, this is how it performs in test mode:

HPP21 pulse width range: 900, 1500, 2100 uS (left, center, right)
Accuracy: 0.2 uS
Resolution: 1.0 uS

This is pretty good in my view.

However, using my DX8, with 150% throws and no subtrim, the AR8000 provides this:

Pulse width range AR8000 with DX8 @ 150%: 919, 1504, 2090 uS (left, center, right)

Notice that the center pulse width is 15004 uS and not 1500 uS. This is probably due to temperature effects on the oscillator in the receiver as well as the accuracy of the receiver's oscillator. I've found that different receivers have different offsets, even when the transmitter has no trim or subtrim programmed.

This leads to problems when you take the time to program your radio. If you're using Spektrum (and probably other radio brands) you will find that the center pulse width is not 1500 uS.

solution to pulse width center deviation from 1500 uS


The solution to this is pretty simple.

If your servo is not reversed, add 3R sub-trim to the channel. If the servo is reversed, add 3L sub-trim to the channel....Continue Reading
Posted by 7oneWo1f | Mar 02, 2013 @ 10:33 PM | 32,861 Views
I own a Spektrum DX18 and a DX8.

For my style of flying (64" and under electric planes), the DX18 is way overkill.

But when I tried a DX18 in the store, I loved the sharp stick ends, and the feel of the radio, so I bought one anyway.

If you're a thumb flyer, instead of a pinch flyer, you will probably agree the DX18 has a great feel.

But recently, I came across some aftermarket transmitter stick ends, sold by Espirit Model, and I bought some.

I still use my DX8 for the flight simulator, and a few other planes, but the DX18 has really spoiled me, so I wanted the same feel for the DX8 I have on the DX18.

Anyway, the transmitter stick ends from Espirt Model are exactly what I was looking for. The tips are very sharp, and you don't need to worry about the sticks slipping even if you fly with light pressure, like I do.

Espirit Model is a great company, too. They really care about their reputation, and, consquently, treat their customers promptly, and are fair. They have many other transmitter products, such as trays and back harnesses, and I've used them as well.

So, if you like the feel of the DX18, but don't want to drop the kind of money it costs, for $5, you can get the same great feel. They also fit the DX6i, as well as hitec and futaba radios.

Transmitter Stick Ends V1 21mm DX6i/DX8/Hitec/Futaba M3

(Disclaimer: Like all of my reviews, this is an unrequested review, and I don't know the owners of Espirit Model, have not been compensated in anyway, and is simply my thanks for a quality product delivered with great customer service.)