I'm pretty sure you can do this on any radio if you fancy a bit of DIY. I certainly did it on my 40
MHz F-14 Tx back in the day -it's still fine after 20 years...
I'm sure I got the idea from Model Boats or Marine Modelling mag. If you look at the back of your "stiks" inside the Tx case it's a small potentiometer of whatever value -I can't remember 4k7 or 10k etc. When you move the stick it may not go to full travel, but the mid-point is somewhere in the middle. All you really need to do is change the resistance of the pot to change the servo position. When I did mine I used a toggle switch and two adjustable pots, one adjusts + on the stick throw, and the other pot adjusts on the - of the stick throw. The switch makes it "dual rates" so off for normal and "on" for the adjusted throw.
If you go across the original stick pot in parallel with the new pot it will reduce the resistance. Reduced resistance is the same as moving the stick less etc. Sounds complicated but it's really very much the opposite and you can split an analogue channel into many, analogue pre-set positions on a servo, or using a sumple multi-switcher decoder using the same technique!
It works very well. Sub £5 of parts, mount it on a really simple double postage stamp sized bit of veroboard and hide it in the Tx case. You need to drill a hole for a toggle switch though. The only downside -and I seem to remember the original warnings is you need to adjust the pots quite finely because if you go too far out of balance, then it adjusts the neutral position when the stick is thrown. I never had much trouble, perhaps just one or detent on the trim to correct at most.
...Or these days just buy one of the £12-14 variants of the plug-in gizmos which plug inbetween the Rx and the servo. I think I got my last one from ebay. Think it's a Turnigy, but Component shop does the same (but a much, much bigger unit), and I think Model Radio Workshop do the same...
https://modelradioworkshop.co.uk/shop/servo-control-devices/servo-end-point-adjuster/...Has anyone ordered from the above company before? They have a few useful gadjets listed. I actually need an end point adjuster myself for a micro boat wih a 7.2v Ni-Mh pack, but the motor is only a 380 and I figure it will work well reducing the max motor speed using a 10A viper micro ESC.
Rich
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Topic: old 27 and 40 kHz radios end point adjustment (Read 2003 times)