regarding the db25 filter:
there were earlier issues with the digiflight series (no matter which screen in that case) where it would cause pitch excursions when transmitting on com1 for example. we're not flying yet, but had it happen when testing the autopilot on the ground.
source was traced to radio frequency interference coming through the main connector into the unit. someone else found out the trick with the db25 filter, then spread it on the net.
here's the one we're using:
https://www.distrelec.ch/ishopWebFro...ries/is/1.html
there are other sources for similar filters in the u.s.
they plug inline between the connector and the autopilot navhead. the problem went away instantly. according to lucas, when asked why they don't incorporate the fix internally, he mentioned it to be impossible for them to retrofit the filter function in the current hardware due to space/pcb constraints. and he claims the problem to appear too randomly to warrant supplying the filter with the autopilot. they aren't that expensive ($25 or so) compared to the autopilot but just another one of the 10000 unnecessary hassles in airplane building. first you need to detect a. that you have a problem, b. that you're not the only one, c. what the cause is, d. find a fix somewhere in the forums, e. find, f. order, g. pay, h. have it shipped, i. then wait and wonder wheter it will fix the problem...
service has been excellent by trutrak but me thinks, given the situation, they should supply these filters free of charge to whoever encounters the problem if not with every autopilot at delivery...
the fact that these filters were even required in the first part shows that there is an underlying EMI/RFI problem in the design.
so it didn't surprise me at all that somebody finds the dimmer(of the new screen) to cause erratic behaviour.
displays/backlights are common "noise generators" and put a new/different one internally into a device that's already critical in that regard and you might end up with a situation like this. wonder why they didn't catch that one during testing though...
i have high regards in trutrak and am sure they will provide a fix.
also it's important to know, that once you have tested the installation under all electrical configurations, ptt presses, dimmer settings etc... and found no problems the units should function just fine and reliably. this is due diligence, but should be a caution for anyone wanting to test it "out of the box" right away in the air. be careful, there might be nasty surprises.
the vsgv version and AFS version are technically identical except for different software loads and button labels as i understand. so these emi/rfi issues affect all in the same way.
rgds, bernie
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