darryl ramm’s blog

I’ve posted most of this in the past to some newsgroups, but people keep asking about the PDA mounts I have in my DG-303 so here we go.. after experimenting with different options I settled on the mounting arrangement shown in the photos above and I really like how they work.

I use HP iPAQ hx4700 PDAs, these are relatively high end PDAs that are no longer in production but may still be available, at least used ones. The hx4705 was the same PDA sold through different channels. The hx4700 have 4″ diagonal transflective VGA resolution (640×480 pixel) screens. I run SeeYou Mobile so the processor power of the hx4700 is useful but the PDAs are not perfect, more on that below. I have the 3600 mAh extended Li-ion battery packsinstaled that allow the PDAs to operate with a CF card GPS for something like 6-8 hours — providing a backup navigation system if everything else fails in the glider. Failing that I’ve got a compass and sectional charts and I’m not afraid to use them.

Although I’m using hx4700s many of the comments below will apply to all PDAs.

Almost all color PDAs use transflective displays, these do not work well in sunlight. The best thing to do is to get the PDA close to your face and pretty vertical looking straight at you. You don’t want to be looking down at a PDA angled partially up at the sky as it will reflect a lot of light back off the screen. I tried the PDAs with bare screens and with the Boxwave ClearTouch Anti-Glare screen protectors which do improve visibility in daylight a little. Make sure you get the ClearTouch Anti-Glare not ClearTouch Crystal screen protectors.

There are not a lot of good choices for mounts for hx4700 PDAs. The best I found were for ProClip USA (aka Brodit in Europe). Go to ProClip USA and enter 971621 in the search by item number text box. I had to make up a jig to route out a groove in the PDA mounts to fit the extended Li-ion battery packs. And since the mounts don’t have any positive lock to keep the PDA in place I rely on self adhesive Velcro tabs on the back of the mount and PDA and a piece of Velcro tape across these to hold the PDA in place. The mounts come with a swivel ball mounted on the back, which I removed and discarded.

I first tried mounting a hx4700 PDA on the right side canopy rail of my DG-303. I used the a RAM A size (9/16″ diameter ) swivel balls mounts attached to the camera mount holes on the canopy rail. There were screen reflection problems with the PDAs because they were angled slightly upwards. Even worse on really hot days the RAM swivel mounts failed because the thin rubber coating on the swivel balls separated from the ball - the weight of the heavy hx4700 and the (Nevada desert) heat was too much for them. After having the PDAs fall into my lap twice on flights this had to change! There was not enough space to use the larger B size (1″ diameter) RAM mounts. The PDA was also just a little too far away from my eyes and I did not have many options for moving the displays further towards me along the canopy he rails, as you need to clear the canopy release mechanisms. I could have tried to use long goosenecks mounted on the rails but I think what I ended up with is much better.

Instead of the canopy rails I attached long gooseneck to the instrument panel. This put the PDAs up closer to my face and in a vertical position. Since there was nowhere on the panel where I could easily attach a gooseneck so I had small metal custom mounts made that attach to the top inside corners of the glareshield over the canopy. The mounts curve to match the inner surface of the corner of the glare shield and bolt through the top and side of the glare shield. See details in the photos above.

I used the 9″ Gneck2 gooseneck with diamond mounting base from Cumulus Soaring. I screwed the diamond base on the back of the ProClip mount with counter sunk screws. The Gneck2 goosenecks mount through a hole in the front of the custom brackets using the nut supplied with the goosencks. The power/serial communications wire from the cradle is fed through the wiring notch in the diamond base, down the hollow middle of the goosdeneck and through a notch it the top of the fiberglass instrument panel. I fly with a Cambridge 302 vario/logger, and the two PDAs get 5V DC DC power and split serial data fom the Cambridge 302 via a Goddard SPS-1. The Cambridge 302 cannot deliver enough 5V DC power for two hx 4700 PDAs even if you did not want to split the serial output as well).

Cumulus Soaring also offers Nimbus PDA mounts that are modified ProClip/Brodit mounts that use shielded wires. While this might be a good idea to protection against VHF radio and transponder RF interference I’ve had no problem with the that in my system. But I put small ferrite filters onto both ends of rthe PDA cables. , I did not test this without the ferrite in place so I don’t know if it makes and difference. Running the PDA cabling through the middle of the gooseneck also help provide some shielding. I’m not sure if the shielded cable on the modified Nimbus mounts would fit down the middle of the Gneck2 gooseneck, I suspect not, but Paul at Cumulus Soaring should be able to easily answer that question.

I have had no problems with the Gneck2 goosenecks sagging even with the weight of the hx4700 and extended batteries. These goosenecks appear to be much better than other ones, especially the ones made by RAM. I push the two PDAs slightly to the center to get in and out of the glider and then move them so they don’t obstruct the instruments or view outside of the cockpit.

The custom brackets are held in place with small bolts through the top and side of the instrument panel glare shield. One of the photos below shows the custom brackets. Rex Mayes at Williams Soaring did a nice job of making the mounts. I wanted to make the bolts thought the instrument panel glare shield looks as nice as possible and looked around for black anodized screws and washers. The only thing I could find was black anodized aluminum countersunk washers, metric bolts and nylock nuts from www.hyperbolt.com in the UK. The anodizing on these is not particularly hard and will wear off with use.

The mounts need to be removed before removing the glare shield/panel cover to access behind the instrument panel. A better solution would be to have the mounts attached to the actual instrument panel. Probably the only way of doing that is to flock a captive nut in place on a little standoff, where the outer top screws instrument mounting screws go on the instrument panel. I’m not sure I know how you would avoid the mount being oriented at random angles when the gooseneck is screwed into the panel . This would have involved more dissasembly and work than we wanted to do for this installation.

One issue on warmer days, especially in full sunlight, the PDA will start having heat related problems, tpically hanging, crashing or the touch sensitive navigation pad stops working. To avoid this I use white terry towels draped over the PDAs, I’m meaning to have these sewn into loose covers.

Finally after some PDA reliability issues (mostly solved by being more careful about the PDAs getting hot) and some annoyances over support for Cambridge 302 features in SeeYou Mobile I wanted to install a Cambridge 303 display. There was no panel space to do this so I made a small custom aluminum bracket that bolts to one side of the right PDA mount and holds the 303 display. A friendly local anodizing shop black anodized it for me for free - well I brought their workers a box of donuts as payment. I put a small soft plastic stick-on bumper on the outside edge of the Cambridge 303 to stop it or the aluminum bracket from rubbing against the inside of the canopy. It normally is a few inches away from the canopy so this is not really an issue. The 303 mounting bracket has worked well.