Garmin Astro Modifications

[cwbullet]

I would like to see more modifications of the Garmin astro that people have made to make it fit in a rocket.

[cjl]

Well, aside from the removal from the collar, the DC-30 doesn't really need any mods if the rocket is 54mm or larger.

[JDcluster]

How long is it with Antenna?
I just bought one ( DC 30 package) through Amazon dot com with some gift certificates that I had. It brought the price down under $425. after S&H.



JD

[cjl]

I don't know exactly - something like 8 inches or so. I can measure it if you need a more exact value.

[Adrian A]

I've heard that it's possible to fit one in a 38mm rocket. Does anyone have details?

[cjl]

Looking at mine, you can't fit it in a 38mm without removing the case. It could well fit in a 38mm tube if you removed the case though. It seems like it's a definite possibility.

[mikec]

I've heard that it's possible to fit one in a 38mm rocket. Does anyone have details?

There was a pretty extensive article about this by Mike Konshak in a recent Sport Rocketry. Typically it involves removing the case and using a different method to connect the antenna (hardwire or right-angle SMA IIRC.) Or maybe that was a 54mm, I don't recall.

[Adrian A]

There was a pretty extensive article about this by Mike Konshak in a recent Sport Rocketry. Typically it involves removing the case and using a different method to connect the antenna (hardwire or right-angle SMA IIRC.) Or maybe that was a 54mm, I don't recall.

I know Mike and I'm pretty sure he put a DC20 into a 54mm.

[cjl]

I think that's right. The 30 is quite a bit smaller though, and I bet it would fit in 38mm. It would take up quite a bit of length though.

[new2hpr]

Mike's was a 54mm, but there is one in NCR with a stripped-down DC20 stuffed into a 38mm. Don't know him personally, though. Have to check the forums...

I've measured one. It will, with work, fit. I just need to get some hours on Solidworks to design a new case to fit. I'll try to keep it as rugged as the factory case.
-Ken

[mikec]

I went back and read Mike Konshak's article (it's in the Jul/Aug 09 Sport Rocketry) and there is a photo of a stripped DC20 board that fits in a 38mm nose cone (figure 8, page 10). He credits Rick McDonald as coming up with a way to solder the antenna onto the board.

[JDcluster]

I just received mine today!
I got the DC30 package, it should easily fit in a 54mm tube without much effort. It even comes in a plastic hard shell case for safe storage / transport.

One down side is: the menu system; it takes a bit to get use to it. It must have been tested where it was made because without any GPS lock it was showing my location somewhere in Taiwan. Does anyone know if you can use the USB interface to charge your batteries?


I just need to sit down & read up on it more before sticking it into a rocket.


JD

[Diosces]

Cool JD! Keep us updated.
I got mine today, but got the refurbed DC20/Astro 220 package. Was decently priced at $360 packaged new with 1 yr factory warranty.

First ride it goes in my Binder Design Devastator nosecone http://www.rocketryplanet.com/forums...ead.php?t=3666

I might also try in my 2.6" Dia carbon fiber Jaguar. Just bag it in nomex and hook it to the booster shockcord...hmm

[JJT]

How do you go about connecting it in the rocket, and do you leave the antenna in the original position or do you modify it

[JDcluster]

It will be pretty easy.
I already removed it from the dog collar.
Going to reuse the same screws to mount it to a piece of G10 & zip-tie the antenna to the G10 to keep it up right. There are 2 separate antennas one for GPS & the other is VHF for communicating with the 220 hand held unit.
I'll post some pics when I mount it.


Are they for real?
Magazine Back Issues, Sport Rocketry Magazine, Sport Rocketry July/August 2009:
A $6.00 magazine + $5.25 to ship it plus a $0.90 surcharge for not being an NAR member?
$12.15 total what a rip!


JD

[new2hpr]

You can get most of the info from Mike's article in his build threads on his website: www.telerover.com .

-Ken

[cwbullet]

What is the 90 degree adaptor he uses to connect and extend the antenna?

[new2hpr]

I think the connectors are SMA, but I'd have to check mine at home to be sure.

-Ken

[JDcluster]

If you buy the DC30 package, it has the 90 degree connector..
The orientation is different & the antenna comes out the side instead of on top of the battery pack housing.



JD

[JDcluster]

Here's what I did:
Not much as I was putting it in the nose cone that has a 2.78" coupler tube that a hair over 18" long. You can see the nose cone standing next to it on the floor.



JD

[Diosces]

Here's the set up I made for my 4" diameter Custom F/G Devastator which will be flying on some hardhitting motors at Red Glare 7, K1275, and L1060 or L1390G

Used an sma 90 deg male/female connector (radio shack) .125" G10 board i cut down with dremel and assorted machine screw hardware.
Note, the screw inserts for the DC30 are metric M3 . The end of the antenna will be secured to the mount via a tie wrap pulled thru two small holes in the epoxy board.

The 1/2 plywood nosecone ring I had needed to be coped to accomodate the Garmin RF antenna.

After these pix I went ahaead and put self adhering aluminum foil to block radio inteference to the Avionics bay. Also top coated the nosecone bulkhead with West Systems 105/207 laminating epoxy.

I also plan to use the Garmin DC20 in my 2.6 " carbon fiber Jaguar but will use a a slightly different set-up. Basically tuck the board in a nomex deployment bag-secure close with sewn snaps and attached to the drogue line. I dont use a drogue parachute, just separation at apogee.

[Buckeye]

Here's what I did:
Not much as I was putting it in the nose cone that has a 2.78" coupler tube that a hair over 18" long. You can see the nose cone standing next to it on the floor.
JD

JD:

Nice work. Do you think your layout can fit in a 38mm tube? The Garmin specs page says:

Unit dimensions, WxHxD: 1.4" x 1.17" x 3.3" (3.5 x 2.97 x 8.4 cm)

So, it might be close.

Thanks

[JDcluster]

I doubt it,
You can try this page for further modifications on the unit:

http://www.huffperformance.com/tech/...dogcollar.html

Not my page, but looks pretty straight forward.



JD

JD:

Nice work. Do you think your layout can fit in a 38mm tube? The Garmin specs page says:

Unit dimensions, WxHxD: 1.4" x 1.17" x 3.3" (3.5 x 2.97 x 8.4 cm)

So, it might be close.

Thanks

[BMRFlier]

Do you think there is any benefit to mounting the GPS antenna horizontally, the way it came oriented on the dog collar? Otherwise, I was planning to mount it vertically on the same sled as the rest of the unit and install it in the nose cone.

[n5wd]

Do you think there is any benefit to mounting the GPS antenna horizontally, the way it came oriented on the dog collar?

If you have a vertically polarized antenna on the transmit side (the rocket) and a horizontally polarized antenna on the receive side (the HT/GPS on the ground) you'll loose about 20db in path loss, which roughly cuts the signal down to 10% of where it began in signal strength.

Plan on keeping both of the antennas as vertical as you can.

[BobCox]

I think BMRFlier was asking about the GPS antenna orientation in the rocket, not in the handheld unit.

[cwbullet]

As far as functioning, the orientations only matters if you are using the treed readout. I do not. It still functions well.

[BMRFlier]

Sounds great! No use making the installation harder than it needs to be. The DC-30 is so much better than the DC-20 for ease of installation in 3 and 4 inch rockets - definitely worth the extra cost.