MHM Transmitter Coordination - Northern Colorado Rocketry

This topic has 32 replies, 9 voices, and was last updated 17 years, 5 months ago by Adrian.

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April 11, 2008 at 5:31 am #47298
Warren B. Musselman
Moderator
Thanks – it might be a good idea to bring it along, but I think the club already has like a 2′ x 3′ whiteboard for the big launches.

W
April 11, 2008 at 2:13 pm #47299
new2hpr
Participant
I wonder if using shielded or twisted pair wiring would resolve some or all of the RF coupling issue? One problem I note with most altimeters is that except for the power supply negative terminal, there’s not much in the way of a ground to tie to. A common ground for things might also help.

Warren,
I can tell you that twisted pair didn’t help with the Rino (or it helped, but was not sufficient.) However, I could only get the MAWD to trip if the transmit antenna of the Rino was lying right next to the wiring (all in the 6″ length range). I would probably be OK with it in the ebay, on the opposite side of the sled, but moving it up to the nose would make things warm & fuzzy. It’s all a matter of your gambling threshold!

BTW, I suggested decoupling caps to Mike and he has tried it already with no benefit. He’s had EMI experience, so I expect he’s done his homework on this.

Anyone got a suggestion on how to do a removable bulkhead on a LOC plastic 4″ cone? I need roughly a 3″ dia. cavity for the Rino.

Ken
April 11, 2008 at 5:49 pm #47300
slipstick
Anyone got a suggestion on how to do a removable bulkhead on a LOC plastic 4″ cone? I need roughly a 3″ dia. cavity for the Rino.

Ken

Ken, I suggest cutting of the tail end up to the coupler diameter, then epoxying in a bulkhead to which you would mount a plate, like I did in my 5″ Slipstick III. If you bring the Nose cone over, I can cut you a 1/2″ thick plywood ring using a circle cutter on a drill press (or you can do it while I do other things). The circle cutter is fine with G10 as well if you have some. See this page of my website for a step by step process on cutting out the ring and attaching it to the nose cone.

http://telerover.com/rockets/L3-6.shtml
Here’s a couple thumbs:

The other option is to cutout a 3″ diameter hole concentric with the NC and insert a 3″ tube. PML did that on a 2.1″ payload prototype that they sent me to evaluate. I can help you cut that out (with a rotary tool).
April 11, 2008 at 5:54 pm #47301
slipstick
FYI: FRS and GMRS Frequency Chart

Larger size:http://telerover.com/rockets/GPS/Rhino_FRS_GMRS_Frequencies.jpg
April 17, 2008 at 12:13 am #47302
Ed Dawson
Mike,

Can you have multiple receivers tracking the same rocket transmitter at the same time? For example, could I track from the launch site and have someone else positioned a few miles downwind tracking the same rocket?

Or, is it strictly a one to one pairing of transmitter to receiver?

I bought into a system, but have not been able to test a 2:1 configuration for added margin.
April 25, 2008 at 6:38 pm #47303
mule
Participant
I need some input from the boss men.

I am going to let Scott use one of my Beelines in his little bird and need to know what frequency (70CM) you want me to tune it to.

FYI, I’m using a DC20 in my VA.

Greg
April 26, 2008 at 11:49 pm #47304
SCOTT EVANS
Greg wanted me to let everyone know, the 2 B-lines we will be using will be on 449.850 plus what ever the Dog collers are runnimg on.

Scotte
April 27, 2008 at 12:47 am #47305
Warren B. Musselman
Moderator
449.850 is definitely a non-interfering frequency for the Adept beacon transmitters – our main concern. The Adept’s are typically 433.750 at the center though they drift as low as 433.5 and as high as 433.9.

Warren
April 28, 2008 at 8:21 pm #47306
slipstick
Mike,

Can you have multiple receivers tracking the same rocket transmitter at the same time? For example, could I track from the launch site and have someone else positioned a few miles downwind tracking the same rocket?

Or, is it strictly a one to one pairing of transmitter to receiver?

I bought into a system, but have not been able to test a 2:1 configuration for added margin.

As far as I know,(last time I talked to Garmin) is that multiple handhelds can be used with the same rockets(dogs). The handheld has to’identify’ the DC20 first, however. We can try it at MHM. I’ve got three DC20’s now captured in my handheld (Greg Sctott’s “Hair-Of-TheDog”).
April 28, 2008 at 10:05 pm #47307
Warren B. Musselman
Moderator
I’ll have DC20 with me to test with the handhelds.

Warren
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