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Ematches
#1
What is the best source/brand for reliable ematches to use with onboard altimeters (marsa 54 for example) ??  There is a lot of info out there and it can be confusing. 
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#2
John,

I highly recommend JTek matches, Ken Allen should have some.

I highly discourage Quest Q2G2's.

--john
John Derimiggio
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#3
(04-15-2013, 09:05 AM)jderimig link Wrote: I highly discourage Quest Q2G2's.

Don't be shy, J.D., tell us how you really feel! ;D  Better yet - share with the class WHY you really feel this way.

Dale
Dale Stoyer - L3
NAR #91256
TRA #13499
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#4
I don't like Q2G2 with MARSA's that's all.

Now the technical reasons:

-Q2G2 design intent was igniters.
-Quest most likely prioritized cost over reliability and quality control (consistency) to their Chinese supplier.
-Because the consquence of an ignition failure is small (just walk out and stick another one in the bottom).
-There are no official published specs for all-fire and no-fire current ratings.
-The required procedure for specifying the above is a statistical test where those current values are 3sigma away from the mean.
-The lack of such ratings indicate there is no statistical quality control (which required) to publish such ratings.
-The construction is a bridgewire connected to a twisted pair.
-That construction is structurally weak as compared to a commercial ematch bridgewire chip.
- I am not comfortable with the low required fire current (needless and compromises safety).
- Leads are too short (but just right for Nat).
John Derimiggio
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#5
I do like my short leads.  My designs use external terminals on the AV bay bulkheads, thus the charge and the connection are close together.

This design vs ematch wire direct to altimeter is something that I expected discussion of in the best practices thread.

N
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#6
Jury is out on what is the best practice for wiring ematches.  I like using a terminal on the bulkhead but there is one less opportunity for failure by wiring directly to the altimeter (providing you maintain a seal).
John Derimiggio
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#7
My av bays are wired like Nat's.  I have short leads as I connect to external terminals.  I tried direct wiring to the altimeter but could never keep all the gases out.  For some rockets I needed long igniter lead and the JTek's are perfect.

As for igniters, I'm with JD.  JTek matches with the MARSA4 and MARSA54 as well as Perfectflite's work well, and have had I've no failures so far.  They are very reliable.
Jg
Jim Goggins NAR  L3
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#8
I like to connect my ematches directly to my altimeters, I do so by using parts from the CPR3000 system from PML or Public Missles; http://publicmissiles.com/frontpage.asp The parts you need are the charge holder:CPR3KCHAHOL and the charge cylinder: CPR3KCHACYLE They both go for $3.99 and I use two each for the top and bottom of my altimeter bays. I also have extras of the charge cylinders so I can pre-load them before I get to the field.
I just wanna fly ROCKETS!!

Dutch
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#9
(05-17-2013, 07:00 AM)Jim Goggins link Wrote: My av bays are wired like Nat's.  I have short leads as I connect to external terminals.  I tried direct wiring to the altimeter but could never keep all the gases out.  For some rockets I needed long igniter lead and the JTek's are perfect.

As for igniters, I'm with JD.  JTek matches with the MARSA4 and MARSA54 as well as Perfectflite's work well, and have had I've no failures so far.  They are very reliable.
Jg

I just (finally) had a chance to play with the JTeks, for ground testing my DD IROC that I will be flying again this weekend (this time painted!).
I calculated out the BP I would need, using the recommended range of 8 - 15 psi. I used 15, figuring I would rather have a little extra than not enough.
It kicked the payload out with quite a report. The second charge went off a few seconds later, although it was not as loud, as the payload section was now open.
I wired the matches to a terminal strip, and had sealed with epoxy the wiring where it come through the bulkead to the ebay electronics, so there was no entry point for any ejection gases in the electronic section.
Now it's time to be gathering what I need for my level 3 cert project..
Greg Young - L3
NAR #42065
TRA #00234
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