[NSRCA-discussion] Spektrum DX7

[jonlowe at aol.com]

Ron,
Here is what I posted on RCU after using my Dad's DX7 over the holidays.

====================================================================

I've been working with my Dad's DX-7 all day, trying to get the Arresti 
III I gave him set up. I'd previously set this plane up with a 10x, so 
I can give a fair comparison.

Servos track more or less the same as with the 10x. If you use too much 
subtrim, they won't track, just like a 10x. The servo matching servo to 
servo is still the biggest variable. Minimize subtrims, and they track 
well, same as the 10x. Didn't have problems with latency with the 10x, 
this seems no better or worse. And, yes, I've seen horrible latency in 
other systems.

Several things the DX7 doesn't have that makes it not very friendly for 
pattern usage:

No variable trim rates. Easy to end up between trims, and the trim rate 
is very course.

No throttle curve. I've made a quasi curve using the suggestion Pizza 
came up with, but it doesn't substitute for a real curve. This is a 
biggie in my book.

No conditional mixes. I use a rudder to rudder mix to get a higher rate 
for stall turns switched with the throttle stick at low throttle. 
Doesn't appear possible on this.

No origin mixes.

No built in mix for knife edge. Uses two separate mixes to do it. The 
lack of origin mixing can affect these.

No multipoint mixes.

No split expo rates so you can get different rates for, say, up and 
down elevator.

No built in mix for two elevator servos. Only two mixes include a trim 
function, so you use one up to get this. Why EVERY computer radio 
doesn't include this is beyond me, given the number of two servo planes 
on the market.

No snap switches. I use them only for the avalanche, as I can get 
better timing this way.

Sticks were the softest I've seen, even when set full stiff. A set of 
HD springs helped. Sticks are smooth though.

Transmitter doesn't balance well at all on a lanyard, being very bottom 
heavy due to no antenna. We added a lanyard hook extension helping this 
a lot. This is a chronic problem with JR radios, and the lack of a long 
antenna just makes it worse.

This is a sport radio, and as long as you don't expect more from it, 
you will be ok. If you are used to a full function radio, especially 
one as easy to program as the 10x, you will get frustrated quickly.

Just my $.02.

=========================================================================
=

It works very well, solid link, no range issues.  My Dad has gone back 
and forth between this and his 10x; he flies with zero expo and pretty 
high rates all of the time, and the plane feels basically the same to 
him either way.  He is VERY sensitive to latency and responsiveness.  
Bottomline, other than eliminating frequency conflicts, I see no real 
reason to buy a DX7, and lots of reasons why it may not be suitable for 
a lot of pattern flyers.  I'm waiting for a module for my 10x or a high 
end radio from them.

Jon


-----Original Message-----
From: vanputte at cox.net
To: nsrca-discussion at lists.nsrca.org
Sent: Mon, 8 Jan 2007 2:23 PM
Subject: [NSRCA-discussion] Spektrum DX7

Has anyone "with credentials" made an evaluation of the Spektrum DX7
for precision aerobatics?   Please don't feel maligned if you're one
of many of us who might not be able to tell the difference.

I've heard from several accomplished helicopter pilots that the DX7
is superior to what they have been flying with.  They keep talking
about "feel".  What's the story on precision aerobatics?

I understand that the DX7s frame rate has been quoted by different
sources as being "more than a Futaba 14MZ" and, alternately, "less
than 1024".  I don't know who's right.  Frankly, I can't tell the
difference between 512 and 1024, but that's me.

Ron Van Putte


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